The role of tissue damage in whiplash-associated disorders: discussion paper 1

Abnormal Static Sagittal Cervical Curvatures following Motor Vehicle Collisions: A Retrospective Case Series of 41 Patients before and after a Crash Exposure

Previous investigations have found a correlation between abnormal curvatures and a variety of patient complaints such as cervical pain and disability. However, no study has shown that loss of the cervical curve is a direct result of exposure to a motor vehicle collision (MVC). This investigation presents a retrospective consecutive case series of patients with both a pre-injury cervical lateral radiograph (CLR) and a post-injury CLR after exposure to an MVC. Computer analysis of digitized vertebral body corners on CLRs was performed to investigate the possible alterations in the geometric alignment of the sagittal cervical curve.

METHODS

Three spine clinic records were reviewed over a 2-year period, looking for patients where both an initial lateral cervical X-ray and an examination were performed prior to the patient being exposed to a MVC; afterwards, an additional exam and radiographic analysis were obtained. A total of 41 patients met the inclusion criteria. Examination records of pain intensity on numerical pain rating scores (NPRS) and neck disability index (NDI), if available, were analyzed. The CLRs were digitized and modeled in the sagittal plane using curve fitting and the least squares error approach. Radiographic variables included total cervical curve (ARA C2-C7), Chamberlain's line to horizontal (skull flexion), horizontal translation of C2 relative to C7, segmental translations (retrolisthesis and anterolisthesis), and circular modelling radii.

RESULTS

There were 15 males and 26 females with an age range of 8-65 years. Most participants were drivers (28) involved in rear-end impacts (30). The pre-injury NPRS was 2.7 while the post injury was 5.0; p < 0.001. The NDI was available on 24/41 (58.5%) patients and increased after the MVC from 15.7% to 32.8%, p < 0.001. An altered cervical curvature was identified following exposure to MVC, characterized by an increase in the mean radius of curvature (265.5 vs. 555.5, p < 0.001) and an approximate 8° reduction of lordosis from C2-C7; p < 0.001. The mid-cervical spine (C3-C5) showed the greatest curve reduction with an averaged localized mild kyphosis at these levels. Four participants (10%) developed segmental translations that were just below the threshold of instability, segmental translations < 3.5 mm.

CONCLUSIONS

The post-exposure MVC cervical curvature was characterized by an increase in radius of curvature, an approximate 8° reduction in C2-C7 lordosis, a mild kyphosis of the mid-cervical spine, and a slight increase in anterior translation of C2-C7 sagittal balance. The modelling result indicates that the post-MVC cervical sagittal alignment approximates a second-order buckling alignment, indicating a significant alteration in curve geometry. Future biomechanics experiments and clinical investigations are needed to confirm these findings.

A 13-Year Long-Term Follow-Up of a Case Report With Continued Improvement in Severe Chronic Neck and Head Pain Alleviated With Chiropractic BioPhysics® Spinal Rehabilitation Protocols

Alleviation of headaches (HAs), neck pain (NP), and disability is a desirable clinical outcome for the billions globally who suffer from these conditions. Chiropractic BioPhysics® (CBP®) methods may provide an option for head and neck-injured patients. A 62-year-old female historically injured multiple times including two motor vehicle collisions (MVC), and a strike to the face with a hockey puck; all resulting in chronic pain and suffering. The subject sought and received successful treatment in 2016 using this conservative protocol at a facility in the USA. The resolution of symptoms following 36 treatments was previously reported. Following 13 years without treatment beyond home exercises, the subject was re-evaluated and found to be stable in the long term for pain, structural and functional assessment. Thirty-six treatments over 12 weeks in 2016 led to an improvement in numerical pain rating scale (NPRS) for NP (5/10 to 1/10), and HA (9+/10 to 0/10), resolution of NP disability (6/100 to 0/100) as well as normalization of ROM without pain and resumption of all activities of daily living including high-level athletics without pain and disability. A 13-year follow-up found continued stability objectively and subjectively. We provide a case of successful conservative treatment using specific traction, exercises, and spine manipulation procedures. CBP® provides an option to treat pain and this case adds to growing evidence.

Biomechanical analysis of cervical spine (C2-C7) at different flexed postures

Musculoskeletal diseases are often related with postural changes in the neck region that can be caused by prolonged cervical flexion. This is one of the contributing factors. When determining the prevalence, causes, and related risks of neck discomfort, having a solid understanding of the biomechanics of the cervical spine (C1-C7) is absolutely necessary. The objective of this study is to make predictions regarding the intervertebral disc (IVD) stress values across C2-C7 IVD, the ligament stress, and the variation at 0°, 15°, 30°, 45°, and 60° of cervical neck angle using finite element analysis (FEA). In order to evaluate the mechanical properties of the cervical spine (particularly, C2-C7), this investigation makes use of computed tomography (CT) scans to develop a three-dimensional FEA model of the cervical spine. A preload of 50 N compression force was applied at the apex of the C2 vertebra, and all degrees of freedom below the C7 level were constrained. The primary objective of this investigation is to assess the distribution of von Mises stress within the IVDs and ligaments spanning C2-C7 at various flexion angles: 0°, 15°, 30°, 45°, and 60°, utilizing FEA. The outcomes derived from this analysis were subsequently compared to previously published experimental and FEA data to validate the model's ability to replicate the physiological motion of the cervical spine across different flexion angles.

Physical testing in patients with acute whiplash-associated disorders: A within session test-retest reliability study

BACKGROUND

People with whiplash-associated disorders (WAD) commonly present with a variety of physical impairments. However, the reliability of physical tests has not been established for patients with acute WAD.

OBJECTIVE

To assess test-retest reliability of different physical tests in acute WAD.

DESIGN

Intra-rater test-retest reliability.

METHODS

Patients with acute WAD were recruited. Physical tests were used to evaluate articular, muscular and neural systems in two blocks of measurements separated by 10 min. Bland-Altman plots were performed to assess intrarater agreement, which included calculation of the mean difference (d) between rates, the 95% CI for d, the standard deviation of the differences and the 95% limits of agreement. Reliability was calculated via the standard error of measurement, the minimal detectable change, percent of agreement, the intraclass-correlation coefficient, and kappa coefficient.

RESULTS

47 patients participated. Test-retest reliability was excellent or good for almost all measures, except for extension ROM, ULTT for the radial nerve, and active cervical extension and upper cervical rotation performed in 4-point kneeling, which presented moderate reliability. Systematic bias was found in cervical ROM in flexion, left and right lateral-flexion, left and right rotation; left ULTT for radial nerve; right trapezius, suboccipitalis and temporalis muscles, left temporalis; C3, both sides of C1-C2, left C3-C4.

CONCLUSION

The majority of physical tests achieved good or excellent test-retest intra-rater reliability when tested in patients with acute WAD. Findings must be considered with caution for those tests which demonstrated systematic bias. Additional research is warranted to evaluate inter-rater reliability.

Five to ten-year prognosis of whiplash injury-related chronic neck pain: A brief report

BACKGROUND

Whiplash injury-related neck pain frequently hinders daily life activities, resulting in poor quality of life. Recovery time is prolonged in many patients. Long-term outcomes of refractory whiplash injury-related neck pain remain poorly understood.

OBJECTIVE

This study aimed to evaluate the long-term prognosis of chronic whiplash injury-related neck pain.

METHODS

We evaluated the prognosis of 38 patients with whiplash injury-induced neck pain via phone interviews. We investigated the data on current presence and degree of neck pain, current pain medication, physical modality or injection procedures, and difficulty performing daily life activities or occupational duties.

RESULTS

At least 5 years after the whiplash injury, 34 patients (89.5%) experienced whiplash injury-related neck pain. The average numeric rating scale (NRS) score on the initial visit to our spine center was 5.3 ± 1.7 and that at the follow-up interview was 4.3 ± 2.6. Twenty-six (68.4%) patients had pain scores ⩾ 3 on the NRS. Additionally, 26 (68.4%) patients were receiving at least one of the following pain-management treatments: oral pain medications, physical modality, and injection procedures. Twenty-eight (73.7%) patients encountered difficulty performing daily life activities and occupational duties.

CONCLUSIONS

The long-term prognosis of patients with whiplash injury-related neck pain was found to be poor.

A clinical test to assess isometric cervical strength in chronic whiplash associated disorder (WAD): a reliability study

Background

Cervical spine muscle weakness is well demonstrated in individuals with chronic neck pain. There is a lack of literature evaluating clinically applicable means of assessing isometric cervical strength in chronic whiplash associated disorder (WAD). This study assessed the reliability of self-resisted isometric cervical strength testing using a handheld dynamometer. The relationship between strength and neck pain-related disability and kinesiophobia was also investigated.

Methods

Twenty subjects with chronic WAD performed maximum-effort isometric cervical flexion, extension, side flexion, and rotation against a hand held dynamometer. The dynamometer was held by the subject, who provided self-resistance. Subjects completed two sessions of testing on one day with two different examiners, and one session on a subsequent day with one of the original examiners. Subjects completed the Neck Disability Index (NDI) and Tampa Scale for Kinesiophobia (TSK) prior to the first testing session.

Results

Intraclass correlation coefficients (ICC) for directional strength measures were fair to high (0.71–0.88 for intra-rater and 0.79–0.91 for inter-rater). Total strength (sum of all directional strengths) ICCs were high for both intra-rater (ICC = 0.91) and inter-rater (ICC = 0.94) measures. All statistical tests for ICCs demonstrated significance (α < 0.05). Agreement was assessed using Bland Altman (BA) analysis with 95% limits of agreement. BA analysis demonstrated difference scores between the two testing sessions that ranged from 3.0—17.3% and 4.5—28.5% of the mean score for intra and inter-rater measures, respectively. Most measures did not meet the a priori standard for agreement. A moderate to good inverse relationship was demonstrated between kinesiophobia (TSK score) and six out of seven strength measures (α < .05). No significant correlation was found between neck disability (NDI) and cervical strength in any direction.

Conclusion

This study demonstrated fair to high reliability of self resisted isometric cervical strength testing in the chronic WAD population. All directional strength measures except flexion demonstrated a significant inverse relationship with kinesiophobia. No cervical strength measures were correlated with neck disability. These results support testing cervical strength in this manner to reliably assess change over time within individual patients. The value of such measurement requires further consideration given the lack of correlation between cervical strength and disability. Further research is required to establish normative values and enhance clinical utility.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-022-05703-0.

Nerve pathology and neuropathic pain after whiplash injury: a systematic review and meta-analysis

ABSTRACT

There is no clear understanding of the mechanisms causing persistent pain in patients with whiplash-associated disorder (WAD). The aim of this systematic review was to assess the evidence for nerve pathology and neuropathic pain in patients with WAD. EMBASE, PubMed, CINAHL (EBSCO), and MEDLINE were searched from inception to September 1, 2020. Study quality and risk of bias were assessed using the Newcastle-Ottawa Quality Assessment Scales. Fifty-four studies reporting on 390,644 patients and 918 controls were included. Clinical questionnaires suggested symptoms of predominant neuropathic characteristic in 34% of patients (range 25%-75%). The mean prevalence of nerve pathology detected with neurological examination was 13% (0%-100%) and 32% (10%-100%) with electrodiagnostic testing. Patients independent of WAD severity (Quebec Task Force grades I-IV) demonstrated significantly impaired sensory detection thresholds of the index finger compared with controls, including mechanical (SMD 0.65 [0.30; 1.00] P < 0.005), current (SMD 0.82 [0.25; 1.39] P = 0.0165), cold (SMD -0.43 [-0.73; -0.13] P = 0.0204), and warm detection (SMD 0.84 [0.25; 1.42] P = 0.0200). Patients with WAD had significantly heightened nerve mechanosensitivity compared with controls on median nerve pressure pain thresholds (SMD -1.10 [-1.50; -0.70], P < 0.0001) and neurodynamic tests (SMD 1.68 [0.92; 2.44], P = 0.0004). Similar sensory dysfunction and nerve mechanosensitivity was seen in WAD grade II, which contradicts its traditional definition of absent nerve involvement. Our findings strongly suggest a subset of patients with WAD demonstrate signs of peripheral nerve pathology and neuropathic pain. Although there was heterogeneity among some studies, typical WAD classifications may need to be reconsidered and include detailed clinical assessments for nerve integrity.

Cervical facet joint platelet-rich plasma in people with chronic whiplash-associated disorders: A prospective case series of short-term outcomes

Objective

To explore the safety and feasibility of a single autologous injection of platelet-rich plasma (PRP) in cervical facet joints of people with chronic WAD and facet-mediated pain, and explore the association between pain relief reported with diagnostic medial branch blocks (MBBs) and 3-months post-PRP.

Design

A prospective case series of people with chronic whiplash-associated disorders and cervical facet joint mediated pain in a community setting.

Interventions

A single autologous PRP injection was provided to cervical facet joints under ultrasound and fluoroscopic guidance.

Measures

Adverse events were recorded one-week, and measures of pain (numerical pain rating scale - NPRS) and disability (Neck Disability Index - NDI) were collected prior to and 3-months following cervical facet joint PRP. People not reached for follow-up were considered failures for worst-case analysis. The correlation between percentage response to diagnostic cervical medial branch blocks (MBBs) and percentage pain relief reported at 3-months was also investigated.

Results

Forty-four people (82% female; mean age (SD): 45.2 (10.8) years) underwent cervical facet joint PRP. There was a significant improvement in pain and disability following PRP. Seventy percent of people exceeded MCID for pain. For NDI scores, 80% of people exceeded MCID. Forty-one percent of people reported greater than 50% relief of pain 3-months post-cervical facet joint PRP.There was no significant correlation between percentage relief of pain with cervical MBBs and percentage relief of pain 3-months post-PRP (r ​= ​0.06, p ​= ​0.73).There were no adverse events reported.

Conclusion

In people with chronic WAD and facet-mediated pain, preliminary data suggests that PRP is safe and it is feasible to move forwards with randomized studies to further investigate efficacy and effectiveness.

The effect of prolonged experimental neck pain on exercise-induced hypoalgesia

ABSTRACT

Neck pain is a common musculoskeletal problem often accompanied by reduced exercise-induced hypoalgesia (EIH) or hyperalgesia compared to an asymptomatic population. This study investigated EIH in a healthy population during experimental neck pain. Forty participants were randomized into this double-blinded parallel-group study. On four separate test days (Day0, Day2, Day4, Day15), participants completed the Neck Disability Index (NDI) and scored neck pain intensity during head movements on a numerical rating scale (NRS). At the end of Day0 and Day2, Nerve Growth Factor (NGF) or isotonic saline (control) was injected into the right splenius capitis muscle. Pressure pain thresholds (PPTs) were recorded bilaterally over splenius capitis (neck), temporalis (head) and tibialis anterior (leg) muscles on all days. On Day0, Day4 and Day15, PPTs were recorded before and after a hand-bike exercise. EIH was defined as the PPT increase caused by the exercise. Compared with the control-group, the NGF-group demonstrated higher NDI scores at Day2 and Day4 (P<0.001,η2>0.557) and higher NRS scores (P<0.03,η2>0.09) along with reduced neck PPTs (P<0.01,d>0.44) at Day2(Right:95%CI[26.0,54.0];Left:95%CI[6.8,26.9]), Day4(Right:95%CI[40.5, 67.9];Left:95%CI[6.9,28.2]) and Day15(Right:95%CI[5.6,37.2];Left:95%CI[6.9,34.8]). Across days, the EIH-effect was reduced at the neck site in the NGF-group compared to the control-group (P<0.001,η2P=0.367,95%CI[-34.5,-13.7]). At the head and leg sites, the NGF-group showed reduced EIH-effect compared to the control-group (P<0.05,d>0.43) on Day4(Head:95%CI[-61.4,-22.9];Leg:95%CI[-154.7,-72.4]) and Day15(Head:95%CI[-54.3,-7.6];Leg:95%CI[-122.7,-34.4]). These results indicate that a few days of clinically comparable neck pain and hyperalgesia might have a negative impact on EIH-responses and may help explain why some neck pain patients do not experience immediate positive effects of exercise.

Whiplash injuries associated with experienced pain and disability can be visualized with [11C]-D-deprenyl positron emission tomography and computed tomography

ABSTRACT

Knowledge of etiological mechanisms underlying whiplash-associated disorders is incomplete. Localisation and quantification of peripheral musculoskeletal injury and inflammation in whiplash-associated disorders would facilitate diagnosis, strengthen patients' subjective pain reports, and aid clinical decisions, all of which could lead to improved treatment. In this longitudinal observational study, we evaluated combined [11C]-D-deprenyl positron emission tomography and computed tomography after acute whiplash injury and at 6-month follow-up. Sixteen adult patients (mean age 33 years) with whiplash injury grade II were recruited at the emergency department. [11C]-D-deprenyl positron emission tomography and computed tomography, subjective pain levels, self-rated neck disability, and active cervical range of motion were recorded within 7 days after injury and again at 6-month follow-up. Imaging results showed possible tissue injuries after acute whiplash with an altered [11C]-D-deprenyl uptake in the cervical bone structures and facet joints, associated with subjective pain locale and levels, as well as self-rated disability. At follow-up, some patients had recovered and some showed persistent symptoms and reductions in [11C]-D-deprenyl uptake correlated to reductions in pain levels. These findings help identify affected peripheral structures in whiplash injury and strengthen the idea that positron emission tomography and computed tomography detectable organic lesions in peripheral tissue are relevant for the development of persistent pain and disability in whiplash injury.

Cranio-Mandibular Disorders after Whiplash Injury: A Mono-Institutional Clinical Study on 31 Patients

BACKGROUND

Whiplash is a consequence of traumatic injuries, mostly related to road accidents, with variable clinical manifestations, also known as Whiplash Associated Disorders, such as neck, head and temporo-cranio-mandibular pain.

METHODS

The current study aims to evaluate the onset and evolution of temporomandibular joint pain in people with whiplash in a study group treated with the use of Zimmer Collars (adjustable rigid cervical collars for neck immobilization), as compared to a control group. This prospective study included 31 patients followed by the Dental Prosthesis Department of the University of Bari "Aldo Moro": 20 patients with whiplash (age range: 20-39 years) treated with Zimmer collars and 11 patients with whiplash (age range: 20-33 years) who were not. Immediately after the whiplash occurred, a visual analogue scale (VAS) was used to describe the intensity of pain and to complete the chart of the European Academy of Craniomandibular Disorders. Five out of twenty patients, already treated with a Zimmer collar, wore an occlusal splint as well because of persistent pain reported at the 28-day and 60-day follow-up and were supported by pharmacological therapy with analgesics (paracetamol) and muscle relaxants (thiocolchicoside).

RESULTS

During the last follow-up (at six months), three out of five patients displayed a residual VAS score of 3, 4, and 5, respectively, while the remaining two displayed a VAS of 0. In the control group, four out of eleven patients needed to wear an occlusal splint but without muscle relaxants and analgesics pharmacological therapy; these four corresponded to the patients showing a residual painful symptomatology, with VAS reaching value of 2, and also were the oldest patients of the group. Data regarding VAS values and Zimmer collar use, both at the first visit and six months later, were statistically analyzed.

CONCLUSION

Our prospective study highlights how whiplash-associated acute disorders are often self-limiting over a period of few months, thus reducing the possibility of symptom chronicity; the latter seems to be strictly related to lesion severity, pre-existence of a craniomandibular dysfunction and patient age, but appears to be independent from Zimmer collar use, as statistically confirmed.

Advanced magnetic resonance imaging of chronic whiplash patients: a clinical practice-based feasibility study

BACKGROUND

Whiplash injury is common following road traffic crashes affecting millions worldwide, with up to 50% of the injured developing chronic symptoms and 15% having a reduced working capability due to ongoing disability. Many of these patients receive treatment in primary care settings based upon clinical and diagnostic imaging findings. Despite the identification of different types of injuries in the whiplash patients, clinically significant relationships between injuries and chronic symptoms remains to be fully established. This study investigated the feasibility of magnetic resonance imaging (MRI) techniques including quantitative diffusion weighted imaging and measurements of cerebrospinal fluid (CSF) flow as novel non-invasive biomarkers in a population of healthy volunteers and chronic whiplash patients recruited from a chiropractic clinic for the purpose of improving our understanding of whiplash injury.

METHODS

Twenty chronic whiplash patients and 18 healthy age- and gender matched control subjects were included [mean age ± SD (sex ratio; females/males), case group: 37.8 years ± 9.1 (1.22), control group: 35.1 years ± 9.2 (1.25)]. Data was collected from May 2019 to July 2020. Data from questionnaires pertaining to the car crash, acute and current symptoms were retrieved and findings from clinical examination and MRI including morphologic, diffusion weighted and phase-contrast images were recorded. The apparent diffusion coefficient and fractional anisotropy were calculated, and measurement and analysis of CSF flow was conducted. Statistical analyses included Fisher's exact test, Mann Whitney U test and analysis of variance between groups.

RESULTS

The studied population was described in detail using readily available clinical tools. No statistically significant differences were found between the groups on MRI.

CONCLUSIONS

This study did not show that MRI-based measures of morphology, spinal cord and nerve root diffusion or cerebrospinal fluid flow are sensitive biomarkers to distinguish between chronic whiplash patients and healthy controls. The detailed description of the chronic whiplash patients using readily available clinical tools may be of great relevance to the clinician. In the context of feasibility, clinical practice-based advanced imaging studies with a technical setup similar to the presented can be expected to have a high likelihood of successful completion.

Sex, Age and Stature Affects Neck Biomechanical Responses in Frontal and Rear Impacts Assessed Using Finite Element Head and Neck Models

The increased incidence of injury demonstrated in epidemiological data for the elderly population, and females compared to males, has not been fully understood in the context of the biomechanical response to impact. A contributing factor to these differences in injury risk could be the variation in geometry between young and aged persons and between males and females. In this study, a new methodology, coupling a CAD and a repositioning software, was developed to reposture an existing Finite element neck while retaining a high level of mesh quality. A 5th percentile female aged neck model (F05_75YO) and a 50th percentile male aged neck model (M50_75YO) were developed from existing young (F05_26YO and M50_26YO) neck models (Global Human Body Models Consortium v5.1). The aged neck models included an increased cervical lordosis and an increase in the facet joint angles, as reported in the literature. The young and the aged models were simulated in frontal (2, 8, and 15 g) and rear (3, 7, and 10 g) impacts. The responses were compared using head and relative facet joint kinematics, and nominal intervertebral disc shear strain. In general, the aged models predicted higher tissue deformations, although the head kinematics were similar for all models. In the frontal impact, only the M50_75YO model predicted hard tissue failure, attributed to the combined effect of the more anteriorly located head with age, when compared to the M50_26YO, and greater neck length relative to the female models. In the rear impacts, the F05_75YO model predicted higher relative facet joint shear compared to the F05_26YO, and higher relative facet joint rotation and nominal intervertebral disc strain compared to the M50_75YO. When comparing the male models, the relative facet joint kinematics predicted by the M50_26YO and M50_75YO were similar. The contrast in response between the male and female models in the rear impacts was attributed to the higher lordosis and facet angle in females compared to males. Epidemiological data reported that females were more likely to sustain Whiplash Associated Disorders in rear impacts compared to males, and that injury risk increases with age, in agreement with the findings in the present study. This study demonstrated that, although the increased lordosis and facet angle did not affect the head kinematics, changes at the tissue level were considerable (e.g., 26% higher relative facet shear in the female neck compared to the male, for rear impact) and relatable to the epidemiology. Future work will investigate tissue damage and failure through the incorporation of aged material properties and muscle activation.

Soft-collar use in rehabilitation of whiplash-associated disorders - A systematic review and meta-analysis

BACKGROUND

Active rehabilitation of Whiplash Associated Disorders (WAD) is favoured over passive modalities such as soft-collars. However, the effectiveness of soft-collar use remains unclear.

OBJECTIVE

To investigate the effectiveness of soft-collar use on pain and disability in WAD.

DESIGN

Systematic review.

METHOD

Databases (AMED, CINAHL Complete, Cochrane Library, Embase, Medline, PEDro, PsycINFO, PubMed, SPORTDiscus) were searched for guidelines, reviews and RCTs on soft-collar use as part of WAD treatment. Reference lists of reviews and guidelines were screened for additional RCTs. Study quality was rated using the PEDro-scale and overall quality of evidence with GRADE.

RESULTS

Four RCTs (n = 409) of fair-good quality (PEDro-scores) were included with three using a soft collar in addition to other conservative treatment while one study compared soft-collar use to act-as-usual. All studies found that an active or act-as-usual approach was more effective in reducing pain intensity compared to soft-collar use, confirmed by meta-analysis (two RCTs with data: SMD of -0.80 (-1.20, -0.41)). No studies reported disability outcomes while contrasting results were found between groups regarding total cervical range of motion (two RCTs with data: SMD of 0.16 (-0.21, 0.54)) or rotation (two RCTs with data: SMD of 0.54 (-0.19, 1.27)). Overall quality of the evidence was low to very low.

CONCLUSION

All four RCTs favoured an active approach/act-as-usual over soft-collar treatment. However, due to methodological concerns and low certainty of evidence, future studies investigating soft collar use in combination with an active rehabilitation strategy for acute/subacute WAD are needed.

Changes in Pain Sensitivity and Conditioned Pain Modulation During Recovery From Whiplash-associated Disorders

OBJECTIVE

The objective of this study was to investigate the pain-sensory profile of patients with whiplash-associated disorders (WADs) prior and post 2 weeks of standardized rehabilitation and after a 6-month follow-up.

MATERIALS AND METHODS

Twenty-two WAD participants (grade II; 14 women) and 22 sex-matched and age-matched healthy pain-free controls were enrolled. Pressure pain thresholds (PPTs) were assessed at local and distal muscles. Conditioned pain modulation (CPM) of PPTs was assessed using cuff pressure around the upper arm. Referred area of pain following supra-threshold pressure stimulation of the infraspinatus muscle was recorded on a body chart. Psychometric variables (pain intensity, area of perceived pain, pain catastrophizing, kinesiophobia, sleep problems, and depression level) were assessed. WAD group additionally completed the Neck Disability Index.

RESULTS

The WAD group demonstrated lower local PPTs compared with controls at all time points (P<0.05) and lower distal PPTs at baseline and at 2 weeks when compared with 6 months (within-group) (P<0.05). The WAD group had a reduced CPM response and larger induced referred pain areas compared with controls (P<0.05), while no within-group changes were observed at any time point. The WAD group reported higher pain intensity and perceived area of pain compared with controls at all time points (P<0.05) and a mean Neck Disability Index score of 41% at baseline, 16% at 2 weeks, and 4% at 6 months. Furthermore, the WAD group reported improvements in all other psychometric variables (P<0.05), although only pain catastrophizing levels were comparable to controls at 2 weeks.

DISCUSSION

PPTs but not CPM improved in the WAD group and were comparable to controls following 2 weeks following standardized rehabilitation, indicating that normalization of CPM may not be required to recover from WAD.

Importance of the cervical capsular joint cartilage geometry on head and facet joint kinematics assessed in a Finite element neck model

Finite element human neck models (NMs) aim to predict neck response and injury at the tissue level; however, contemporary models are most often assessed using global response such as head kinematics. Additionally, many NMs are developed from subject-specific imaging with limited soft tissue resolution in small structures such as the facet joints in the neck. Such details may be critical to enable NMs to predict tissue-level response. In the present study, the capsular joint cartilage (CJC) geometry in a contemporary NM was enhanced (M50-CJC) based on literature data. The M50-CJC was validated at the segment and full neck levels and assessed using relative facet joint kinematics (FJK), capsular ligament (CL) and intervertebral disc (IVD) strains, a relative vertebral rotation assessment (IV-NIC) and head kinematics in frontal and rear impact. The validation ratings at the segment level increased from 0.60 to 0.64, with improvements for modes of deformation associated with the facet joints, while no difference was noted at the head kinematic level. The improved CJC led to increased FJK rotation (188%) and IVD strain (152.2%,) attributed to the reduced facet joint gap. Further enhancements of the capsular joint representation or a link between the FJK and CL injury risk are recommended. Enhancements at the tissue level demonstrated a large effect on the IVD strain, but were not apparent in global metrics such as head kinematics. This study demonstrated that a biofidelic and detailed geometrical representation of the CJC contributes significantly to the predicted joint response, which is critical to investigate neck injury risk at the tissue level.

Changes in Muscle Morphology in Female Chronic Neck Pain Patients Using Magnetic Resonance Imaging

STUDY DESIGN

Population-based cross-sectional study.

OBJECTIVE

The aim of this study was to gain a better understanding of changes in muscle morphology in patients with chronic idiopathic neck pain (CINP) and chronic whiplash-associated disorder (CWAD).

SUMMARY OF BACKGROUND DATA

Worldwide, neck pain (NP) is a common health problem with high socioeconomic burden. A high percentage of these patients evolves toward chronic symptoms. Efficacy of treatments for these complaints remains variable. In current literature, changes in muscle morphology (muscle fat infiltration and cross-sectional area) have been reported in patients with NP, both CWAD and CINP. However, no strong conclusions could be made.

METHODS

In this study, magnetic resonance imaging was used to obtain data on muscle morphology from 14 cervical flexor and extensor muscles in 117 female subjects with NP (CWAD = 37; CINP = 45) and healthy controls (HC = 35).

RESULTS

The CWAD group had a significantly larger muscle fat infiltration in some extensor (semispinalis and splenius capitis, trapezius, obliquus capitis inferior) and flexor (sternocleidomastoid) muscles compared to the CINP and/or HC group. A significantly larger (muscle) cross-sectional area was found in some extensor (levator scapulae, semispinalis capitis, trapezius) and flexor (longus colli, longus capitis, sternocleidomastoid) muscles in the HC group compared to the CINP and/or CWAD group. No clear associations were found between group differences and factors as pain duration, kinesiophobia, and disability.

CONCLUSION

The results in this study suggest changes in muscle morphology in both NP cohorts. These results show some similarities with earlier findings in this research domain. Further studies based on controlled longitudinal designs are needed to facilitate data compilation, to draw stronger conclusions, and to integrate them into the treatment of patients with chronic NP.Level of Evidence: 4.

MRI-Based Assessment of Masticatory Muscle Changes in TMD Patients after Whiplash Injury

Objective: to investigate the change in volume and signal in the masticatory muscles and temporomandibular joint (TMJ) of patients with temporomandibular disorder (TMD) after whiplash injury, based on magnetic resonance imaging (MRI), and to correlate them with other clinical parameters. Methods: ninety patients (64 women, 26 men; mean age: 39.36 ± 15.40 years), including 45 patients with symptoms of TMD after whiplash injury (wTMD), and 45 age- and sex-matched controls with TMD due to idiopathic causes (iTMD) were included. TMD was diagnosed using the study diagnostic criteria for TMD Axis I, and MRI findings of the TMJ and masticatory muscles were investigated. To evaluate the severity of TMD pain and muscle tenderness, we used a visual analog scale (VAS), palpation index (PI), and neck PI. Results: TMD indexes, including VAS, PI, and neck PI were significantly higher in the wTMD group. In the wTMD group, muscle tenderness was highest in the masseter muscle (71.1%), and muscle tenderness in the temporalis (60.0%), lateral pterygoid muscle (LPM) (22.2%), and medial pterygoid muscle (15.6%) was significantly more frequent than that in the iTMD group (all p < 0.05). The most noticeable structural changes in the masticatory muscles occurred in the LPM with whiplash injury. Volume (57.8% vs. 17.8%) and signal changes (42.2% vs. 15.6%) of LPM were significantly more frequent in the wTMD group than in the iTMD group. The presence of signal changes in the LPM was positively correlated with the increased VAS scores only in the wTMD group (r = 0.346, p = 0.020). The prevalence of anterior disc displacement without reduction (ADDWoR) (53.3% vs. 28.9%) and disc deformity (57.8% vs. 40.0%) were significantly higher in the wTMD group (p < 0.05). The presence of headache, sleep problems, and psychological distress was significantly higher in the wTMD group than in the iTMD group. Conclusion: abnormal MRI findings and their correlations with clinical characteristics of the wTMD group were different from those of the iTMD group. The underlying pathophysiology may differ depending on the cause of TMD, raising the need for a treatment strategy accordingly.

Medial Branch Blocks for Diagnosis of Facet Joint Pain Etiology and Use in Chronic Pain Litigation

A commonly disputed medicolegal issue is the documentation of the location, degree, and anatomical source of an injured plaintiff’s ongoing pain, particularly when the painful region is in or near the spine, and when the symptoms have arisen as result of a relatively low speed traffic crash. The purpose of our paper is to provide health and legal practitioners with strategies to identify the source of cervical pain and to aid triers of fact (decision makers) in reaching better informed conclusions. We review the medical evidence for the applications and reliability of cervical medial branch nerve blocks as an indication of painful spinal facets. We also present legal precedents for the legal admissibility of the results of such diagnostic testing as evidence of chronic spine pain after a traffic crash. Part of the reason for the dispute is the subjective nature of pain, and the fact that medical documentation of pain complaints relies primarily on the history given by the patient. A condition that can be documented objectively is chronic cervical spine facet joint pain, as demonstrated by medial branch block (injection). The diagnostic accuracy of medial branch blocks has been extensively described in the scientific medical literature, and evidence of facet blocks to objectively document chronic post-traumatic neck pain has been accepted as scientifically reliable in courts and tribunals in the USA, Canada and the United Kingdom. We conclude that there is convincing scientific medical evidence that the results of cervical facet blocks provide reliable objective evidence of chronic post-traumatic spine pain, suitable for presentation to an adjudicative decision maker.

Management of whiplash-associated disorder in the Italian emergency department: the feasibility of an evidence-based continuous professional development course provided by physiotherapists

PURPOSE

The management of whiplash and associated disorders (WAD) in the Italian Health System is still empirical and influenced by a single professional's expertise. Therefore, the purpose of our study is to describe a structured management changes in an Italian emergency department (ED) after an evidence based continuous professional development (CPD) course.

METHODS

A CPD course was organized by Orthopedic Manipulative Physical Therapists (OMPT) for personnel of ED in the hospital Girolamo Fracastoro (San Bonifacio, Verona, Italy), based on latest scientific evidence. Data regarding the number of X-Rays, computed tomography (CT) scan, orthopaedic referrals, neck collars and WAD IV (i.e., severe diagnosis) before and after the course were compared.

RESULTS

3066 cases of WAD have been analyzed in 2016 and 2185 in 2017/2018. The number of X-Rays dropped down from 15.1% to 13.5%; the CT scans increased from 1.3% to 1.9%; the WAD IV diagnosis increased from 0.7% to 1.6%; the orthopaedic referrals dropped from 1.5% to 1.1%; the collars prescription dropped from 8.8% to 2.5%.

CONCLUSION

An updated framework increased the efficiency of ED's maintaining the same level of safety (i.e., WAD IV diagnosis). Given that, it can also be argued that, in line with other countries, the implementation of an OMPT role within the ED multidisciplinary team is advised also in Italy.Implications for rehabilitationPhysiotherapists were commissioned to organize a management change of patients in an Italian Emergency Department clinical setting for the management of whiplash;Guidelines and other appropriate clinical rules facilitate the delivery of an evidence-based and more appropriate management and care plan;An inter-disciplinary continuous professional development course has the potential to positively influence patients' journey and to optimize the use of departmental resources;The involvement of other health professionals (e.g., Physiotherapists) within the Italian Emergency Department organizational chart might lead to further improvement of service provided.

Osteopathic manipulative treatment combined with exercise improves pain and disability in individuals with non-specific chronic neck pain: A pragmatic randomized controlled trial

PURPOSE

To determine effectiveness of osteopathic manipulative treatment combined with stretching and strengthening exercises in the cervical region on pain and disability in individuals with non-specific chronic neck pain.

METHODS

90 adults with non-specific chronic neck pain were randomized to either exercises group (EG, n = 45) or osteopathic manipulative treatment associated with exercises group (OMT/EG, n = 45). The primary outcomes were obtained by the use of Numeric Pain-Rating Scale (NPRS), Pressure Pain Threshold (PPT) and Neck Disability Index (NDI). Secondary outcomes included range of motion (ROM) for cervical spine rotation, Fear-Avoidance Beliefs Questionnaire Work/Physical Activity (FABQ-W/PA) and Pain-self efficacy at two different moments: baseline and 4 weeks after the first treatment. Techniques and dosages of OMT were selected pragmatically by a registered osteopath. Generalized Estimating Equations model (GEE), complemented by the Least Significant Difference (LSD) and the intention-to-treat analysis, was used to assess the clinical outcomes.

RESULTS

Analysis with GEE indicated that OMT/EG reduced pain and disability more than the EG alone after 4 weeks of treatment with statistically significant difference (p < 0,05), as well as cervical active rotation was significantly improved (p = 0.03). There were no between-group differences observed in Pressure Pain Threshold (PPT) measure, Fear-Avoidance Beliefs Questionnaire and Pain-self efficacy.

CONCLUSION

The association between OMT and exercises reduces pain and improves functional disability more than only exercise for individuals with non-specific chronic neck pain.

Small fibre pathology in chronic whiplash-associated disorder: A cross-sectional study

BACKGROUND

Mechanisms underpinning ongoing symptoms in chronic whiplash associated-disorder (WAD) are not well understood. People with chronic WAD can exhibit sensory dysfunction consistent with small nerve fibre pathology, including thermal hypoaesthesia and hyperalgesia. This study investigated small fibre structure and function in chronic WAD.

METHODS

Twenty-four people with chronic WAD (median [IQR] age 49 [15] years, 16 females) and 24 pain-free controls (50 [17] years, 16 females) were recruited. Intraepidermal nerve fibre density (IENFD) and dermal innervation were assessed by skin biopsy. This was performed at (a) the lateral index finger on the primary side of pain and (b) superior to the lateral malleolus on the contralateral side. Quantitative sensory testing was performed over the hand.

RESULTS

The WAD group exhibited lower IENFD at the finger (WAD: median [IQR] 4.5 [4.9] fibres/mm; control 7.3 [3.9]; p = .010), but not the ankle (WAD: mean [SD] 7.3 [3.7] fibres/mm; control 9.3 [3.8]; p = .09). Dermal innervation was lower in the WAD group at the finger (WAD: median [IQR] 3.7 [2.8] nerve bundles/mm² ; controls: 4.9 [2.1]; p = .017) but not the ankle (WAD: median [IQR] 2.1 [1.9] nerve bundles/mm² ; controls: 1.8 [1.8]; p = .70). In the WAD group, hand thermal and light touch detection were impaired, and heat pain thresholds were lowered (p ≤ .037).

CONCLUSIONS

Findings suggest small fibre structural and functional deficits in chronic WAD, implicating potential involvement of small fibre pathology.

SIGNIFICANCE

Our study found decreased intraepidermal nerve fibre density, reduced dermal innervation, thermal hypoaesthesia and hypersensitivity in people with chronic WAD, suggestive of small fibre pathology. This observation of peripheral nervous system pathology in chronic whiplash provides novel insights on mechanisms underpinning symptoms and challenges commonly held beliefs regarding this condition.

Widespread Pressure Pain Hypersensitivity, Health History, and Trigger Points in Patients with Chronic Neck Pain: A Preliminary Study

Background

Pain sensitivity in chronic neck pain patients may be influenced by health conditions related to higher levels of widespread pressure pain hypersensitivity (sensitization). Trigger points have also been reported to play a role in the sensitization process.

Objectives

To investigate the association between pressure pain thresholds, trigger points, and health conditions in patients with chronic neck pain.

Design

Original research, preliminary study.

Setting

A private clinic.

Subjects

Thirty-four chronic mechanical neck pain patients and 34 chronic whiplash-associated neck pain patients, giving a final sample of 68 chronic neck pain patients.

Methods

Patients underwent an assessment of pressure pain thresholds over the upper trapezius, extensor carpi radialis longus, and tibialis anterior muscles and were screened for the presence of trigger points in the upper trapezius muscle. Further, information about health history conditions was obtained and collected in a form.

Results

Significantly negative correlations between all pressure pain thresholds and duration of health history conditions were found (all P &lt; 0.02). Significantly lower pressure pain thresholds (all P &lt; 0.01) were found in patients with active trigger points as compared with those with latent trigger points.

Conclusion

Widespread pressure pain hypersensitivity was associated with duration of health history conditions, suggesting that long-lasting health complaints may act as a triggering/perpetuating factor, driving sensitization in individuals with chronic neck pain. Active trigger points may be associated with higher widespread pressure hypersensitivity.

Motor impairment in patients with chronic neck pain: does the traumatic event play a significant role? A case-control study

BACKGROUND CONTEXT

Motor impairment is a key sign in patients with traumatic (whiplash-associated disorder [WAD]) and non-traumatic (idiopathic neck pain [INP]) neck pain.

PURPOSE

This study aimed to analyze differences in motor impairment between two patient groups and to assess the association between motor performance and self-reported symptoms.

STUDY DESIGN

This is a case-control study.

PATIENT SAMPLE

A total of 38 patients with chronic INP, 35 patients with chronic WAD, and 30 healthy pain-free controls were included in the study.

OUTCOME MEASURES

Outcome measures used in this study were mobility (°), strength (N), repositioning accuracy (°), endurance (seconds), sway velocity (cm/s), sway area (cm²), and neuromuscular control.

METHODS

Group differences of motor impairment, together with questionnaires to evaluate pain intensity, fear avoidance, pain catastrophizing, symptoms of central sensitization, and disability, were analyzed with analysis of covariance, including age as a covariate.

RESULTS

Motor impairment was observed in both patient groups with a higher degree in patients with chronic WAD. These impairments were moderately linked to self-reported disability and were in most cases associated with pain, fear avoidance, and symptoms of central sensitization (|ρ| ranging from 0.28 to 0.59).

CONCLUSIONS

Motor impairment should be addressed when treating both groups of patients, keeping in mind the association with self-reported pain and disability, fear-avoidance, and central sensitization.

Repeated High Rate Facet Capsular Stretch at Strains That are Below the Pain Threshold Induces Pain and Spinal Inflammation With Decreased Ligament Strength in the Rat

Repeated loading of ligamentous tissues during repetitive occupational and physical tasks even within physiological ranges of motion has been implicated in the development of pain and joint instability. The pathophysiological mechanisms of pain after repetitive joint loading are not understood. Within the cervical spine, excessive stretch of the facet joint and its capsular ligament has been implicated in the development of pain. Although a single facet joint distraction (FJD) at magnitudes simulating physiologic strains is insufficient to induce pain, it is unknown whether repeated stretching of the facet joint and ligament may produce pain. This study evaluated if repeated loading of the facet at physiologic nonpainful strains alters the capsular ligament's mechanical response and induces pain. Male rats underwent either two subthreshold facet joint distractions (STFJDs) or sham surgeries each separated by 2 days. Pain was measured before the procedure and for 7 days; capsular mechanics were measured during each distraction and under tension at tissue failure. Spinal glial activation was also assessed to probe potential pathophysiologic mechanisms responsible for pain. Capsular displacement significantly increased (p = 0.019) and capsular stiffness decreased (p = 0.008) during the second distraction compared to the first. Pain was also induced after the second distraction and was sustained at day 7 (p < 0.048). Repeated loading weakened the capsular ligament with lower vertebral displacement (p = 0.041) and peak force (p = 0.014) at tissue rupture. Spinal glial activation was also induced after repeated loading. Together, these mechanical, physiological, and neurological findings demonstrate that repeated loading of the facet joint even within physiologic ranges of motion can be sufficient to induce pain, spinal inflammation, and alter capsular mechanics similar to a more injurious loading exposure.

Deformation of dorsal root ganglion due to pressure transients of venous blood and cerebrospinal fluid in the cervical vertebral canal

The dorsal root ganglion (DRG) that is embedded in the foramen of the cervical vertebra can be injured during a whiplash motion. A potential cause is that whilst the neck bends in the whiplash motion, the changes of spinal canal volume induce impulsive pressure transients in the venous blood outside the dura mater (DM) and in the cerebrospinal fluid (CSF) inside the DM. The fluids can dynamically interact with the DRG and DM, which are deformable. In this work, the interaction is investigated numerically using a strong-coupling partitioned method that synchronize the computations of the fluid and structure. It is found that the interaction includes two basic processes, i.e., the pulling and pressing processes. In the pulling process, the DRG is stretched towards the spinal canal, and the venous blood is driven into the canal via the foramen. This process results from negative pressure in the fluids. In contrast, the pressing process is caused by positive pressure that leads to compression of the DRG and the outflow of the venous blood from the canal. The largest pressure gradient is observed at the foramen, where the DRG is located at. The DRG is subject to prominent von Mises stress near its end, which is fixed without motions. The negative internal pressure is more efficient to deform the DRG than the positive internal pressure. This indicates that the most hazardous condition for the DRG is the pulling process.

Do findings identified on magnetic resonance imaging predict future neck pain? A systematic review

BACKGROUND CONTEXT

Magnetic resonance imaging (MRI) has the potential to identify pathology contributing to neck pain. However, the importance of findings on MRI remains unclear.

PURPOSE

We aimed to investigate whether findings on cervical spine MRI predict future neck pain.

STUDY DESIGN

A systematic review was carried out.

PATIENT SAMPLE

People with or without neck pain comprised the study sample.

OUTCOME MEASURES

Clinically important neck pain outcomes such as pain and disability.

METHODS

The review protocol was registered on PROSPERO [CRD42016049228]. MEDLINE, CINAHL, and EMBASE databases were searched. Prospective cohort studies investigating the association between baseline MRI findings and clinical outcome were included. Cohorts with serious underlying diseases as the cause of their neck pain were excluded. Associations between MRI findings and neck pain outcomes were extracted from the included studies.

RESULTS

A total of 12 studies met all inclusion criteria. Eight studies presented data on participants with current neck pain, two studies included a mixed sample, and two studies included a sample of participants with no current neck pain. Because of the heterogeneity between the studies in terms of MRI findings, populations, and clinical outcomes investigated, it was not possible to pool the results. No consistent associations between MRI findings and future outcomes were identified. Single studies of populations with neck pain reported significant associations for neck muscle fatty infiltrate (risk ratio [RR]: 21.00, 95% confidence interval [CI]: 2.97-148.31) with persistent neck disability; disc protrusion (mean difference ranged from -1.83 to -2.88 on a 10-point pain scale), and disc degeneration (RR: 0.59; 95% CI: 0.36-0.98) with neck pain. In a population without pain, the development of foraminal stenosis over a 10-year period was associated with development of neck pain (RR: 2.99; 95% CI: 1.23-7.23).

CONCLUSION

The limited number, heterogeneity, and small sample size of the included studies do not permit definitive conclusions on the association between MRI findings of the cervical spine with future neck pain.

Influence of morphological variations on cervical spine segmental responses from inertial loading

OBJECTIVES

The objective of this study was to investigate the influence of morphological variations in osteoligamentous lower cervical spinal segment responses under postero-anterior inertial loading.

METHODS

A parametric finite element model of the C5-C6 spinal segment was used to generate models. Variations in the vertebral body and facet depth (anteroposterior), posterior process length, intervertebral disc height, facet articular process height and slope, segment orientation ranging from lordotic to straight, and segment size were parameterized. These variations included male-female differences. A Latin hypercube sampling method was used to select parameter values for model generation. Forces and moments associated with the inertial loading were applied to the generated model segments. The 7 parameters were grouped as local or global depending on the number of spinal components involved in the shape variation. Four output responses representing overall segmental and soft tissue responses were analyzed for each model variation: response angle of the segment, anterior longitudinal ligament stretch, anterior capsular ligament stretch, and facet joint compression in the posterior region. Pearson's correlation coefficient was used to compute the correlations of these output responses with morphological variations.

RESULTS

Fifty models were generated from the parameterized model using a Latin hypercube sampling technique. Variation in response angle among the models was 4° and was most influenced by change in the combined dimension of vertebral body and facet depth, followed by size of the segment. The maximum anterior longitudinal ligament stretch varied between 0.1 and 0.3 and was strongly influenced by the change in the segment orientation. The anterior facet joint region sustained tension, whereas the posterior region sustained compression. For the anterior capsular ligament stretch, the most influential global variation was segment orientation, whereas the most influential local variations were the facet height and facet angle parameters. In the case of posterior facet joint compression, segment orientation was again most influential, whereas among the local variations, the facet angle had the most influence.

CONCLUSION

Shape variations in the intervertebral disc influenced segmental rotation and ligament responses; however, the influence of shape variations in the facet joint was confined to capsular ligament responses. Response angle was most influenced by the vertebral body depth variations, explaining greater segmental rotations in female spines. Straighter spine segments sustained greater posterior facet joint compression, which may offer an explanation for the higher incidence of whiplash-associated disorders among females, who exhibit a straighter cervical spine. The anterior longitudinal ligament stretch was also greater in straighter segments. These findings indicate that the morphological features specific to the anatomy of the female cervical spine may predispose it to injury under inertial loading.

Tactile acuity is reduced in people with chronic neck pain

BACKGROUND

Tactile acuity deficits have been demonstrated in a range of persistent pain conditions and may reflect underlying cortical re-organisation.

OBJECTIVE

This study aimed to determine whether tactile acuity is impaired in people with chronic neck pain relative to controls, and whether deficits relate to pain location, duration and intensity.

METHODS

In this cross-sectional study, 20 people with chronic neck pain (5 idiopathic neck pain; 15 whiplash-associated disorder) and 20 pain-free controls underwent two-point discrimination (TPD) testing at the neck, back and arm, and point-to-point (PTP) and graphesthesia tests of tactile acuity at the neck and arm.

RESULTS

Linear mixed effects models demonstrated a significant group*body region interaction for TPD, Graphesthesia and PTP tests (Ps < 0.001), with post hoc tests showing impaired TPD in people with neck pain relative to controls at the neck, low back, and arm (P ≤ 0.001). Graphesthesia and PTP was also impaired at the neck (P < 0.001) but not the arm (P ≥ 0.48). TPD correlated with intensity and duration of pain (Pearson's r = 0.48, P < 0.05; Pearson's r = 0.77, P < 0.01). There was no sig difference between the two neck pain groups for any tactile acuity measure (TPD: P = 0.054; Graphesthesia; P = 0.67; Point to Point: P = 0.77), however, low power limited confidence in this comparison.

CONCLUSION

People with chronic neck pain demonstrated tactile acuity deficits in painful and non-painful regions when measured using the TPD test, with the magnitude of deficits appearing greatest at the neck. The study also revealed a positive relationship between TPD and pain intensity/duration, further supporting the main study finding.

Biomechanics of coupled motion in the cervical spine during simulated whiplash in patients with pre-existing cervical or lumbar spinal fusion: A Finite Element Study

Objectives

Loss of motion following spine segment fusion results in increased strain in the adjacent motion segments. However, to date, studies on the biomechanics of the cervical spine have not assessed the role of coupled motions in the lumbar spine. Accordingly, we investigated the biomechanics of the cervical spine following cervical fusion and lumbar fusion during simulated whiplash using a whole-human finite element (FE) model to simulate coupled motions of the spine.

Methods

A previously validated FE model of the human body in the driver-occupant position was used to investigate cervical hyperextension injury. The cervical spine was subjected to simulated whiplash exposure in accordance with Euro NCAP (the European New Car Assessment Programme) testing using the whole human FE model. The coupled motions between the cervical spine and lumbar spine were assessed by evaluating the biomechanical effects of simulated cervical fusion and lumbar fusion.

Results

Peak anterior longitudinal ligament (ALL) strain ranged from 0.106 to 0.382 in a normal spine, and from 0.116 to 0.399 in a fused cervical spine. Strain increased from cranial to caudal levels. The mean strain increase in the motion segment immediately adjacent to the site of fusion from C2-C3 through C5-C6 was 26.1% and 50.8% following single- and two-level cervical fusion, respectively (p = 0.03, unpaired two-way t-test). Peak cervical strains following various lumbar-fusion procedures were 1.0% less than those seen in a healthy spine (p = 0.61, two-way ANOVA).

Conclusion

Cervical arthrodesis increases peak ALL strain in the adjacent motion segments. C3-4 experiences greater changes in strain than C6-7. Lumbar fusion did not have a significant effect on cervical spine strain.

Cite this article: H. Huang, R. W. Nightingale, A. B. C. Dang. Biomechanics of coupled motion in the cervical spine during simulated whiplash in patients with pre-existing cervical or lumbar spinal fusion: A Finite Element Study. Bone Joint Res 2018;7:28–35. DOI: 10.1302/2046-3758.71.BJR-2017-0100.R1.

The biomechanical impact of facet tropism on the intervertebral disc and facet joints in the cervical spine

BACKGROUND CONTEXT

Facet tropism is defined as the angular difference between the left and the right facet orientation. Facet tropism was suggested to be associated with the disc degeneration and facet degeneration in the lumbar spine. However, little is known about the relationship between facet tropism and pathologic changes in the cervical spine and the mechanism behind.

PURPOSE

This study was conducted to investigate the biomechanical impact of facet tropism on the intervertebral disc and facet joints.

STUDY DESIGN

A finite element analysis study.

METHODS

The computed tomography (CT) scans of a 28-year-old male volunteer was used to construct the finite element model. First, a symmetrical cervical model from C2 to C7 was constructed. The facet orientations at each level were simulated using the data from our previously published study. Second, the facet orientations at the C5-C6 level were altered to simulate facet tropism with respect to the sagittal plane. The angular difference of the moderate facet tropism model was set to be 7 degrees, whereas the severe facet tropism model was set to be 14 degrees. The inferior of the C7 vertebra was fixed. A 75 N follower loading was applied to simulate the weight of the head. A 1.0 N⋅m moments was applied on the odontoid process of the C2 to simulate flexion, extension, lateral bending, and axial rotation.

RESULTS

The intradiscal pressure (IDP) at the C5-C6 level of the severe facet tropism model increased by 49.02%, 57.14%, 39.06%, and 30.67%, under flexion, extension, lateral bending, and axial rotation moments, in comparison with the symmetrical model. The contact force of the severe facet tropism model increased by 35.64%, 31.74%, 79.26%, and 59.47% from the symmetrical model under flexion, extension, lateral bending, and axial rotation, respectively.

CONCLUSIONS

Facet tropism with respect to the sagittal plane at the C5-C6 level increased the IDP and facet contact force under flexion, extension, lateral bending, and axial rotation. The results suggested that facet tropism might be the anatomic risk factor of the development of cervical disc degeneration or facet degeneration. Future clinical studies are in need to verify the biomechanical impact of facet tropism on the development of degenerative changes in the cervical spine.

The influence of cervical movement on eye stabilization reflexes: a randomized trial

To investigate the influence of the amount of cervical movement on the cervico-ocular reflex (COR) and vestibulo-ocular reflex (VOR) in healthy individuals. Eye stabilization reflexes, especially the COR, are changed in neck pain patients. In healthy humans, the strength of the VOR and the COR are inversely related. In a cross-over trial the amplitude of the COR and VOR (measured with a rotational chair with eye tracking device) and the active cervical range of motion (CROM) was measured in 20 healthy participants (mean age 24.7). The parameters were tested before and after two different interventions (hyperkinesia: 20 min of extensive active neck movement; and hypokinesia: 60 min of wearing a stiff neck collar). In an additional replication experiment the effect of prolonged (120 min) hypokinesia on the eye reflexes were tested in 11 individuals. The COR did not change after 60 min of hypokinesia, but did increase after prolonged hypokinesia (median change 0.220; IQR 0.168, p = 0.017). The VOR increased after 60 min of hypokinesia (median change 0.155, IQR 0.26, p = 0.003), but this increase was gone after 120 min of hypokinesia. Both reflexes were unaffected by cervical hyperkinesia. Diminished neck movements influences both the COR and VOR, although on a different time scale. However, increased neck movements do not affect the reflexes. These findings suggest that diminished neck movements could cause the increased COR in patients with neck complaints.

Comparison of spatial summation properties at different body sites

Background and aims

The nociceptive system appears to have evolved a range of protective characteristics that are of great interest in understanding both acute and chronic pain. Spatial summation is one important characteristic, whereby increasing area of a stimulus, or distance between multiple stimuli, results in more intense pain—not only greater area of pain. One of the mysteries of chronic pain is why spinal pain is so prevalent relative to pain at other sites. Since pathological tissue models have failed to fully explain spinal pain, we theorized that body region specific differences in sensory processing—such as a greater propensity for spatial summation—may help to explain its vulnerability. We aimed to examine this by comparing the properties of summation at different body parts: the dorsal forearm, neck, and back.

Methods

Spatial summation of pain was investigated using noxious intra-dermal electrical stimuli in healthy pain-free adults (14 males, 6 females), and the perceived pain intensity was rated on a 0-100 pain scale. Area-based stimulation was investigated by doubling the stimulation area with the addition of a second electrode placed adjacent to the first. Distance-based summation was investigated by randomly varying the separation distance between paired noxious electrical stimuli at separations of 0,10,15, and 20 cm.

Results

This study demonstrated that the properties of area- and distance-based summation are uniform across the neck, back, and forearm in healthy adults. Spatial summation of pain was also found to be greatest at 15- and 20-cm paired separations for all body regions tested, confirming that noxious information can be integrated over an extensive anatomical area.

Conclusion

Data from this investigation refutes the thesis that spatial summation of pain may be a contributing factor for the reported difference in chronicity rates between spinal and peripheral sites. It remains, however, a potentially important mechanism by which noxious inputs from multi-level pathology might integrate and contribute to pain.

Implications

While data from this project suggest that there are no regional differences in the properties of spatial summation of noxious stimuli, regional differences in other characteristics of the nociceptive system may yet provide insight into why some spinal pain is so highly prevalent; nociceptive distance-based summation may be highly relevant where two or more conditions co-exist in close proximity.

Neck Pain: Revision 2017

The Orthopaedic Section of the American Physical Therapy Association (APTA) has an ongoing effort to create evidence-based practice guidelines for orthopaedic physical therapy management of patients with musculoskeletal impairments described in the World Health Organization's International Classification of Functioning, Disability, and Health (ICF). The purpose of these revised clinical practice guidelines is to review recent peer-reviewed literature and make recommendations related to neck pain. J Orthop Sports Phys Ther. 2017;47(7):A1-A83. doi:10.2519/jospt.2017.0302.

Eye stabilization reflexes in traumatic and non-traumatic chronic neck pain patients

BACKGROUND

Many chronic neck pain patients experience problems with vision. These problems are possibly induced by deviations of the eye stabilization reflexes. It is not known whether these eye reflex alterations occur both in traumatic and non-traumatic neck pain patients.

OBJECTIVE

To investigate if the cervico-ocular reflex (COR) and the vestibulo-ocular reflex (VOR) are changed in tertiary care patients with prolonged, chronic neck pain with various origin of complaints.

DESIGN

Cross sectional study.

METHODS

Ninety-one chronic neck pain patients were subdivided into three groups by origin of complaints, and compared with healthy controls. COR and VOR gains were measured with an infrared eye tracking device with the subject sitting on a rotating chair in a darkened room and with the head fixed.

RESULTS

Neck pain patients had a higher COR gain (median 0.41, IQR 0.289) compared with healthy controls (median 0.231, IQR 0.179). The mean COR gain did not differ between the three patient groups (Whiplash Associated Disorders 0.444 (SD 0.221); traumatic 0.397 (SD0.205); non-traumatic 0.468 (SD0.236)). There was no difference in VOR gain between the groups.

CONCLUSION

Chronic neck pain patients, who already received primary care, still have an elevated cervico-ocular reflex. The origin of complaints did not seem to be associated with this deviant oculomotor behavior.

Do Subjects with Whiplash-Associated Disorders Respond Differently in the Short-Term to Manual Therapy and Exercise than Those with Mechanical Neck Pain?

Objective

To compare the short-term effects of manual therapy and exercise on pain, related disability, range of motion, and pressure pain thresholds between subjects with mechanical neck pain and whiplash-associated disorders.

Methods

Twenty-two subjects with mechanical neck pain and 28 with whiplash-associated disorders participated. Clinical and physical outcomes including neck pain intensity, neck-related disability, and pain area, as well as cervical range of motion and pressure pain thresholds over the upper trapezius and tibialis anterior muscles, were obtained at baseline and after the intervention by a blinded assessor. Each subject received six sessions of manual therapy and specific neck exercises. Mixed-model repeated measures analyses of covariance (ANCOVAs) were used for the analyses.

Results

Subjects with whiplash-associated disorders exhibited higher neck-related disability ( P  = 0.021), larger pain area ( P  = 0.003), and lower pressure pain thresholds in the tibialis anterior muscle ( P  = 0.009) than those with mechanical neck pain. The adjusted ANCOVA revealed no between-group differences for any outcome (all P  > 0.15). A significant main effect of time was demonstrated for clinical outcomes and cervical range of motion with both groups experiencing similar improvements (all P  < 0.01). No changes in pressure pain thresholds were observed in either group after treatment ( P  > 0.222).

Conclusions

The current clinical trial found that subjects with mechanical neck pain and whiplash-associated disorders exhibited similar clinical and neurophysiological responses after a multimodal physical therapy intervention, suggesting that although greater signs of central sensitization are present in subjects with whiplash-associated disorders, this does not alter the response in the short term to manual therapy and exercises.

An Attempt of Early Detection of Poor Outcome after Whiplash

The main concern with whiplash is that a large proportion of whiplash patients experience disabling symptoms or whiplash-associated disorders (WAD) for months if not years following the accident. Therefore, identifying early prognostic factors of WAD development is important as WAD have widespread clinical and economic consequences. In order to tackle that question, our study was specifically aimed at combining several methods of investigation in the same WAD patients at the acute stage and 6 months later. Our longitudinal, open, prospective, multi-center study included 38 whiplash patients, and 13 healthy volunteers matched for age, gender, and socio-economic status with the whiplash group. Whiplash patients were evaluated 15-21 days after road accident, and 6 months later. At each appointment, patients underwent a neuropsychological evaluation, a full clinical neurological examination, neurophysiological and postural tests, oto-neurological tests, cervical spine cord magnetic resonance imaging (MRI) with tractography (DTI). At 6 months, whiplash patients were categorized into two subgroups based on the results of the Diagnostic and Statistical Manual of Mental Disorders as having either favorable or unfavorable progression [an unfavorable classification corresponding to the presence of post-concussion symptom (PCS)] and we searched retrospectively for early prognostic factors of WAD predicting the passage to chronicity. We found that patients displaying high level of catastrophizing at the acute stage and/or post-traumatic stress disorder associated with either abnormalities in head or trunk kinematics, abnormal test of the otolithic function and at the Equitest or a combination of these syndromes, turned to chronicity. This study suggests that low-grade whiplash patients should be submitted as early as possible after the trauma to neuropsychological and motor control tests in a specialized consultation. In addition, they should be evaluated by a neuro-otologist for a detailed examination of vestibular functions, which should include cervical vestibular evoked myogenic potential. Then, if diagnosed at risk of WAD, these patients should be subjected to an intensive preventive rehabilitation program, including vestibular rehabilitation if required.

Eye movements in patients with Whiplash Associated Disorders: a systematic review

Background

Many people with Whiplash Associated Disorders (WAD) report problems with vision, some of which may be due to impaired eye movements. Better understanding of such impaired eye movements could improve diagnostics and treatment strategies.

This systematic review surveys the current evidence on changes in eye movements of patients with WAD and explains how the oculomotor system is tested.

Methods

Nine electronic data bases were searched for relevant articles from inception until September 2015. All studies which investigated eye movements in patients with WAD and included a healthy control group were screened for inclusion. Qualifying studies were retrieved and independently assessed for methodological quality using the Methodology Checklists provided by the Scottish Intercollegiate Guidelines Network.

Results

Fourteen studies out of 833 unique hits were included. Ten studies reported impaired eye movements in patients with WAD and in four studies no differences compared to healthy controls were found. Different methods of eye movement examination were used in the ten studies: in five studies, the smooth pursuit neck torsion test was positive, in two more the velocity and stability of head movements during eye-coordination tasks were decreased, and in another three studies the cervico-ocular reflex was elevated.

Conclusions

Overall the reviewed studies show deficits in eye movement in patients with WAD, but studies and results are varied. When comparing the results of the 14 relevant publications, one should realise that there are significant differences in test set-up and patient population. In the majority of studies patients show altered compensatory eye movements and smooth pursuit movements which may impair the coordination of head and eyes.

Chronic neck pain patients with traumatic or non-traumatic onset: Differences in characteristics. A cross-sectional study

BACKGROUND AND AIMS

Patients with chronic neck pain can present with disability, low quality of life, psychological factors and clinical symptoms. It is unclear whether patients with a traumatic onset differ from those with a non-traumatic onset, by having more complex and severe symptoms. The purpose of this study was to investigate the clinical presentation of chronic neck pain patients with and without traumatic onset by examining cervical mobility, sensorimotor function, cervical muscle performance and pressure pain threshold in addition to the following self-reported characteristics: quality of life, neck pain and function, kinesiophobia, depression, and pain bothersomeness.

METHODS

This cross-sectional study included 200 participants with chronic neck pain: 120 with traumatic onset and 80 with non-traumatic onset. Participants were recruited from physiotherapy clinics in primary and secondary health care. For participants to be included, they were required to be at least 18 years of age, have had neck pain for at least 6 months, and experienced neck-related activity limitation as determined by a score of at least 10 on the Neck Disability Index. We conducted the following clinical tests of cervical range of motion, gaze stability, eye movement, cranio-cervical flexion, cervical extensors, and pressure pain threshold. The participants completed the following questionnaires: physical and mental component summary of the Short Form Health Survey, EuroQol-5D, Neck Disability Index, Patient-Specific Functional Scale, Pain Bothersomeness, Beck Depression Inventory-II, and TAMPA scale of kinesiophobia. The level of significance for all analyses was defined as p<0.01. Differences between groups for the continuous data were determined using either a Student's t-test or Mann Whitney U test.

RESULTS

In both groups, the majority of the participants were female (approximately 75%). Age, educational level, working situation and sleeping patterns were similar in both groups. The traumatic group had symptoms for a shorter duration (88 vs. 138 months p=0.001). Participants in the traumatic group showed worse results on all measures compared with those in the non-traumatic group, significantly on neck muscle function (cervical extension mobility p=0.005, cranio-cervical flexion test p=0.007, cervical extensor test p=0.006) and cervical pressure pain threshold bilateral (p=0.002/0.004), as well on self-reported function (Neck Disability Index p=0.001 and Patient-Specific Functional Scale p=0.007), mental quality of life (mental component summary of the Short Form Health Survey p=0.004 and EuroQol-5D p=0.001) and depression (Beck Depression Inventory-II p=0.001).

CONCLUSIONS

This study showed significant differences between chronic neck pain patients when differentiated into groups based on their onset of pain. However, no specific clinical test or self-reported characteristic could differentiate between the groups at an individual patient level.

IMPLICATIONS

Pressure pain threshold tests, cervical muscle performance tests and patient-reported characteristics about self-perceived function and psychological factors may assist in profiling chronic neck pain patients. The need for more intensive management of those with a traumatic onset compared with those with a non-traumatic onset should be examined further.

Pharmacological and Interventional Management of Pain After Whiplash Injury

Synopsis Whiplash-associated disorder (WAD) is a group of symptoms and clinical manifestations resulting from rear-end or side impact. Despite the wide use of medications in WAD, the published research does not allow recommendations based on high evidence level. It may be meaningful to use nonsteroidal anti-inflammatory drugs in the acute posttraumatic phase. In chronic WAD, the use of nonsteroidal anti-inflammatory drugs is more concerning due to potential gastrointestinal and renal complications with prolonged use and lack of evidence for long-term benefits. Antidepressants can be used in patients with clinically relevant hyperalgesia, sleep disorder associated with pain, or depression. Anticonvulsants are unlikely first-choice medications, but can be considered if other treatments fail. The use of opioids in patients with chronic pain has become the object of severe concern, due to the lack of evidence for long-term benefits and the associated risks. Extreme caution in prescribing and monitoring opioid treatment is mandatory. Nerve blocks of the zygapophyseal (facet) joints have validity for the diagnosis of facet joint pain, which is one of the possible manifestations of WAD. One randomized sham-controlled trial and several high-quality prospective studies support the efficacy of radiofrequency neurotomy for the treatment of facet joint pain. The efficacy of trigger point treatments is uncertain. They can be offered due to possible efficacy and limited risks. Any medication or procedure has to be considered in the frame of a comprehensive patient evaluation. As for any chronic pain condition, concomitant consideration of rehabilitation and psychosocial interventions is mandatory. J Orthop Sports Phys Ther 2016;46(10):845-850. Epub 3 Sep 2016. doi:10.2519/jospt.2016.6906.

Morphology of Cervical Spine Meniscoids in Individuals With Chronic Whiplash-Associated Disorder: A Case-Control Study

Study Design Case-control study. Background Cervical spine meniscoids are thought to contribute to neck pain and hypomobility in individuals with chronic whiplash-associated disorder (WAD); however, their morphology has not been studied in a clinical population. Objectives To investigate cervical spine meniscoid morphology in individuals with chronic WAD. Methods Twenty volunteers with chronic WAD (mean ± SD age, 39.3 ± 11.0 years; 10 female) and 20 age- and sex-matched controls (age, 39.1 ± 10.6 years) underwent cervical spine magnetic resonance imaging. Lateral atlantoaxial and zygapophyseal joints (C2-3 to C6-7) were inspected for meniscoids. Length of meniscoid protrusion was measured and composition (adipose/fibrous/fibroadipose) assessed. Data were analyzed using Wilcoxon signed-rank tests and linear and logistic regression (P<.05). Results Meniscoids were identified in the chronic WAD (n = 317) and control (n = 296) groups. At the lateral atlantoaxial joints, median meniscoid length was greater in the control group (ventral, 6.07 mm; dorsal, 7.24 mm) than the WAD group (ventral, 5.01 mm; P = .06 and dorsal, 6.48 mm; P<.01). At the dorsal aspect of zygapophyseal joints, meniscoids were more frequently fibrous in the chronic WAD group (odds ratio = 2.38, P<.01; likelihood ratio test: χ²₂, 9.02; P = .01). Conclusion In individuals with chronic WAD, lateral atlantoaxial meniscoids were shorter and dorsal cervical zygapophyseal meniscoids were more fibrous, suggesting alterations in meniscoid composition. This may have pathoanatomical implications in chronic WAD. J Orthop Sports Phys Ther 2016;46(10):902-910. Epub 3 Sep 2016. doi:10.2519/jospt.2016.6702.

Advancements in Imaging Technology: Do They (or Will They) Equate to Advancements in Our Knowledge of Recovery in Whiplash?

Synopsis It is generally accepted that up to 50% of those with a whiplash injury following a motor vehicle collision will fail to fully recover. Twenty-five percent of these patients will demonstrate a markedly complex clinical picture that includes severe pain-related disability, sensory and motor disturbances, and psychological distress. A number of psychosocial factors have shown prognostic value for recovery following whiplash from a motor vehicle collision. To date, no management approach (eg, physical therapies, education, psychological interventions, or interdisciplinary strategies) for acute whiplash has positively influenced recovery rates. For many of the probable pathoanatomical lesions (eg, fracture, ligamentous rupture, disc injury), there remains a lack of available clinical tests for identifying their presence. Fractures, particularly at the craniovertebral and cervicothoracic junctions, may be radiographically occult. While high-resolution computed tomography scans can detect fractures, there remains a lack of prevalence data for fractures in this population. Conventional magnetic resonance imaging has not consistently revealed lesions in patients with acute or chronic whiplash, a "failure" that may be due to limitations in the resolution of available devices and the use of standard sequences. The technological evolution of imaging techniques and sequences eventually might provide greater resolution to reveal currently elusive anatomical lesions (or, perhaps more importantly, temporal changes in physiological responses to assumed lesions) in those patients at risk of poor recovery. Preliminary findings from 2 prospective cohort studies in 2 different countries suggest that this is so, as evidenced by changes to the structure of skeletal muscles in those who do not fully recover. In this clinical commentary, we will briefly introduce the available imaging decision rules and the current knowledge underlying the pathomechanics and pathophysiology of whiplash. We will then acknowledge known prognostic factors underlying functional recovery. Last, we will highlight emerging evidence regarding the pathobiology of muscle degeneration/regeneration, as well as advancements in neuroimaging and musculoskeletal imaging techniques (eg, functional magnetic resonance imaging, magnetization transfer imaging, spectroscopy, diffusion-weighted imaging) that may be used as noninvasive and objective complements to known prognostic factors associated with whiplash recovery, in particular, poor functional recovery. J Orthop Sports Phys Ther 2016;46(10):861-872. doi:10.2519/jospt.2016.6735.

Altered Regional Cerebral Blood Flow in Chronic Whiplash Associated Disorders

There is increasing evidence of central hyperexcitability in chronic whiplash-associated disorders (cWAD). However, little is known about how an apparently simple cervical spine injury can induce changes in cerebral processes. The present study was designed (1) to validate previous results showing alterations of regional cerebral blood flow (rCBF) in cWAD, (2) to test if central hyperexcitability reflects changes in rCBF upon non-painful stimulation of the neck, and (3) to verify our hypothesis that the missing link in understanding the underlying pathophysiology could be the close interaction between the neck and midbrain structures. For this purpose, alterations of rCBF were explored in a case-control study using H₂¹⁵O positron emission tomography, where each group was exposed to four different conditions, including rest and different levels of non-painful electrical stimulation of the neck. rCBF was found to be elevated in patients with cWAD in the posterior cingulate and precuneus, and decreased in the superior temporal, parahippocampal, and inferior frontal gyri, the thalamus and the insular cortex when compared with rCBF in healthy controls. No differences in rCBF were observed between different levels of electrical stimulation. The alterations in regions directly involved with pain perception and interoceptive processing indicate that cWAD symptoms might be the consequence of a mismatch during the integration of information in brain regions involved in pain processing.

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Differences of rCBF were explored by PET in cWAD patients and healthy volunteers exposed to four conditions.

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Changes in rCBF were observed in cWAD patients in regions involved in pain perception and interoceptive sensory information.

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These changes might be the consequence of a mismatch in the integration of interoceptive stimuli in pain processing regions.

In the past, published work on chronic whiplash-associated disorders (cWAD) has caused much confusion and discussion, yet functional imaging methods such as positron emission tomography (PET) have demonstrated a variety of different significant alterations in the perfusion or glucose utilization of the brain. The present study, using PET and the perfusion marker, H₂¹⁵O, is a step forward in whiplash research. It shows changes in perfusion in regions directly involved in pain perception and interoceptive sensory information, such as the insular cortex, precuneus, and posterior cingulate, indicating a mismatch in the integration of interoceptive information in pain processing brain regions.