Mechanisms-based classifications of musculoskeletal pain: part 1 of 3: symptoms and signs of central sensitisation in patients with low back (± leg) pain

Revisiting the Corticomotor Plasticity in Low Back Pain: Challenges and Perspectives

Chronic low back pain (CLBP) is a recurrent debilitating condition that costs billions to society. Refractoriness to conventional treatment, lack of improvement, and associated movement disorders could be related to the extensive brain plasticity present in this condition, especially in the sensorimotor cortices. This narrative review on corticomotor plasticity in CLBP will try to delineate how interventions such as training and neuromodulation can improve the condition. The review recommends subgrouping classification in CLBP owing to brain plasticity markers with a view of better understanding and treating this complex condition.

Subjective and clinical assessment criteria suggestive for five clinical patterns discernible in nonspecific neck pain patients. A Delphi-survey of clinical experts

BACKGROUND

Nonspecific neck pain patients form a heterogeneous group with different musculoskeletal impairments. Classifying nonspecific neck pain patients into subgroups based on clinical characteristics might lead to more comprehensive diagnoses and can guide effective management.

OBJECTIVE

To establish consensus among a group of experts regarding the clinical criteria suggestive of a clinical dominance of 'articular', 'myofascial', 'neural', 'central' and 'sensorimotor control' dysfunction patterns distinguishable in patients with nonspecific neck pain.

STUDY DESIGN

Delphi study.

METHODS

A focus group with 10 academic experts was organized to elaborate on the different dysfunction patterns discernible in neck pain patients. Consecutively, a 3-round online Delphi-survey was designed to obtain consensual symptoms and physical examination findings for the 5 distinct dysfunction patterns resulting from the focus group.

RESULTS

A total of 21 musculoskeletal physical therapists from Belgium and the Netherlands experienced in assessing and treating neck pain patients completed the 3-round Delphi-survey. Respectively, 33 (response rate, 100.0%), 27 (81.8%) and 21 (63.6%) respondents replied to rounds 1, 2 and 3. Eighteen 'articular', 16 'myofascial', 20 'neural', 18 'central' and 10 'sensorimotor control' clinical indicators reached a predefined ≥80% consensus level.

CONCLUSION

These indicators suggestive of a clinical dominance of 'articular', 'myofascial', 'neural', 'central', and 'sensorimotor control' dysfunction patterns may help clinicians to assess and diagnose patients with nonspecific neck pain. Future validity testing is needed to determine how these criteria may help to improve the outcome of physical therapy interventions in nonspecific neck pain patients.

Treatment-Based Classification System for Low Back Pain: Revision and Update

The treatment-based classification (TBC) system for the treatment of patients with low back pain (LBP) has been in use by clinicians since 1995. This perspective article describes how the TBC was updated by maintaining its strengths, addressing its limitations, and incorporating recent research developments. The current update of the TBC has 2 levels of triage: (1) the level of the first-contact health care provider and (2) the level of the rehabilitation provider. At the level of first-contact health care provider, the purpose of the triage is to determine whether the patient is an appropriate candidate for rehabilitation, either by ruling out serious pathologies and serious comorbidities or by determining whether the patient is appropriate for self-care management. At the level of the rehabilitation provider, the purpose of the triage is to determine the most appropriate rehabilitation approach given the patient's clinical presentation. Three rehabilitation approaches are described. A symptom modulation approach is described for patients with a recent-new or recurrent-LBP episode that has caused significant symptomatic features. A movement control approach is described for patients with moderate pain and disability status. A function optimization approach is described for patients with low pain and disability status. This perspective article emphasizes that psychological and comorbid status should be assessed and addressed in each patient. This updated TBC is linked to the American Physical Therapy Association's clinical practice guidelines for low back pain.

Listening is therapy: Patient interviewing from a pain science perspective

The interview of a patient attending physical therapy is the cornerstone of the physical examination, diagnosis, plan of care, prognosis, and overall efficacy of the therapeutic experience. A thorough, skilled interview drives the objective tests and measures chosen, as well as provides context for the interpretation of those tests and measures, during the physical examination. Information from the interview powerfully influences the treatment modalities chosen by the physical therapist (PT) and thus also impacts the overall outcome and prognosis of the therapy sessions. Traditional physical therapy focuses heavily on biomedical information to educate people about their pain, and this predominant model focusing on anatomy, biomechanics, and pathoanatomy permeates the interview and physical examination. Although this model may have a significant effect on people with acute, sub-acute or postoperative pain, this type of examination may not only gather insufficient information regarding the pain experience and suffering, but negatively impact a patient's pain experience. In recent years, physical therapy treatment for pain has increasingly focused on pain science education, with increasing evidence of pain science education positively affecting pain, disability, pain catastrophization, movement limitations, and overall healthcare cost. In line with the ever-increasing focus of pain science in physical therapy, it is time for the examination, both subjective and objective, to embrace a biopsychosocial approach beyond the realm of only a biomedical approach. A patient interview is far more than "just" collecting information. It also is a critical component to establishing an alliance with a patient and a fundamental first step in therapeutic neuroscience education (TNE) for patients in pain. This article highlights the interview process focusing on a pain science perspective as it relates to screening patients, establishing psychosocial barriers to improvement, and pain mechanism assessment.

Mechanisms of low back pain: a guide for diagnosis and therapy

Chronic low back pain (CLBP) is a chronic pain syndrome in the lower back region, lasting for at least 3 months. CLBP represents the second leading cause of disability worldwide being a major welfare and economic problem. The prevalence of CLBP in adults has increased more than 100% in the last decade and continues to increase dramatically in the aging population, affecting both men and women in all ethnic groups, with a significant impact on functional capacity and occupational activities. It can also be influenced by psychological factors, such as stress, depression and/or anxiety. Given this complexity, the diagnostic evaluation of patients with CLBP can be very challenging and requires complex clinical decision-making. Answering the question "what is the pain generator" among the several structures potentially involved in CLBP is a key factor in the management of these patients, since a mis-diagnosis can generate therapeutical mistakes. Traditionally, the notion that the etiology of 80% to 90% of LBP cases is unknown has been mistaken perpetuated across decades. In most cases, low back pain can be attributed to specific pain generator, with its own characteristics and with different therapeutical opportunity. Here we discuss about radicular pain, facet Joint pain, sacro-iliac pain, pain related to lumbar stenosis, discogenic pain. Our article aims to offer to the clinicians a simple guidance to identify pain generators in a safer and faster way, relying a correct diagnosis and further therapeutical approach.

Mechanisms of low back pain: a guide for diagnosis and therapy

Chronic low back pain (CLBP) is a chronic pain syndrome in the lower back region, lasting for at least 3 months. CLBP represents the second leading cause of disability worldwide being a major welfare and economic problem. The prevalence of CLBP in adults has increased more than 100% in the last decade and continues to increase dramatically in the aging population, affecting both men and women in all ethnic groups, with a significant impact on functional capacity and occupational activities. It can also be influenced by psychological factors, such as stress, depression and/or anxiety. Given this complexity, the diagnostic evaluation of patients with CLBP can be very challenging and requires complex clinical decision-making. Answering the question "what is the pain generator" among the several structures potentially involved in CLBP is a key factor in the management of these patients, since a mis-diagnosis can generate therapeutical mistakes. Traditionally, the notion that the etiology of 80% to 90% of LBP cases is unknown has been mistaken perpetuated across decades. In most cases, low back pain can be attributed to specific pain generator, with its own characteristics and with different therapeutical opportunity. Here we discuss about radicular pain, facet Joint pain, sacro-iliac pain, pain related to lumbar stenosis, discogenic pain. Our article aims to offer to the clinicians a simple guidance to identify pain generators in a safer and faster way, relying a correct diagnosis and further therapeutical approach.

Association of low back pain, somatic dysfunction, and lumbar bone mineral density: reproducibility of findings

CONTEXT

Somatic dysfunction as diagnosed by palpation should be associated with an objective measure. Bone mineral density (BMD) has been shown to be elevated in lumbar vertebrae with somatic dysfunction and in the lumbar region of individuals with chronic low back pain (LBP).

OBJECTIVE

To investigate the association of lumbar somatic dysfunction and BMD T-score variability in participants with chronic LBP and without LBP (non-LBP) and to determine the reproducibility of previously published results.

METHODS

Two examiners, blinded to symptom history, evaluated participants for tissue texture abnormalities, rotational asymmetry, anterior motion restriction, and tenderness at vertebral levels L1 to L4. Participants also underwent dual-energy x-ray absorptiometry of vertebral levels L1 to L4 for the assessment of BMD T scores. Generalized linear models were used to compare the chronic LBP and non-LBP groups on the presence and severity of somatic dysfunction and to test whether group and the presence and severity of somatic dysfunction were related to BMD T scores.

RESULTS

Forty-three chronic LBP (54%) and 36 non-LBP participants (46%) completed the study. Although the presence of somatic dysfunction in the 2 groups was not significantly different, the presence of tenderness was significantly more common in the chronic LBP group (P<.001), as was the severity for tissue texture abnormalities (P=.03), motion restriction (P=.04), and tenderness (P<.001). Of the 316 vertebrae assessed, 31 (10%, all in the chronic LBP group) had moderate/severe tenderness. The vertebral somatic dysfunction burden score, the total somatic dysfunction burden score, the vertebral somatic dysfunction severity score, and the total somatic dysfunction severity score were higher in the chronic LBP group (all P<.001). The vertebral BMD T score was significantly higher for vertebrae demonstrating moderate/severe rotational asymmetry compared with those demonstrating mild or no rotational asymmetry (P=.01) and for vertebrae demonstrating moderate/severe tenderness compared with those demonstrating no tenderness (P=.04).

CONCLUSION

Study results suggest that somatic dysfunction was more significant in chronic LBP participants. Although the correlation between the presence of somatic dysfunction and segmental BMD T scores was not reproduced, BMD T scores were higher for vertebrae demonstrating moderate/severe rotational asymmetry and tenderness.

Predictive factors and clinical biomarkers for treatment in patients with chronic pain caused by osteoarthritis with a central sensitisation component

AIMS

The aim of this non-systematic review was to provide a practical guide for clinicians on the evidence for central sensitisation in chronic osteoarthritis (OA) pain and how this pain mechanism can be addressed in terms of clinical diagnosis, investigation and treatment.

METHODS

The authors undertook a non-systematic review of the literature including a MEDLINE search (search terms included central sensitisation, osteoarthritis, osteoarthrosis) for relevant and current clinical studies, systematic reviews and narrative reviews. Case reports, letters to the editor and similar literature sources were excluded. Information was organised to allow a pragmatic approach to the discussion of the evidence and generation of practical recommendations.

RESULTS

There is good evidence for a role of central sensitisation in chronic OA pain in a subgroup of patients. Clinically, a central sensitisation component in chronic OA pain can be suspected based on characteristic pain features and non-pain features seen in other conditions involving central sensitisation. However, there are currently no diagnostic inventories for central sensitisation specific to OA. Biomarkers may be helpful for confirming the presence of central sensitisation, especially when there is diagnostic uncertainty. Several non-pharmacological and pharmacological treatments may be effective in OA patients with central sensitisation features. Multimodal therapy may be required to achieve control of symptoms.

DISCUSSION

Clinicians should be aware of central sensitisation in patients with chronic OA pain, especially in patients presenting with severe pain with unusual features.

Do MRI findings identify patients with low back pain or sciatica who respond better to particular interventions? A systematic review

PURPOSE

Magnetic resonance imaging (MRI) can reveal a range of degenerative findings and anatomical abnormalities; however, the clinical importance of these remains uncertain and controversial. We aimed to investigate if the presence of MRI findings identifies patients with low back pain (LBP) or sciatica who respond better to particular interventions.

METHODS

MEDLINE, EMBASE and CENTRAL databases were searched. We included RCTs investigating MRI findings as treatment effect modifiers for patients with LBP or sciatica. We excluded studies with specific diseases as the cause of LBP. Risk of bias was assessed using the criteria of the Cochrane Back Review Group. Each MRI finding was examined for its individual capacity for effect modification.

RESULTS

Eight published trials met the inclusion criteria. The methodological quality of trials was inconsistent. Substantial variability in MRI findings, treatments and outcomes across the eight trials prevented pooling of data. Patients with Modic type 1 when compared with patients with Modic type 2 had greater improvements in function when treated by Diprospan (steroid) injection, compared with saline. Patients with central disc herniation when compared with patients without central disc herniation had greater improvements in pain when treated by surgery, compared with rehabilitation.

CONCLUSIONS

Although individual trials suggested that some MRI findings might be effect modifiers for specific interventions, none of these interactions were investigated in more than a single trial. High quality, adequately powered trials investigating MRI findings as effect modifiers are essential to determine the clinical importance of MRI findings in LBP and sciatica (

PROSPERO

CRD42013006571).

Chronic pain and the thoracic spine

In recent years there has been an increased interest in pain neuroscience in physical therapy.1,2 Emerging pain neuroscience research has challenged prevailing models used to understand and treat pain, including the Cartesian model of pain and the pain gate.2-4 Focus has shifted to the brain's processing of a pain experience, the pain neuromatrix and more recently, cortical reorganisation of body maps.2,3,5,6 In turn, these emerging theories have catapulted new treatments, such as therapeutic neuroscience education (TNE)7-10 and graded motor imagery (GMI),11,12 to the forefront of treating people suffering from persistent spinal pain. In line with their increased use, both of these approaches have exponentially gathered increasing evidence to support their use.4,10 For example, various randomised controlled trials and systematic reviews have shown that teaching patients more about the biology and physiology of their pain experience leads to positive changes in pain, pain catastrophization, function, physical movement and healthcare utilisation.7-10 Graded motor imagery, in turn, has shown increasing evidence to help pain and disability in complex pain states such as complex regional pain syndrome (CRPS).11,12 Most research using TNE and GMI has focussed on chronic low back pain (CLBP) and CRPS and none of these advanced pain treatments have been trialled on the thoracic spine. This lack of research and writings in regards to the thoracic spine is not unique to pain science, but also in manual therapy. There are, however, very unique pain neuroscience issues that skilled manual therapists may find clinically meaningful when treating a patient struggling with persistent thoracic pain. Utilising the latest understanding of pain neuroscience, three key clinical chronic thoracic issues will be discussed - hypersensitisation of intercostal nerves, posterior primary rami nerves mimicking Cloward areas and mechanical and sensitisation issues of the spinal dura in the thoracic spine.

Predictors of response to physical therapy intervention for plantar heel pain

BACKGROUND

Age, weight, and duration of symptoms have been associated with a poor response to treatment for plantar heel pain (PHP), but no studies were identified that examined predictors of response to physical therapy intervention. The purpose of this investigation was to examine the influence of age, body mass index (BMI), and symptom duration on treatment response to physical therapy intervention.

METHODS

Sixty participants received 6 visits over 4 weeks of physical therapy intervention that included manual therapy and exercise or electrophysiological agents and exercise. Outcomes were assessed using the Foot and Ankle Ability Measure (FAAM), Numeric Pain Rating Scale (NPRS), and Global Rating of Change Scale (GRC). Logistic regression (P < .05) was used to analyze age, BMI, and symptom duration as potential predictors of a successful response based on the minimal clinically important difference of the outcome measures. Sensitivity analysis was used to assess the influence of success based on minimal clinically important changes in the FAAM, NPRS, and GRC or only the FAAM and NPRS. Receiver operating curves were used to determine the cut point for the significant predictor.

RESULTS

At the 6-month follow-up to physical therapy intervention, NPRS was improved by 3 points (95% CI, 2.4-3.6) and FAAM improved by 22.5 points (95% CI, 16.8-28.2). Individuals with symptoms less than 7.2 months were 4.2 (95% CI, 1.3-13.8; P = .016) and 8.5 (95% CI, 2.5-28.9; P = .001) times more likely to respond to treatment based on the NPRS/FAAM/GRC and NPRS/FAAM success criteria, respectively. Age and BMI were not significant predictors (P ≥ .455 and P ≥ .450, respectively).

CONCLUSION

Age and BMI were not associated with outcomes and obese individuals did achieve a successful outcome with the physical therapy intervention used in the clinical trial. Individuals with PHP symptoms longer than 7 months require additional consideration and further investigation of effective strategies to improve treatment response.

LEVEL OF EVIDENCE

Prognosis, level 2b comparative study.

Individualized low-load motor control exercises and education versus a high-load lifting exercise and education to improve activity, pain intensity, and physical performance in patients with low back pain: a randomized controlled trial

STUDY DESIGN

Randomized controlled trial.

BACKGROUND

Low back pain is a common disorder. Patients with low back pain frequently have aberrant and pain-provocative movement patterns that often are addressed with motor control exercises.

OBJECTIVE

To compare the effects of low-load motor control (LMC) exercise and those of a high-load lifting (HLL) exercise.

METHODS

Seventy participants with recurrent low back pain, who were diagnosed with nociceptive mechanical pain as their dominating pain pattern, were randomized to either LMC or HLL exercise treatments. Participants were offered 12 treatment sessions over an 8-week period. All participants were also provided with education regarding pain mechanisms.

METHODS

Participants were assessed prior to and following treatment. The primary outcome measures were activity (the Patient-Specific Functional Scale) and average pain intensity over the last 7 days (visual analog scale). The secondary outcome measure was a physical performance test battery that included 1 strength, 3 endurance, and 7 movement control tests for the lumbopelvic region.

RESULTS

Both interventions resulted in significant within-group improvements in pain intensity, strength, and endurance. The LMC group showed significantly greater improvement on the Patient-Specific Functional Scale (4.2 points) compared with the HLL group (2.5 points) (P<.001). There were no significant between-group differences in pain intensity (P=.505), strength, and 1 of the 3 endurance tests. However, the LMC group showed an increase (from 2.9 to 5.9) on the movement control test subscale, whereas the HLL group showed no change (from 3.9 to 3.1) (P<.001).

CONCLUSION

An LMC intervention may result in superior outcomes in activity, movement control, and muscle endurance compared to an HLL intervention, but not in pain intensity, strength, or endurance. Registered at ClinicalTrials.gov (NCT01061632).

LEVEL OF EVIDENCE

Therapy, level 2b-.

Diagnostic accuracy of self-report and subjective history in the diagnosis of low back pain with non-specific lower extremity symptoms: A systematic review

Subjective history questions/self-report items are commonly used to triage the patient with low back pain and related leg symptoms. However the value of the history taking process for decision-making to identify common classifications/diagnosis for patients presenting with low back related leg pain (LBRLP) have not been considered. The purpose of this study was to investigate the diagnostic accuracy of self-report items/history-taking questions used to identify patients with LBRLP. Eligible studies included: 1)subjects with low back pain AND related lower extremity pain, 2)details of subjective examination/self-report items, 3)cohort, prospective/longitudinal studies, and randomized control trials, 4)use of statistical reporting, 5)an acceptable reference standard. Quality was evaluated using the Quality Assessment of Diagnostic Accuracy Studies 2. A synthesis of history items that met the threshold for at least a small shift in the likelihood of the condition with a +LR ≥ 2 or -LR ≤ 0.5 were reported. Conditions commonly reported in the literature: lumbar spinal stenosis, lumbosacral nerve root compression/radiculopathy, disc herniation and neurophysiological low back pain ± leg pain. Eleven studies met the inclusion criteria. This is the first systematic review of diagnostic accuracy studies that examined only the history-taking items for their ability to identify LBRLP conditions. Clustering key items may provide a more precise clinical picture necessary to detect and treat a patient's presentation. History questions formed within the interview and their contributing value for decision-making remain understudied. There is a need for better designs to determine a more accurate diagnostic power to identify conditions with LBRLP.

Management of a patient with chronic low back pain and multiple health conditions using a pain mechanisms-based classification approach

STUDY DESIGN

Case report.

BACKGROUND

Pain can lead to a significant reduction in quality of life. A pain mechanisms-based classification scheme has been outlined to improve management of patients with pain, but studies describing its use are limited. Evidence for physical therapy interventions in those with chronic pain and multiple health conditions is also lacking. This case report describes management of a patient with chronic pain and multiple health conditions.

CASE DESCRIPTION

A 29-year-old man presented with a 3-year history of low back pain and 11-month history of lower extremity paresthesia. Current health conditions included left-sided hemiparesis secondary to a stroke, pancreatic kidney transplant, left-sided blindness, and osteoporosis secondary to hyperparathyroidism. Inability to walk to school and sit through class, and pain-related sleep disruption were the primary activity and participation restrictions. Outcome measures included the numeric pain rating scale, global rating of change, Oswestry Disability Index, and pain medication usage. A score of 12 on the Leeds assessment of neuropathic symptoms and signs (LANSS) pain scale indicated the presence of neuropathic pain, but other pain mechanisms were also hypothesized to be present. Treatment was designed to improve patient goals considering these pain mechanisms.

OUTCOMES

The patient was seen for 20 visits over 6 months. Ten months after the initial evaluation, the patient's Oswestry Disability Index scores improved by more than 50% and the patient achieved all initially stated goals without pain medication.

DISCUSSION

A pain mechanisms-based approach assisted in the management of a patient with chronic pain and multiple health conditions. Using this approach may enhance clinical decision making when managing individuals with chronic pain.

LEVEL OF EVIDENCE

Therapy, level 4.

Untangling nociceptive, neuropathic and neuroplastic mechanisms underlying the biological domain of back pain

SUMMARY Current clinical practice guidelines advocate a model of diagnostic triage for back pain, underpinned by the biopsychosocial paradigm. However, limitations of this clinical model have become apparent: it can be difficult to classify patients into the diagnostic triage categories; patients with ‘nonspecific back pain‘ are clearly not a homogenous group; and mean effects of treatments based on this approach are small. In this article, it is proposed that the biological domain of the biopsychosocial model needs to be reconceptualized using a neurobiological mechanism-based approach. Recent evidence about nociceptive and neuropathic contributors to back pain is outlined in the context of maladaptive neuroplastic changes of the somatosensory system. Implications for clinical practice and research are discussed.

Preclinical studies of low back pain

Chronic low back pain is a major cause of disability and health care costs. Current treatments are inadequate for many patients. A number of preclinical models have been developed that attempt to mimic aspects of clinical conditions that contribute to low back pain. These involve application of nucleus pulposus material near the lumbar dorsal root ganglia (DRG), chronic compression of the DRG, or localized inflammation of the DRG. These models, which are primarily implemented in rats, have many common features including behavioral hypersensitivity of the hindpaw, enhanced excitability and spontaneous activity of sensory neurons, and locally elevated levels of inflammatory mediators including cytokines. Clinically, epidural injection of steroids (glucocorticoids) is commonly used when more conservative treatments fail, but clinical trials evaluating these treatments have yielded mixed results. There are relatively few preclinical studies of steroid effects in low back pain models. One preclinical study suggests that the mineralocorticoid receptor, also present in the DRG, may have pro-inflammatory effects that oppose the activation of the glucocorticoid receptor. Although the glucocorticoid receptor is the target of anti-inflammatory steroids, many clinically used steroids activate both receptors. This could be one explanation for the limited effects of epidural steroids in some patients. Additional preclinical research is needed to address other possible reasons for limited efficacy of steroids, such as central sensitization or presence of an ongoing inflammatory stimulus in some forms of low back pain.

Mechanisms-based classifications of musculoskeletal pain: part 2 of 3: symptoms and signs of peripheral neuropathic pain in patients with low back (± leg) pain

As a mechanisms-based classification of pain 'peripheral neuropathic pain' (PNP) refers to pain arising from a primary lesion or dysfunction in the peripheral nervous system. Symptoms and signs associated with an assumed dominance of PNP in patients attending for physiotherapy have not been extensively studied. The purpose of this study was to identify symptoms and signs associated with a clinical classification of PNP in patients with low back (± leg) pain. Using a cross-sectional, between-subjects design; four hundred and sixty-four patients with low back (± leg) pain were assessed using a standardised assessment protocol. Patients' pain was assigned a mechanisms-based classification based on experienced clinical judgement. Clinicians then completed a clinical criteria checklist specifying the presence or absence of various clinical criteria. A binary logistic regression analysis with Bayesian model averaging identified a cluster of two symptoms and one sign predictive of PNP, including: 'Pain referred in a dermatomal or cutaneous distribution', 'History of nerve injury, pathology or mechanical compromise' and 'Pain/symptom provocation with mechanical/movement tests (e.g. Active/Passive, Neurodynamic) that move/load/compress neural tissue'. This cluster was found to have high levels of classification accuracy (sensitivity 86.3%, 95% CI: 78.0-92.3; specificity 96.0%, 95% CI: 93.4-97.8; diagnostic odds ratio 150.9, 95% CI: 69.4-328.1). Pattern recognition of this empirically-derived cluster of symptoms and signs may help clinicians identify an assumed dominance of PNP mechanisms in patients with low back pain disorders in a way that might usefully inform subsequent patient management.

Mechanisms-based classifications of musculoskeletal pain: part 3 of 3: symptoms and signs of nociceptive pain in patients with low back (± leg) pain

As a mechanisms-based classification of pain 'nociceptive pain' (NP) refers to pain attributable to the activation of the peripheral receptive terminals of primary afferent neurones in response to noxious chemical, mechanical or thermal stimuli. The symptoms and signs associated with clinical classifications of NP have not been extensively studied. The purpose of this study was to identify symptoms and signs associated with a clinical classification of NP in patients with low back (± leg) pain. Using a cross-sectional, between-subjects design; four hundred and sixty-four patients with low back (± leg) pain were assessed using a standardised assessment protocol after which their pain was assigned a mechanisms-based classification based on experienced clinical judgement. Clinicians then completed a clinical criteria checklist indicating the presence/absence of various symptoms and signs. A regression analysis identified a cluster of seven clinical criteria predictive of NP, including: 'Pain localised to the area of injury/dysfunction', 'Clear, proportionate mechanical/anatomical nature to aggravating and easing factors', 'Usually intermittent and sharp with movement/mechanical provocation; may be a more constant dull ache or throb at rest', and the absence of 'Pain in association with other dysesthesias', 'Night pain/disturbed sleep', 'Antalgic postures/movement patterns' and 'Pain variously described as burning, shooting, sharp or electric-shock-like'. This cluster was found to have high levels of classification accuracy (sensitivity 90.9%, 95% CI: 86.6-94.1; specificity 91.0%, 95% CI: 86.1-94.6). Pattern recognition of this empirically-derived cluster of symptoms and signs may help clinicians identify an assumed dominance of NP mechanisms in patients with low back pain disorders.