An experimental pain model to investigate the specificity of the neurodynamic test for the median nerve in the differential diagnosis of hand symptoms

Current and future utility of ultrasound imaging in upper extremity musculoskeletal rehabilitation: A scoping review

STUDY DESIGN

This study was a scoping review.

BACKGROUND

Continued advances in musculoskeletal sonography technology and access have increased the feasibility of point-of-care use to support day-to-day clinical care and decision-making. Sonography can help improve therapeutic outcomes in upper extremity (UE) rehabilitation by enabling clinicians to visualize underlying structures during treatment.

PURPOSE OF THE STUDY

This study aimed to (1) evaluate the growth, range, extent, and composition of sonography literature supporting UE rehabilitation; (2) identify trends, gaps, and opportunities with regard to anatomic areas and diagnoses examined and ultrasound techniques used; and (3) evaluate potential research and practice utility.

METHODS

Searches were completed in PubMed, CINAHL, SPORTDiscus, PsycINFO, and BIOSIS. We included data-driven articles using ultrasound imaging for upper extremity structures in rehabilitation-related conditions. Articles directly applicable to UE rehabilitation were labeled direct articles, while those requiring translation were labeled indirect articles. Articles were further categorized by ultrasound imaging purpose. Article content between the two groups was descriptively compared, and direct articles underwent an evaluation of evidence levels and narrative synthesis to explore potential clinical utility.

RESULTS

Average publication rates for the final included articles (n = 337) steadily increased. Indirect articles (n = 288) used sonography to explore condition etiology, assess measurement properties, inform medical procedure choice, and grade condition severity. Direct articles (n = 49) used sonography to assess outcomes, inform clinical reasoning, and aid intervention delivery. Acute UE conditions and emerging sonography technology were rarely examined, while tendon, muscle, and soft tissue conditions and grayscale imaging were common. Rheumatic and peripheral nerve conditions and Doppler imaging were more prevalent in indirect than direct articles. Among reported sonography service providers, there was a high proportion of nonradiologist clinicians.

CONCLUSION

Sonography literature for UE rehabilitation demonstrates potential utility in evaluating outcomes, informing clinical reasoning, and assisting intervention delivery. A large peripheral knowledge base provides opportunities for clinical applications; however, further research is needed to determine clinical efficacy and impact for specific applications.

Patient expectations about a clinical diagnostic test may influence the clinician's test interpretation

BACKGROUND

With medical information widely available, patients often have preconceived ideas regarding diagnostic procedures and management strategies.

OBJECTIVES

To investigate whether expectations, such as beliefs about the source of symptoms and knowledge about diagnostic tests, influence pain perception during a clinical diagnostic test.

DESIGN

Cross-sectional study.

METHODS

Pain was induced by intramuscular hypertonic saline infusion in the thenar muscles. In line with sample size calculations, fifteen participants were included. All participants received identical background information regarding basic median nerve biomechanics and basic concepts of differential diagnosis via mechanical loading of painful structures. Based on different explanations about the origin of their induced pain, half of the participants believed (correctly) they had 'muscle pain' and half believed (incorrectly) they had 'nerve pain'. Pain intensity and size of the painful area were evaluated in five different positions of the median nerve neurodynamic test (ULNT1 _MEDIAN). Data were analysed with two-way analyses of variance.

RESULTS

/findings: Changes in pain in the ULNT1 _MEDIAN positions were different between the 'muscle pain' and 'nerve pain' group (p < 0.001). In line with their expectations, the 'muscle pain' group demonstrated no changes in pain throughout the test (p > 0.38). In contrast, pain intensity (p ≤ 0.003) and size of the painful area (p ≤ 0.03) increased and decreased in the 'nerve pain' group consistent with their expectations and the level of mechanical nerve loading.

CONCLUSION

Pain perception during a clinical diagnostic test may be substantially influenced by pain anticipation. Moreover, pain was more aligned with beliefs and expectations than with the actual pathobiological process.

Normal response to tibial neurodynamic test in asymptomatic subjects

BACKGROUND

The straight leg raise test (SLR) is one of the most performed physical tests for mechanosensitivity and impairment of the nervous system. According to the anatomy of the tibial nerve, ankle dorsiflexion and eversion movements could be used to perform the tibial neurodynamic test (TNT). To date, no study has documented the normal responses of the TNT.

OBJECTIVE

To document normal responses of the TNT in asymptomatic individuals and to investigate influences from sex and leg dominance.

METHODS

A cross-sectional study with 44 asymptomatic volunteer subjects, a total of 88 lower limbs, was carried out. The range of motion (ROM), quality, and distribution of sensory responses were recorded. The hip flexion ROM was measured when subjects reported an intensity of their symptoms of 2/10 (P1) and 8/10 (P2).

RESULTS

The mean ROM for hip flexion at P1 was 44.22 ± 13.13∘ and 66.73 ± 14.30∘ at P2. Hip flexion was significantly greater at P2 than P1 (p< 0.001). However, it was not different between sex or limbs (p> 0.05). The descriptor of the quality of sensory responses most often used by participants was stretching (88.6% and 87.5% for P1 and P2, respectively) in the popliteal fossa and posterior calf.

CONCLUSIONS

This study describes the sensory responses of asymptomatic subjects resulting from the TNT. Our findings indicate that TNT responses are independent of the influence of sex or leg dominance.

Effects of Diacutaneous Fibrolysis on Mechanosensitivity, Disability, and Nerve Conduction Studies in Mild to Moderate Carpal Tunnel Syndrome: Secondary Analysis of a Randomized Controlled Trial

OBJECTIVE

People diagnosed with carpal tunnel syndrome (CTS) have fibrosis between the soft, connective, and neural tissues that could worsen the compression of the median nerve. The diacutaneous fibrolysis (DF) technique may release tissue adhesions and increase the mobility of connective tissues. The purpose of this study was to compare the outcomes of DF in people with mild to moderate CTS on mechanosensitivity, disability, and nerve conduction studies.

METHODS

This was a secondary analysis of a double-blinded, randomized, placebo-controlled trial. Patients were recruited between April and September 2016 from the Department of Neurophysiology at the Hospital Miguel Servet, Zaragoza, Spain. Thirty-nine people (52 wrists) diagnosed with mild to moderate CTS were included. Participants were randomly assigned to either the DF group (n = 26) or the sham group (n = 26). Both groups received 5 therapy sessions, 2 sessions per week. Mechanosensitivity with the Upper Limb Neurodynamic Test 1, symptom severity and functional status with the Boston Carpal Tunnel Questionnaire, and median nerve sensory conduction velocity with nerve conduction studies were the outcomes measured. Assessments were recorded at baseline and after the intervention.

RESULTS

The DF group showed significant improvements in the following: mechanosensitivity, with 28.46 degrees of elbow extension range of motion (95% CI = 19.2-37.7); an increase of 1.0 point (95% CI = 0.7-1.4) for the Boston Carpal Tunnel Questionnaire symptom severity and functional status score; and sensory conduction velocity of median nerve, which improved to 5.8 m/s (95% CI = 2.5-9.2).

CONCLUSION

Participants with mild to moderate CTS experienced improvements in symptom severity, functional status, mechanosensitivity, and nerve conduction studies after 5 sessions of DF.

IMPACT

This study provides evidence of an approach based on soft and connective tissues around the median nerve in patients with CTS.

Acute experimentally-induced pain replicates the distribution but not the quality or behaviour of clinical appendicular musculoskeletal pain. A systematic review

OBJECTIVES

Experimental pain is a commonly used method to draw conclusions about the motor response to clinical musculoskeletal pain. A systematic review was performed to determine if current models of acute experimental pain validly replicate the clinical experience of appendicular musculoskeletal pain with respect to the distribution and quality of pain and the pain response to provocation testing.

METHODS

A structured search of Medline, Scopus and Embase databases was conducted from database inception to August 2020 using the following key terms: "experimental muscle pain" OR "experimental pain" OR "pain induced" OR "induced pain" OR "muscle hyperalgesia" OR ("Pain model" AND "muscle"). Studies in English were included if investigators induced experimental musculoskeletal pain into a limb (including the sacroiliac joint) in humans, and if they measured and reported the distribution of pain, quality of pain or response to a provocation manoeuvre performed passively or actively. Studies were excluded if they involved prolonged or delayed experimental pain, if temporomandibular, orofacial, lumbar, thoracic or cervical spine pain were investigated, if a full text of the study was not available or if they were systematic reviews. Two investigators independently screened each title and abstract and each full text paper to determine inclusion in the review. Disagreements were resolved by consensus with a third investigator.

RESULTS

Data from 57 experimental pain studies were included in this review. Forty-six of these studies reported pain distribution, 41 reported pain quality and six detailed the pain response to provocation testing. Hypertonic saline injection was the most common mechanism used to induce pain with 43 studies employing this method. The next most common methods were capsaicin injection (5 studies) and electrical stimulation, injection of acidic solution and ischaemia with three studies each. The distribution of experimental pain was similar to the area of pain reported in clinical appendicular musculoskeletal conditions. The quality of appendicular musculoskeletal pain was not replicated with the affective component of the McGill Pain Questionnaire consistently lower than that typically reported by musculoskeletal pain patients. The response to provocation testing was rarely investigated following experimental pain induction. Based on the limited available data, the increase in pain experienced in clinical populations during provocative maneuvers was not consistently replicated.

CONCLUSIONS

Current acute experimental pain models replicate the distribution but not the quality of chronic clinical appendicular musculoskeletal pain. Limited evidence also indicates that experimentally induced acute pain does not consistently increase with tests known to provoke pain in patients with appendicular musculoskeletal pain. The results of this review question the validity of conclusions drawn from acute experimental pain studies regarding changes in muscle behaviour in response to pain in the clinical setting.

Effect of cervical contralateral lateral flexion on displacement and strain in the median nerve and flexor digitorum superficialis at the wrist during the ULNT1 - Cadaveric study

INTRODUCTION

A key issue in neurodynamic testing is whether a manoeuvre designed to produce differential biomechanical behaviour (structural differentiation) of nerve compared to adjacent muscle is mechanically accurate. The aim of this study was to investigate the capacity of cervical contralateral lateral flexion to produce differential biomechanical behaviour of the median nerve at the wrist (mechanical specificity) in relation to the adjacent muscle (flexor digitorum superficialis) at different ranges of upper limb neurodynamic test 1 in cadavers.

MATERIAL AND METHODS

A cross-sectional study was carried out. In fresh frozen cadavers, with microstrain devices and Vernier calipers, strain and excursion in the median nerve and flexor digitorum superficialis muscle were measured during cervical contralateral lateral flexion at 0°, 30°, 60° and 90° of elbow flexion of the upper limb neurodynamic test 1.

RESULTS

The cervical movement resulted in proximal excursion and significant changes in strain in the median nerve at 0°, 30° and 60° of elbow flexion during the upper limb neurodynamic test 1 (p < 0.05). In contrast, the structural differentiation manoeuvre did not affect the strain nor the excursion in the muscle at any position of the elbow (p > 0.05).

CONCLUSION

Adding CCLF to each ULNT1 median elbow angle increased strain and created proximal excursion of the median nerve at the wrist. Neck movement produced no changes in strain nor excursion of the flexor digitorum superficialis. This study adds to evidence that, in certain circumstances, neck movement may be used in differentiation of nerve and muscle disorders in the wrist.

Effect of ankle dorsiflexion on displacement and strain in the tibial nerve and biceps femoris muscle at the posterior knee during the straight leg raise: Investigation of specificity of nerve movement

BACKGROUND

A structural differentiation maneuver has been proposed to differentiate between muscle and nerve involvement during the straight leg raise test. However, to date, the mechanical specificity of this maneuver for the tibial nerve at the posterior knee has not been tested. The aim of this study was to investigate the specificity of ankle dorsiflexion as a differentiation maneuver between the tibial nerve and the biceps femoris muscle at the posterior knee during the straight leg raise in cadavers.

METHODS

A cross-sectional study was carried out. In fresh frozen cadavers, with microstrain devices and Vernier calipers, strain and excursion in the tibial nerve and distal biceps femoris muscle were measured during ankle dorsiflexion at 0°, 30°, 60° and 90° of hip flexion of the straight leg raise.

FINDINGS

Ankle dorsiflexion resulted in significant distal excursion and increased strain in the tibial nerve (p < 0.05) whilst the muscle was not affected by the dorsiflexion (p > 0.05) at all hip flexion angles.

INTERPRETATION

Ankle dorsiflexion was mechanically specific between the tibial nerve and biceps femoris during the straight leg raise. This study adds to evidence that, in certain circumstances, dorsiflexion may be used in differentiation of nerve and muscle disorders in the posterior knee.

Differential movement of the sciatic nerve and hamstrings during the straight leg raise with ankle dorsiflexion: Implications for diagnosis of neural aspect to hamstring disorders

INTRODUCTION

In hamstrings injuries, sciatic nerve and muscle disorders can coexist. Therefore, differential diagnosis to include or exclude nerve involvement is an important aspect of evaluation. The objective of this paper is to investigate the mechanical behaviour of the sciatic nerve and biceps femoris muscle in the proximal thigh with the ankle dorsiflexion manoeuvre at different degrees of hip flexion during the straight leg raise in cadavers.

MATERIAL AND METHODS

A cross-sectional study was carried out. Linear displacement transducers were inserted into the sciatic nerve and the biceps femoris muscle of 11 lower extremities from 6 fresh cadavers to measure potential strain of both structures during ankle dorsiflexion at 0°, 30°, 60° and 90° of hip flexion during the straight leg raise. Excursion was also measured with a digital calliper.

RESULTS

Ankle dorsiflexion resulted in significant strain and distal excursion of the sciatic nerve at all ranges of hip flexion during the straight leg raise (p < 0.05). In contrast, the ankle movement did not affect the strain in biceps femoris at any position of the hip (p > 0.05).

CONCLUSION

Ankle dorsiflexion at different degrees of hip flexion during the straight leg raise produces changes in the strain and excursion of the sciatic nerve in the upper thigh. In contrast, the biceps femoris muscle at the same location was not affected by ankle movement. These findings show differential behaviour between the nerve and muscle with ankle dorsiflexion at this location that could be used as differential diagnosis in posterior hip pain.

Effect of neurodynamic mobilization on fluid dispersion in median nerve at the level of the carpal tunnel: A cadaveric study

OBJECTIVES

To evaluate the effect of neurodynamics mobilization (NDM) on an artificially induced edema in the median nerve at the level of the carpal tunnel in unembalmed cadavers and to assess whether NDM tensioning techniques (TT) and NDM sliding techniques (SLT) induce similar effects on intraneural fluid dispersion.

DESIGN

Fourteen upper extremities of seven unembalmed cadavers were used in this study. A biomimetic solution was injected directly under the epineurium of the median nerve at the level of the proximal transverse carpal ligament. The initial dye spread was allowed to stabilize and measured with a digital caliper. Tensioning and sliding techniques were applied following a randomized crossover design to each upper extremity and were performed for a total of 5 min each. Post-intervention dye spread measurements were taken after each technique.

RESULTS

After the first mobilization, the mean longitudinal dye spread (7.5 ± 6.6 mm) was significantly greater (p = 0.024) compared to the stabilized dye spread. There was a significant longitudinal diffusion effect with both, TT (p = 0.018) and SLT (p = 0.016), with no statistically significant difference between techniques (p = 0.976). The order in which techniques were administered did not influence the diffusion.

CONCLUSION

Five minute of passive NDM in the form of tensioning or sliding technique induced significant fluid dispersion in the median nerve at the carpal tunnel of unembalmed human cadavers. This study provides support for clinical mechanism of NDM in reducing intraneural edema.

Differences in Neural Mechanosensitivity Between Patients with Chronic Nonspecific Neck Pain With and Without Neuropathic Features. A Descriptive Cross-Sectional Study

OBJECTIVE

To assess differences in neural mechanosensitivity between patients with chronic nonspecific neck pain with and without neuropathic features (NF and No-NF, respectively).

DESIGN

Descriptive, cross-sectional study.

SETTING

A primary care center, a hospital physiotherapy outpatient department, and a university campus.

SUBJECTS

Chronic nonspecific neck pain patients classified by the self-completed leeds assessment of neuropathic symptoms and signs pain scale (S-LANSS; 49 patients with NF [S-LANSS ≥ 12] and 50 patients with No-NF [S-LANSS < 12]) and a healthy control group (n = 48).

METHODS

The primary measurements were the mechanosensitivity of the median nerve and cervical region, specifically the assessment of the onset of symptoms and submaximal pain intensity according to the upper limb neural test 1 (ULNT1) for the median nerve and the modified passive neck flexion test (MPNFT) for the cervical region; secondary measurements included pain intensity, neck disability, kinesiophobia, and pain catastrophizing.

RESULTS

Statistically significant differences between the NF and No-NF groups were found with respect to the onset of symptoms of ULNT1 (-15.11 [-23.19 to -7.03]) and MPNFT (-6.58 [-11.54 to -1.62]), as well as the outcomes of the visual analogue scale (Mean difference [95% Confidence Interval]; 7.12 [1.81-12.42]) and neck disability index (3.72 [1.72-5.71]). Both chronic nonspecific neck pain groups showed statistically significant differences compared with the control group for all outcomes assessed (P < 0.01) except for the onset of symptoms of ULNT1 in the No-NF group.

CONCLUSIONS

The findings of this study suggest that chronic nonspecific neck pain patients with NF have greater neural mechanosensitivity, pain intensity, and neck disability than those with No-NF.

Upper Limb Neurodynamic Test 1 on Healthy Individuals: Intra- and Intersession Reliability of the Angle between Pain Onset and Submaximal Pain

Assessment of nerve trunk mechanosensitivity using the upper limb neurodynamic test 1 (ULNT1) often includes measurement of the angle of occurrence in the range of pain onset (PO) and submaximal pain (SP). A measurement that better fits the idea of mechanosensitivity could be the angle between PO and SP (AbOS). This study investigated the intra- and intersession reliability of AbOS, PO, and SP during the ULNT1. Forty-four healthy volunteers underwent three ULNT1 to the point of PO and SP, twice in the first session and once in the second. AbOS, PO, and SP angles of occurrence reliability were examined using the Intraclass Correlation Coefficient (ICC 3,1) and Bland-Altman plots. The intra- and intersession ICC values for AbOS were 0.71 (95% CI: 0.47; 0.85) and 0.79 (95% CI: 0.60; 0.89), respectively. The intra- and intersession mean difference and 95% limits of agreement (±1.96 SD) in the Bland-Altman plots were 2.3° (-18.3°; 23.1°) and 2.8° (-14.7°; 20.4°), respectively. The intra- and intersession reliability of the AbOS during the ULNT1 in healthy individuals is high and higher than the reliability of PO and SP angles of occurrence. The AbOS could be a preferable variable in the assessment of neural mechanosensitivity.

Intrarater Agreement of Elbow Extension Range of Motion in the Upper Limb Neurodynamic Test 1 Using a Smartphone Application

OBJECTIVE

To estimate the intrarater agreement of the Compass application of a smartphone in the assessment of elbow extension range of motion (EE-ROM) at pain onset and maximum tolerable point during the Upper Limb Neurodynamic Test 1 (ULNT1).

DESIGN

Within-day intrarater agreement study.

SETTING

Private and university clinical settings.

PARTICIPANTS

Volunteers (N=41; 21 men; age, 31.34±13.27y; height, 1.67±0.07m; body mass, 70.53±12.37kg) recruited from the community, with no symptoms or musculoskeletal abnormalities in their upper body quadrant and no regional or systemic nerve dysfunction.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Ninety-five percent limits of agreement (LOA), standard error of the measurement, and minimal detectable change at the 95% confidence level (MDC₉₅) of EE-ROM at pain onset and maximum tolerable point during the ULNT1.

RESULTS

Standard error of the measurement and MDC₉₅ were relatively high on both sides when considering the onset of pain (standard error of the measurement, 6.6°-6.8°; MDC₉₅, 18.4°-18.8°). Better results were found for the maximum tolerable point (standard error of the measurement, 4.2°-4.8°; MDC₉₅, 11.7°-13.2°). The 95% LOA showed a similar trend.

CONCLUSIONS

Smartphone measurements showed relatively wide agreement parameters of elbow extension during the ULNT1. These results are, nevertheless, comparable with previous studies using goniometric assessment when considering maximal pain tolerance. Further research is needed before the possible widespread use of the smartphone in neurodynamic assessment.

New Insight into the Time-Course of Motor and Sensory System Changes in Pain

Background

Pain-related interactions between primary motor (M1) and primary sensory (S1) cortex are poorly understood. In particular, the time-course over which S1 processing and corticomotor output are altered in association with muscle pain is unclear. We aimed to examine the temporal profile of altered processing in S1 and altered corticomotor output with finer temporal resolution than has been used previously.

Methods

In 10 healthy individuals we recorded somatosensory evoked potentials (SEPs) and motor evoked potentials (MEPs) in separate sessions at multiple time-points before, during and immediately after pain induced by hypertonic saline infusion in a hand muscle, and at 15 and 25 minutes follow-up.

Results

Participants reported an average pain intensity that was less in the session where SEPs were recorded (SEPs: 4.0±1.6; MEPs: 4.9±2.3). In addition, the time taken for pain to return to zero once infusion of hypertonic saline ceased was less for participants in the SEP session (SEPs: 4.7±3.8 mins; MEPs 9.4±7.4 mins). Both SEPs and MEPs began to reduce almost immediately after pain reached 5/10 following hypertonic saline injection and were significantly reduced from baseline by the second (SEPs) and third (MEPs) recording blocks during pain. Both parameters remained suppressed immediately after pain had resolved and at 15 and 25 minutes after the resolution of pain.

Conclusions

These data suggest S1 processing and corticomotor output may be co-modulated in association with muscle pain. Interestingly, this is in contrast to previous observations. This discrepancy may best be explained by an effect of the SEP test stimulus on the corticomotor pathway. This novel finding is critical to consider in experimental design and may be potentially useful to consider as an intervention for the management of pain.

Exogenously applied muscle metabolites synergistically evoke sensations of muscle fatigue and pain in human subjects

NEW FINDINGS

What is the central question of this study? Can physiological concentrations of metabolite combinations evoke sensations of fatigue and pain when injected into skeletal muscle? If so, what sensations are evoked? What is the main finding and its importance? Low concentrations of protons, lactate and ATP evoked sensations related to fatigue. Higher concentrations of these metabolites evoked pain. Single metabolites evoked no sensations. This suggests that the combination of an ASIC receptor and a purinergic P2X receptor is required for signalling fatigue and pain. The results also suggest that two types of sensory neurons encode metabolites; one detects low concentrations of metabolites and signals sensations of fatigue, whereas the other detects higher levels of metabolites and signals ache and hot. The perception of fatigue is common in many disease states; however, the mechanisms of sensory muscle fatigue are not understood. In mice, rats and cats, muscle afferents signal metabolite production in skeletal muscle using a complex of ASIC, P2X and TRPV1 receptors. Endogenous muscle agonists for these receptors are combinations of protons, lactate and ATP. Here we applied physiological concentrations of these agonists to muscle interstitium in human subjects to determine whether this combination could activate sensations and, if so, to determine how the subjects described these sensations. Ten volunteers received infusions (0.2 ml over 30 s) containing protons, lactate and ATP under the fascia of a thumb muscle, abductor pollicis brevis. Infusion of individual metabolites at maximal amounts evoked no fatigue or pain. Metabolite combinations found in resting muscles (pH 7.4 + 300 nm ATP + 1 mm lactate) also evoked no sensation. The infusion of a metabolite combination found in muscle during moderate endurance exercise (pH 7.3 + 400 nm ATP + 5 mm lactate) produced significant fatigue sensations. Infusion of a metabolite combination associated with vigorous exercise (pH 7.2 + 500 nm ATP + 10 mm lactate) produced stronger sensations of fatigue and some ache. Higher levels of metabolites (as found with ischaemic exercise) caused more ache but no additional fatigue sensation. Thus, in a dose-dependent manner, intramuscular infusion of combinations of protons, lactate and ATP leads to fatigue sensation and eventually pain, probably through activation of ASIC, P2X and TRPV1 receptors. This is the first demonstration in humans that metabolites normally produced by exercise act in combination to activate sensory neurons that signal sensations of fatigue and muscle pain.

Interventions in the disturbances in the motor and sensory environment

Treatment of peripheral nervous system (PNS) pathology presents intervention challenges to every therapist. Many of the current and future interventions will be directed at restoring the normal anatomy, function, and biomechanical properties of the PNS, restoring normal neural physiology and ultimately patient function and quality of life. Present interventions use mechanical (movement) or electrical procedures to affect various properties of the peripheral nerve. The purpose of this article was to apply basic science to clinical practice. The pathology and accompanying structural and biomechanical changes in the PNS will be presented in three specific areas commonly encountered in the clinic: nerve injury and laceration; compression neuropathies; and neuropathic pain and neural tension dysfunction. The intent is to address possible interventions exploring the clinical reasoning process that combines basic science and evidence-based best practice. The current lack of literature to support any one intervention requires a strong foundation and understanding of the PNSs' structure and function to refine current and develop new intervention strategies. Current evidence will be presented and linked with future considerations for intervention and research. During this interlude of development and refinement, best practice will rely on sound clinical reasoning skills that incorporate basic science to achieve a successful outcome when treating these challenging patients.

Quantitative sensory testing somatosensory profiles in patients with cervical radiculopathy are distinct from those in patients with nonspecific neck-arm pain

The aim of this study was to establish the somatosensory profiles of patients with cervical radiculopathy and patients with nonspecific neck-arm pain associated with heightened nerve mechanosensitivity (NSNAP). Sensory profiles were compared to healthy control (HC) subjects and a positive control group comprising patients with fibromyalgia (FM). Quantitative sensory testing (QST) of thermal and mechanical detection and pain thresholds, pain sensitivity and responsiveness to repetitive noxious mechanical stimulation was performed in the maximal pain area, the corresponding dermatome and foot of 23 patients with painful C6 or C7 cervical radiculopathy, 8 patients with NSNAP in a C6/7 dermatomal pain distribution, 31 HC and 22 patients with FM. For both neck-arm pain groups, all QST parameters were within the 95% confidence interval of HC data. Patients with cervical radiculopathy were characterised by localised loss of function (thermal, mechanical, vibration detection P<.009) in the maximal pain area and dermatome (thermal detection, vibration detection, pressure pain sensitivity P<.04), consistent with peripheral neuronal damage. Both neck-arm pain groups demonstrated increased cold sensitivity in their maximal pain area (P<.03) and the foot (P<.009), and this was also the dominant sensory characteristic in patients with NSNAP. Both neck-arm pain groups differed from patients with FM, the latter characterised by a widespread gain of function in most nociceptive parameters (thermal, pressure, mechanical pain sensitivity P<.027). Despite commonalities in pain characteristics between the 2 neck-arm pain groups, distinct sensory profiles were demonstrated for each group.

Common interlimb asymmetries and neurogenic responses during upper limb neurodynamic testing: implications for test interpretation

STUDY DESIGN

Clinical measurement pilot study.

INTRODUCTION

Upper limb neurodynamic testing (ULNT1) uses interlimb comparisons to investigate nerve sensitivity to movement.

PURPOSE OF THE STUDY

To establish the magnitude of range of motion asymmetries between limbs and the frequency of neurogenic sensory responses during ULNT1.

METHODS

Elbow extension range of motion (EE-ROM) and sensory responses were measured during ULNT1 in dominant and nondominant limbs for 40 asymptomatic participants. Structural differentiation was performed to examine if sensory responses were associated with neurogenic sources.

RESULTS

The average intraindividual EE-ROM asymmetry was 7.28 deg (6.68 standard deviation) (95% confidence interval: 5.18, 9.28). Sensory responses in the limbs during ULNT1 were altered by structural differentiation in 95% of participants. An intraindividual, interlimb difference of ≥10 deg exceeds the range of common asymmetry during ULNT1.

CONCLUSIONS

Neurogenic sensory responses are common findings in healthy individuals and should be acknowledged when interpreting ULNT1 findings.

LEVEL OF EVIDENCE

3a.

The validity of upper-limb neurodynamic tests for detecting peripheral neuropathic pain

The validity of upper-limb neurodynamic tests (ULNTs) for detecting peripheral neuropathic pain (PNP) was assessed by reviewing the evidence on plausibility, the definition of a positive test, reliability, and concurrent validity. Evidence was identified by a structured search for peer-reviewed articles published in English before May 2011. The quality of concurrent validity studies was assessed with the Quality Assessment of Diagnostic Accuracy Studies tool, where appropriate. Biomechanical and experimental pain data support the plausibility of ULNTs. Evidence suggests that a positive ULNT should at least partially reproduce the patient's symptoms and that structural differentiation should change these symptoms. Data indicate that this definition of a positive ULNT is reliable when used clinically. Limited evidence suggests that the median nerve test, but not the radial nerve test, helps determine whether a patient has cervical radiculopathy. The median nerve test does not help diagnose carpal tunnel syndrome. These findings should be interpreted cautiously, because diagnostic accuracy might have been distorted by the investigators' definitions of a positive ULNT. Furthermore, patients with PNP who presented with increased nerve mechanosensitivity rather than conduction loss might have been incorrectly classified by electrophysiological reference standards as not having PNP. The only evidence for concurrent validity of the ulnar nerve test was a case study on cubital tunnel syndrome. We recommend that researchers develop more comprehensive reference standards for PNP to accurately assess the concurrent validity of ULNTs and continue investigating the predictive validity of ULNTs for prognosis or treatment response.

Muscle pain differentially modulates short interval intracortical inhibition and intracortical facilitation in primary motor cortex

Excitability of the motor cortex can be suppressed during muscle pain. Yet the mechanisms are largely unknown. Short interval intracortical inhibition (SICI) and intracortical facilitation (ICF) were examined as possible candidate mechanisms to underpin this change. SICI and ICF were investigated in 11 healthy individuals before, during and after infusion of hypertonic saline into right first dorsal interosseous (FDI). Using paired-pulse transcranial magnetic stimulation (TMS), interstimulus intervals of 2, 3, and 13 ms were investigated. Pain intensity and quality were recorded using a 10-cm visual analogue scale and the McGill Pain Questionnaire. Resting motor threshold and motor-evoked potentials (MEPs) to single TMS stimuli were recorded before and after pain. Electromyographic recordings were made from right FDI and abductor digiti minimi. Participants reported an average pain intensity of 5.8 (1.6) cm. MEP amplitudes decreased in both muscles. Compared with the pre-pain condition, SICI was increased following pain, but not during. ICF was decreased both during and after pain when compared with the pre-pain condition. These findings suggest that muscle pain differentially modulates SICI and ICF. Although the functional relevance is unknown, we hypothesize decreased facilitation and increased inhibition may contribute to the restriction of movement of a painful body part.

PERSPECTIVE

This article provides evidence for decreased intracortical facilitation and increased short interval intracortical inhibition in response to muscle pain. This finding is relevant to clinicians as a mechanism which may underlie restricted movement in acute and chronic pain.

Upper Limb Neurodynamic Test 1 and symptoms reproduction in carpal tunnel syndrome. A validity study

The aim of this study was to estimate the validity of the Upper Limb Neurodynamic Test 1 (ULNT1) for the diagnosis of Carpal Tunnel Syndrome (CTS) with blind comparison to a reference criterion of a compatible clinical presentation and abnormal nerve conduction. 47 subjects with suspected CTS were enrolled. All patients were tested with nerve conduction studies and ULNT1. Considering results as positive in the presence of reproduction of symptoms on affected upper limb, or side-to-side differences in elbow extension, or symptoms modified by lateral neck side-bending, we estimated sensitivity as 91.67%, specificity as 15%, positive likelihood ratio as 1.0784, negative likelihood ratio as 0.5556, and post-test probability for negative test as 40%. Using a new criterion, i.e. the reproduction of symptoms only in the first three digits of the affected hand, we estimated sensitivity as 54.17%, specificity as 70%, positive and negative likelihood ratios as 1.8056 and 0.6548, respectively, and post-test probability for positive test as 68%. Our investigation suggests that the reproduction of the typical current CTS symptoms in the affected hand during ULNT1 testing, improves estimation of the probability of the presence of this condition, even if this test alone cannot be used to diagnose CTS.

Screening for head, neck, and shoulder pathology in patients with upper extremity signs and symptoms

NARRATIVE REVIEW: Conditions of the head, neck, thorax, and shoulder may occur simultaneously with arm pathology or produce symptoms perceived by the patient to originate in the elbow, wrist, or hand. Identification of the tissue disorder and associated impairments, followed by matching the rehabilitative intervention to address these issues, leads to optimal outcomes. With this goal in mind, the hand therapist needs to recognize clinical findings that signal potentially serious medical conditions of the brain, cervical region, chest, or shoulder. Additionally, less serious but potentially debilitating, musculoskeletal or neurogenic pain from proximal sources must also be differentiated from somatic pain originating in the elbow, wrist, or hand so that the clinician can decide to further examine and intervene or refer to an appropriate health care provider. This article describes clinical findings that suggest the presence of serious medical pathology in the head, neck, or thorax and presents a screening algorithm to assist in discriminating pain derived from local structures in the distal arm from referred pain originating in the more proximal regions of the shoulder, thorax, neck, or brain.

LEVEL OF EVIDENCE

5.

An investigation of somatosensory profiles in work related upper limb disorders: a case-control observational study protocol

Background

Work related upper limb disorders constitute 45% of all occupational diseases and are a significant public health problem. A subgroup, non specific arm pain (NSAP), remains elusive in terms of understanding its pathophysiological mechanisms with its diagnosis based on the absence of specific clinical findings. One commonly proposed theory is that a neural tissue disorder is the primary dysfunction in NSAP and findings from previous studies lend some support to this theory. However, it is not clear if changes identified are simply a consequence of ongoing pain rather than due to specific neural changes. The presence of neuropathic pain has been investigated in several other musculoskeletal conditions but currently, there is no specific diagnostic tool or gold standard which permits an unequivocal diagnosis of neuropathic pain. The purpose of this study is to further describe the somatosensory profiles in patients with NSAP and to compare these profiles to a group of patients with MRI confirmed cervical radiculopathy who have been previously classified as having neuropathic pain.

Methods/Design

Three groups of participants will be investigated: Groups 1 and 2 will be office workers with either NSAP or cervical radiculopathy and Group 3 will be a control group of non office workers without upper limb pain. Participants will undergo a clinical assessment, pain questionnaires (LANSS, Short Form McGill, DASH and TSK) and quantitative sensory testing comprising thermal detection and pain thresholds, vibration thresholds and pressure pain thresholds.

Discussion

The spectrum of clinically suspected neuropathic pain ranges from more obvious conditions such as trigeminal neuralgia to those with vague signs of nerve disorder such as NSAP. A thorough description of the somatosensory profiles of NSAP patients and a comparison with a more defined group of patients with evidence of neuropathic pain will help in the understanding of underlying neurophysiology in NSAP and may influence future classification and intervention studies relating to this condition.

Effects of upper extremity neural mobilization on thermal pain sensitivity: a sham-controlled study in asymptomatic participants

STUDY DESIGN

A single-blinded, quasi-experimental, within- and between-sessions assessment.

OBJECTIVES

To investigate potential mechanisms of neural mobilization (NM), using tensioning techniques in comparison to sham NM on a group of asymptomatic volunteers between the ages of 18 and 50.

BACKGROUND

NM utilizing tensioning techniques is used by physical therapists in the treatment of patients with cervical and/or upper extremity symptoms. The underlying mechanisms of potential benefits associated with NM tensioning techniques are unknown.

METHODS AND MEASURES

Participants (n = 62) received either a NM or sham NM intervention 2 to 3 times a week for a total of 9 sessions, followed by a 1-week period of no intervention to assess carryover effects. A-delta (first pain response) and C-fiber (temporal summation) mediated pain perceptions were tested via thermal quantitative sensory testing procedures. Elbow extension range of motion (ROM) and sensory descriptor ratings were obtained during a neurodynamic test for the median nerve. Data were analyzed with repeated-measures analysis of variance (ANOVA).

RESULTS

No group differences were seen for A-delta mediated pain perception at either immediate or carryover times. Group differences were identified for immediate C-fiber mediated pain perception (P = .032), in which hypoalgesia occurred for the NM group but not the sham NM group. This hypoalgesic effect was not maintained at carryover (P = .104). Group differences were also identified for the 3-week and carryover periods for elbow extension ROM (P = .004), and for the participant sensory descriptor ratings (P = .018), in which increased ROM and decreased sensory descriptor ratings were identified in participants in the NM group but not the sham NM group.

CONCLUSION

This study provides preliminary evidence that mechanistic effects of tensioning NM differ from sham NM for asymptomatic participants. Specifically, NM resulted in immediate, but not sustained, C-fiber mediated hypoalgesia. Also, NM was associated with increased elbow ROM and a reduction in sensory descriptor ratings at 3-week and carryover assessment times. These differences provide potentially important information on the mechanistic effects of NM, as well as the description of a sham NM for use in future clinical trials.

Reliability of clinical tests to evaluate nerve function and mechanosensitivity of the upper limb peripheral nervous system

Background

Clinical tests to assess peripheral nerve disorders can be classified into two categories: tests for afferent/efferent nerve function such as nerve conduction (bedside neurological examination) and tests for increased mechanosensitivity (e.g. upper limb neurodynamic tests (ULNTs) and nerve palpation). Reliability reports of nerve palpation and the interpretation of neurodynamic tests are scarce. This study therefore investigated the intertester reliability of nerve palpation and ULNTs. ULNTs were interpreted based on symptom reproduction and structural differentiation. To put the reliability of these tests in perspective, a comparison with the reliability of clinical tests for nerve function was made.

Methods

Two experienced clinicians examined 31 patients with unilateral arm and/or neck pain. The examination included clinical tests for nerve function (sensory testing, reflexes and manual muscle testing (MMT)) and mechanosensitivity (ULNTs and palpation of the median, radial and ulnar nerve). Kappa statistics were calculated to evaluate intertester reliability. A meta-analysis determined an overall kappa for the domains with multiple kappa values (MMT, ULNT, palpation). We then compared the difference in reliability between the tests of mechanosensitivity and nerve function using a one-sample t-test.

Results

We observed moderate to substantial reliability for the tests for afferent/efferent nerve function (sensory testing: kappa = 0.53; MMT: kappa = 0.68; no kappa was calculated for reflexes due to a lack of variation). Tests to investigate mechanosensitivity demonstrated moderate reliability (ULNT: kappa = 0.45; palpation: kappa = 0.59). When compared statistically, there was no difference in reliability for tests for nerve function and mechanosensitivity (p = 0.06).

Conclusion

This study demonstrates that clinical tests which evaluate increased nerve mechanosensitivity and afferent/efferent nerve function have comparable moderate to substantial reliability. To further investigate the clinometric properties of these tests, more studies are needed to evaluate their validity.

Carpal tunnel syndrome--a comprehensive review

PURPOSE

To provide a comprehensive review of the management of carpal tunnel syndrome.

METHODS AND RESULTS

A systematic literature review is provided of the history, anatomy, pathophysiology, epidemiology, diagnostic criteria, investigative surgical techniques, results and complications for carpal tunnel syndrome.

CONCLUSION

Surgery for carpal tunnel syndrome requires meticulous attention to history-taking, investigation, counseling, training and surgical technique if unsatisfactory results and complications are to be avoided.