Minor peripheral nerve injuries: an underestimated source of pain?

Effect of massage, passive neural mobilization and transcutaneous electrical nerve stimulation on magnetic resonance diffusion tensor imaging (MR-DTI) of the tibial nerve in a patient with type 2 diabetes mellitus induced neuropathy: a case report

BACKGROUND

MR-DTI parameters namely fractional anisotropy (FA) and apparent diffusion coefficient values (ADC) of diffusion imaging demonstrate the directional preference and speed of diffusion of water molecules. The purpose of this case report is to explore the effect of massage, passive neural mobilization and transcutaneous electrical nerve stimulation on MR-DTI of the tibial nerve in a patient with type 2 diabetes mellitus having chronic distal symmetrical sensorimotor neuropathy.

CASE DESCRIPTION

A 63-year-old male with type 2 diabetes mellitus diagnosed with chronic symmetrical sensorimotor diabetic peripheral neuropathy on the basis of medical examination and electrophysiological testing. Altered mechanosensitivity of the tibial nerve was confirmed through neurodynamic testing. MR-DTI revealed severe damage of the tibial nerve as shown by chaotic diffusion of water molecules and damaged microstructural integrity.

INTERVENTION

A total six sessions over 3 weeks including nerve massage in a longitudinal and transverse direction; passive neural mobilization consisting of sliders and tensioners of the tibial nerve; and followed by 15 minutes of continuous transcutaneous electrical nerve stimulation directed along the nerve course.

OUTCOME

FA and ADC values, pain,neuropathy quality of life and range of motion data were collected pre and post intervention. Analysis revealed clinical improvement in all the outcome measures.

CONCLUSION

This case report identified improvement in radiological MR-DTI outcomes following rehabilitation in a patient with diabetic peripheral neuropathy.

Pain areas and mechanosensitivity in patients with chronic pelvic pain syndrome: a controlled clinical investigation

OBJECTIVE

A thorough clinical assessment including physical examination is crucial in a diagnostic work-up, including in patients with chronic pelvic pain syndrome (CPPS). This study investigated the prevalence of pain areas and the mechanosensitivity of peripheral nerves in patients with CPPS and compared the findings with a healthy control group.

MATERIALS AND METHODS

Healthy volunteers and patients diagnosed with CPPS were assessed with physical examinations and neurodynamic testing.

RESULTS

The CPPS group (n = 26) and the control group (n = 28) showed no statistical differences between males and females for age and body mass index (Mann-Whitney U test). The patients in the CPPS group were significantly older and had a significantly higher weight compared to controls. Healthy volunteers did not show any pain area or mechanosensitivity of the examined peripheral nerves of the lumbosacral plexus. Patients with CPPS showed a variety of pain from different musculoskeletal origins. Neurodynamic testing demonstrated significant mechanosensitivity in at least one nerve of the lumbosacral plexus in 88% of the patients with CPPS, suggesting minor nerve injuries. Pudendal nerve mechanosensitivity was found in 85% of patients, while 42% had multiple nerves involved. Unilateral or bilateral pudendal channel palpatory pain was present in 62% of the CPPS group and not in controls.

CONCLUSIONS

This study shows musculoskeletal pain and a high prevalence of minor nerve injuries in CPPS patients, indicating the presence of abnormal impulse generation sites that can help in understanding the clinical picture in CPPS patients and guiding their treatment.

Effects of simulated neural mobilization on fluid movement in cadaveric peripheral nerve sections: implications for the treatment of neuropathic pain and dysfunction

BACKGROUND AND PURPOSE

Neural mobilization techniques are used clinically to treat neuropathic pain and dysfunction. While selected studies report efficacy of these techniques, the mechanisms of benefit are speculative. The purpose of this study was to evaluate the effects of in vitro simulated stretch/relax neural mobilization cycles on fluid dispersion within sections of unembalmed cadaveric peripheral nerve tissue.

METHODS

Bilateral sciatic nerve sections were harvested from six cadavers. Matched pairs of nerve sections were secured in a tissue tester and injected with a plasma/Toluidine Blue dye solution. Once the initial dye spread stabilized, the experimental nerve sections underwent 25 stretch/relaxation cycles (e.g. simulated neural mobilization) produced by a mechanical tissue tester. Post-test dye spread measurements were compared to pre-test measurements as well as control findings (no simulated mobilization). Data were analyzed using paired t-tests.

RESULTS

Individual dye spread measurements were reliable [ICC(3,1) = 0·99]. The post-test intraneural fluid movement (dye spread) in the experimental section increased significantly with simulated neural mobilization compared to pre-test measurements (3·2±2·1 mm; P = 0·015) and control measurements (3·3±2·7 mm; P = 0·013).

CONCLUSION

Repetitive simulated neural mobilization, incorporating stretch/relax cycles, of excised cadaveric peripheral nerve tissue produced an increase in intraneural fluid dispersion. Neural mobilization may alter nerve tissue environment, promoting improved function and nerve health, by dispersing tissue fluid and diminishing intraneural swelling and/or pressure.

Mechanosensitivity of the median nerve in patients with chronic carpal tunnel syndrome

The aim was to investigate the relationship between the effects of median nerve strain during the elbow extension component of the upper limb neurodynamic test 1 (ULNT1) and the evoked musculoskeletal changes. 11 patients with chronic carpal tunnel syndrome (CTS) and 11 matched asymptomatic controls participated in the study. In all subjects, elbow extension was carried out in both ULNT1 and neutral positions of the shoulder and arm. From these two starting positions a KIN-COM(®) dynamometer carried out passive elbow extension while EMG activity of 10 arm and shoulder muscles, elbow-flexor resistive torque and elbow extension ROM were measured concurrently. The result showed that, in the ULNT1 position, increased EMG activity of the involved muscles, increased elbow extension resistive torque and pain responses occurred much earlier in the range of elbow extension in the CTS group compared to healthy controls. These findings demonstrated increased mechanosensitivity of the median nerve in CTS patients compared to healthy controls.

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.

Upper limb neurodynamic test of the radial nerve: a study of responses in symptomatic and asymptomatic subjects

STUDY DESIGN

Clinical measurement.

INTRODUCTION

Nonspecific cervical pain is a common clinical presentation. The role of upper limb neurodynamic tests (ULNT), for evaluation and treatment intervention, is not well defined for this population.

PURPOSE OF THE STUDY

This study's purpose was to determine if the radial-biased (RB)-ULNT discriminates any response differences between symptomatic subjects with a positive (+) RB-ULNT (n=36), symptomatic subjects with a negative (-) RB-ULNT (n=24), and asymptomatic subjects (n=60).

METHODS

Sixty asymptomatic and 60 subjects presenting with nonspecific cervical and/or unilateral upper extremity pain were compared using the RB-ULNT. Symptomatic subjects were further divided in (+) and (-) RB-ULNT groups due to their response to the RB-ULNT. Within the symptomatic population, a positive response to the RB-ULNT was defined by the symptomatic subject reporting their sensations were increased with contralateral cervical lateral flexion and decreased with ipsilateral cervical lateral flexion. Sensation provocation and location were evaluated using the RB-ULNT in all the subjects during each stage of the testing.

RESULTS

Significant differences on stage of reproduction and type of sensations were identified between 1) the (+) RB-ULNT symptomatic subjects, 2) the (-) RB-ULNT symptomatic subjects, and 3) the asymptomatic subjects. The (+) RB-ULNT group showed significantly increased pain responses during the first stage of the RB-ULNT compared with the (-) RB-ULNT group and the asymptomatic subjects. The (+) RB-ULNT also showed significantly decreased glenohumeral abduction passive range of motion when compared with the asymptomatic group.

CONCLUSION

Clinically, the differences found between the groups in their response to the RB-ULNT suggest heightened mechanosensitivity in the (+) RB-ULNT group.

LEVEL OF EVIDENCE

3a.

A cross-sectional study of the relation between symptoms and physical findings in computer operators

BACKGROUND

The character of upper limb disorder in computer operators is subject to debate. A peripheral nerve-involvement is suggested from the common presence of a triad of symptoms consisting of pain, paraestesiae and subjective weakness, and from physical findings suggesting neuropathy. This study aimed to examine the outcome of a detailed neurological examination in computer operators and to compare findings with the presence of symptoms.

METHODS

96 graphical computer operators answered a modified Nordic Questionnaire including information on perceived pain in the shoulder, elbow, and wrist/hand scored for each region on a VAS-scale 0-9. In addition, they underwent a physical examination including the subjective assessment of the individual function of 11 upper limb muscles, of algesia in five and vibratory threshold in three territories, respectively, and of mechanosensitivity of nerves at seven locations. In order to reflect an involvement of the brachial plexus (chord level), the posterior interosseous nerve and the median nerve at elbow level we defined three patterns of neurological findings illustrating the course of nerves and their innervation. The pain scores summarized for the three upper limb regions (min. = 0, max = 27) in the mouse-operating and contralateral limbs were compared by a Wilcoxon test and the relation to each physical item analyzed by Kendall's rank correlation. The relation of summarized pain to each pattern was studied by application of a test of the trend across ordered groups (patterns).

RESULTS

Pain, paraestesiae and subjective weakness was reported for 67, 23, and 7 mouse-operating limbs, respectively, with the summarized pain scores exceeding 4 in 33 limbs. Abnormal physical findings were prevalent. The summarized pain was significantly related to a reduced function in five muscles, to mechanical allodynia at one location and to elevated threshold to vibration in two territories. Brachial plexopathy was diagnosed in 9/2, median neuropathy in 13/5 and posterior interosseous neuropathy in 13/8 mouse operating/contralateral limbs, respectively. The summarized pain was significantly higher in the mouse-operating limbs and in limbs with any of the defined patterns. There was a significant trend between the summarized pain and the summarized scores for the items contained in each pattern.

CONCLUSION

This small-scale study of a group of computer-operators currently in work and with no or minor upper limb symptoms has indicated in symptomatic subjects the presence of peripheral nerve-afflictions with specific locations.

Vibrotactile sense in patients with different upper limb disorders compared with a control group

BACKGROUND

Upper limb disorders (ULDs) are common, and so are the difficulties with regard to their specific diagnoses. According to diagnostic consensus criteria, specific diagnoses include neuropathy and muscular- and connective-tissue disorders (MCDs). There is a need for valid objective diagnostic tools to reveal underlying mechanisms for specific diagnoses.

OBJECTIVE

To investigate the possible differences in vibration perception threshold (VPT) and tolerance to suprathreshold stimulation (STS) between controls and specific diagnostic ULD patient groups with uni- and bilateral neuropathy and/or MCD.

METHODS

In 161 ULD patients and 40 controls, the VPT of the median, ulnar, and radial nerves innervating the hand was examined by vibrometry using the "method of limits". The tolerance to STS of the anterior forearm was tested in 128 of the patients and all controls.

RESULTS

The ULD patients in all diagnostic groups had significantly higher VPT (P<0.05) in all the nerves in limbs, with and without diagnoses compared with controls. Only patient groups defined with neuropathy demonstrated significantly higher VPT in the limb with diagnoses compared with the contralateral limb without diagnoses. The highest VPTs were found in the patient group with unilateral neuropathy and MCD, and for the radial nerve, VPT was significantly higher than that for patients with unilateral MCD alone. These findings were confirmed by almost similar findings in STS responses.

CONCLUSIONS

The ULD patients generally demonstrated increased VPT compared with controls, indicating a neurogenous component independent of specific ULD diagnosis. Contralateral significant findings in limbs without diagnoses compared with controls indicate central neurogenous affection and/or the possibility of certain exposures elevating VPT before a positive status of a limb diagnosis is attained. Significantly higher VPT values in limbs with neuropathy diagnoses compared with limbs without and not in MCD alone, may indicate peripheral sensibilization or nerve affection only in the group with a specific diagnosis of neuropathy. These findings underline the importance of specific diagnoses among ULD patients.

Pressure and stretch mechanosensitivity of peripheral nerve fibres following local inflammation of the nerve trunk

Patients with non-specific limb pain often show signs of nerve mechanosensitivity, i.e. local tenderness over nerve trunks and pain in response to limb movements that cause nerve stretch. In such patients a nerve lesion is not apparent, and it has been suggested that local neural inflammation may be a key factor. The present study examines the extent to which nerve fibres in regions of local inflammation respond to small stretches, and whether functional changes occur throughout the primary afferent neurone. A local neuritis was induced in adult rats by wrapping oxidised cellulose saturated in complete Freund's adjuvant (CFA) around the peroneal or sciatic nerves. A small cut was made in the perineurium of some of the peroneal lesioned animals. A- and C-fibre recordings were made 2-10 days post-surgery from filaments dissected proximal to the lesion. Local mechanosensitivity was assessed using a glass probe and by small stretches. Responses to stretch and local pressure were recorded in 7% of C- and 8% of A-fibres from the peroneal nerve following CFA treatment with the sheath opened. A smaller proportion of stretch sensitive fibres were seen in sciatic and peroneal nerves after CFA treatment alone (2% of C- and 3% of A-fibres), but such fibres were not seen in control preparations. The most responsive fibres fired to 3% stretch, which is within the range of nerve stretch seen during normal limb movements. Less than 1% of stretch sensitive fibres had peripheral fields, indicating that most had probably degenerated distally.

Effect of straight leg raise examination and treatment on vibration thresholds in the lower limb: a pilot study in asymptomatic subjects

Individuals who participate in repetitive functional activities may have alteration in large diameter neural activity. It has been proposed that neurodynamic examination and treatment may affect large diameter afferent activity, and that neurological integrity tests should be carried out prior to neurodynamic testing. Vibration threshold testing (VTT) has been shown to be a valid measure of large diameter afferent conduction. The aim of this study was to assess whether examination and treatment of straight leg raise with plantar flexion and inversion (SLR) has an effect on the conduction of large diameter afferents supplying the lower leg in normal subjects and in a group of runners. Twenty sedentary asymptomatic subjects and 10 asymptomatic runners underwent VTT at the second and fourth metatarsals (representing the distribution of the superficial peroneal nerve) before and after examination of the SLR and after a mimicked treatment with SLR (VTT carried out immediately and 10min after treatment). A repeated measures ANOVA revealed no significant baseline differences in VT between runners and non-runners (P=0.171), or between any of the four test conditions in either group (P=0.5). Although not significant there was a trend for runners to have raised mean VT compared to non-runners, and for SLR treatment to cause an elevation in VT in both groups. These results suggest that examination and treatment of SLR may not be detrimental to function of the large diameter afferents in asymptomatic subjects.

Widespread Sensory Hypersensitivity Is a Feature of Chronic Whiplash-Associated Disorder but not Chronic Idiopathic Neck Pain

OBJECTIVES

To investigate sensory changes present in patients with chronic whiplash-associated disorders and chronic idiopathic neck pain using a variety of quantitative sensory tests to better understand the pain processing mechanisms underlying persistent symptoms.

METHODS

A case control study was used with 29 subjects with chronic whiplash-associated disorders, 20 subjects with chronic idiopathic neck pain, and 20 pain-free volunteers. Pressure pain thresholds were measured over the articular pillars of C2-C3, C5-C6, the median, radial, and ulnar nerve trunks in the arm and over a remote site, the muscle belly of tibialis anterior. Heat pain thresholds, cold pain thresholds, and von Frey hair sensibility were measured over the cervical spine, tibialis anterior, and deltoid insertion. Anxiety was measured with the Short-Form of the Spielberger State Anxiety Inventory.

RESULTS

Pressure pain thresholds were decreased over cervical spine sites in both subject groups when compared with controls (P < 0.05). In the chronic whiplash-associated disorders group, pressure pain thresholds were also decreased over the tibialis anterior, median, and radial nerve trunks (P < 0.001). Heat pain thresholds were decreased and cold pain thresholds increased at all sites (P < 0.03). No differences in heat pain thresholds or cold pain thresholds were evident in the idiopathic neck pain group at any site compared with the control group (P > 0.27). No abnormalities in von Frey hair sensibility were evident in either neck pain group (P > 0.28).

DISCUSSION

Both chronic whiplash-associated disorders and idiopathic neck pain groups were characterized by mechanical hyperalgesia over the cervical spine. Whiplash subjects showed additional widespread hypersensitivity to mechanical pressure and thermal stimuli, which was independent of state anxiety and may represent changes in central pain processing mechanisms. This may have implications for future treatment approaches.

Upper limb neuropathy in computer operators? A clinical case study of 21 patients

BACKGROUND

The character of upper limb disorder in computer operators remains obscure and their treatment and prevention have had limited success. Symptoms tend to be mostly perceived as relating to pathology in muscles, tendons or insertions. However, the conception of a neuropathic disorder would be supported by objective findings reflecting the common complaints of pain, subjective weakness, and numbness/tingling. By examining characteristics in terms of symptoms, signs, and course, this study aimed at forming a hypothesis concerning the nature and consequences of the disorder.

METHODS

I have studied a consecutive series of 21 heavily exposed and severely handicapped computer-aided designers. Their history was recorded and questionnaire information was collected, encompassing their status 1/2 - 1 1/2 years after the initial clinical contact. The physical examination included an assessment of the following items: Isometric strength in ten upper limb muscles; sensibility in five homonymously innervated territories; and the presence of abnormal tenderness along nerve trunks at 14 locations.

RESULTS

Rather uniform physical findings in all patients suggested a brachial plexus neuropathy combined with median and posterior interosseous neuropathy at elbow level. In spite of reduced symptoms at follow-up, the prognosis was serious in terms of work-status and persisting pain.

CONCLUSIONS

This small-scale study of a clinical case series suggests the association of symptoms to focal neuropathy with specific locations. The inclusion of a detailed neurological examination would appear to be advantageous with upper limb symptoms in computer operators.

Responses to a clinical test of mechanical provocation of nerve tissue in whiplash associated disorder

Involvement of nerve tissue may contribute to the persistence of pain following a whiplash injury. This study aimed to investigate responses to the brachial plexus provocation test (BPPT) in 156 subjects with chronic whiplash associated disorder (WAD) with and without associated arm pain and 95 asymptomatic control subjects. The range of elbow extension (ROM) and visual analogue scale (VAS) pain scores were measured. Subjects with chronic WAD demonstrated significantly less ROM and higher VAS scores with the BPPT than the asymptomatic subjects (P<0.001). These effects occurred bilaterally. Within the whiplash population, subjects whose arm pain was reproduced by the BPPT demonstrated significantly less ROM on both the symptomatic and asymptomatic sides when compared to the whiplash subjects whose arm pain was not reproduced by the BPPT (P=0.003) and significantly less ROM and higher VAS scores than those whiplash subjects with no arm pain (P=0.003, 0.01). Only the whiplash subjects whose arm pain was reproduced by the BPPT demonstrated differences between the symptomatic and asymptomatic sides. These generalized hyperalgesic responses to the BPPT support the hypothesis of central nervous system hypersensitivity as contributing to persistent pain experienced by WAD patients.

The use of ultrasound imaging to demonstrate reduced movement of the median nerve during wrist flexion in patients with non-specific arm pain

Following clinical screening, we examined movement of the median nerve at the wrist using high-resolution (10-22 MHz) ultrasound in 16 controls and 12 patients with non-specific arm pain (also referred to as repetitive strain injury). Imaging was performed just proximal to the carpal tunnel with the wrist in neutral, 30 degrees of extension and 30 degrees of flexion. In control subjects the position of the median nerve was 4.8 (SE=0.4) mm more radial with the wrist flexed than with the wrist extended. In the twelve arm pain patients the average change was only 1.2 (SE=0.5) mm. It appears that ultrasound imaging may be helpful in diagnosing non-specific arm pain, a condition for which there are no well-defined diagnostic tests at present. The reduced nerve movement seen with ultrasound imaging confirms previous work with magnetic resonance imaging.

Addition of test components during neurodynamic testing: effect on range of motion and sensory responses

STUDY DESIGN

Single session, repeated-measures design.

OBJECTIVES

To analyze the impact of different components of the neural tissue provocation test for the median nerve (NTPT1) on the range of motion (ROM) of the elbow and wrist and the sensory responses elicited by the test.

BACKGROUND

The assessment of minor peripheral nerve injuries by neurodynamic tests is becoming more integrated in physical therapy practice. The influence of different test components on the nervous system has been analyzed in numerous in vitro studies, but in vivo studies are still lacking.

METHODS AND MEASURES

Five test variations were performed on 35 asymptomatic men (23.5 +/- 2.3 years). Elbow extension was performed (1) without additional components (NTPT1NEUTRAL), (2) with wrist extension (NTPT1WE), (3) with cervical contralateral lateral flexion (NTPT1CLLF), and (4) with both wrist extension and cervical contralateral lateral flexion (NTPT1WE+CLLF). In the fifth variant, the wrist was extended from a preloaded position (WENTPT1). The range of elbow and wrist extension when a submaximal discomfort was elicited was measured with 2 electrogoniometers.

RESULTS

The addition of each test component resulted in a significantly reduced ROM (NTPT1NEUTRAL: 179.5 +/- 8.8 degrees, NTPT1WE: 169.0 +/- 13.9 degrees, NTPT1CLLF: 154.7 +/- 13.2 degrees, NTPT1WE+CLLF: 143.9 +/- 16.1 degrees; WENTPT1: 67.1 +/- 11.0 degrees). Sensory responses were predominantly evoked at the region of the added component.

CONCLUSIONS

The different test components, whose mechanical influence on the nervous system has been demonstrated in anatomical studies, also have an effect on joint ROM and sensory responses during neurodynamic testing, when individually or simultaneously added. If the nerve bedding is elongated throughout its whole length, the available ROM is markedly reduced and sensory responses can be elicited throughout the entire arm.

Pressure pain thresholds of upper limb peripheral nerve trunks in asymptomatic subjects

BACKGROUND AND PURPOSE

Palpation of peripheral nerve trunks has been advocated as a method of assessing the presence of hyperalgesic nerve tissue as a contributing factor to pain syndromes in musculoskeletal disorders of the upper quadrant. This study investigated, in the first instance, the pressure pain thresholds of the median, radial and ulnar nerve trunks of the upper limb in healthy, asymptomatic subjects.

METHOD

Forty-five male and 50 female healthy volunteer subjects participated in this study which involved measurement of pressure pain thresholds by use of pressure algometry bilaterally over the three peripheral nerve trunks in the upper limbs.

RESULTS

Pressure pain thresholds were shown to be lowest in the median nerve (p = 0.001) and lower in female subjects (p = 0.001). Laterality (p = 0.077) or the age of the subject (p = 0.254) did not significantly influence results.

CONCLUSIONS

The study demonstrated differences in pressure pain thresholds in the three nerve trunks of the upper limb. These findings should be taken into account when interpreting the findings of nerve palpation in musculoskeletal upper quadrant disorders.

Chronic pain/dysfunction in whiplash-associated disorders

OBJECTIVE

The purposes of this article are (1) to review current knowledge of and recent concepts pertaining to the causes of chronic pain and/or dysfunction following whiplash-type injuries and (2) to acquaint those who treat these types of injuries with possible mechanisms of continued pain and or dysfunction following whiplash.

DATA COLLECTION

A review of the literature on mechanisms of injury and neurologic considerations was undertaken. A hand search of relevant medical, neuroscience, chiropractic, and online Index Medicus sources and other sources involving mechanisms of nociception, neurotransmitters, and receptors that might evolve from whiplash-type soft tissue injuries was conducted.

RESULTS

Pain is a complex phenomenon that has great variability. Chronic pain appears to involve a deficient descending inhibitory process and/or ongoing excitatory input.

CONCLUSIONS

There is a wide variety of reactions by individuals to any given type of stimulus. Injury may lead to increases in neuronal activity and prolonged changes in the nervous system. Chronic pain may be seen as part of a central disturbance accompanied by disinhibition or sensitization of central pain modulation, mirrored in the immune and endocrine systems. Patients with chronic whiplash syndrome may have a generalized central hyperexcitability from a loss of tonic inhibitory input (disinhibition) and/or ongoing excitatory input contributing to dorsal horn hyperexcitability. Dysfunction of the motor system may also occur, with or without pain. The purpose of treatment should be not only to relieve pain but also to allow for proper proprioception.

Injury threshold: whiplash-associated disorders

OBJECTIVES

To review current knowledge and recent concepts of the causes of injuries after minor impact automobile collisions and to acquaint those who treat these types of injuries with possible injury thresholds and mechanisms that may contribute to symptoms.

DATA SOURCES

A review of literature involving mechanisms of injury, tissue tensile threshold, and neurologic considerations was undertaken. A hand-search of relevant engineering, medical/chiropractic, and computer Index Medicus sources in disciplines that cover the variety of symptoms was gathered.

RESULTS

Soft-tissue injuries are difficult to diagnose or quantify. There is not one specific injury mechanism or threshold of injury. With physical variations of tissue tensile strength, anatomic differences, and neurophysiologic considerations, such threshold designation is not possible.

CONCLUSIONS

To make a competent assessment of injury, it is important to evaluate each patient individually. The same collision may cause injury to some individuals and leave others unaffected. With the variability of human postures, tensile strength of the ligaments between individuals, body positions in the vehicle, collagen fibers in the same specimen segment, the amount of muscle activation and inhibition of muscles, the size of the spinal canals, and the excitability of the nervous system, one specific threshold is not possible. How individuals react to a stimulus varies widely, and it is evident peripheral stimulation has effects on the central nervous system. It is also clear that the somatosensory system of the neck, in addition to signaling nociception, may influence the control of neck, eyes, limbs, respiratory muscles, and some preganglionic sympathetic nerves.

Schwann cell-derived Desert hedgehog controls the development of peripheral nerve sheaths

We show that Schwann cell-derived Desert hedgehog (Dhh) signals the formation of the connective tissue sheath around peripheral nerves. mRNAs for dhh and its receptor patched (ptc) are expressed in Schwann cells and perineural mesenchyme, respectively. In dhh-/- mice, epineurial collagen is reduced, while the perineurium is thin and disorganized, has patchy basal lamina, and fails to express connexin 43. Perineurial tight junctions are abnormal and allow the passage of proteins and neutrophils. In nerve fibroblasts, Dhh upregulates ptc and hedgehog-interacting protein (hip). These experiments reveal a novel developmental signaling pathway between glia and mesenchymal connective tissue and demonstrate its molecular identity in peripheral nerve. They also show that Schwann cell-derived signals can act as important regulators of nerve development.

Reduced movement of median nerve in carpal tunnel during wrist flexion in patients with non-specific arm pain

Magnetic resonance scans on patients with non-specific arm pain (repetitive strain injury) show reduced median-nerve movement in the carpal tunnel, suggesting that this common condition may involve nerve entrapment.

Nerve trunk pain: physical diagnosis and treatment

The management of peripheral neuropathic pain or nerve trunk pain relies upon accurate differential diagnosis. In part neurogenic pain has been attributed to increased activity in, as well as to abnormal processing of non-nociceptive input from, the nervi nervorum. For neurogenic pain to be identified as the dominant feature of a painful condition there should be evidence of increased nerve trunk mechanosensitivity from all aspects of the physical examination procedure. Consistent dysfunction should be identified on key active and passive movements, neural tissue provocation tests as well as nerve trunk palpation. A local cause for the neurogenic pain disorder should also be identified if the condition is to be treated by manual therapy. A treatment approach is presented which has been shown to have efficacy in the relief of pain and restoration of function in cervicobrachial pain disorders where there is evidence according to the outlined examination protocol of nerve trunk pain.