Electrophysiological Evaluation of Peripheral and Autonomic Involvement in Leprosy

Objective:

Motor and sensory nerve conductions, F responses, sympathetic skin responses and R-R interval variations (RRIV) were studied to determine the type of peripheral neuropathy among patients with leprosy.

Methods:

Twenty-nine consecutive patients with leprosy (25 male, 4 female) hospitalized in the “Istanbul Leprosy Hospital'' between January - December, 1999 were included in this study. Ten patients had borderline lepromatous leprosy, and 19 had lepromatous leprosy. None of the patients studied had the tuberculoid form. The mean age was 55±12 years. The control group consisted of 30 (26 male, 4 female) healthy volunteers (mean age: 58.1±7.8 years). All subjects included in the study underwent neurological examination and electrophysiological evaluation. Standard procedures were performed for evaluating sensory and motor conduction studies. Motor studies were carried out on both left and right median, ulnar, tibial and common peroneal nerves while median, ulnar, sural and superficial peroneal nerves were examined for sensory studies. Sympathetic skin response recordings on both hands and RRIV recordings on precordial region were done in order to evaluate the autonomic involvement.

Results:

The lower extremity was found to be more severely affected than the upper, and sensory impairment predominated over motor. Of 58 upper limbs examined, no sympathetic skin responses was recorded in 46 (79.3%). Compared with the controls, the RRIVs of the leprosy patients were found to be reduced during both resting and deep forced hyperventilation.

Conclusion:

Our results indicate that leprosy causes a predominantly axonal polyneuropathy that is more severe in the lower extremities. Sensory nerve damage is accompanied by autonomic involvement.

Sciatic cross-over in patients with peroneal and tibial intraneural ganglia confirmed by knee MR arthrography

BACKGROUND

A predictable mechanism and stereotypic patterns of peroneal intraneural ganglia are being defined based on careful analysis of MRIs. Peroneal and tibial intraneural ganglia extending from the superior tibiofibular joint which extend to the level of the sciatic nerve have been observed leading to the hypothesis that sciatic cross-over could exist. Such a cross-over phenomenon would allow intraneural cyst from the peroneal nerve by means of its shared epineurial sheath within the sciatic nerve to cross over to involve the tibial nerve, or vice versa from a tibial intraneural cyst to the peroneal nerve.

METHOD AND FINDINGS

One patient with a peroneal intraneural ganglion and another with a tibial intraneural ganglion each underwent a knee MR arthrogram. These studies were not only definitive in demonstrating the communication of the cyst to the superior tibiofibular joint connection but also in confirming sciatic cross-over. Contrast injected into the knee could be demonstrated tracking to the superior tibiofibular joint and then proximally into the common peroneal or tibial nerve respectively, crossing over at the sciatic nerve, and then descending down the tibial and peroneal nerves. The arthrographic findings mirrored MR images upon their retrospective review.

CONCLUSIONS

This study provides direct in vivo proof of the nature of sciatic cross-over theorized by critical review of MRIs and/or experimental dye injections done in cadavers. This study is important in clarifying the potential paths of propagation of intraneural cysts at points of major bifurcation.

Chondrotinase ABC enhances axonal regeneration across nerve gaps

We evaluated the effects of chondroitinase ABC on axonal regeneration across peripheral nerve gaps. We compared axonal regeneration after 15-mm tibial nerve resection and repair with a silicone tube filled with type I collagen gel (negative control group), with a silicone tube filled with type I collagen gel containing chondroitinase ABC at three different concentrations (2.5 units/mL, 5 units/mL, 10 units/mL) (chondroitinase ABC groups), and with an autologous nerve segment (nerve autograft group). Electrophysiological and histological assessments were carried out 12 weeks after surgery. In the electrophysiological study, compound muscle action potentials (CMAPs) and nerve conduction velocities (NCVs) were recorded in all groups except the negative control group. Although both CMAPs and NCVs were highest in the nerve autograft group, there were no significant differences among the three chondroitinase ABC groups in either parameter. Histological findings were consistent with electrophysiological results. Based on these findings, we conclude that topical injection of chondroitinase ABC can significantly increase the critical length of nerve gap repair by tubulization or artificial nerve placement.

Dynamic phases of peroneal and tibial intraneural ganglia formation: a new dimension added to the unifying articular theory

OBJECT

The pathogenesis of intraneural ganglia has been a controversial issue for longer than a century. Recently the authors identified a stereotypical pattern of occurrence of peroneal and tibial intraneural ganglia, and based on an understanding of their pathogenesis provided a unifying articular explanation. Atypical features, which occasionally are observed, have offered an opportunity to verify further and expand on the authors' proposed theory.

METHODS

Three unusual cases are presented to exemplify the dynamic features of peroneal and tibial intraneural ganglia formation.

RESULTS

Two patients with a predominant deep peroneal nerve deficit shared essential anatomical findings common to peroneal intraneural ganglia: namely, 1) joint connections to the anterior portion of the superior tibiofibular joint, and 2) dissection of the cyst along the articular branch of the peroneal nerve and proximally. Magnetic resonance (MR) images obtained in these patients demonstrated some unusual findings, including the presence of a cyst within the tibial and sural nerves in the popliteal fossa region, and spontaneous regression of the cysts, which was observed on serial images obtained weeks apart. The authors identified a clinical outlier, a case that could not be understood within the context of their previously reported theory of intraneural ganglion cyst formation. Described 32 years ago, this patient had a tibial neuropathy and was found at surgery to have tibial, peroneal, and sciatic intraneural cysts without a joint connection. The authors' hypothesis about this case, based on their unified theory, was twofold: 1) the lesion was a primary tibial intraneural ganglion with proximal extension followed by sciatic cross-over and distal descent; and 2) a joint connection to the posterior aspect of the superior tibiofibular joint with a remnant cyst within the articular branch would be present, a finding that would help explain the formation of different cysts by a single mechanism. The authors proved their hypothesis by careful inspection of a recently obtained postoperative MR image.

CONCLUSIONS

These three cases together with data obtained from a retrospective review of the authors' clinical material and findings reported in the literature provide firm evidence for mechanisms underlying intraneural ganglia formation. Thus, expansion of the authors' unified articular theory permits understanding and elucidation of unusual presentations of intraneural cysts. Whereas an articular connection and fluid following the path of least resistance was pivotal, the authors now incorporate dynamic aspects of cyst formation due to pressure fluxes. These basic principles explain patterns of ascent, cross-over, and descent down terminal nerve branches based on articular connections, paths of diminished resistance to fluid flow within recognized anatomical compartments, and the effects of fluctuating pressure gradients.

Ultrasonography of the tibial nerve in vasculitic neuropathy

Ultrasonography is a new imaging method for visualizing peripheral nerves. In vasculitic neuropathy, pain or axonopathy often can prevent the lesion from being localized during electrophysiological examinations, but the ability of ultrasonography to evaluate it morphologically is unknown. Our aim was to determine whether ultrasonography could be used to detect abnormalities in tibial vasculitic neuropathy at the medial ankle. We evaluated 11 tibial nerves in 8 patients with tibial vasculitic neuropathy, and 35 tibial nerves in 35 control subjects. In the controls, the tibial nerve was successfully visualized as a hyperechoic nodule with multiple round hypoechoic areas transversely; in the patients, the tibial nerve appeared enlarged and hypoechoic. The affected nerve area was significantly larger (13.5 +/- 3.7 mm(2)) than in controls (7.2 +/- 1.5 mm(2)). Our results suggest that ultrasonography is a useful neuroimaging method for evaluation of tibial vasculitic neuropathy, especially when nerve conduction study findings are inconclusive.

Does the tibial and sural nerve transection model represent sympathetically independent pain?

Neuropathic pain can be divided into sympathetically maintained pain (SMP) and sympathetically independent pain (SIP). Rats with tibial and sural nerve transection (TST) produce neuropathic pain behaviors, including spontaneous pain, tactile allodynia, and cold allodynia. The present study was undertaken to examine whether rats with TST would represent SMP- or SIP-dominant neuropathic pain by lumbar surgical sympathectomy. The TST model was generated by transecting the tibial and sural nerves, leaving the common peroneal nerve intact. Animals were divided into the sympathectomy group and the sham group. For the sympathectomy group, the sympathetic chain was removed bilaterally from L2 to L6 one week after nerve transection. The success of the sympathectomy was verified by measuring skin temperature on the hind paw and by infra red thermography. Tactile allodynia was assessed using von Frey filaments, and cold allodynia was assessed using acetone drops. A majority of the rats exhibited withdrawal behaviors in response to tactile and cold stimulations after nerve stimulation. Neither tactile allodynia nor cold allodynia improved after successful sympathectomy, and there were no differences in the threshold of tactile and cold allodynia between the sympathectomy and sham groups. Tactile allodynia and cold allodynia in the neuropathic pain model of TST are not dependent on the sympathetic nervous system, and this model can be used to investigate SIP syndromes.

Intraneural ganglion cyst of the tibial nerve

Intraneural ganglion cyst of the tibial nerve is very rare. To date, only 5 cases of this entity in the popliteal fossa have been reported. We report a new case and review the previously reported cases. A 40-year-old man experienced a mild vague pain in the medial half of his right foot for 3 years. Magnetic resonance imaging scan demonstrated a soft-tissue mass along the right tibial nerve. At surgery, an intraneural ganglion cyst was evacuated. After 12 months, the patient was pain-free with no signs of recurrence. Trauma might be a contributing factor to the development of intraneural ganglion cysts. Application of microsurgical techniques is encouraged.

An abnormal mRNA produced by a novel PMP22 splice site mutation associated with HNPP

Hereditary neuropathy with liability to pressure palsies (HNPP) is an autosomal dominant, demyelinating neuropathy. Point mutations in the PMP22 gene are a rare cause of HNPP. A novel PMP22 splice site mutation (c.179+1 G-->C) is reported in an HNPP family. By reverse transcriptase-polymerase chain reaction experiments, this mutation was shown to cause the synthesis of an abnormal mRNA in which a premature stop codon probably produces a truncated non-functional protein.

Loss of neurons from laminas I-III of the spinal dorsal horn is not required for development of tactile allodynia in the spared nerve injury model of neuropathic pain

It has been proposed that death of inhibitory interneurons in the dorsal horn contributes to the neuropathic pain that follows partial nerve injury. In this study, we have used two approaches to test whether there is neuronal death in the dorsal horn in the spared nerve injury (SNI) model. We performed a stereological analysis of the packing density of neurons in laminas I-III 4 weeks after operation and found no reduction on the ipsilateral side compared with that seen on the contralateral side or in sham-operated or naive rats. In addition, we used two markers of apoptosis, terminal deoxynucleotidyl transferase-mediated biotinylated UTP nick end labeling (TUNEL) staining and immunocytochemical detection of cleaved (activated) caspase-3. Neither of these methods demonstrated apoptotic neurons in the dorsal spinal cord 1 week after operation. Although TUNEL-positive cells were present throughout the gray and white matter at this stage, they were virtually all labeled with antibody against ionized calcium-binding adapter molecule 1, a marker for microglia. All animals that underwent SNI showed clear signs of tactile allodynia affecting the ipsilateral hindpaw. These results suggest that a significant loss of neurons from the dorsal horn is not necessary for the development of tactile allodynia in the SNI model.

[The peculiarities of plantar pressure distribution during gait in different variants of functional system impairment in patients with multiple sclerosis]

Gait disturbance is a prominent disabling presentation of multiple sclerosis. The data on the distribution of plantar pressure during gait and its relation to the level of neurological deficit in various disturbances of pyramidal and cerebral functions in remitting type of multiple sclerosis are presented.

Hereditary neuropathy with liability to pressure palsy combined with schwannomas of the median and medial plantar nerves

A 42-year-old woman was surgically treated for carpal tunnel syndrome, revealing schwannoma of the median nerve. A year later, she developed a tarsal tunnel syndrome. At time of this diagnosis, hereditary neuropathy with liability to pressure palsies (HNPP) was diagnosed genetically and a schwannoma of the medial plantar nerve was treated surgically. The occurrence of HNPP and schwannomas in the same patient might be purely coincidental, but it is tempting to speculate that they share a common genetic basis.

"Pressure gradient" as an indicator of plantar skin injury

OBJECTIVE

Peak plantar pressures (PPPs) have been studied extensively as a contributing factor to skin breakdown, especially in the forefoot where most plantar neuropathic ulcers occur. The purposes of this article were to 1) describe an additional pressure variable, the peak pressure gradient (PPG), 2) determine whether the PPG is higher in the forefoot than in the rearfoot (even when compared with PPP), and 3) determine the correlation between the PPG and PPP at the forefoot and rearfoot in subjects with diabetes, peripheral neuropathy, and a history of plantar ulcer.

RESEARCH DESIGN AND METHODS

Twenty subjects (12 male and 8 female) with diabetes, peripheral neuropathy, and a mean +/- SD age of 57 +/- 9 years participated. Plantar pressures were collected during walking in footwear. The PPP and the PPG (defined as the spatial change in plantar pressure across adjacent sites of the foot surface around the PPP) were determined for the forefoot and rearfoot, and the forefoot-to-rearfoot ratios for each variable were calculated.

RESULTS

The mean PPG was 143% higher in the forefoot than in the rearfoot, whereas the mean PPP was only 36% higher in the forefoot than in the rearfoot (P < 0.0001). The PPG forefoot-to-rearfoot ratio (2.84 +/- 1.36) was nearly two times greater than the PPP forefoot-to-rearfoot ratio (1.48 +/- 0.58) (P < 0.0001). The correlation between PPP and PPG was r = 0.59 at the forefoot and r = 0.75 at the rearfoot.

CONCLUSIONS

The PPG was substantially higher in the forefoot than in the rearfoot even when compared with the PPP. The PPG appears to be providing additional information about the stresses experienced by the soft tissues of the foot, especially in the forefoot. The PPG may be a useful indicator of skin trauma because spatial changes in high plantar pressures may identify high stress concentrations within the soft tissue.

Origin of Regenerated Axons in Nerve Bypass Grafts

It has been shown that end-to-side coaptation and nerve bypass grafting, which are essentially two sequential end-to-side coaptations, induce axonal outgrowth in peripheral nerve injuries. However, it is unknown whether the axons regenerated after end-to-side coaptation originate by collateral sprouting at the suture site or by elongation from the spinal neuronal pool. Also unknown is the extent of functional recovery that can be expected after bypass grafting for the reconstruction of injured peripheral nerves. We conducted a study to evaluate the origin of regenerated axons after end-to-side coaptation and the utility of nerve bypass grafting for peripheral nerve injury. For this purpose, we performed electrophysiological studies using bypass grafting (end-to-side coaptation) and conventional cable grafting (end-to-end coaptation) to treat complete paralysis of the peroneal nerve in rabbit models, and compared the recovery time and extent of functional recovery achieved with the two techniques. We assessed, by electromyography, the time to appearance of reinnervation potentials from the tibialis anterior muscle on the affected side. These times were not significantly different in the two study groups of animals (p = 0.5390). After a 12-week recovery period, electrophysiological findings and histological assessment showed similar recovery in both groups of animals. It is known that collateral sprouting of axons from the nodes of Ranvier proximal to the transected nerve stump occurs in cable grafting, and that axon elongation from the spinal cord requires more time. Our findings in the present study strongly suggest that collateral sprouting across end-to-side sutures is the chief means of axonal outgrowth in nerve bypass grafts, and that functional recovery can be expected in bypass grafting to nearly the same extent as in cable grafting.

Prognostic Ability of Tinel Sign in Determining Outcome for Decompression Surgery in Diabetic and Nondiabetic Neuropathy

During the past 12 years, 6 studies reported restoration of sensation and relief of pain in the foot by decompression of the tibial nerve and its distal branches in diabetic neuropathy. Although a positive Tinel sign related to favorable outcomes in some of the reports, this relationship was not evaluated specifically. In this study, the presence of the Tinel sign, positive or negative, over the tibial nerve was recorded in 46 patients with diabetic neuropathy and in 40 patients with idiopathic neuropathy. Outcomes were dichotomized into either a good/excellent or failure/poor category. Postoperative data were analyzed at 1 year. In diabetic neuropathy, the presence of a positive Tinel sign had a sensitivity of 88%, a specificity of 50%, and a positive predictive value of 88% in identifying patients who would have a good/excellent outcome. In idiopathic neuropathy, the presence of a positive Tinel sign had a sensitivity of 95%, a specificity of 56%, and a positive predictive value of 93% in identifying patients who would have a good/excellent outcome. It is concluded that a positive Tinel sign is a reliable indicator of successful outcome from decompression of the tibial nerve in patients with diabetes with symptomatic neuropathy, and in patients with symptomatic idiopathic neuropathy.

Transplanted neural stem cells promote axonal regeneration through chronically denervated peripheral nerves

Regeneration in the peripheral nervous system is impaired after prolonged periods of denervation. Currently, no interventions exist to alter the outcome after prolonged denervation. To examine the role of transplanted neural stem cells (NSC), we prepared chronically denervated distal tibial nerve segments. After 6 months of chronic denervation, we transplanted vehicle, C17.2 mouse NSCs, or C17.2 mouse NSCs engineered to overexpress GDNF to the distal tibial nerve and performed a peroneal nerve cross-suture. In animals transplanted with the NSCs, there was better regeneration of the peroneal axons into the tibial nerve as measured by counting the number of axons and by the emergence of compound motor action potentials in the tibial innervated foot muscles. Improved regeneration correlated with a reduction of chondroitin sulphate proteoglycan (CSPG) immunoreactivity in the extracellular matrix (ECM). In vitro, supernatant from C17.2 NSCs contained large quantities of secreted matrix metalloprotease-2 (MMP-2), degraded the CSPGs on chronically denervated tibial nerve sections, and reversed the CSPG-induced inhibition of neuritic outgrowth of DRG neurons. This reversal was inhibited by selective MMP-2 inhibitors. This is the first successful demonstration of regeneration through a chronically denervated nerve. These findings suggest that improved regeneration in the PNS can be accomplished by combining neurotrophic factor support and removal of axon growth inhibitory components in the extracellular matrix.

Bed footboard peroneal and tibial neuropathy. A further unusual type of Saturday night palsy

An uncommon cause of bilateral tibial and peroneal compression neuropathy is reported. After taking alcohol and drugs, a young heroin-addicted man lay unconscious overnight in supine position, with both legs crossing the wooden board at the end of the bed, the posterior aspect of the flexed knees pressing against its edge. The following day, he had weakness of foot flexion and extension and a sensory loss consistent with a bilateral tibial and peroneal neuropathy. Symptoms resolved rapidly in the left side; in the right side, a conduction block was still demonstrable 3 weeks later.

[Neurophysiological pain and sensory disorders correlates in patients with syringomyelia]

Short-latent and pain-related long-latent somatosensory evoked potentials (SEP) in response to electrical stimulation of n. medianus, n. tibialis and n. mandibularis were studied in 28 patients with syringomyelia. During stimulation in the area of pain-temperature sensitivity disturbance, reduced amplitude of early components N13, N18 and late components P3, N3, P4, N4 (100-500 ms) was detected. In patients with neuropathic pain, increased amplitude of the middle latency waves P2, N2 (40-100 ms) and low amplitude ratio P4/P2 (normal values = 1.5) were found. Patients with stimulus-evoked pain (allodynia and hyperaesthesia) had shortened N18 peak latency, decreased motor threshold and grossly attenuated and delayed P3, N3, P4 (100-350 ms) in SEP after stimulation of the hypersensitive side. In patients without pain, the amplitude of the late tibial SEP was elevated. The results obtained can be used as diagnostic criteria of syringomyelia. The character of SEP changes in patients with neuropathic pain support the hypothesis of central sensitization and abnormal pain transmission through the fast conducting of pain and temperature afferents.

Medial plantar nerve conduction velocities among patients with vibration syndrome due to rock-drill work

OBJECTIVE

The present study was aimed at clarifying the effect of vibration syndrome (VS) on the peripheral nervous system in the lower extremities of patients with VS due to rock-drill work.

METHODS

Fifty-three patients with VS due to previous exposure to vibration from rock-drilling work and 55 age-matched controls were examined for sensory nerve conduction velocities in the medial plantar nerve (SCV-P). The patient group was divided into three subgroups, outdoor rock-drill workers with vibration-induced white finger (VWF) (N = 10), tunnel workers with VWF (N = 27) and tunnel workers without VWF (N = 16).

RESULTS

ANOVA of SCV-P for the four groups showed F = 3.23 (dF = 3, 104, p = 0.0253). A significant difference was found between the controls and outdoor rock-drill workers with VWF group (p = 0.0261) by multiple comparison using Scheffe's method.

CONCLUSION

These findings suggest that peripheral nervous system function in the lower extremities of patient with VS is affected by cold exposure and circulatory disturbance manifested as VWF.

Near-nerve needle sensory conduction study of the medial calcaneal nerve: New method and report of four cases of medial calcaneal neuropathy

There has been one previously published antidromic method for studying medial calcaneal nerve (MCN) conduction. However, the origin of the compound nerve action potentials (CNAPs) with this technique is uncertain because of the antidromic nature of stimulation. We report a new orthodromic method for MCN conduction study using the near-nerve needle technique. In 35 normal controls, maximum nerve conduction velocity (NCV) and negative-peak NCV of MCN were 42.4 +/- 3.9 m/s and 33.6 +/- 3.0 m/s, respectively. The amplitude of the CNAP was 4.1 +/- 2.2 micro V. We also report four cases of medial calcaneal neuropathy, three of which were confirmed by this technique. We conclude that the present technique is capable of recording the sensory nerve action potentials of MCN in isolation and confirming the diagnosis of medial calcaneal neuropathy electrophysiologically.

Main trunk tibial neuropathies

The authors present a retrospective study of 52 patients with main trunk tibial neuropathy. They found trauma and ischemia to be the most frequent causes, followed by tumors. These etiologic groups are underrepresented in the literature. Electrodiagnostic examination was helpful for localizing the lesion as well as for excluding S1 radiculopathies, with which tibial neuropathies can be confused clinically.

A decline in glial cell-line-derived neurotrophic factor expression is associated with impaired regeneration after long-term Schwann cell denervation

In the peripheral nervous system, regeneration of motor and sensory axons into chronically denervated distal nerve segments is impaired compared to regeneration into acutely denervated nerves. In order to find possible causes for this phenomenon we examined the changes in the expression pattern of the glial cell-line-derived neurotrophic factor (GDNF) family of growth factors and their receptors in chronically denervated rat sciatic nerves as a function of time with or without regeneration. Among the GDNF family of growth factors, only GDNF mRNA expression was rapidly upregulated in Schwann cells as early as 48 h after denervation. This upregulation peaked at 1 week and then declined to minimal levels by 6 months of denervation. The changes in the protein expression paralleled the changes in the expression of the GDNF mRNA. The mRNAs for receptors GFRalpha-1 and GFRalpha-2 were upregulated only after maximal GDNF upregulation and remained elevated as late as 6 months. There were no significant changes in the expression of GFRalpha-3 or the tyrosine kinase coreceptor, RET. When we examined the expression of GDNF in a delayed regeneration paradigm, there was no upregulation in the distal chronically denervated tibial nerve even when the freshly axotomized peroneal branch of the sciatic nerve was sutured to the distal tibial nerve. This study suggests that one of the reasons for impaired regeneration into chronically denervated peripheral nerves may be the inability of Schwann cells to maintain important trophic support for both motor and sensory neurons.

Large-fiber neuropathy in distal sensory neuropathy with normal routine nerve conduction

Near-nerve needle sensory nerve conduction of plantar nerves in 100 patients with distal sensory neuropathy with normal routine nerve conduction (DSN-NNC) found the definite neuropathy pattern (abnormality in more than three of six tested nerves) in 65%, axonal neuropathy in 35%, and the known cause in 37% of patients. Absent or diminished reflexes were a reliable indicator for large fiber neuropathy (LFN). This near-nerve needle plantar nerve study provides useful and unequivocal evidence of its value in identifying neuropathy in DSN-NNC by finding LFN in 65% of patients.

Tibial nerve entrapment in the popliteal fossa

Details are presented of nine cases of tibial nerve entrapment by the tendinous arch of origin of the soleus muscle. The diagnosis was confirmed by surgical exploration of the popliteal fossa in six patients, who recovered fully after division of the soleus arch, whereas the other three improved spontaneously. This condition can be distinguished clinically from tibial nerve compression at the ankle, and from S1 radiculopathy, by the presence of severe pain and tenderness and a positive Tinel sign in the popliteal fossa, and by electrodiagnostic studies.

Medial plantar nerve conduction velocities among patients with vibration syndrome due to chain-saw work

OBJECTIVE

The present study examined the effect of the vibration syndrome (VS) on the peripheral nervous system in the lower extremities.

METHODS

Thirty-eight patients with VS due to previous exposure to vibration from chain-saw work and 55 age-matched controls were examined for sensory nerve conduction velocities in the medial plantar nerve (SCV-P). The patient group was divided into two subgroups, one with (n=19) and the other without vibration-induced white finger (VWF; n=19).

RESULTS

Analysis of variance of SCV-P for the three groups showed significant difference (F(2,89)=10.65, P < 0.0001). A significant difference was found between the controls and the VWF(+) group (P < 0.0001) but not between the controls and the VWF(-) group (P=0.0508) by multiple comparison using Scheffe's method.

CONCLUSION

These findings suggest that VS affects the peripheral nervous system function in the lower extremities via mediation of circulatory disturbance manifested as VWF.