Method: Ulnar motor nerve conduction studies were performed bilaterally in twenty healthy adult volunteers. For each limb, nerve conduction study was carried out in two different positions. In the first position, shoulder were abducted, elbow and wrist flexed to 90^o. For the second position, all joints were kept constant except for the wrist where it was extended. Routine conduction study was performed in both wrist positions. All data were statistically analyzed.

Results: The average conduction velocities in the wrist flexed position were 61.6 m/sec for the forearm segment and 62.3 m/sec across elbow. With the wrist extended, the average was 62.6 m/sec and 64.1 m/sec, respectively. The differences in conduction velocities between two different wrist positions were statistically significant (p＜0.05). In the wrist flexed position, the average measured latencies were 2.3 msec with wrist, 5.4 msec below elbow, and 7.4 msec above elbow stimulation, compared to wrist extended which showed 2.4, 5.4 and 7.2 msec, respectively. The difference of latencies at wrist between the two wrist positions was statistically significant (p＜0.05).

Conclusion: The authors conclude that wrist position affect ulnar nerve conduction velocity.

Objective: The purpose of this study is to find out whether amplitude ratio and area ratio have correlation with nerve conduction velocity in the diabetes mellitus patients.

Method: Median and deep peroneal motor nerve conduction study was performed in thirty-five normal control group and sixty diabetes mellitus patients group. The motor conduction velocity, amplitude ratio, and area ratio of the compound muscle action potential (CMAP) were measured. The experimental subjects were divided into 6 subgroups (in median nerve: M1, M2, M3, in peroneal nerve: P1, P2, P3) according to the median value of conduction velocity of each nerve; group M1 (n=35) and P1 (n=30): normal control group, group M2 (n=25) and P2 (n=30): below the median value of motor nerve conduction velocity in diabetes mellitus patients, group M3 (n=23) and P3 (n=29): above the median value of motor nerve conduction velocity in diabetes mellitus patients.

Results: There was no significant difference of area ratio between the each subgroups in both median and peroneal nerves. There was a significant difference of amplitude ratio between the M1 and M2 subgroups. There was a significant difference of amplitude ratio between the P1 and P2, P3 subgroups.

Conclusion: According to above results, the decrease of amplitude of compound muscle action potential along with the decrease of conduction velocity seems to be helpful in the electrophysiologic diagnosis of diabetic neuropathy.

Objective: Tarsal tunnel syndrome (TTS) is relatively rare and can be difficult to diagnose with conventional electrodiagnostic techniques. To increase the diagnostic sensitivity, we measured transtarsal conduction velocities of medial and lateral plantar nerves recorded by orthodromic near-nerve recording.

Method: Twenty normal subjects (aged 24∼59) were studied. For below flexor retinaculum (BFR) recordings, near-nerve needle recording electrodes were positioned posteriorly to the flexor digitorum longus tendon in medial plantar nerve and anteriorly to the calcaneus in lateral plantar nerve at the level of lower border of medial malleolus. For above flexor retinaculum (AFR) recordings, near-nerve needle recording electrodes were positioned anteriorly to the Achilles tendon 4 cm proximal to the BFR recording electrodes in medial and lateral plantar nerves. Stimulating ring electrodes were placed to the digit I and V.

Results: Transtarsal latencies and conduction velocities for medial plantar nerve were 0.7⁑0.1 msec, 56⁑6 m/sec, respectively. Transtarsal latencies and conduction velocities for lateral plantar nerve were 0.8⁑0.1 msec, 54⁑6 m/sec, respectively.

Conclusion: This approach may improve the diagnostic sensitivity in TTS.

Objective: To find out the incidence of reduced median conduction velocity of forearm (MNCV-F) in carpal tunnel syndrome (CTS) and to compare clinical and electrophysiologic characteristics of CTS with reduced MNCV-F and to observe the changes of reduced MNCV-F after carpal tunnel release.

Method: One hundred and fifty nine hands with CTS are divided into two groups; MNCV-F of 50 m/sec and above as group I and that of below 50 m/sec as group II. For the electrophysiologic comparison, median sensorimotor distal latency, peak-to-peak amplitudes and abnormal spontaneous activity of abductor pollicis brevis were observed and for clinical comparison, sensorimotor symptoms, Phalen and Tinel sign were observed. Twenty four hands which had successful carpal tunnel release were examined for the changes of MNCV-F.

Results: The hands with reduced MNCV-F were 29 among 159 hands. Sensorimotor distal latency were significantly prolonged and sensorimotor amplitudes also significantly reduced in group II. Sensory change and Phalen signs were more frequently observed in group II. MNCV-F in group I had not changed after carpal tunnel release, but MNCV-F in group II was improved significantly. The changes MNCV-F in group II were much delayed than the improvement of parameters of distal conduction studies.

Conclusion: The incidence of reduced MNCV-F in CTS was 18.24%. Patients with reduced MNCV-F had more severe CTS both electrophysiologically and clinically. Reduced MNCV-F had improved significantly, but there was significant time gap between the electrophysiologic improvements of distal and proximal portions of nerve. This findings may suggest that retrograde degeneration may play a partial role in reduced forearm motor nerve conduction velocity of the median nerve in CTS.

Objective: To investigate the muscle fiber conduction velocity and histopathologic changes in skeletal muscle after 7% phenol solutions intramuscular injection.

Method: Forty-five Sprague Dawley rats were divided into two groups: Experimental group, 30; Control group, 15. Experimental and control groups were injected with 0.1 cc of 7% phenol solution and 0.9% saline in right gastrocnemius, respectively. The histopathologic findings and muscle fiber conduction velocity were evaluated at 0, 1, 5, 14, and 28 days after each injection.

Results: In the light microscopic examination of experimental groups, vacuolar change, atrophy of myofibers, and intermyofiber cell proliferation were shown. The expression of synaptophysin began to be seen at 5 days and S-100 protein was increased 14 days after injection. In the electron microscopic examination of experimental groups, vacuolar change and denuded postsynaptic membrane were shown. In muscle fiber conduction study of experimental groups, the mean velocity were significantly slowed at 1, 5, 14, and 28 days after injection than those of control groups (p＜0.05).

Conclusion: On the basis of histopathologic findings, it is presumed that the mechanisms of paralysis following intramuscular injection of 7% phenol solutions were both myogenic and neurogenic. The slowing of muscle fiber conduction velocity tended to be related with the histopathologic changes of skeletal muscles after intramuscular injection with 7% phenol solution.

Objective: The purpose of this study is to prove protective action of melatonin on the development of neuropathy in diabetic rat.

Method: The experimental rats (Sprague-Dawley) were divided into 3 groups: Group 1, streptozotocin-induced diabetic rats with trial of melatonin; Group 2, streptozotocin-induced diabetic rats without trial of melatonin; Group 3, normal control. Streptozotocin was injected intraperitoneally in group 1 and 2. Melatonin was administered per orally in group 1 from 1 week after the injection of streptozotocin. The melatonin effect on diabetic neuropathy was evaluated by the measurement of conduction velocities and amplitudes of rat tail mixed nerve action potentials. The electrophysiologic examinations were performed before and 2, 4, and 6 weeks after administration of streptozotocin.

Results: The rat tail mixed nerve conduction velocities were decreased at 4 weeks in group 1 and 2, and showed significant improvement at 6 weeks in group 1 as compared with those of group 2 (p＜0.05). The amplitudes of the compound nerve action potentials did not show difference before and after streptozotocin and melatonin trials, neither among groups.

Conclusion: In this experimental study, we observed the inhibitory effect of melatonin on the progression of polyneuropathy in early stage of diabetic rat. For the clinical application to human beings, further study is required.

Objective: To investigate the conduction velocity of sympathetic skin response(SSR) in normal adults.

Method: The latency of SSR was measured in 41 normal healthy subjects by the simultaneous recordings from three sites of the hand. And we also measured the distance and conduction time between the recording sites of the hand. The conduction velocity of SSR was calculated by dividing the distance by conduction time.

Results: The SSR was obtainable in all subjects from three sites of the hand. The mean latencies of SSR recorded from wrist, midpalm and index finger were 1.29, 1.40 and 1.54 seconds respectively. And the mean latency showed a significant increase from wrist to index finger(p＜0.05). The conduction velocity of the SSR from wrist to index was 0.57 m/sec, and segmental conduction velocities from wrist to palm and palm to index were 0.62 and 0.66 m/sec respectively. The conduction velocity of SSR in the distal segment was slightly faster than in the proximal segment with no statistical significance.

Conclusion: The conduction velocity of SSR by the simultaneous recordings at two or more sites of the hand can be easily obtained and offers a useful parameter along with the amplitude and latency of SSR.