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Dominantly inherited spinocerebellar ataxias (SCAs) are a group of the heterogenous neurodegenerative diseases that are characterized by chronic progressive cerebellar ataxia associated with various combinations of other neurological signs. Clinical classification is difficult because of the phenotypic overlap. With the evolution of molecular genetics, the loci and mutations for many of the ataxias have been identified, allowing more definitive molecular classification.
We experienced 42 years-old man who presented with progressive both lower leg weakness, dysarthria, ataxia, ophthalmoplegia, and nystagmus. The family history was remarkably suspicious. We could not observe the upper extremity weakness, definite evidences of peripheral neuropathy and myopathy in electrodiagnosis. No abnormal findings in blood chemistry and brain MRI. We performed polymerase chain reaction (PCR) and polyacrylamide gel electrophoresis (PAGE) analysis, found that his gene contained expanded CAG repeats (CAG repeat number was 72). Although no effective treatment exists for most the ataxic syndromes, the accurate diagnosis and the genetic counseling are often important to the patient's family for prognostication.
Objective: Distance between the active and reference electrodes can affect the waveform configuration and amplitude of sensory nerve action potential (SNAP). This study was purposed to determine the change of SNAP parameters with varying interelectrode distance.
Metohod: Median sensory nerve conduction study was performed in the middle finger of 40 young healthy subjects by antidromic method. To ensure firm contact with skin, strip adhesive electrode was used for recording responses. The active electrode was fixed on 1 cm distal to the proximal flexion crease of middle finger and interelectrode separation was increased from 1 to 5 cm by 1.0 cm increments. Bar electrode was fixed 14 cm proximal from active electrode for stimulation in the wrist area.
Results: As the interelectrode distance increased from 1 cm to 5 cm, onset latency remained unchanged. The peak latency increased with increasing the distance up to 3 cm but didn't change beyond 3 cm (1 cm: 2.89⁑0.89 msec, 2 cm: 2.97⁑0.89 msec, 3 cm: 3.02⁑0.19 msec, 4 cm: 3.02⁑0.19 msec, 5 cm: 3.02⁑0.20 msec). Base-to-peak amplitude significantly increased only up to 3 cm (1 cm: 30.3⁑6.7μV, 2 cm: 43.7⁑8.6μV, 3 cm: 50.8⁑10.4μV, 4 cm: 51.1⁑10.9 μV, 5c m: 51.3⁑11.4μV) but peak-to-peak amplitude sequentially increased to 5 cm (1 cm: 49.6⁑12.1μV, 2 cm: 72.8⁑14.4μv, 3 cm: 83.6⁑19.4μV, 4 cm: 91.3⁑22.5μV, 5 cm: 93.4⁑23.9μV)(p＜.05).
Conclustion: This study showed that changing interelectrode distance altered some parameters of SNAP, especially the peak-to peak amplitude.
Objective: Intraoperative somatosensory evoked potentials (SEPs) are widely used for the early detections of cerebral ischemia during temporary occlusive procedures of the parent vessels in aneurysm surgery. This study intended to evaluate the usefulness of median nerve SEPs during intracranial aneurysm surgery.
Method: Between September 1995 and June 1997, we monitored 42 aneurysm patients in Uijongbu St. Mary's hospital. Median nerve SEPs were detected on scalp and cervical spine during surgery. We measured latencies, amplitudes of N20 and N13 waveforms and central conduction time (CCT, N20-N13). We analyzed pre- and post-surgical radiologic findings and changes of neurologic signs.
Results: The delayed latencies, CCT, and reduced amplitudes of median nerve SEPs during intraoperative monitoring were closely related to neurological deficits after surgery.
Conclusion: Intraoperative SEPs are useful in preventing clinical neurological injury during surgery of intracranial aneurysm and in predicting which patients will have unfavourable outcomes.
Objective: To obtain reference values of early potential latency and amplitude of pudendal SEP in Korean normal women and to correlate those values with height and age.
Method: Twenty-three normal female with mean age of 45.27 years were evaluated for pudendal SEP. Stimulation was applied on the dorsal aspect of the clitoris with a bar electrode. Onset, P1, N1, P2 latencies and P0-P1, P1-N1, N1-P2 amplitudes were measured and those of both sides were analyzed.
Results: The mean latency of P0, P1, N1, P2 were 29.0⁑2.83 msec, 35.5⁑2.91 msec, 45.1⁑4.10 msec, 56.3⁑5.20 msec by the right pudendal nerve, and 28.6⁑3.11 msec, 35.2⁑2.93 msec, 45.0⁑3.83 msec, 56.5⁑5.33 msec by the left pudendal nerve. The amplitude ranges of P0-P1, P1-N1, N1-P2 were 0.31∼2.45 uV, 0.11∼2.24 uV, 0.21∼2.62 uV by the right pudendal nerve, and 0.29∼2.46 uV, 0.25∼2.21 uV, 0.12∼5.07 uV by the left pudendal nerve. There was tendency of prolongation of the latency with increasing the height. There is no difference of amplitude according to the height and the age. There was no significant difference between right and left sides in mean latency and range of amplitude of pudendal nerve SEPs, and between premenopause and postmenopause.
Conclusion: Normal reference of female pudendal SEP were established. We suggest that pudendal SEP can be used as one of useful diagnostic tools for female urogenital and neurologic disease.
A sepsis or multiple organ dysfunction occurs frequently in the intensive care unit and causes a significant number of mortality and morbidity. Somtimes polyneuropathy of varying severity occurs in association with a sepsis or critical illness. Since the clinical evaluation is often difficult, electrophysiologic studies are employed to reveal a definitive evidence for polyneuropathy.
The purpose of this study was to investigate the frequency of polyneuropathy and to determine the electrophysiologic features of critically ill patients.
The subjects were 23 patients between ages of 42 and 72 with a sepsis or systemic inflammatory response syndrome combinded with the multiple organ failure.
The results revealed reductions in the amplitude of compound motor action potential and sensory nerve action potential, as the most marked abnormality. Needle EMG revealed the signs of denervation of limb muscles. Approximately 65.3% of adult patient with sepsis or multiple organ dysfunction has an axonal polyneuropathy.
We suspect that the axonal polyneuropathy is related to the severity of multiple organ dysfunction.
Pudendal nerve somatosensory evoked potential(PSEP) study has been utilized for the evaluation of neurogenic dysfunctions of bowel, bladder and sex. However, the reluctance of sexual organ exposure during the study can be a serions limiting factor. Sacral dermatomal somatosensory evoked potential(SDSEP) study stimulating sacral dermatome can be an alternative or a supportive method for the PSEP study.
The purpose of this study is to present the techniques, normal values and clinical significance of SDSEP study in spinal cord injured patients. Thirty control subjects and thirty-five spinal cord injured patients were enrolled for the study. Using ring electrodes, S3 dermatome was stimulated by Nicolet Viking IV EMG/EP system. Evoked responses were recorded at the cortex(Cz'-Fz) by the needle electrodes. The latencies and amplitudes of SDSEP and PSEP responses were obtained and analyzed. In control subjects, the P1 latencies of SDSEP were 34.72⁑2.68 msec for the right and 33.54⁑1.95 msec for the left. The N1 latencies were 43.06⁑2.31 msec for the right and 42.14⁑2.29 msec for the left, respectively. The P1N1 amplitudes of control subjects were 0.73⁑0.40 ㄍV for the right and 0.69⁑0.22 ㄍV for the left. The coincidence of SDSEP and PSEP was 86.7% of the spinal cord injured patients.
In conclusion, SDSEP study could be used for the evaluation of neurogenic dysfunctions of bladder, bowel, and sex in conjunction with the PSEP study.
The effect of electrical nerve stimulation are controversial because of the inconsistent variables of stimulating current and electrophysiologic study. The purposes of this study are to reconfirm the electrophysiolgic changes by electrical stimulation of the peripheral nerve that had been reported in 1993, and to monitor how long they will be maintained. In this study, the following conditioning stimulations were applied to 20 healthy volunteers; interferential current(frequency: 80∼100 Hz, intensity: 27∼34 mA) on the sacral paraspinal area. The H reflex, the F response, and the somatosensory evoked potential(SEP) of the tibial nerve were evaluated as the electrophysiologic study before, immediately after, 30 minutes, 60 minutes, and 120 minutes after the above conditioning stimulation. The following results were obtained;
1) Latencies of the H reflex, the F response and the SEP(P1), and the F wave conduction time, the F wave conduction velocity and the F ratio in the tibial nerve conduction study were increased by conditioning stimulation of the proximal peripheral nerves(P＞0.01).
2) Changes of the amplitude of the H reflex, the H/M ratio, and the amplitude(P1N1) of the tibial SEP were not significant in the same conditioning stimulation(P＞0.05).
3) Prolongations of the latencies of H reflex, F response and P1 SEP of the tibial nerve were the most significant immediately after conditioning stimulation and sustained for 45 minutes after conditioning on average (P＜0.01).
The above results suggest that certain conditional electrical stimulation of the peripheral nerves causes reversible changes in the conduction of the H reflex, the F response and the SEP and they may be inhibitory effect of the proximal conduction via the spinal cord.
We studied diabetic central neuropathy(DCN) that is not well-known neurologic disorder, for confirming its existence and then presenting objective diagnostic criteria and methods. Thirty-six diabetics(NIDDM: 30, IDDM: 6), mean age 53.1 years, 21 males and 15 females, were compared with 36 controls, mean age 51.5 years, 18 males and 18 females, electrophysiologically. First, we diagnosed peripheral polyneuropathy(PN) in diabetics by means of Diabetic Neuropathy Staging(DNS) developed at the University of Michigan and classified diabetics into two groups; group I indicates diabetics with PN, group II diabetics without PN. Second, we studied central(cortico-cervical and cortico-lumbar) motor conduction time(CMCT) by means of magnetic motor-evoked potentials(MEP) and central somatosensory conduction time by means of somatosensory-evoked potentials(SEP) stimulating on median and posterior tibial nerves.
There were no significant differences(p>0.05) statistically in cortico-cervical CMCT between diabetics and controls. There were significantly more prolonged(p<0.01) in cortico-lumbar CMCT between diabetics and controls. In median nerve-evoked 3-channel SEP, N13-N20(cortico-cervical) interpeak latency was significantly more prolonged(p<0.01) in diabetics than controls. In tibial nerve-evoked 2-channel SEP, P38-N22(cortico-lumbar) interpeak latency was significantly more prolonged(p<0.01) in diabetics than controls. In 30 patients(83.3%) of 36 diabetics, the study revealed central conduction delay in view of that above 2 or more abnormalities representing central conduction delay, that is, central neuropathy. In 10 patients(33.3%, M:7, F:3) of diabetics with central neuropathy(30 patients), even though they had no PN, central conduction delay was revealed.
Conclusively, in view of representing central conduction delay in 83.3% of patients, we believe that more active evaluations are needed in diabetics representing nonspecific central neurologic symptoms, for example, psychomotor slowing or cognitive dysfunctions, and MEP and SEP are useful in diagnosing DCN.
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