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Somatosensory evoked potentials in myelopathies
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either of the segments to be slower or faster than the other. A series of patients with carpal tunnel syndrome were also studied in this manner. Those with proximal slowing without pronator syndrome had no evidence of localized conduction block proximal to the wrist. However, two patients with concomitant pronator syndrome were discovered by this method and confirmed by the "inching technique".
A-10.06 SHORT-LATENCY SOMATOSENSORY EVOKED POTENTIALS FOLLOWING TRIGEMINAL NERVE STIMULATION IN MAN. N. Singh, K. Sachdev and R. Brisman (New York, NY, USA)
Late motor responses with the essential characteristics of the H wave were recorded from the flexor carpi ulnaris muscle in normal adults after electrical stimulation of the ulnar nerve at the elbow. In most instances it was necessary to employ special techniques of facilitation to evoke these reflex responses. In all respects these indirect motor responses were comparable to the monosynaptic reflexes derived from the superficial forearm flexors after electrical stimulation of the median nerve in the cubital fossa(Oeschuytere et al.: J. Neurol. Neurosurg. Psychiat. 1976, 39, 555). The clinical significance will be briefly documented.
A technique for trigeminal somatosensory evoked potentials, stimulating the mentalis nerve at the mandibular foramen using a near-nerve electrode, evoked an early potential at 3.2 msec. The early potential can easily be recognized in all normal subjects and on the asymptomatic side of patients with various facial pain syndromes. The latency of this early potential in normals is 1-2 msec less than twice the mechanically induced jaw jerk latency using an electronic hammer. This potential simultaneously appeared on both sides of the head on stimulation of right or left mentalis nerve. The possibility of the origin of the early potential at the Gasserian ganglion and deep structures in and around the brain-stem is suggested. This recorded bilaterallv at the scale ootential. yielded results which are compatible with representation of orofacial cortical stimulation studies of these structures previously reported. The technique is useful in detecting and documenting functional integrity of peripheral and central afferent pathways of the Vth cranial nerve.
B-7.05 CHANGES IN LATENCY OF PlOO OF THE VEP IN PATIENTS WITH MULTIPLE SCLEROSIS. F.M. Taylor and E.M. Sedgwick (Southampton, G.B.)
B-10.04 SOMATOSENSORY EVOKED POTENTIALS IN MYELOPATHIES. K. Sachdev, N. Singh and R. Koelhe (New York, NY, USA)
Many reports of the VEP in multiple sclerosis (MS) mention reduction of latency of the Pm component, sometimes to normal, in a small proReturn of VEP to normal is portion of cases. clinically important as it represents a false The pathophysiological process negative test. underlying latency reduction may imply re-myelination within the central nervous system but other explanations are possible. In a series of 54 patients (20 definite, 12 probable and 22 possible MS) 38 showed a change of latency of more than 2 standard deviations of normal (10 msec) but in 5 the reThe inter-test interval ponse became normal. In 15 patients the was 15 days to 3 years. latency of Pm shortened by > 10 msec and 7 of these qave a history of optic neuritis in the past.Of the 5 oatients whose PlOO returned to normal, 2 had brevious clinical optic neuritis and were in the possible MS group. Abnormal VEPs fluctuate significantly in a high proportion of cases and sometimes return to within the normal range.
Somatosensory evoked potentials (SEPs) were studied in 172 patients with myelopathies and 46 patients with subjective sensory loss, weakness or "pain". SEP results were compared with Fortv-six oatients had VEP and BAEP studies. definite, 39 probable, 25 "probabie progressive" and 8 were suspected to have, multiplesclerosis. Cord compression in 33 (cervical 27), motor neurone disease in 7 and 14 had miscellaneous aetiology for their myelopathies. SEPs were obtained-following median. nerve stimulation at In oatients with definite M.S., the wrist. SEPs were abnormal in 65%; VEPs in 88% and Incidence of abnormal SEPs was BAEPs in 47%. 33% in orobable M.S. as cornoared to 56% for VEP In probable progressive and lO%'for BAEPs. r7.S.) SEP abnormality was present in 20%, VEP in 55%. BAEP in 10%. In susoected M.S. VEPs were abnormal in l/3 while SEPs and BAEPs were The VEPs were superior in abnormal in all. detecting M.S. as compared to SEPs (upper exIn cervical cord tremity results) and BAEPs. compression SEPs were abnormal in 65% with extramedullary lesions and 25% with intramedul37% patients with miscellaneous lary lesions. myelopathies had abnormal SEPs, however, in 1 patient with tabes dorsalis the study was norCorrelation of SEPs with sensory modalimal. ties will be presented.
B-3.01 MONOSYNAPTIC REFLEXES IN THE FLEXOR CARP1 ULNARIS MUSCLE IN MAN. J. Oeschuytere, C. De Keyser, N. Rosselle and il. Oeschuttere. (Antwerp, Belgium)
either of the segments to be slower or faster than the other. A series of patients with carpal tunnel syndrome were also studied in this manner. Those with proximal slowing without pronator syndrome had no evidence of localized conduction block proximal to the wrist. However, two patients with concomitant pronator syndrome were discovered by this method and confirmed by the "inching technique".
A-10.06 SHORT-LATENCY SOMATOSENSORY EVOKED POTENTIALS FOLLOWING TRIGEMINAL NERVE STIMULATION IN MAN. N. Singh, K. Sachdev and R. Brisman (New York, NY, USA)
Late motor responses with the essential characteristics of the H wave were recorded from the flexor carpi ulnaris muscle in normal adults after electrical stimulation of the ulnar nerve at the elbow. In most instances it was necessary to employ special techniques of facilitation to evoke these reflex responses. In all respects these indirect motor responses were comparable to the monosynaptic reflexes derived from the superficial forearm flexors after electrical stimulation of the median nerve in the cubital fossa(Oeschuytere et al.: J. Neurol. Neurosurg. Psychiat. 1976, 39, 555). The clinical significance will be briefly documented.
A technique for trigeminal somatosensory evoked potentials, stimulating the mentalis nerve at the mandibular foramen using a near-nerve electrode, evoked an early potential at 3.2 msec. The early potential can easily be recognized in all normal subjects and on the asymptomatic side of patients with various facial pain syndromes. The latency of this early potential in normals is 1-2 msec less than twice the mechanically induced jaw jerk latency using an electronic hammer. This potential simultaneously appeared on both sides of the head on stimulation of right or left mentalis nerve. The possibility of the origin of the early potential at the Gasserian ganglion and deep structures in and around the brain-stem is suggested. This recorded bilaterallv at the scale ootential. yielded results which are compatible with representation of orofacial cortical stimulation studies of these structures previously reported. The technique is useful in detecting and documenting functional integrity of peripheral and central afferent pathways of the Vth cranial nerve.
B-7.05 CHANGES IN LATENCY OF PlOO OF THE VEP IN PATIENTS WITH MULTIPLE SCLEROSIS. F.M. Taylor and E.M. Sedgwick (Southampton, G.B.)
B-10.04 SOMATOSENSORY EVOKED POTENTIALS IN MYELOPATHIES. K. Sachdev, N. Singh and R. Koelhe (New York, NY, USA)
Many reports of the VEP in multiple sclerosis (MS) mention reduction of latency of the Pm component, sometimes to normal, in a small proReturn of VEP to normal is portion of cases. clinically important as it represents a false The pathophysiological process negative test. underlying latency reduction may imply re-myelination within the central nervous system but other explanations are possible. In a series of 54 patients (20 definite, 12 probable and 22 possible MS) 38 showed a change of latency of more than 2 standard deviations of normal (10 msec) but in 5 the reThe inter-test interval ponse became normal. In 15 patients the was 15 days to 3 years. latency of Pm shortened by > 10 msec and 7 of these qave a history of optic neuritis in the past.Of the 5 oatients whose PlOO returned to normal, 2 had brevious clinical optic neuritis and were in the possible MS group. Abnormal VEPs fluctuate significantly in a high proportion of cases and sometimes return to within the normal range.
Somatosensory evoked potentials (SEPs) were studied in 172 patients with myelopathies and 46 patients with subjective sensory loss, weakness or "pain". SEP results were compared with Fortv-six oatients had VEP and BAEP studies. definite, 39 probable, 25 "probabie progressive" and 8 were suspected to have, multiplesclerosis. Cord compression in 33 (cervical 27), motor neurone disease in 7 and 14 had miscellaneous aetiology for their myelopathies. SEPs were obtained-following median. nerve stimulation at In oatients with definite M.S., the wrist. SEPs were abnormal in 65%; VEPs in 88% and Incidence of abnormal SEPs was BAEPs in 47%. 33% in orobable M.S. as cornoared to 56% for VEP In probable progressive and lO%'for BAEPs. r7.S.) SEP abnormality was present in 20%, VEP in 55%. BAEP in 10%. In susoected M.S. VEPs were abnormal in l/3 while SEPs and BAEPs were The VEPs were superior in abnormal in all. detecting M.S. as compared to SEPs (upper exIn cervical cord tremity results) and BAEPs. compression SEPs were abnormal in 65% with extramedullary lesions and 25% with intramedul37% patients with miscellaneous lary lesions. myelopathies had abnormal SEPs, however, in 1 patient with tabes dorsalis the study was norCorrelation of SEPs with sensory modalimal. ties will be presented.
B-3.01 MONOSYNAPTIC REFLEXES IN THE FLEXOR CARP1 ULNARIS MUSCLE IN MAN. J. Oeschuytere, C. De Keyser, N. Rosselle and il. Oeschuttere. (Antwerp, Belgium)