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Evoked potentials in syringomyelia
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VIII C O N G R E S S OF E M G A N D R E L A T E / ) C L I N ICAL N E U R O P H Y S 1 O L O G Y
examined radiologically as well. Eight of the 21 patients consequently underwent surgery. In 60% of the patients the findings of the SSEP tests showed a good correlation with those of E M G and radiological examinations. In the other patients there was a correlation between the results of SSEP and those of the other examinations. Therefore we concluded that in over half of the patients clinically suspected of unilateral lumbosacral hernia nuclei pulposi the SSEP findings corresponded with the results of EMG, radiological tests, and surgery. In an additional study we investigated the possibilities of the application of dermato-somatosensory evoked potentials. This type of test also turned out to represent an important tool in detecting lumbosacral lesions.
PS. Evoked potentials in syringomyelia. - M. Nogu~s, A. Cammarota, M. Bianco and H. Garcia (Instituto de Investigaclones Neurol6gicas Dr. Raid Carrea~ 1112 Buenos Aires, Argentina) The purpose of this study has been to correlate EP abnormalities with the clinical and radiological findings of a group of patients with cervical syringomyelia with a variable degree of motor, sensory and brain-stem involvement. Short latency somatosensory (SEPs) and brain-stem auditory evoked potentials (BAEPs) were recorded in 11 patients with syringomyelia, 6 of w h o m had in addition brain-stem signs. Duration of symptoms ranged from 1 to 11 years, and disability status (modified Kurtzke's scale) from 2 to 6. Median SEPs showed a delayed ERB potential in 6 patients, and an absent or delayed P14 in 8. Posterior tibial SEPs were abnormal in 9 cases. BAEPs showed an increased V - I interval in 5 out of 8 patients tested, usually bilaterally. Four out of the 5 patients affected had an associated cranio-vertebral malformation. From this study we conclude: (1) lower limb SEPs are frequently affected in cervical syringomyelia, even in the absence of posterior column signs; (2) BAEP abnormalities are common, particularly in patients with an associated cranio-vertebral anomaly; and (3) EP abnormalities are not correlated with disability status or duration of symptoms.
SY. Abnormal ortho- and antidromic discharges from primary sensory units in man. - J. Ochoa, M. Cline *, W. Comstock and P. Marcbettini * * (Departments of Neurology, Good Samaritan Hospital and Medical Center, Portland, OR, * Neurophysiology, Univ. of Wisconsin, Madison, Wl, U.S.A., and * * Neurology, Univ. of Milan, Milan, Italy) The pathophysiological basis for sensory disorders of positive character, emanating from dysfunction of the primary sensory unit in man, escapes detection through routine clinical neurophysiology. Through microneurography, a procedure requiring intraneural recordings, it has been established that the basis for several such disorders is ectopic spontaneous generation of nerve impulses. On the other hand, for abnormal positive phenomena induced by natural stimulation of receptors
(like hyperalgesia), as opposed to spontaneously occurring phenomena (like ongoing pain or paresthesias), it is generally accepted that the pathophysiology involves secondary disinhibition in CNS due to injury to primary sensory neurons. However, it has been shown recently that abnormal sensitization qf the peripheral polymodal nociceptor neuron may occur in patients and m a y by itself account for the symptomatology. Based upon such evidence and upon known electrical and neurosecretory functions of those receptors, a set of additional characteristics was predicted for the clinical expression of hyperexcitable and antidromically neurosecreting polymodal nociceptors. These have been confirmed in rigorously studied patients. This angry backfiring C nociceptor (ABC) syndrome is identical to at least a subpopulation with reflex sympathetic dystrophy. Supported by N1NCDS Grant No. R01 NS24740-01 and N I H - N R S A Grant No. 5 T32 NS07026-09.
SMi. Peripheral and tentative central changes after peripheral nerve lesion in man. - G. Oehs, M. Scbenk and A. Struppler (Dept. Neurology, Technical University, Munich, F.R.G.) Up to now 22 patients with complete ulnar, median or digital nerve lesions have been examined 8 m o n t h s - 7 years after suture, interponat or replantation. Microneurography, microstimulation and a subtile clinical test procedure (mechanical, thermal, sympathetic, differential block) have been performed to quantify the deficit and the stage of reinnervation. Properties of regenerated single receptors/nerve fibers turned out to be comparable or equal to controls, as had already been demonstrated elsewhere. Most of the regenerated receptors recorded from were located in skin areas with less sensory disturbance. There was no evidence that thin fibers,did regenerate better than myelinated ones. The territories projected by intrafascicular microstimulation did show various irregularities in comparison to controls. Differential block by ischemia made dysesthesias, present in many patients at least in the first stage of regeneration, disappear. Hyperpathia and cold allodynia, however, persisted during ischemia. In summary, the results of the study make proximal or central changes essential to understand many of the clinical features encountered after peripheral nerve trauma.
PS. Differentiation between the Eaton-Lambert syndrome and myastbenia gravis: a ~ t i c challenge. - S.J. Oh, J.L. Joy, E. Hurwitz and A.I. Baysal * (Birmingham, AL, U.S.A. and * Antalya, Turkey) The Eaton-Lambert syndrome (ELS) is a pre-synaptic autoimmune disorder which is thought to be easily differentiated from myasthenia gravis (MG). Analysis of 15 patients with ELS showed frequent atypical features which rendered this differentiation more difficult: (1) In 60% of the cases, there were oculo-bulbar symptoms and signs.
VIII C O N G R E S S OF E M G A N D R E L A T E / ) C L I N ICAL N E U R O P H Y S 1 O L O G Y
examined radiologically as well. Eight of the 21 patients consequently underwent surgery. In 60% of the patients the findings of the SSEP tests showed a good correlation with those of E M G and radiological examinations. In the other patients there was a correlation between the results of SSEP and those of the other examinations. Therefore we concluded that in over half of the patients clinically suspected of unilateral lumbosacral hernia nuclei pulposi the SSEP findings corresponded with the results of EMG, radiological tests, and surgery. In an additional study we investigated the possibilities of the application of dermato-somatosensory evoked potentials. This type of test also turned out to represent an important tool in detecting lumbosacral lesions.
PS. Evoked potentials in syringomyelia. - M. Nogu~s, A. Cammarota, M. Bianco and H. Garcia (Instituto de Investigaclones Neurol6gicas Dr. Raid Carrea~ 1112 Buenos Aires, Argentina) The purpose of this study has been to correlate EP abnormalities with the clinical and radiological findings of a group of patients with cervical syringomyelia with a variable degree of motor, sensory and brain-stem involvement. Short latency somatosensory (SEPs) and brain-stem auditory evoked potentials (BAEPs) were recorded in 11 patients with syringomyelia, 6 of w h o m had in addition brain-stem signs. Duration of symptoms ranged from 1 to 11 years, and disability status (modified Kurtzke's scale) from 2 to 6. Median SEPs showed a delayed ERB potential in 6 patients, and an absent or delayed P14 in 8. Posterior tibial SEPs were abnormal in 9 cases. BAEPs showed an increased V - I interval in 5 out of 8 patients tested, usually bilaterally. Four out of the 5 patients affected had an associated cranio-vertebral malformation. From this study we conclude: (1) lower limb SEPs are frequently affected in cervical syringomyelia, even in the absence of posterior column signs; (2) BAEP abnormalities are common, particularly in patients with an associated cranio-vertebral anomaly; and (3) EP abnormalities are not correlated with disability status or duration of symptoms.
SY. Abnormal ortho- and antidromic discharges from primary sensory units in man. - J. Ochoa, M. Cline *, W. Comstock and P. Marcbettini * * (Departments of Neurology, Good Samaritan Hospital and Medical Center, Portland, OR, * Neurophysiology, Univ. of Wisconsin, Madison, Wl, U.S.A., and * * Neurology, Univ. of Milan, Milan, Italy) The pathophysiological basis for sensory disorders of positive character, emanating from dysfunction of the primary sensory unit in man, escapes detection through routine clinical neurophysiology. Through microneurography, a procedure requiring intraneural recordings, it has been established that the basis for several such disorders is ectopic spontaneous generation of nerve impulses. On the other hand, for abnormal positive phenomena induced by natural stimulation of receptors
(like hyperalgesia), as opposed to spontaneously occurring phenomena (like ongoing pain or paresthesias), it is generally accepted that the pathophysiology involves secondary disinhibition in CNS due to injury to primary sensory neurons. However, it has been shown recently that abnormal sensitization qf the peripheral polymodal nociceptor neuron may occur in patients and m a y by itself account for the symptomatology. Based upon such evidence and upon known electrical and neurosecretory functions of those receptors, a set of additional characteristics was predicted for the clinical expression of hyperexcitable and antidromically neurosecreting polymodal nociceptors. These have been confirmed in rigorously studied patients. This angry backfiring C nociceptor (ABC) syndrome is identical to at least a subpopulation with reflex sympathetic dystrophy. Supported by N1NCDS Grant No. R01 NS24740-01 and N I H - N R S A Grant No. 5 T32 NS07026-09.
SMi. Peripheral and tentative central changes after peripheral nerve lesion in man. - G. Oehs, M. Scbenk and A. Struppler (Dept. Neurology, Technical University, Munich, F.R.G.) Up to now 22 patients with complete ulnar, median or digital nerve lesions have been examined 8 m o n t h s - 7 years after suture, interponat or replantation. Microneurography, microstimulation and a subtile clinical test procedure (mechanical, thermal, sympathetic, differential block) have been performed to quantify the deficit and the stage of reinnervation. Properties of regenerated single receptors/nerve fibers turned out to be comparable or equal to controls, as had already been demonstrated elsewhere. Most of the regenerated receptors recorded from were located in skin areas with less sensory disturbance. There was no evidence that thin fibers,did regenerate better than myelinated ones. The territories projected by intrafascicular microstimulation did show various irregularities in comparison to controls. Differential block by ischemia made dysesthesias, present in many patients at least in the first stage of regeneration, disappear. Hyperpathia and cold allodynia, however, persisted during ischemia. In summary, the results of the study make proximal or central changes essential to understand many of the clinical features encountered after peripheral nerve trauma.
PS. Differentiation between the Eaton-Lambert syndrome and myastbenia gravis: a ~ t i c challenge. - S.J. Oh, J.L. Joy, E. Hurwitz and A.I. Baysal * (Birmingham, AL, U.S.A. and * Antalya, Turkey) The Eaton-Lambert syndrome (ELS) is a pre-synaptic autoimmune disorder which is thought to be easily differentiated from myasthenia gravis (MG). Analysis of 15 patients with ELS showed frequent atypical features which rendered this differentiation more difficult: (1) In 60% of the cases, there were oculo-bulbar symptoms and signs.