- Email: [email protected]
32. Usefulness and limitation of intraoperative visual evoked potential (VEP) monitoring
e26
Society Proceedings / Clinical Neurophysiology 121 (2010) e19–e34
measured the DMLs, compound muscle action potentials (CMAP) and nerve conduction velocities in 73 consecutive patients with ALS, 12 with spinal muscular atrophy (SMA), 12 with spinal-bulbar muscular atrophy (SBMA), and 36 with axonal neuropathy due to vasculitis (VN). Multiple axonal excitability measurements were performed for the median nerve in the ALS patients. The DML was prominently prolonged (=5.4 ms: over 125% of the upper limit of normal) in 8 ALS patients (11%), 1 SMA/SBMA patient (4.2%) and no VN patients (0%). In threshold electrotonus, the results of the ALS patients with markedly prolonged DML showed a tendency that the axonal resting membrane potential shifts in the depolarizing direction. Our findings suggest that, in ALS, there is a subgroup with prolonged DML unexplained by merely loss of the fastest axons, which is rare in other motor neuron diseases and neuropathies. The robust resting membrane depolarization in motor axon may result in inactivation of sodium channels, and thereby distal nerve conduction slowing in the terminal stage of ALS. doi:10.1016/j.clinph.2010.02.110
30. Sleep spindles in the early phase of acute encephalitis/ encephalopathy with acute gastroenteritis in infants and children—Kuniaki Iyoda, Yukiko Ishiguchi, Kazunori Ogawa, Hideaki Ochi (Hiroshima City Hospital, Hiroshima, Japan) We studied the significance of sleep spindles( SS ) in the early phase of acute encephalitis/encephalopathy( AE ) with gastroenteritis, to clarify the pathological sleep changes and to predict prognosis. The retrospective inspection on sampled serial EEGs of 9 patients with AE (M:F = 2:7, mean age = 2.7 years), and the consciousness disturbance (CD) classified in clinical by JCS (1978) and in EEG by Hockaday (1965), were investigated. (1) All patients were hospitalized within 3rd day of illness; mild to moderate cases were 6 and severe ones were 3, and recovered after averaging 7.6 days of illness (the former : the latter = 3.8:15.3 days, P < 0.001). (2) SS were seen within 2.6 days on average. Eight of 9 patients showed abnormal SS in morphology, duration and distribution, and returned to normal in averaging 2.5 months. SS of 3 cases observed after 4 days of illness, were delayed both recovery of CD and SS normalization; especially 4 cases remaining with extreme SS, tended to complicate with mental retardation (P < 0.05). These findings are possibly useful to evaluate the abnormal sleep changes in AE and predict the prognosis. doi:10.1016/j.clinph.2010.02.111
31. Early diagnosis of cerebral vasospasm by oxygen-pulse near infrared optical topography—Yuichi Tanaka, Takehiko Konno, Akira Ebihara, Eiju Watanabe (Jichi Medical University, Tochigi, Japan) We propose a new alternative method for the early diagnosis of delayed ischemic neurological deficit (DIND) due to cerebral vasospasm using oxygen pulse-based near infrared optical topography (OT). We used 48-channel OT system covering the bilateral frontotemporal areas. The study was conducted with 42 cases of SAH. The subjects inhaled room air and then oxygen for 2 min and room air again in block fashion and SpO2 was monitored at the finger tip. In ischemic regions, the oxy-Hb increase was delayed and/or lowered. To confirm this change, the principal component analysis referring to the systemic SpO2 was used. In 42 cases with SAH, 30 showed ischemic findings by OT before DIND occurred. Eleven cases (36%) of 30 showed DIND. But 19 cases ischemic findings by OT
disappeared and they showed no DIND. In 18 cases, IMP-SPECT and OT were performed on the same day. The diagnostic agreement rate for diagnosis of ischemia between SPECT and OT is 83.3%. These results suggest that this method can detects ischemia due to vasospasm before DIND. This method uses oxy-Hb as a tracer of OT. It can be clinically utilized as a real time and noninvasive assessment method of cerebral ischemia on cerebral vasospasm. doi:10.1016/j.clinph.2010.02.112
32. Usefulness and limitation of intraoperative visual evoked potential (VEP) monitoring—Ryoji Yamada, Yusuke Tabei, Tomoyuki Koizumi, Miho Akiyama, Kumiko Sukegawa, Hitoshi Kobayashi, Taminori Obayashi, Yuichi Suzuki, Toshiyuki Onodera, Kotoyo Kurokawa, Kazuo Yagi, Nobusada Shinoura (Tokyo Metropolitan Komagome Hospital, Tokyo, Japan) The aim of this study was to reveal the relationship between intraoperative VEP findings and postoperative visual function. The subjects were 35 patients operated with intraoperative VEP monitoring. The patients were classified into two groups; group A as 9 cases with tumors adjacent to optic nerve, and group B as 26 cases with tumors adjacent to optic radiation. Intraoperative VEP was recorded by 2000 Lux, 1.1 Hz stimulation, and 100 times of addition. The recording electrodes were placed at occipital skin, dura mater, or cerebral surface. VEP was assessed by an amplitude difference of N75 and P100 components. In group A, there was a highly correlation between VEP and postoperative visual function. In all 3 cases that showed decrease of amplitude to less than 50% and no recovery, visual function was deteriorated transiently or permanently. In group B, although the same tendency as group A was recognized in 22 cases, in resting 4 cases, the VEP findings did not correspond to postoperative visual function with 10% of false positive and 33% of false negative rates. Our finding suggests that intraoperative VEP possesses high reliability for optic nerve lesions, but does not have so highly predictive value for optic radiation lesions. doi:10.1016/j.clinph.2010.02.113
33. Diagnosis of incomplete conduction block in compressive spinal cord using spinal cord evoked magnetic fields from peripheral nerve stimulation—Kyohei Sakaki, Shigenori Kawabata, Senichi Ishii, Adachi Yoshiaki, Ryuichi Nakamura, Susumu Fujii, Yuki Matsuda, Kenichi Shinomiya (Tokyo Medical and Dental University, Tokyo, Japan) We have reported the spinal conduction block in rabbit models by using spinal cord evoked magnetic fields (SCEFs) from the Superconducting Quantum Interference Device (SQUID) system previously. The method was not quite non-invasive because an epidural electrode was placed in epidural space for electric stimulation. In this study, we measured SCEFs of spinal conduction block in rabbit models after peripheral nerve stimulation, and showed usefulness for diagnosis of spinal disorder compared to spinal cord evoked potentials (SCEPs) recorded from the epidural electrode. We made one complete and three incomplete spinal conduction block models by the insertion of the fogarty catheter into lumbar cord epidural space. We measured SCEFs and SCEPs by stimulating sciatic nerve before and after injury. The obtained SCEFs conducted to cranial side along the spine from stimulated side. After injury, the amplitude of waves attenuated and their conduction velocity was delayed around the injury site. In addition, this attenuated point almost corresponded to the point of
Society Proceedings / Clinical Neurophysiology 121 (2010) e19–e34
measured the DMLs, compound muscle action potentials (CMAP) and nerve conduction velocities in 73 consecutive patients with ALS, 12 with spinal muscular atrophy (SMA), 12 with spinal-bulbar muscular atrophy (SBMA), and 36 with axonal neuropathy due to vasculitis (VN). Multiple axonal excitability measurements were performed for the median nerve in the ALS patients. The DML was prominently prolonged (=5.4 ms: over 125% of the upper limit of normal) in 8 ALS patients (11%), 1 SMA/SBMA patient (4.2%) and no VN patients (0%). In threshold electrotonus, the results of the ALS patients with markedly prolonged DML showed a tendency that the axonal resting membrane potential shifts in the depolarizing direction. Our findings suggest that, in ALS, there is a subgroup with prolonged DML unexplained by merely loss of the fastest axons, which is rare in other motor neuron diseases and neuropathies. The robust resting membrane depolarization in motor axon may result in inactivation of sodium channels, and thereby distal nerve conduction slowing in the terminal stage of ALS. doi:10.1016/j.clinph.2010.02.110
30. Sleep spindles in the early phase of acute encephalitis/ encephalopathy with acute gastroenteritis in infants and children—Kuniaki Iyoda, Yukiko Ishiguchi, Kazunori Ogawa, Hideaki Ochi (Hiroshima City Hospital, Hiroshima, Japan) We studied the significance of sleep spindles( SS ) in the early phase of acute encephalitis/encephalopathy( AE ) with gastroenteritis, to clarify the pathological sleep changes and to predict prognosis. The retrospective inspection on sampled serial EEGs of 9 patients with AE (M:F = 2:7, mean age = 2.7 years), and the consciousness disturbance (CD) classified in clinical by JCS (1978) and in EEG by Hockaday (1965), were investigated. (1) All patients were hospitalized within 3rd day of illness; mild to moderate cases were 6 and severe ones were 3, and recovered after averaging 7.6 days of illness (the former : the latter = 3.8:15.3 days, P < 0.001). (2) SS were seen within 2.6 days on average. Eight of 9 patients showed abnormal SS in morphology, duration and distribution, and returned to normal in averaging 2.5 months. SS of 3 cases observed after 4 days of illness, were delayed both recovery of CD and SS normalization; especially 4 cases remaining with extreme SS, tended to complicate with mental retardation (P < 0.05). These findings are possibly useful to evaluate the abnormal sleep changes in AE and predict the prognosis. doi:10.1016/j.clinph.2010.02.111
31. Early diagnosis of cerebral vasospasm by oxygen-pulse near infrared optical topography—Yuichi Tanaka, Takehiko Konno, Akira Ebihara, Eiju Watanabe (Jichi Medical University, Tochigi, Japan) We propose a new alternative method for the early diagnosis of delayed ischemic neurological deficit (DIND) due to cerebral vasospasm using oxygen pulse-based near infrared optical topography (OT). We used 48-channel OT system covering the bilateral frontotemporal areas. The study was conducted with 42 cases of SAH. The subjects inhaled room air and then oxygen for 2 min and room air again in block fashion and SpO2 was monitored at the finger tip. In ischemic regions, the oxy-Hb increase was delayed and/or lowered. To confirm this change, the principal component analysis referring to the systemic SpO2 was used. In 42 cases with SAH, 30 showed ischemic findings by OT before DIND occurred. Eleven cases (36%) of 30 showed DIND. But 19 cases ischemic findings by OT
disappeared and they showed no DIND. In 18 cases, IMP-SPECT and OT were performed on the same day. The diagnostic agreement rate for diagnosis of ischemia between SPECT and OT is 83.3%. These results suggest that this method can detects ischemia due to vasospasm before DIND. This method uses oxy-Hb as a tracer of OT. It can be clinically utilized as a real time and noninvasive assessment method of cerebral ischemia on cerebral vasospasm. doi:10.1016/j.clinph.2010.02.112
32. Usefulness and limitation of intraoperative visual evoked potential (VEP) monitoring—Ryoji Yamada, Yusuke Tabei, Tomoyuki Koizumi, Miho Akiyama, Kumiko Sukegawa, Hitoshi Kobayashi, Taminori Obayashi, Yuichi Suzuki, Toshiyuki Onodera, Kotoyo Kurokawa, Kazuo Yagi, Nobusada Shinoura (Tokyo Metropolitan Komagome Hospital, Tokyo, Japan) The aim of this study was to reveal the relationship between intraoperative VEP findings and postoperative visual function. The subjects were 35 patients operated with intraoperative VEP monitoring. The patients were classified into two groups; group A as 9 cases with tumors adjacent to optic nerve, and group B as 26 cases with tumors adjacent to optic radiation. Intraoperative VEP was recorded by 2000 Lux, 1.1 Hz stimulation, and 100 times of addition. The recording electrodes were placed at occipital skin, dura mater, or cerebral surface. VEP was assessed by an amplitude difference of N75 and P100 components. In group A, there was a highly correlation between VEP and postoperative visual function. In all 3 cases that showed decrease of amplitude to less than 50% and no recovery, visual function was deteriorated transiently or permanently. In group B, although the same tendency as group A was recognized in 22 cases, in resting 4 cases, the VEP findings did not correspond to postoperative visual function with 10% of false positive and 33% of false negative rates. Our finding suggests that intraoperative VEP possesses high reliability for optic nerve lesions, but does not have so highly predictive value for optic radiation lesions. doi:10.1016/j.clinph.2010.02.113
33. Diagnosis of incomplete conduction block in compressive spinal cord using spinal cord evoked magnetic fields from peripheral nerve stimulation—Kyohei Sakaki, Shigenori Kawabata, Senichi Ishii, Adachi Yoshiaki, Ryuichi Nakamura, Susumu Fujii, Yuki Matsuda, Kenichi Shinomiya (Tokyo Medical and Dental University, Tokyo, Japan) We have reported the spinal conduction block in rabbit models by using spinal cord evoked magnetic fields (SCEFs) from the Superconducting Quantum Interference Device (SQUID) system previously. The method was not quite non-invasive because an epidural electrode was placed in epidural space for electric stimulation. In this study, we measured SCEFs of spinal conduction block in rabbit models after peripheral nerve stimulation, and showed usefulness for diagnosis of spinal disorder compared to spinal cord evoked potentials (SCEPs) recorded from the epidural electrode. We made one complete and three incomplete spinal conduction block models by the insertion of the fogarty catheter into lumbar cord epidural space. We measured SCEFs and SCEPs by stimulating sciatic nerve before and after injury. The obtained SCEFs conducted to cranial side along the spine from stimulated side. After injury, the amplitude of waves attenuated and their conduction velocity was delayed around the injury site. In addition, this attenuated point almost corresponded to the point of