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PS-35-10 Comparison of nerve conduction studies in carpal tunnel syndrome
Postersession 36. lntraoperativemonitoring
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amplitude ratio (Fa/Ma), F wave conduction velocity (FWCV) and chronodispersion (Fch). In neonates, the incidence of F waves was 100%, the mean value of Fmin was 17.1 + 1.4 ms, Fa was 918.2 + 464.6.#V, Fa/Ma was 16.9 + 9.3%, Fd was 9.46 4- 1.25 ms and FWCV was 29.5 4- 3.6 m/s. In addition, lower Fch values were found in neonates. The high amplitude of the F waves and the increased F/M amplitude ratio were both characteristic findings of the F waves in neonates. These findings could therefore be interpreted as indicating an increased excitability of the motor neurons due to the immaturity of the central nervous system.
PS-35-91 Waveform analysis of M waves evoked by ulnar nerve stimulation
Tomoyoshi Otsuka l, Yasutomo Okajima l, Kozo Hanayama 1, Hiroyuki Toikawa 1, Akio Kimura i, Chino Naoichi 2. t Keio
Tukigase Rehabilitation Center; 2Dept. of Rehabilitation Medicine, School of Medicine, Keio Univ. M wave elicited by stimulation of the ulnar nerve has two major negative peaks or a prominent negative peakwith a notch. In order to identify the origins of the two peaks, we analyzed the M waveforms using several different references and also using topographical maps. Ten men (age 30--40 years old) without any neurological deficits were included. Fourteen recording electrodes are placed over the palmar side of the left hand with reference to the right hand, to the left little finger or to the left wrist. We stimulate the ulnar nerve at wrist and elbow and the median nerve at wrist. The potential amplitude was the largest when the electrode was placed on the belly of the abductor digiti minimi regardless of position of the reference. Typical bipeaked M wave with reference to the little finger changed in shape when other references were used. When the thumb was abducted, the peaks of the M wave was variously altered. Results of the topographical mapping indicated that the first peak is derived from the muscles of the thenar side while the latter peak is derived from the muscles of the hypothenar side.
I PS-35-11 I A novel electrodiagnostic medicine teaching tool Francis O. Walker Department of Neurology, Bowman Gray School of Medicine, USA Between 1992-1995, the American Association of Electrodiagnostic Medicine (AAEM) produced 3 Self-Assessment Examinations, each consisting of 100 written multiple-choice questions and 50 videotaped questions for interpretation. Each year, this examination was administered under standardized conditions to approximately 500 Neurology and Physical Medicine and Rehabilitation residents and fellows in the United States and Canada, representing over 80 different training programs. Approximately 200 additional physicians have taken the examination independently. Following the examination, all participants received a personal copy of the examination, their test results, an analysis of their performance compared to candidates of equal training, comments on individual questions, and the statistical analysis of each test question. Despite the wide range of E M G training for participants, (0-12 months or greater), the overall reliability coefficient of the examination was 0.9, rivaling that of national board examinations. The mean discrimination index for written questions was 0.38 and, for videotape questions, 0.23. All faculty proctors of the examination and over 95% of candidates rated the examination favorably. Written comments have been equally enthusiastic. The videotaped portion of the examination is now routinely used for instructional purposes at national meetings, and training programs routinely use previous examinations as study guides. This examination, which continues to be rewritten and administered yearly, provides candidates and programs with a useful means of self-assessment, establishes the value of videotape-based questions, demonstrates the feasibility of a yearly international self-assessment examination in clinical neurophysiology, and highlights the unique contributions that subspecialty societies have to offer residency training programs.
PS-36. INTRAOPERATIVEMONITORING
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PS-35-101 Comparison of nerve conduction studies in carpal tunnel syndrome
Motohide Arita, Yoshihisa Masakado, Akio Kimura, Naoichi Chino. Department of Rehabilitation Medicine, Keio
University School of Medicine We studied, on the basis of the criteria which the Quality Assuarance Committee of the American Association of Electrodiagnostic Medicine had proposed, 30 hands of 15 healthy women, 43 affected hands and 17 subclinical hands of 30 patients referred for carpal tunnel syndrome. We performed 4 conduction studies (1) abductor pollicis brevis (APB), second lumbricals (2L) and interossei muscle (INT) motor distal latency; (2) digit 2 (D2M) and digit 4 sensory latency (D4M) to median nerve stimulation; (3) difference between D4M and digit 4 sensory latency (D4U) to ulnar nerve stimulation (D4M-D4U). The APB and D4M were abnormal in 85% of the subclinical hands, and the tests were more sensitive than 2L (64%) and D2M (50%). In the cases of the clinically diagnosed hands the sensitivities of APB, D4 and D4M-D4U exceeded 95%, while 2L and D2M were abnormal in 82% and 90% respectively. As the clinical findings became more severe, the difference between APB and 2L (APB 2L) increased. The conclusion drawn is that the radial and ulnar-sided fibers in the carpal tunnel are more susceptible compared to the fibers located more centrally and the motor fiber innervating 2L are less severely affected than the fiber to the innervating thenar muscles.
I PS-36-1 I Relationship between middle latency cerebral evoked potentials (MCEP), electroencephalography (EEG) change and neurological prognosis in abnormal circulation during cardiovascular surgery Toshikazu Takada 1, Hitoshi Fujioka 1, Sadahei Denda 2, Hiroshi Baba 2, Koki Shimoji 2. 1Department of Anesthesia,
Nagaoka Redcross Hospital; 2Department of Anesthesiology, Niigata University, School of Medicine In cardiovascular surgery, ischemic brain damage is one of the most severe neurological complications. Short latency cerebral evoked potentials and E E G does not always predict brain damage. In order to monitor higher brain function more accurate diagnosis of cerebrospinal ischemic changes is necessary for brain protection during cardiovascular surgery. MCEPs were simultaneously recorded with spinal evoked potential in response to alternate median nerve stimulation in 57 cases. Six patients showed abnormal circulatory disorders with MCEPs abnormalities. In selective cerebral perfusion (2 cases), both N32 and N20 of MCEPs disappeared, and N32 never recovered with slight decrease in N20 and slow EEG, resulting in postoperative unconsciousness, convulsion and brain edema. In a case of severe hypotension, both N32 and N20 were profoundly decreased, and N32 didn't recover to preoperative level. The patient became unconscious caused by
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amplitude ratio (Fa/Ma), F wave conduction velocity (FWCV) and chronodispersion (Fch). In neonates, the incidence of F waves was 100%, the mean value of Fmin was 17.1 + 1.4 ms, Fa was 918.2 + 464.6.#V, Fa/Ma was 16.9 + 9.3%, Fd was 9.46 4- 1.25 ms and FWCV was 29.5 4- 3.6 m/s. In addition, lower Fch values were found in neonates. The high amplitude of the F waves and the increased F/M amplitude ratio were both characteristic findings of the F waves in neonates. These findings could therefore be interpreted as indicating an increased excitability of the motor neurons due to the immaturity of the central nervous system.
PS-35-91 Waveform analysis of M waves evoked by ulnar nerve stimulation
Tomoyoshi Otsuka l, Yasutomo Okajima l, Kozo Hanayama 1, Hiroyuki Toikawa 1, Akio Kimura i, Chino Naoichi 2. t Keio
Tukigase Rehabilitation Center; 2Dept. of Rehabilitation Medicine, School of Medicine, Keio Univ. M wave elicited by stimulation of the ulnar nerve has two major negative peaks or a prominent negative peakwith a notch. In order to identify the origins of the two peaks, we analyzed the M waveforms using several different references and also using topographical maps. Ten men (age 30--40 years old) without any neurological deficits were included. Fourteen recording electrodes are placed over the palmar side of the left hand with reference to the right hand, to the left little finger or to the left wrist. We stimulate the ulnar nerve at wrist and elbow and the median nerve at wrist. The potential amplitude was the largest when the electrode was placed on the belly of the abductor digiti minimi regardless of position of the reference. Typical bipeaked M wave with reference to the little finger changed in shape when other references were used. When the thumb was abducted, the peaks of the M wave was variously altered. Results of the topographical mapping indicated that the first peak is derived from the muscles of the thenar side while the latter peak is derived from the muscles of the hypothenar side.
I PS-35-11 I A novel electrodiagnostic medicine teaching tool Francis O. Walker Department of Neurology, Bowman Gray School of Medicine, USA Between 1992-1995, the American Association of Electrodiagnostic Medicine (AAEM) produced 3 Self-Assessment Examinations, each consisting of 100 written multiple-choice questions and 50 videotaped questions for interpretation. Each year, this examination was administered under standardized conditions to approximately 500 Neurology and Physical Medicine and Rehabilitation residents and fellows in the United States and Canada, representing over 80 different training programs. Approximately 200 additional physicians have taken the examination independently. Following the examination, all participants received a personal copy of the examination, their test results, an analysis of their performance compared to candidates of equal training, comments on individual questions, and the statistical analysis of each test question. Despite the wide range of E M G training for participants, (0-12 months or greater), the overall reliability coefficient of the examination was 0.9, rivaling that of national board examinations. The mean discrimination index for written questions was 0.38 and, for videotape questions, 0.23. All faculty proctors of the examination and over 95% of candidates rated the examination favorably. Written comments have been equally enthusiastic. The videotaped portion of the examination is now routinely used for instructional purposes at national meetings, and training programs routinely use previous examinations as study guides. This examination, which continues to be rewritten and administered yearly, provides candidates and programs with a useful means of self-assessment, establishes the value of videotape-based questions, demonstrates the feasibility of a yearly international self-assessment examination in clinical neurophysiology, and highlights the unique contributions that subspecialty societies have to offer residency training programs.
PS-36. INTRAOPERATIVEMONITORING
I
]
PS-35-101 Comparison of nerve conduction studies in carpal tunnel syndrome
Motohide Arita, Yoshihisa Masakado, Akio Kimura, Naoichi Chino. Department of Rehabilitation Medicine, Keio
University School of Medicine We studied, on the basis of the criteria which the Quality Assuarance Committee of the American Association of Electrodiagnostic Medicine had proposed, 30 hands of 15 healthy women, 43 affected hands and 17 subclinical hands of 30 patients referred for carpal tunnel syndrome. We performed 4 conduction studies (1) abductor pollicis brevis (APB), second lumbricals (2L) and interossei muscle (INT) motor distal latency; (2) digit 2 (D2M) and digit 4 sensory latency (D4M) to median nerve stimulation; (3) difference between D4M and digit 4 sensory latency (D4U) to ulnar nerve stimulation (D4M-D4U). The APB and D4M were abnormal in 85% of the subclinical hands, and the tests were more sensitive than 2L (64%) and D2M (50%). In the cases of the clinically diagnosed hands the sensitivities of APB, D4 and D4M-D4U exceeded 95%, while 2L and D2M were abnormal in 82% and 90% respectively. As the clinical findings became more severe, the difference between APB and 2L (APB 2L) increased. The conclusion drawn is that the radial and ulnar-sided fibers in the carpal tunnel are more susceptible compared to the fibers located more centrally and the motor fiber innervating 2L are less severely affected than the fiber to the innervating thenar muscles.
I PS-36-1 I Relationship between middle latency cerebral evoked potentials (MCEP), electroencephalography (EEG) change and neurological prognosis in abnormal circulation during cardiovascular surgery Toshikazu Takada 1, Hitoshi Fujioka 1, Sadahei Denda 2, Hiroshi Baba 2, Koki Shimoji 2. 1Department of Anesthesia,
Nagaoka Redcross Hospital; 2Department of Anesthesiology, Niigata University, School of Medicine In cardiovascular surgery, ischemic brain damage is one of the most severe neurological complications. Short latency cerebral evoked potentials and E E G does not always predict brain damage. In order to monitor higher brain function more accurate diagnosis of cerebrospinal ischemic changes is necessary for brain protection during cardiovascular surgery. MCEPs were simultaneously recorded with spinal evoked potential in response to alternate median nerve stimulation in 57 cases. Six patients showed abnormal circulatory disorders with MCEPs abnormalities. In selective cerebral perfusion (2 cases), both N32 and N20 of MCEPs disappeared, and N32 never recovered with slight decrease in N20 and slow EEG, resulting in postoperative unconsciousness, convulsion and brain edema. In a case of severe hypotension, both N32 and N20 were profoundly decreased, and N32 didn't recover to preoperative level. The patient became unconscious caused by