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P30.4 The role of somatosensory evoked potentials (SEP) in the evaluation of the tethered cord syndrome
Posters / Clinical Neurophysiology 117 (2006) S121–S336
P30.3 Changes of recovery function of median nerve somatosensory evoked potentials (SEP) from awake to sleep H. Ichikawa, T. Yamada, S. Taniguchi, M. Hara, R. Fujisawa, J. Kimura University of Iowa, Neurology, USA Background: Previous studies concerning refractory period and recovery function by conditioning and test paired stimuli paradigm were done primarily in awake state. Little attention has been paid to the effect of consciousness. Aim/objective: The aim of this study is to find how the sleep affects the recovery functions in median nerve SEP. Methods: The paired (S1 + S2) stimuli with varying interstimulus intervals (ISIs) were delivered alternately with single (S1) stimulus. EEG was continuously monitored throughout the night. SEPs were obtained as of off line and grouped according to the sleep stages. One response consisted of minimal of 1000 averages. Only one or two ISIs were examined in one night study, thus several nights studies were required for each subject to complete the series. The test response affected by the conditioning stimulus was compared with the control response in awake and each stage of sleep. Results: The responses (P14-N20, N20-P26, P26-N30) at 4 ms. ISI were depressed from awake to all stages of sleep. At 50 ms. ISI, the test response, which was close to control in awake state, became 1.5 to 2 times larger than the control in each stage of sleep: for example, P26-N30 amplitude was 114 ± 27% at awake, 209 ± 47% (p = 0.045) at stage 2, 206 ± 36% (p = 0.005) at stage 3 and 4, 82 ± 85% (p = 0.121) at REM sleep in four normal subjects. No significant change was noted in P14-N20 amplitude. Discussion: The suppression at short ISI is due to the refractory period by the preceding conditioning stimulus. During recovery process, previous studies have shown additional interfering input after the activation of peripheral receptors which interfere with the recovery process. Sleep appeared to inhibit the interfering input or actually enhance the recovery process brought by preceding conditioning stimulus. Conclusion: Sleep enhances SEP recovery process either by decease of inhibitory or increase of excitatory function.
S249
the body of L2 instead of at the normal L1–L2 disc space level. The syndrome presents wit signs and symptoms of lower lumbar and sacral root lesion. We could expect that SEP, as a way of testing the afferent sensory pathways, could help in monitoring patients at risk. Objective: To study the role of SEP in the evaluation of spinal cord function in patients with tethered cord in lipomeningocele. Patients and method: We have studied the neurophysiological changes occurring in 13 patients with lumbosacral lipomeningocele. The range of age was 1 month to 50 years, mean 17 y/o. Seven patients had had surgery. Evidence of spinal malformations was provided by magnetic resonance imaging. The functional assessment of the spinal cord was performed by analysing the lumbar spinal and cortical somatosensory evoked responses after electrical stimulation of tibialis nerve at the ankle. Results: In three cases no lumbar and no cortical responses were recorded. They were the older patients, two of them had had late surgery and all had prominent clinical symptoms. In the 10 remaining cases, range of age 1 month to 17 years, mean 9.5 y/o, we could obtain lumbar spinal and/or cortical responses of normal latency despite the presence of clinical symptoms in all except two of them, in some cases as prominent as incontinence, pes cavus and leg atrophy. Conclusion: Our findings suggest that SEP are not of useful application in evaluating the clinical course in patients with tethered cord in lipomeningocele, because the abnormalities do not anticipate the appearance of symptoms. Only in some cases and after many years, SEP become unequivocally abnormal. The results could also support the idea of the progressive nature of the disease, and the theory of early surger before symptoms appear. doi:10.1016/j.clinph.2006.06.494
P30.5 Use of somatosensory evoked potentials (SSEP) in assessing recovery of incomplete traumatic spinal cord injury (iSCI) I. Izzeldin 1, D. Allan 2, B. Conway 1 1
University of Strathclyde, Bioengineering Unit, UK Southern General Hospital, Queen Elizabeth National Spinal Injuries Unit, UK
2
doi:10.1016/j.clinph.2006.06.493
P30.4 The role of somatosensory evoked potentials (SEP) in the evaluation of the tethered cord syndrome M.C. Maeztu 1, J. Martinez-Lage 2 1
Hospital Universitario Reina Sofia, Clinical Neurophysiology, Spain 2 Hospital Universitario Arrixaca, Neurosurgery, Spain Background: Tethered cord syndrome is classically defined as having the tip of the conus medullaris below
Background: Assessment of light touch and pin prick are components of the standard assessment of SCI. However, in common with many clinical assessment scales the method lacks sensitivity and requires the patient’s attention. Electrophysiological methods based on SSEP’s may offer a more sensitive method for assessing sensory function and its recovery following iSCI. Aims: This study has examined the use of SSEPs and dermatomal SEPs (D-SEP) for assessing sensory pathways following iSCI.
P30.3 Changes of recovery function of median nerve somatosensory evoked potentials (SEP) from awake to sleep H. Ichikawa, T. Yamada, S. Taniguchi, M. Hara, R. Fujisawa, J. Kimura University of Iowa, Neurology, USA Background: Previous studies concerning refractory period and recovery function by conditioning and test paired stimuli paradigm were done primarily in awake state. Little attention has been paid to the effect of consciousness. Aim/objective: The aim of this study is to find how the sleep affects the recovery functions in median nerve SEP. Methods: The paired (S1 + S2) stimuli with varying interstimulus intervals (ISIs) were delivered alternately with single (S1) stimulus. EEG was continuously monitored throughout the night. SEPs were obtained as of off line and grouped according to the sleep stages. One response consisted of minimal of 1000 averages. Only one or two ISIs were examined in one night study, thus several nights studies were required for each subject to complete the series. The test response affected by the conditioning stimulus was compared with the control response in awake and each stage of sleep. Results: The responses (P14-N20, N20-P26, P26-N30) at 4 ms. ISI were depressed from awake to all stages of sleep. At 50 ms. ISI, the test response, which was close to control in awake state, became 1.5 to 2 times larger than the control in each stage of sleep: for example, P26-N30 amplitude was 114 ± 27% at awake, 209 ± 47% (p = 0.045) at stage 2, 206 ± 36% (p = 0.005) at stage 3 and 4, 82 ± 85% (p = 0.121) at REM sleep in four normal subjects. No significant change was noted in P14-N20 amplitude. Discussion: The suppression at short ISI is due to the refractory period by the preceding conditioning stimulus. During recovery process, previous studies have shown additional interfering input after the activation of peripheral receptors which interfere with the recovery process. Sleep appeared to inhibit the interfering input or actually enhance the recovery process brought by preceding conditioning stimulus. Conclusion: Sleep enhances SEP recovery process either by decease of inhibitory or increase of excitatory function.
S249
the body of L2 instead of at the normal L1–L2 disc space level. The syndrome presents wit signs and symptoms of lower lumbar and sacral root lesion. We could expect that SEP, as a way of testing the afferent sensory pathways, could help in monitoring patients at risk. Objective: To study the role of SEP in the evaluation of spinal cord function in patients with tethered cord in lipomeningocele. Patients and method: We have studied the neurophysiological changes occurring in 13 patients with lumbosacral lipomeningocele. The range of age was 1 month to 50 years, mean 17 y/o. Seven patients had had surgery. Evidence of spinal malformations was provided by magnetic resonance imaging. The functional assessment of the spinal cord was performed by analysing the lumbar spinal and cortical somatosensory evoked responses after electrical stimulation of tibialis nerve at the ankle. Results: In three cases no lumbar and no cortical responses were recorded. They were the older patients, two of them had had late surgery and all had prominent clinical symptoms. In the 10 remaining cases, range of age 1 month to 17 years, mean 9.5 y/o, we could obtain lumbar spinal and/or cortical responses of normal latency despite the presence of clinical symptoms in all except two of them, in some cases as prominent as incontinence, pes cavus and leg atrophy. Conclusion: Our findings suggest that SEP are not of useful application in evaluating the clinical course in patients with tethered cord in lipomeningocele, because the abnormalities do not anticipate the appearance of symptoms. Only in some cases and after many years, SEP become unequivocally abnormal. The results could also support the idea of the progressive nature of the disease, and the theory of early surger before symptoms appear. doi:10.1016/j.clinph.2006.06.494
P30.5 Use of somatosensory evoked potentials (SSEP) in assessing recovery of incomplete traumatic spinal cord injury (iSCI) I. Izzeldin 1, D. Allan 2, B. Conway 1 1
University of Strathclyde, Bioengineering Unit, UK Southern General Hospital, Queen Elizabeth National Spinal Injuries Unit, UK
2
doi:10.1016/j.clinph.2006.06.493
P30.4 The role of somatosensory evoked potentials (SEP) in the evaluation of the tethered cord syndrome M.C. Maeztu 1, J. Martinez-Lage 2 1
Hospital Universitario Reina Sofia, Clinical Neurophysiology, Spain 2 Hospital Universitario Arrixaca, Neurosurgery, Spain Background: Tethered cord syndrome is classically defined as having the tip of the conus medullaris below
Background: Assessment of light touch and pin prick are components of the standard assessment of SCI. However, in common with many clinical assessment scales the method lacks sensitivity and requires the patient’s attention. Electrophysiological methods based on SSEP’s may offer a more sensitive method for assessing sensory function and its recovery following iSCI. Aims: This study has examined the use of SSEPs and dermatomal SEPs (D-SEP) for assessing sensory pathways following iSCI.