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Performance testing during spike-wave activity as a clinical service
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effectiveness is largely determined by the ergonomic efficiency-of the monitoring facility. The system illustrated has been developed over some 4 years and has been used for over 600 long-term EEG and video registrations. Particular features are: 1) Use of self-contained monitoring suite providing an agreeable environment in which patients are observed for several days by specially trained personnel. 2) Cable-telemetry giving high quality EEG registrations of 16 3) Continuous video monitoring by channels. multiple cameras with remote control of all 4) Continuous magnetic tape backfunctions. up of EEG registration as an insurance against 5) Direct PCM to video conversvstem failure. sion of the EEG signals to provide video displays of the EEG for quality control without the need for intermediate write out on the paper 6) Sinale frame reaistration of the vichart. deo-EEG images-to allow subsequent rapid review 7) Buffering of the EEG in page-turning mode. of EEG in digital memory to allow storage of signals preceding and during ictal events. 8) On-line recognition of absence seizures and of spikes with optional triggering of the buffer 9) Where indicated, continuous performemory. mance testing, by means of television games, to detect transitory cognitive impairment during 10) Frequent withsubclinical EEG discharges. drawal of blood samples by means of an indwelling catheter for serum anti-epileptic drug estimations. D-14.01 LIMITATIONS OF THE lo-20 SYSTEM. E. Dekker, C.D. Binnie, G.J. Linden and A.M. Smit (Heemstede, The Netherlands) Although the lo-20 system of the International Federation was originally proposed as a basis for discussion, there has been little published comment of its strengths and weaknesses or suggestions for its improvement. There are inherent ambiguities in the system, which can be applied strictly in accordance with the published specification (Jasper, H. et al. Electroenceph. clin. Neurophysiol. 1958, 10:370), only in a subject where the 4 measurements between the right and left pre-auricular points and the nasion and the inion are all equal. A study of the cranial measurements of 20 normal adults showed that this criterion was fulfilled to Furwithin a margin of 10% in less than half. ther, the standard placements of the lo-20 system cover less than 3/4 of the cerebral convexity. A study of 100 subjects with fronto-temporal spikes or sharp waves indicated that in the majority these were of maximum amplitude over the anterior temporal region, some 2 cm below the typical positions of F7 and F8. The imlications of these and similar findings for the design of electrode placement systems will be illustrated.
D-9.06 PERFORMANCE TESTING DURING SPIKE-WAVE ACTIVITY AS A CLINICAL SERVICE. J.H.P. Aarts, C.D. Binnie and A.J. Wilkins (Heemstede, The Netherlands) Transitory cognitive impairment (TCI) is often demonstrable during generalized spike-wave discharges, even without overt absence. Recognition of TCI is often crucial to treatment. However, the psychological tests used in most published studies are unsuitable for routine clinical use, being too demanding to be carried out for long periods or requiring a degree of attention which suppresses the discharges. Usually too few discharges occur during the task for their effects to be assessed. Various tasks have therefore been devised meeting the follow1) Acceptable to patients ing requirements: when administered for 30 minutes or longer. 2) Task difficultv adaotive to oerformance level. 3) Continuous performance or’frequent responses, required to detect brief impairment. 4).Loading for psychological functions. known to be sensitive to the effects of eoileotiform activitv. the task must demonstrate im5) Face validity: pairments of practical consequence. Currently 3 tasks are used which meet most of these re1) A linauistic task which monitors quirements: 2) A choice reading speed and comprehension. reaction time presented as a television game. 3) A verbal and non-verbal short-term memory task again presented as a television game. Some or all of these tasks have proved to be acceptable to all patients of normal intelligence so far tested and to children from the age of nine. They have repeatedly demonstrated statistically significant impairment during spike-wave discharges where simple ad hoc tests and observation had failed to do so. C-14.05 SELF-INDUCTION OF EPILEPTIC SEIZURES: INCIDENCE, CLINICAL FEATURES AND TREATMENT. C.D. Binnie, D.G.A. Kasteleijn-Nolst Trenite, R.A. de Korte and J. Overweg (Heemstede, The Netherlands) Self-induction of epileptic seizures has long been recognized in photosensitive, mentally subnormal patients, who typically induce attacks by waving one hand in front of the eyes whilst gazHowever, recent telemetric EEG ina at the sun. studies of photosensitive subjects show that many patients, including those of normal intelligence, induce seizures of EEG discharges by Prospective studies of means of eye-closure. unselected photosensitive patients suggest that the incidence of this phenomenon approaches 50%. The characteristic clinical features include: 1) Sensitivity to intermittent photic stimula2) Slow eye-closures with forced upwards tion. deviation of the eyes followed by epileptiform EEG discharges. 3) Frequently other stereotyped behaviour associated with self induction(touching or 4) Admisconcealing the face, smiling, etc.). sion of self-induction generally with a descrip-
effectiveness is largely determined by the ergonomic efficiency-of the monitoring facility. The system illustrated has been developed over some 4 years and has been used for over 600 long-term EEG and video registrations. Particular features are: 1) Use of self-contained monitoring suite providing an agreeable environment in which patients are observed for several days by specially trained personnel. 2) Cable-telemetry giving high quality EEG registrations of 16 3) Continuous video monitoring by channels. multiple cameras with remote control of all 4) Continuous magnetic tape backfunctions. up of EEG registration as an insurance against 5) Direct PCM to video conversvstem failure. sion of the EEG signals to provide video displays of the EEG for quality control without the need for intermediate write out on the paper 6) Sinale frame reaistration of the vichart. deo-EEG images-to allow subsequent rapid review 7) Buffering of the EEG in page-turning mode. of EEG in digital memory to allow storage of signals preceding and during ictal events. 8) On-line recognition of absence seizures and of spikes with optional triggering of the buffer 9) Where indicated, continuous performemory. mance testing, by means of television games, to detect transitory cognitive impairment during 10) Frequent withsubclinical EEG discharges. drawal of blood samples by means of an indwelling catheter for serum anti-epileptic drug estimations. D-14.01 LIMITATIONS OF THE lo-20 SYSTEM. E. Dekker, C.D. Binnie, G.J. Linden and A.M. Smit (Heemstede, The Netherlands) Although the lo-20 system of the International Federation was originally proposed as a basis for discussion, there has been little published comment of its strengths and weaknesses or suggestions for its improvement. There are inherent ambiguities in the system, which can be applied strictly in accordance with the published specification (Jasper, H. et al. Electroenceph. clin. Neurophysiol. 1958, 10:370), only in a subject where the 4 measurements between the right and left pre-auricular points and the nasion and the inion are all equal. A study of the cranial measurements of 20 normal adults showed that this criterion was fulfilled to Furwithin a margin of 10% in less than half. ther, the standard placements of the lo-20 system cover less than 3/4 of the cerebral convexity. A study of 100 subjects with fronto-temporal spikes or sharp waves indicated that in the majority these were of maximum amplitude over the anterior temporal region, some 2 cm below the typical positions of F7 and F8. The imlications of these and similar findings for the design of electrode placement systems will be illustrated.
D-9.06 PERFORMANCE TESTING DURING SPIKE-WAVE ACTIVITY AS A CLINICAL SERVICE. J.H.P. Aarts, C.D. Binnie and A.J. Wilkins (Heemstede, The Netherlands) Transitory cognitive impairment (TCI) is often demonstrable during generalized spike-wave discharges, even without overt absence. Recognition of TCI is often crucial to treatment. However, the psychological tests used in most published studies are unsuitable for routine clinical use, being too demanding to be carried out for long periods or requiring a degree of attention which suppresses the discharges. Usually too few discharges occur during the task for their effects to be assessed. Various tasks have therefore been devised meeting the follow1) Acceptable to patients ing requirements: when administered for 30 minutes or longer. 2) Task difficultv adaotive to oerformance level. 3) Continuous performance or’frequent responses, required to detect brief impairment. 4).Loading for psychological functions. known to be sensitive to the effects of eoileotiform activitv. the task must demonstrate im5) Face validity: pairments of practical consequence. Currently 3 tasks are used which meet most of these re1) A linauistic task which monitors quirements: 2) A choice reading speed and comprehension. reaction time presented as a television game. 3) A verbal and non-verbal short-term memory task again presented as a television game. Some or all of these tasks have proved to be acceptable to all patients of normal intelligence so far tested and to children from the age of nine. They have repeatedly demonstrated statistically significant impairment during spike-wave discharges where simple ad hoc tests and observation had failed to do so. C-14.05 SELF-INDUCTION OF EPILEPTIC SEIZURES: INCIDENCE, CLINICAL FEATURES AND TREATMENT. C.D. Binnie, D.G.A. Kasteleijn-Nolst Trenite, R.A. de Korte and J. Overweg (Heemstede, The Netherlands) Self-induction of epileptic seizures has long been recognized in photosensitive, mentally subnormal patients, who typically induce attacks by waving one hand in front of the eyes whilst gazHowever, recent telemetric EEG ina at the sun. studies of photosensitive subjects show that many patients, including those of normal intelligence, induce seizures of EEG discharges by Prospective studies of means of eye-closure. unselected photosensitive patients suggest that the incidence of this phenomenon approaches 50%. The characteristic clinical features include: 1) Sensitivity to intermittent photic stimula2) Slow eye-closures with forced upwards tion. deviation of the eyes followed by epileptiform EEG discharges. 3) Frequently other stereotyped behaviour associated with self induction(touching or 4) Admisconcealing the face, smiling, etc.). sion of self-induction generally with a descrip-