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Schweiz. Vereinigung für elektroenzephalographie und klinische neurophysiologie
40P
Electroencephalography and Clinical Neurophysiology, 1978, 45: 40P--42P © Elsevier/North-Holland Scientific Publishers, Ltd.
Society proceedings SCHWEIZ. VEREINIGUNG FOR ELEKTROENZEPHALOGRAPHIE KLINISCHE NEUROPHYSIOLOGIE
UND
Bern, November 24, 1977
Secretary: PD Dr. med. G. SCOLLO-LAVIZZARI Neurologische Universit~'tsklinik, Kantonsspital Basel, Spitalstrasse 21, 4004 (Basel)
1. EEG in old age. -- K. Karbowski (Berne) The most important characteristic of the EEG in old age is the frequency decrease of background activity, which can be traced back to a lessening of cerebral oxygen uptake. In the healthy subjects examined by the author, the dominant average frequencies were as follows: in young adults in their thirties -- 10.3 c/sec; in persons in their s i x t i e s - 9.6 c/sec, and in a random group of 68--84 year o l d s - 8.5 c/sec. One third of healthy test subjects aged 60 or over also showed temporal (usually left sided) slow wave groups. The degree of EEG change in cerebrovascular insults depends on the nature and the localization of these disturbances. Temporary clinical and electroencephalographic focal seizure symptoms are observed, in particular, in circulatory disturbances within the temporo-parieto-occipital territory (the 'terminal field of irrigation'). Recurring epileptic seizures which start only in old age usually have either a vascular or a tumoral cause. During the attack-free intervals EEG spikes or sharp waves may be less frequently recorded than in younger subjects. The EEG often contributes to the differentiation of 'absence-like' attacks. Thanks to its highly typical EEG pattern, Creutzfeldt-Jakob subacute spongiform encephalopathy can be distinguished from other presenile or senile affections of the brain.
2. EEG findings in pure whiplash injury o f the cervical s p i n e . - E. Pavlincova, M. Mumenthaler and K. Karbowski (Berne) The results of 36 EEG examinations in 30 patients with a pure whiplash injury of the cervical spine were studied. In this negatively selected group of patients electrical abnormalities were found in 30% of the cases. In 80% of the abnormal records non-specific paroxysmal discharges but no epileptic activity, in
20% a general abnormality with or without a focal accentuation, were present. There was no correlation between the severity of clinical symptoms and the incidence or degree of EEG abnormality. The incidence of EEG abnormalities was higher within the first 10 months after the accident.
3. Routine EEG controls during 2 years under lithium treatment. -- R. Kocher and R. Richter (Basel) During 2 years at intervals of 6 months the following data were established for 15 patients under treatment with lithium: serum lithium levels, serum electrolytes, thyroid gland functions, urea and creatinine, routine EEG. The serum lithium levels were on average 0.64 mval/1 and stayed at the same level during the 2 following years. Before starting treatment a baseline EEG was always performed. The visual evaluation of the EEGs did not show any indications of specific potentials, focal signs or asymmetries as reported in the literature. Concerning slight generalized abnormalities, only at the beginning a slight increase was shown, which in the course of the 2 years disappeared again.
4. Epileptic psychosis: localization and frequency of epileptic discharges in relation to psychopathology. - - M . Koukkou and D. Zimmer (Zurich) Epileptic psychoses are psychotic episodes with schizophrenia-like symptomatology, without impairment of consciousness in seizure-free patients who had a long history of epilepsy (often including temporal seizures with confusional states). In 4 patients with an epileptic psychosis a longitudinal study was performed to investigate the correlation between the localization and frequency of epileptic EEG discharges and the degree and type of psychopathology. Tw o patients had generalized spike-wave activity, and 2 showed bitemporal sharp waves with changing
SWISS EEG SOCIETY hemisphere dominance. EEGs and psychopathology ratings (AMP scales) were collected on the same day at weekly intervals for 17, 17, 20 and 25 weeks. EEGs were evaluated by 'blind' reviewers. Correlation coefficients were computed between the values of the nine psychopathological scales and the frequency of epileptic discharges in the temporal areas. The 2 patients with generalized spike-wave patterns showed no significant correlations. The 2 patients with temporal sharp waves showed significant (P < 0.05) negative correlations between the frequency of occurrence of temporal sharp waves and the values of the paranoid-hallucinatory scale (right r = 0 . 4 4 , left r = 0 . 4 0 and right r = - - 0 . 6 9 , left r = ---0.45), i.e., the intensity of this psychopathology was inversely related to the frequency of occurrence of the epileptic discharges. The correlations were higher for right hemisphere data. These results demonstrate a quantitative and graded relation between frequency and localization of the temporal epileptic discharges, and the degree of improvement of paranoid-hallucinatory symptoms during the psychotic episodes.
5. Anticonvulsive action of taurine in the r a b b i t . H.R. Zumstein, A. F~/ssler, J.-C. Roches, G. ScolloLavizzari and L. HSsli (Basel) Biochemical and electrophysiological studies suggest that the amino acid taurine might be an inhibitory transmitter in the mammalian CNS. Furthermore, there is evidence that seizure activity is associated with disturbances in cerebral taurine metabolism. We have examined the effects of taurine on convulsions induced by strychnine in the rabbit. Ten animals received 4 × 200 mg/kg taurine intravenously prior to the strychnine injection. Six animals were used as controls and had no pretreatment with taurine. Strychnine (0.05 mg/kg) was injected each 5 min until a tonic-clonic seizure occurred. The seizure activity was monitored by cortical EEG and by EMG of fore- and hindlegs. The results showed that the strychnine dose necessary to produce the tonicclonic attack was significantly (P < 0 . 0 5 ) h i g h e r in animals pretreated with taurine (0.55 -+ 0.15 mg/kg) than in control animals (0.39-+ 0.09 mg/kg), suggesting that taurine possesses an anticonvulsive action in the rabbit.
6. Video demonstration of a patient with supplementary motor s e i z u r e s . - C. Bernoulli, H.G. Wieser and J. Siegfried (Zurich) A 29-year-old male suffering from supplementary mot or epilepsy following a head injury with thrombosis of the superior sagittal sinus 4 years ago is pre-
41P sented. In the immediate post-traumatic period a status epilepticus and a right hemiparesis occurred. The seizures are characterized by adversion of the head to the left, abduction and flexion of the left arm, extension of the right and speech arrest. Because of drug resistance a chronic stereo-electroencephalogram on a 32-channel machine was performed. The analysis of the spontaneous and induced ictal events originating in the left supplementary m o t o r area is based on a continuous video system recording synchronized moving pictures of the patient and EEG. The interest of this method in delineating an epileptogenic area is discussed.
7. Comparative value of spontaneous and chemically and electrically induced seizures, as well as of spontaneous paroxysmal interictal activity ('spiking') in localizing the side of origin of temporal lobe e p i l e p s y . - H.G. Wieser, J. Bancaud and C. Bernoulli (Zurich--Paris) A retrospective clinical study is presented which is based on 133 patients with drug resistant temporal lobe epilepsy, explored by bilateral stereo EEG. The aim of the study is to evaluate quantitatively the accordance between the different kinds of seizures (spontaneous, chemically and electrically induced). Also a correlation was made between the different seizures and the spontaneous interictal activity ('spiking') as well as an estimation of the value of stimulating the amygdala and A m m o n ' s horn formation. Special attention was paid to whether a seizure was propagated to the homotopic regions of the opposite hemisphere. The outcome of 64 patients operated on, based on the conclusions of SEEG exploration and examined as to whether a spontaneous seizure was present, has served as covalidation of the outstanding importance of the spontaneous seizure in delineating the epileptogenic zone. The degree of positive accordance between the spontaneous and induced seizures varies from 77% for the electrically and 60% for the chemically induced seizure. The spontaneous interictal activity agrees best with the electrically induced and only less with the spontaneous seizure. Chemically induced seizures agree the least. If a seizure is without propagation to the opposite hemisphere the accordance of every parameter studied increases.
8. A new EEG method for assessing changes in vigilance: chronospectrogram a n a l y s i s . - M. Matejcek (Basel) Loss of alpha rhythm when the EEG is recorded under resting conditions (i.e., the appearance of so-
42P called subvigilant phases) has been shown in numerous studies to be associated with impaired precision of the adaptive reactions orientated towards the environment. The scale of decreasing vigilance which the subject passes through, for example while falling asleep, and its EEG correlates are well known. In the process of falling asleep an individual requires a certain time to pass consecutively through the various EEG stages. The length of this period depends upon the state of the individual at the time, and one way in which it may be altered is by psychoactive drugs. To take account of rapid fluctuations in vigilance (EEG dynamics), power spectra from each EEG lead are calculated for 1-sec intervals. The pertinent variables are then obtained from the power spectra (powers of the EEG frequency bands: delta, theta, alpha, beta, etc.). The time course of the variables extracted at 1-sec intervals is known as a chronospectrogram. The chronospectrograms are presented graphically and stored numerically in a data bank for statistical processing. It is now possible to analyse two EEG channels simultaneously, thus permitting an appraisal of interhemispheric and intrahemispheric relations (symmetry, scalp topography, etc.), which are also important in vigilance studies.
9. Imagined speech information determines topography of sound-evoked scalp potential f i e l d s . W.S. Brown, D. Lehmann and C. M~/tzener (Zurich) A speech-like sound sequence (a 500 Hz tone amplitude modulated by the electronic envelope of a sentence) was presented repeatedly to 7 normal volunteers via a loudspeaker. The sound sequence was not understandable, but after suggestion of meanings ('e sch6ni clini f l i i i i g e ' - - l i t . , a pretty little fly, or 'en vogel chunnt z ' f l i i i i g e ' - - lit., a bird comes to fly) either meaning was judged equally likely. Evoked potential data were collected from 12 scalp positions, starting with the onset of the sound which was modulated by the envelope of ' f l i i i i g e ' . Average evoked scalp field maps were constructed in
SOCIETY PROCEEDINGS 15-msec intervals, and the locations of field maximal and minimal values determined. Paired comparisons of these data showed that the sound with suggested noun meaning evoked field maxima at a scalp location which was significantly anterior to that evoked by suggested verb meaning, up to about 175 msec after onset. Up to about 340 msec, the minimal values were significantly more posterior for suggested noun meaning than for suggested verb meaning of the same sound stimulus. The evaluation is independent of the choice of the reference. The results are similar to data which we obtained earlier with understandable homophones. The results indicate that there are different neural populations which process noun and verb meaning, independent of the decoding of the actual stimulus.
10. Median nerve-evoked scalp potentials: right--left differences in multiple s c l e r o s i s . - U. Gabathuler and D. Lehmann (Zurich) Early components of averaged scalp potentials evoked by median nerve stimulation (2/sec, 0.02 msec, n = 220, voltage just below motor effect) in healthy controls show a very similar time course for right and left wrist stimuli: mean difference of the scalp-negative peak at about 20 msec latency was 0.29 msec + 0.28 msec SD (n = 17). Contrariwise, 12 of 13 multiple sclerosis cases selected for minimal arm involvement and normal peripheral nerve conduction velocity showed latency differences of 2 to 14 msec between responses to right and left wrist stimuli (10 of 10 certain and probable cases, and 2 of 3 suspected cases without arm involvement). In all cases, the right--left differences originated between neck and scalp. On the other hand, wrist--neck and wrist-scalp conduction velocities did not usefully differentiate MS cases and controls, although MS cases were somewhat slower on the average. The results suggest that right--left latency comparisons of the early co m p o n en t of somatosensory scalp evoked potentials may serve as an indicator of MS lesions between posterior root and cortex.
Electroencephalography and Clinical Neurophysiology, 1978, 45: 40P--42P © Elsevier/North-Holland Scientific Publishers, Ltd.
Society proceedings SCHWEIZ. VEREINIGUNG FOR ELEKTROENZEPHALOGRAPHIE KLINISCHE NEUROPHYSIOLOGIE
UND
Bern, November 24, 1977
Secretary: PD Dr. med. G. SCOLLO-LAVIZZARI Neurologische Universit~'tsklinik, Kantonsspital Basel, Spitalstrasse 21, 4004 (Basel)
1. EEG in old age. -- K. Karbowski (Berne) The most important characteristic of the EEG in old age is the frequency decrease of background activity, which can be traced back to a lessening of cerebral oxygen uptake. In the healthy subjects examined by the author, the dominant average frequencies were as follows: in young adults in their thirties -- 10.3 c/sec; in persons in their s i x t i e s - 9.6 c/sec, and in a random group of 68--84 year o l d s - 8.5 c/sec. One third of healthy test subjects aged 60 or over also showed temporal (usually left sided) slow wave groups. The degree of EEG change in cerebrovascular insults depends on the nature and the localization of these disturbances. Temporary clinical and electroencephalographic focal seizure symptoms are observed, in particular, in circulatory disturbances within the temporo-parieto-occipital territory (the 'terminal field of irrigation'). Recurring epileptic seizures which start only in old age usually have either a vascular or a tumoral cause. During the attack-free intervals EEG spikes or sharp waves may be less frequently recorded than in younger subjects. The EEG often contributes to the differentiation of 'absence-like' attacks. Thanks to its highly typical EEG pattern, Creutzfeldt-Jakob subacute spongiform encephalopathy can be distinguished from other presenile or senile affections of the brain.
2. EEG findings in pure whiplash injury o f the cervical s p i n e . - E. Pavlincova, M. Mumenthaler and K. Karbowski (Berne) The results of 36 EEG examinations in 30 patients with a pure whiplash injury of the cervical spine were studied. In this negatively selected group of patients electrical abnormalities were found in 30% of the cases. In 80% of the abnormal records non-specific paroxysmal discharges but no epileptic activity, in
20% a general abnormality with or without a focal accentuation, were present. There was no correlation between the severity of clinical symptoms and the incidence or degree of EEG abnormality. The incidence of EEG abnormalities was higher within the first 10 months after the accident.
3. Routine EEG controls during 2 years under lithium treatment. -- R. Kocher and R. Richter (Basel) During 2 years at intervals of 6 months the following data were established for 15 patients under treatment with lithium: serum lithium levels, serum electrolytes, thyroid gland functions, urea and creatinine, routine EEG. The serum lithium levels were on average 0.64 mval/1 and stayed at the same level during the 2 following years. Before starting treatment a baseline EEG was always performed. The visual evaluation of the EEGs did not show any indications of specific potentials, focal signs or asymmetries as reported in the literature. Concerning slight generalized abnormalities, only at the beginning a slight increase was shown, which in the course of the 2 years disappeared again.
4. Epileptic psychosis: localization and frequency of epileptic discharges in relation to psychopathology. - - M . Koukkou and D. Zimmer (Zurich) Epileptic psychoses are psychotic episodes with schizophrenia-like symptomatology, without impairment of consciousness in seizure-free patients who had a long history of epilepsy (often including temporal seizures with confusional states). In 4 patients with an epileptic psychosis a longitudinal study was performed to investigate the correlation between the localization and frequency of epileptic EEG discharges and the degree and type of psychopathology. Tw o patients had generalized spike-wave activity, and 2 showed bitemporal sharp waves with changing
SWISS EEG SOCIETY hemisphere dominance. EEGs and psychopathology ratings (AMP scales) were collected on the same day at weekly intervals for 17, 17, 20 and 25 weeks. EEGs were evaluated by 'blind' reviewers. Correlation coefficients were computed between the values of the nine psychopathological scales and the frequency of epileptic discharges in the temporal areas. The 2 patients with generalized spike-wave patterns showed no significant correlations. The 2 patients with temporal sharp waves showed significant (P < 0.05) negative correlations between the frequency of occurrence of temporal sharp waves and the values of the paranoid-hallucinatory scale (right r = 0 . 4 4 , left r = 0 . 4 0 and right r = - - 0 . 6 9 , left r = ---0.45), i.e., the intensity of this psychopathology was inversely related to the frequency of occurrence of the epileptic discharges. The correlations were higher for right hemisphere data. These results demonstrate a quantitative and graded relation between frequency and localization of the temporal epileptic discharges, and the degree of improvement of paranoid-hallucinatory symptoms during the psychotic episodes.
5. Anticonvulsive action of taurine in the r a b b i t . H.R. Zumstein, A. F~/ssler, J.-C. Roches, G. ScolloLavizzari and L. HSsli (Basel) Biochemical and electrophysiological studies suggest that the amino acid taurine might be an inhibitory transmitter in the mammalian CNS. Furthermore, there is evidence that seizure activity is associated with disturbances in cerebral taurine metabolism. We have examined the effects of taurine on convulsions induced by strychnine in the rabbit. Ten animals received 4 × 200 mg/kg taurine intravenously prior to the strychnine injection. Six animals were used as controls and had no pretreatment with taurine. Strychnine (0.05 mg/kg) was injected each 5 min until a tonic-clonic seizure occurred. The seizure activity was monitored by cortical EEG and by EMG of fore- and hindlegs. The results showed that the strychnine dose necessary to produce the tonicclonic attack was significantly (P < 0 . 0 5 ) h i g h e r in animals pretreated with taurine (0.55 -+ 0.15 mg/kg) than in control animals (0.39-+ 0.09 mg/kg), suggesting that taurine possesses an anticonvulsive action in the rabbit.
6. Video demonstration of a patient with supplementary motor s e i z u r e s . - C. Bernoulli, H.G. Wieser and J. Siegfried (Zurich) A 29-year-old male suffering from supplementary mot or epilepsy following a head injury with thrombosis of the superior sagittal sinus 4 years ago is pre-
41P sented. In the immediate post-traumatic period a status epilepticus and a right hemiparesis occurred. The seizures are characterized by adversion of the head to the left, abduction and flexion of the left arm, extension of the right and speech arrest. Because of drug resistance a chronic stereo-electroencephalogram on a 32-channel machine was performed. The analysis of the spontaneous and induced ictal events originating in the left supplementary m o t o r area is based on a continuous video system recording synchronized moving pictures of the patient and EEG. The interest of this method in delineating an epileptogenic area is discussed.
7. Comparative value of spontaneous and chemically and electrically induced seizures, as well as of spontaneous paroxysmal interictal activity ('spiking') in localizing the side of origin of temporal lobe e p i l e p s y . - H.G. Wieser, J. Bancaud and C. Bernoulli (Zurich--Paris) A retrospective clinical study is presented which is based on 133 patients with drug resistant temporal lobe epilepsy, explored by bilateral stereo EEG. The aim of the study is to evaluate quantitatively the accordance between the different kinds of seizures (spontaneous, chemically and electrically induced). Also a correlation was made between the different seizures and the spontaneous interictal activity ('spiking') as well as an estimation of the value of stimulating the amygdala and A m m o n ' s horn formation. Special attention was paid to whether a seizure was propagated to the homotopic regions of the opposite hemisphere. The outcome of 64 patients operated on, based on the conclusions of SEEG exploration and examined as to whether a spontaneous seizure was present, has served as covalidation of the outstanding importance of the spontaneous seizure in delineating the epileptogenic zone. The degree of positive accordance between the spontaneous and induced seizures varies from 77% for the electrically and 60% for the chemically induced seizure. The spontaneous interictal activity agrees best with the electrically induced and only less with the spontaneous seizure. Chemically induced seizures agree the least. If a seizure is without propagation to the opposite hemisphere the accordance of every parameter studied increases.
8. A new EEG method for assessing changes in vigilance: chronospectrogram a n a l y s i s . - M. Matejcek (Basel) Loss of alpha rhythm when the EEG is recorded under resting conditions (i.e., the appearance of so-
42P called subvigilant phases) has been shown in numerous studies to be associated with impaired precision of the adaptive reactions orientated towards the environment. The scale of decreasing vigilance which the subject passes through, for example while falling asleep, and its EEG correlates are well known. In the process of falling asleep an individual requires a certain time to pass consecutively through the various EEG stages. The length of this period depends upon the state of the individual at the time, and one way in which it may be altered is by psychoactive drugs. To take account of rapid fluctuations in vigilance (EEG dynamics), power spectra from each EEG lead are calculated for 1-sec intervals. The pertinent variables are then obtained from the power spectra (powers of the EEG frequency bands: delta, theta, alpha, beta, etc.). The time course of the variables extracted at 1-sec intervals is known as a chronospectrogram. The chronospectrograms are presented graphically and stored numerically in a data bank for statistical processing. It is now possible to analyse two EEG channels simultaneously, thus permitting an appraisal of interhemispheric and intrahemispheric relations (symmetry, scalp topography, etc.), which are also important in vigilance studies.
9. Imagined speech information determines topography of sound-evoked scalp potential f i e l d s . W.S. Brown, D. Lehmann and C. M~/tzener (Zurich) A speech-like sound sequence (a 500 Hz tone amplitude modulated by the electronic envelope of a sentence) was presented repeatedly to 7 normal volunteers via a loudspeaker. The sound sequence was not understandable, but after suggestion of meanings ('e sch6ni clini f l i i i i g e ' - - l i t . , a pretty little fly, or 'en vogel chunnt z ' f l i i i i g e ' - - lit., a bird comes to fly) either meaning was judged equally likely. Evoked potential data were collected from 12 scalp positions, starting with the onset of the sound which was modulated by the envelope of ' f l i i i i g e ' . Average evoked scalp field maps were constructed in
SOCIETY PROCEEDINGS 15-msec intervals, and the locations of field maximal and minimal values determined. Paired comparisons of these data showed that the sound with suggested noun meaning evoked field maxima at a scalp location which was significantly anterior to that evoked by suggested verb meaning, up to about 175 msec after onset. Up to about 340 msec, the minimal values were significantly more posterior for suggested noun meaning than for suggested verb meaning of the same sound stimulus. The evaluation is independent of the choice of the reference. The results are similar to data which we obtained earlier with understandable homophones. The results indicate that there are different neural populations which process noun and verb meaning, independent of the decoding of the actual stimulus.
10. Median nerve-evoked scalp potentials: right--left differences in multiple s c l e r o s i s . - U. Gabathuler and D. Lehmann (Zurich) Early components of averaged scalp potentials evoked by median nerve stimulation (2/sec, 0.02 msec, n = 220, voltage just below motor effect) in healthy controls show a very similar time course for right and left wrist stimuli: mean difference of the scalp-negative peak at about 20 msec latency was 0.29 msec + 0.28 msec SD (n = 17). Contrariwise, 12 of 13 multiple sclerosis cases selected for minimal arm involvement and normal peripheral nerve conduction velocity showed latency differences of 2 to 14 msec between responses to right and left wrist stimuli (10 of 10 certain and probable cases, and 2 of 3 suspected cases without arm involvement). In all cases, the right--left differences originated between neck and scalp. On the other hand, wrist--neck and wrist-scalp conduction velocities did not usefully differentiate MS cases and controls, although MS cases were somewhat slower on the average. The results suggest that right--left latency comparisons of the early co m p o n en t of somatosensory scalp evoked potentials may serve as an indicator of MS lesions between posterior root and cortex.