Towards understanding pharmaco-EEG phenomena

majority

of the symmetrical

group had structural

brain disease, these brain

lesions were diffuse, not lateralized. This group also included all patients who had cryptogenic etiology and normal development (7 patients). Conciusion: asymmetrical hypsarrhythmiaiinfantile spasms accurately localize, and symmetrical hypsarrhythmia is rarely found with, focal cerebral lesions that are visible on CT/MRI.

enign Rolandic Focus to Occipital Areas i Fulgente, M. Onofrj. lstituto Clinica Neurologica,

Chieti, Italy

We describe the migration of a Rolandic focus in an 8 years old female patient, from para-rolandic to the parieto-occipital area, occurring over a period of two years. The patient was affected by Benign Rolandic Epilepsy. Only two morfeic seizures were observed, the first when the patient came to our observation and a second one, 1 year later. Initial interictal EEG recordings showed characteristic centro-temporal discharges consisting of high amplitude broad spikes (90-150 bV), negative on the temporal region and positive over frontal region, followed by a large slow wave of opposite polarity and a small wave of the same polarity prominent on the right side, with a frequency of 1 spike every 5-20 sec. In the following two years, serially performed EEG recordings showed a migration of the Rolandic focus, at first on right parieto-occipital areas and finally on occipital regions. Occipital spike and wave complexes (> 100 aU) were recorded 2-3 years after initial recordings, and were suppressed by eye opening. Our observation confirms that Benign Juvenile Partial Epilepsy can undergo an EEG pattern modification from Rolandic to Occipital areas, and suggest that, at least in this case, a real migration of an EEG focus can occur.

ency of Grafopathologies

in Elementary

109-09

1The

Importance of Proper Timi

Monitoring of Children and Ad Syndromes N. Jovid, 2 Martinovic, M. Mihajlovid. V Jovanovid, S. Jankovic, N. Rajlic. University of Belgrade, Belgrade The need for ambulatory EEG monitoring (A-EEG) i?ay be evrdent after initiai EEG-clinical assessment or it may arise during the patient’s follow-up. Both situations occurred in 26 patients aged 5-17 years who were examined and/or treated because of a various epi!eptic disorders. All patients were selected from a larger sample of 142 patients of the same age when initial or subsequent assessments (including neuroiogical and other clinical examinations, both short lasting waking and sleep EEGs) could not provide all diagnostic criteria of the supposed epileptic syndrome(s). Proper timing of 32 A-EEGs (performed with the use of Medilog 9000 and 9200 equipment) in these 26 patients enabled the diagnosis of the syndrome with continous bilateral spike-waves (CBSW) in NREM sleep in 5 patients and he!ped to diagnose: benign partial epilepsy types in 6. juvenile myocionic epilepsy in two and I_ennox-Gastaut syndrome in two patients. On other occasions, A-EEG polygraphic findings (lasting from 24 to 72 hours) were useful for one or several planned purposes: 1. to observe seizures related to precipitating circumstances, 2. to correlate behaviour disorders and/or neuropsychoiogical dysfunctions with EEG abnormalities, 3. to assess the effects of antiepileptic drug therapy on the frequency of seizures and/or EEG paroxysms, 4. to analyse sleep architecture in comparison with heaithy control subjects. Careful individual planning of both time and duration for repeated A+EEGs during the follow-up is necessary to better define the EEG-clinical evolution in children and adolescents with above mentioned and other epileptic syndromes.

0%

IO ‘Lennox-Gastaut Syndrame’ an Synchrony

5. Go!uboviC, Lj. Alimpic. M. Ognjanovic. UniversifyofBelgrade It is a well-known fat? that there exists a range of factors underlying the differences related to the abilities of written expression, the interaction of which results in the forms of handwriting specific for each individual. This paper deals with the frequency of graphopathologis in elementary school children. The examination comprises a total of 340 children from the 1st to the 5th forms. The results obtained demonstrate that the highest percentage of disorders in writing has been found with the 1st form children. A comparatively high percentage of graphic disorders has also been noted with the 5th form children, which indicates the seriousness of the problem not dealt with ~IIthe iower forms,

a&sensory Evoked “Rolandic Discharge -bike Spikes” in Childhood EEGs S. Ichijoh. JR Tokyo General Hospitai, Tokyo, Japan In two children with centro-temporal spikes (“Rolandic discharges, RDs”) in EEGs, somatosensory stimulations evoked “RD.like spikes” in the central regions, which were very similar to “RDs” in waveforms, amplitudes. and loca!izations in the scalp. The cases were a 8-year-old girl with epilepsy and a 6-year-old girl with febrile convulsions. The EEGs showed spikes or sharp waves in the central and mid-temporal regions (“Roiandic discharges, RDs”). The median nerve stimulation evoked “RD-like spikes”. The amplitudes of these spikes were 20 -40 bV, when earlobe electrodes were used as reference. The onset latencies. the peak latencies, and the duration of the spikes were 30-40 msec, 60-80 msec, and 70-80 msec, respectively. The centro-temporal spikes or “Rolandic discharges, RDs” are observed in children with a benign eoilepsy, but the site of origin of the discharges is not clear. As the somatosensory evoked “RD-like spikes” in this study are very similar to “RDs”. the origins of “RD.like sptkes” and “RDs” are considered to be in same regions or in close areas. However, the latencies of the “RD-like spikes” are too long to suppose the somatosensory cortex as the origin of these spikes. Therefore, the site of origin of “RD-like spikes” as well as “RDs” may be a deeperstructure of the brain such as the hippocampus.

K. Kobayashi, Y Ohtsuka, E. Oka, S. Ohtahara. Okayama University Medical School, Okayama Clinical importance of differentiation between Lennox-Gastaut syndrome (LGS) and symptomatic partial epilepsy with secondary bilateral synchrony (SBS) on the EEG and with ciinico-electrical characteristics resembling those of LGS was recently stressed (Gastaut et al. 1987). Previcusly, however, it was very difficult to differentiate SBS from primary bilateral synchrany (PBS) by visual inspection of the EEG. As we newly developed a method of the differentiation by estimation of interhemispheric small time differences (TDs) during apparently bilaterally synchronous spike-wave activity by coherence and phase analysis via the two-dimensional autoregressive model [Kobayashi et al. 1992). the method was applied to nine patients with clinically suspected LGS to differentiate their diffuse slow spike-wave bursts on the EEG between PBS and SBS. Of these patients, three showed consistent IDS z 9 msec at the onset of the bursts indicating SBS, while six without TDs were suggested to have PBS. In the three patients with indicated SBS. TDs tended to diminish in the latter part of the bursts, suggesting a role of the ‘central integrating system’ in the generation of SBS. lnterictal DDmTc-HMPAO SPECT revealed hypoperfusion in the hemisphere ipsilateral to the estimated leading side in two of these three, despite no abnormality in CT/MRI.

SESSION 10: EX~ERl~~~

1O-01 Towards Understanding P~a~rn~c~-~ N. Bogdanov. Institute of Higher Newous Activity and Netirophysiolog~ Moscow, Russia In investigation on animals (nonlinear albino rats with different types of conflict behavior, cottontail rats, inbred mice) established that anxiolytic effect of benzodiazepine and atypical tranquilizers including buspirone is associated only with theta-rhythm slowing on EEG [eveis. At the same time, anxiognnic drugs caused an increase of frequency of theta activity and (in large udoses) low frequency spindles. These EEG changes are close to the patterns of EEG induced by stress. These results suggest that increase in beta activity, especially as a result high frequency spindles which have been reported to be a common feature of all tranquilizers might be connected with adaptive

S42

Postp Sessions

mechanisms of brain which prevent from lesion by psychotropics drugs. It is possible that some abnormal EEG activity of epileptic human and animals (spike-slow wave, spindles) also is reflection of these adaptive mechanisms of brain.

/ 1 O-02

1 Brain Chaos and Cognitive Abilities

T. Elbert, W. Lutzenberger, N. Birbaumer. Universityof Mtinsfer; Mtinster; University of Tijbingen, TUbingen; University of Padova, Padova A series of experiments is described using non-linear analysis (deterministic chaos) of the EEG during various mental tasks. The hypothesis is tested that increasing EEG-complexity (“chaos”) at a particular brain location indicates more pronounced “competition” between simultaneously but asynchronously active cell assemblies (W. Freeman). EEG during mental activities with different degrees of attentional resource competition were compared and analyzed with singular value decomposition algorithms provided by the mathematics of nonlinear dynamics (“synergetics”). These algorithms were compared with traditional power spectral analysis. Simple sensory tasks (visual, tactile) and complex and simple imagery were compared. 20 set of spontaneous EEG during these mental activities and rest was autocorrelated, factorized and phase space dimensions (“chaotic dimensions”) were computed in subjects with high and low intelligence and high and low passionate love scores, Results demonstrate different brain maps for phase space dimensions than for traditional power spectra. Imagery produced higher EEG complexity than actual perception of the same objects, particularly at frontal locations, High IQ Ss reveal much higher complexity than low IQ Ss during resting conditions and young Ss high in passionate love lower complexity than Ss low in passionate love. The data support the interpretation of EEG phase space dimensions as reflecting neuronal cell assembly competition. Research is supported by the German Research Society (DFG, SFB 307. Bl).

1 O-03

Propagation of Seizure Activity Arising from the Hippocampus: A Local Cerebral Blood Flow Study

Y. Goto *, M. Kato *. * Kyushu UniversirY, Fukuoka, Japan; ** Loyola Universi?y Chicago, Chicago, USA Partial seizure activities are experimentally known to have a definite pathway propagating from the epileptic foci. Studies on the propagation pathway of limbic seizures are an important approach to elucidate the etiology and suggest treatment of partial seizures. In the present study, we examined the propagation of spike discharges and the changes in local cerebral blood flow (LCBF) by means of EEG and autoradiography. Forty-five male Sprague-Dawley rats were used. Limbic seizures were induced by microinjection of kainic acid into one dorsal hippocampus. In Experiment 1,seizure stages were classified based on behavioral and EEG changes, In Experiment 2, LCBF changes were measured using the 14C iodoantipyrine method. LCBF was measured in control animals, during the 3 seizure stages identified in Experiment 1, and in the post-ictal stage. Unilateral hippocampal seizure activities propagate initially from the ipsilateral hippocampus CA3 layer to the CA3 layer of the contralateral hippocampus. This is followed by propagation to the ipsilaterai amygdala. nucleus accumbens, bed nucleus of stria terminalis. and to the sensorimotor, auditory and visual cortices, and then to the contralateral bed nucleus of stria terminalis, nucleus accumbens. amygdala and sensorimotor cortex. Finally, EEG and LCBF changes were seen in the ipsilateral globus pallidus, substantia nigra, subthalamic nucleus, thalamus (especially the ventral thalamic nuclei group, the mediodorsal and centromedian thalamic nuclei), the septum and the parietal cortex. This pattern of epileptogenic propagation is complex, but reproducible, and may indicate what occurs in human limbic seizures.

1 1 O-04 1 Transition from lnterictal Bursting to Electrographic Seizure After a Brief Period of Anoxia in the Zeromagnesium Slice Seizure Model H. Kojima. M. Kowada. Akita Universi~

Akita, Japan

Combrned slices of hippocampus (HC) and entorhinal cortex (EC) exhibit electrographic seizures when exposed to magnesium-free (O-Mg) medium. These seizures are eventually suppressed by discharges resembling interictai bursts (IIBs). It has been shown that the IIBs. originating in hippocampal area

CA3, suppress seizure generation in EC and that the suppression of IlBs in CA3 unleashes seizures in EC. Here we report the modulatory effect of brief anoxia on the transition between these epileptiform activities. Extracellular recordings were made in area CA3 and EC of HC/EC slices from male Sprague-Dawley rats. In the 0-Mg medium, seizures occurred first but eventually they gave way to IIBs. After the seizures were completely replaced by IIBs. brief periods of anoxia (2.5, IO. 15, 20 min) were inrroduced by switching the bubbling gas from 95%02 + 5%CO2 to 95%N2 + 5%CO2. During the anoxic periods, both regions showed almost no spontaneous activities. After reoxygenation, in the slices which were subjected to shorter anoxia (515 min), the IlBs in CA3 recovered and the EC-seizures were disrupted by the CA3-IIBs again. However, after the 20 min anoxia. the CA3-IIBs couldn’t recover and the seizures reappeared in EC in 80% of the slices. These results suggest a modulatory effect of anoxia on the epileptic activity and imply a mechanism underlying the transition from IlBs to seizures associated with cerebrovascular diseases.

jIO-05 1Research of Neurophysiological

Mechanisms Epileptic Activity with Chronic lntracerebral Chemoelectrodes (CHICHE)

of

V Matkovsky, L. Lebedev, V Rymar. RCH, KishineK Moldova Neurophysiological mechanisms of epileptic activity that are registered by macroelectrodes unclear. Introduction of neuroactive substances (NAS) through chronic intracerebral chemoelectrodes (CHICHE) to patients suffering from epilepsy proves the hypothesis of equivalence of epileptic activity (EA) and paroxysmal depolarized changes (PDCh) of somatic membrane of neurons, their post-synaptic origin reflecting inactivation mechanisms of epileptic ictus. 10-l 2 CHlCHEs were implanted stereotactically into various structures of patients’ brains for the period of 8 weeks. CHICHE is a polyethylene capillary having 200 mcm in diameter onto which 8 cylindrical contacts having 800 mcm in diameter were consecutively strung and fixed. The research included stereoelectroencephalography, electric stimulation and polarization, introduction of 0.1 ml NAS, using bioelectric and TV-monitoring, to study each patient’s epileptic system and further operative treatment, We used various NAS, lodacaini and dithylinum having certain effect. Lidocaini sharply intensifies EA in the place of introduction and it may result in a ictus. Dithylinum blockades both spontaneous EA and EA induced with lidocaini. Disappearance of EA and PDCh after the introduction of dithylinum depolarizing post-synaptic membrane (PSM) points at post-synaptic origin of this potentials. Pre-ictus intensification of EA that is an ecstatic and hypersynchronized PDCh reflects inactivation mechanism of impulse activity (IA) by deep depolarization of PSM of neurons’ soma, has a protective character, inhibiting the development of a ictus. Introduction of lidocaini blockades IA of neurons, hinders natural normalization of biochemical disruption, results in their accumulation that is accompanied by a sharp increase of PDCh as a mechanism of a negative feedback. Blockade of conduction by lidocaini at dendritis and aksons makes electrical synchronization of excitatory post-synaptic potentials impossible, while PDChs are being hypersynchronized. Hence, PDChs are an independent biochemical mechanism of IA inactivation by deep depolarization of the membrane of neurons’soma.

1O-06 Bilateral Injection of Muscimol into the Striatum Suppresses

Kindled Amygdaloid

N. Mori, M. Watanabe. Fukushima Medical

Seizures in Rats

Coltege, Fukushima, Japan

The effect of bilateral injection of muscimol, a y-aminobutyric acid (GABA) agonist, was examined in amygdaloid-kindled rats. Male Wistar rats were kindled at the left amygdala. and the generalized seizure triggering threshold (GST) was determined. Muscimol was dissolved in saline. The amygdaloidkindled animals were divided into 4 groups, which received a 0.5 /*I injection of saline (n = 7). 10 nmol muscimol (n = 9). 50 nmol muscimol (n = 6), and 100 nmol muscimol (n = 7) into the bilateral striatum. Thirty min after the injection, the kindled amygdala was stimulated at the GST intra-striatal injection of saline did not cause any apparent behavioral or EEG change, but that of muscimol caused some uncoordinated movement of limbs. Saline did not suppress the kindled seizures, but muscimol did so. In 5