ELSEWIER Electroencephalography and clinical Neurophysiology 9.5 (1995) 1 I I P- I l2P Society proceedings Spring meeting of the Belgian Society of Clinical Neurophysiology ( formerly Belgian EEG Society) Munsterbilzen, 25 March 1995 Secretary: Prof. J.M. Gu6rit Cliniques Uniuersiiaires Saint Luc (UCL). Aoenue Hippo-ate 10, B-1200 Brussels. Bel,qium Received for publication: 25 April I995 Ncurophysiological measuring of wakefulness. - A.C. Declerck, I. Vcrbcck and J. Arends (Department of Clinical Ncurophysiology, Kcmpcnhacghe, Heeze, The Netherlands) An ambulatory-polygraphic wakefulness scoring system with 4 stages wakefulness (movement, awake with eye movements, neutral awake and awake with alpha) was developed that had a high inter-observer agreement (kappa = 0.95). With this scoring system, changes in the structure of wakefulness between patients with narcolepsy and anxiety disorders could be demonstrated. Comparison of the evening recorders between narcolepsy (n = 19) and anxiety (n = 13) patients yielded the following statistically significant differences: stagy Disense Narcolepsy Anxiety P value * Trrul awake XY.4 11.7 98.3 2.6 < 0.001 Neutral awake 17.1 II.9 7.1 7.0 0.0 I5 Duration of awake 7.9 1.5 9.9 2.4 0.009 Duralmn 01 awake w,lh eye ~IOY. 9.7 2.6 13.1 5.3 0.024 Toral sleep (minutes) 44.4 48.8 7.8 45.0 < 0.001 As can be derived from the table, patients with narcolepsy had more periods without scanning eye movements (neutral awake) and shorter periods of wakefulness with scanning eye movements. The hierarchy of stages of wakefulness corresponded adequately with changes in the quantitative EEG. However, the scoring system did not distinguish between volunteers with and without lorazepam treatment. Results of intervention studies are awaited and more quantitative EEG and EOG data will be added to the scoring system. 2. Montage-related modifications of the aspect of EEG traces. - L. Sore1 (Ccntre Neurologique Flo&al, Brussels) The conventional EEG techniques are very imprecise due to the anavoidable use of differential amplifiers and bipolar montages. The comparison between the aspects of the same EEG trace recorded with different derivations helps more precisely to localize brain activities. The lateralization of temporal activities is very difficult and 3 exam- ples showing a wrong lateralization are presented. The first 2 examples show an isopotential negative activity and a positive activity at the level of the vertex and the contralateral temporal region. The third example gives the explanation of the wrong lateralization: the same activity appears in phase on one side and with phase reversal on the other side. Finally, examples are given of a true anterior localization of the alpha rhythm with a good arrest reaction which appeared to be posterior in longitudinal derivations. The only way to progress is using a technique that allows to establish the amplitude and the phase at each electrode. This is possible with the neo-electroencephalography which produces a monopolar-like montage after a mathematical and computerized reconstruction performed accord- ing to the electrogenesis of the patient himself. 3. Contingent negative variation (CNV), ambulatory polysomnogra- phy (APSG), and clinical rating scales as evaluation of depressive illness. - M. Derouaux, B. Troisfontaines, C. Brevcrs, F. Corncttc, D. Debatisse and A. Collin (Cliniquc St. Vincent, Rocourt and Clinique St. Joseph, Liege) Amongst the biological markers of depressive illness. the amplitude of the CNV and the shortened latency of REM sleep are well-known parameters. A comparison of the CNV and the APSG has been performed in IO depressive patients and IO normal controls. The preliminary results of this original study are in accordance with the hypothesis of cholinergic preponderance or of cholinergic/adrenergic imbalance in depression, although the precise CNV and REM alterations mechanisms cannot bc currently explained. The study of pharmacologically induced modifications of the CNV and sleep patterns will be the next step for a better comprehension of the neurophysiological mechanisms and brain systems involved in affective disorders and for their treatment. 4. Actigraphic measurement of left and right handedness. - G. Nagels, P. Marien, L. Timmermans, B.A. Pickut and P.P. De Deyn (Department of Neurology, Middelbcim General Hospital, Antwerp, and Laboratory for Neurochemistry and Behaviour, Born Bunge Foundation, Department of Neurology, University of Antwerp, Antwerp) Standard methods for determining handedness include preference and performance measures. Both methods have their own drawbacks. An objective evaluation of motor activity. actigraphy, was evaluated as a new method for determining handedness. The Edinburgh Inventory (El; Old- field, Neuropsychologia, 1971, 9: 97-114) was used to evaluate hand preference in a homogeneous group of 190 young volunteers. The El distribution obtained in the study population was comparable to distribu- 0013-4694/95/$09.50 0 1995 Elsevier Science Ireland Ltd. All rights reserved SSDI 00 13-4694(95)00095-X EEG 95.578