72P Sociey Proceedings normal IQ (WISC). The patients were divided into 2 subgroups, accord- ing to their neuropsychological assessment: (1) SRD, 8 cases (6 M, 2 F) with verba1 impainnent and poor reading, writing, and spelling perfor- mances; (11) no-SRD, 5 cases (3 M, 2 F) with normal school perfor- mances. A group of 30 healthy children (no SRD and no epileptic EEG abnormalities) served as controls. EEG activity was studied by computer- ized EEG topography: (a) power spectra1 analysis (FIT) was performed within main frequency bands (delta 1-4 Hz, theta 4-8 Hz, alpha 8-12 Hz, beta 12-31 Hz), and differences between groups were analysed by probability mapping; (b) topographic analysis of epileptic abnormalities (spike mapping); (c) latency, amplitude, and topographic analysis of visual evoked potentials elicited by pattern reversal (VEP-PR). 169. Quantitative EEG mapping and neuropsychological function in Alzheimer’s disease. - S. Passero, R Rocchi, G. Vatti, L. Burgalassi and N. Battistini (Institute for Nervous and Mental Diseases, University of Siena, Siena) The correlation of quantitative EEG, severity of disease and neuropsy- chological data was analyzed in 31 patients with Alzheimer’s disease. The relative powers (RP) of the 4 bands were used for quantitative analysis. Cognitive impairment was assessed by Mini-Mental Status examination (MMSE) and neuropsychological tests. Indexes of total performance and memory performance were calculated. The Global Dete- rioration scale (GDS) was used to stage disease severity. There was a close relation between GDS score and changes in the RP of the theta and beta bands, and also with changes in RP of the delta and alpha bands in certain posterior regions. The global neuropsychological test score was significantly associated with changes in RP of the theta and beta bands. MMSE was associated with changes in RP of the beta band in anterior centra1 regions only. Performance of memory tests showed only sporadic correlations with changes in the RP of the theta and beta bands. 170. Abnormal brain glucose metabolism in partial cryptogenic epilepsy: a PET study. - L. Murri, R. Massetuni, S. Marchetti ‘, S. Antongiovanni b, N. Nista b, P. Salvadori b, R. Guzzardi b and M. Guazzelli ’ (1st. di Clinica Neurologica, Cattedra di Neurofisiopatologia, ’ 1st. di Psichiatria, Università di Pisa, and b 1st. di Fisiologia Clinica, CNR, Pisa) Refractory complex partial seizures are often associated with struc- tural lesions of the cerebral hemispheres. The lesions may be small, however. and structural neuroimaging studies (CT, MR) often fail to show them. The aim of this work was to investigate regional abnormali- ties of cerebral glucose metabolism (i.e., intercritical hypometabolism and critical hypermetabolism) in patients with partial cryptogenic epilepsy (PCE) in comparison with patients with electroencephalographically well-defined focal epileptic seizures. Patients with panic attack disorder (PAD) were also tested. PET study with fluorodeoxyglucose (FDG) was performed under EEG control and after the administration of 0.10 mCi FDG/kg body weight. Serial PET slices (9 slices) every 10 mm starting 10 mm above the inferior orbito-meatal line were evaluated by means of the Siemens 911 PET Scan. Regional cerebral metabolic rates for glucose were calculated using the operational equation of Sokoloff. The results indicate that patients with PCE and patients with electroencephalographi- cally well-defined seizures have similar intercritical regional brain hy- pometabolism. Intercritical cerebral glucose metabolism of epileptics differs from intercritical metabolism of patients with PAD. 171. 3D location of interictal epileptic activity by neuromagnetic method. - M. Peresson ‘, V. Pizzella b, G. Romani aYband P. Curatolo ’ (” 1st. Tecnologie Biomediche, Chieti, b 1st. Elettron- ica, CNR, Rome, ’ 1st. di Fisica Medica, and d 1st. di Neuro- psichiatrla Infantile, Univ. of Chieti, Chieti) We compared the results of SEEG investigation and DLMs (using a spherical head model, centered approximately in the posterior white commissure (PWC)) applied to scalp EEG to define the spike foei in 2 epileptic patients undergoing presurgical evaluation. Fronto-tempora1 (both patients) and temgoro-parieto-occipital (1 patient) spikes were observed. SEEGs demonstrate that several cerebral structures participated in spike generation (external tempora1 neocortex, tempora1 pole, external fronto-orbitary cortex for fronto-tempora1 spikes; parietal, posterior tem- poral, temporo-parieto-occipital cortices for temporo-parieto-occipital spikes). DLMs located the dipoles in the correct hemisphere, and identi- fied different generators for fronto-tempora1 and temporo-parieto-oc- cipital spikes, in agreement with SEEG. However, compared with SEEG, dipole locations were consistently deeper (range: 34-51 mm from PWC, in the horizontal plane). DLMs, as compared with SEEG, seem to be able to identify the correct side of the focus and to discriminate different generators; however, the unprecise estimation of the source depth limits the anatomie definition of the generator. 174. Electrophysiologic studies in HNPP with 17~11.2 deletion. - D. Pareyson, V. Scaioli, D. Lorenzetti, M. Pandolfo, S. Di Donato and A. Sghirlanzoni (Istituto Nazionale Neurologico “C. Besta,” Milan) Localization and quantification of epileptic foei and the epileptogenic Hereditary neuropathy with liability to pressure palsies (HNPP) is an area is essential for surgical treatment of partial epilepsy which is not autosomal dominant disorder characterized by recurrent transitory wel1 treated with conventional drug therapy. We studied 6 patients affected by refractory partial epilepsy (age range 13-18 years). Etiology included 4 patients with tuberous sclerosis and 2 patients with gliosis. MEG recording was performed in a magnetically shielded room with a 2%Channel system (CNR IESS) which was placed over 4 different positions of the scalp in order to obtain complete head covering. All subjects underwent MRI examination. Anatomical and functional infor- mation was integrated using appropriate reference markers placed on predefined anatomical landmarks (nose and pre-auricular points). Epilep- tic complexes were automatically identified on the basis of a pre-selected template. Averaging of the corresponding MEG complexes provided the field distribution over the scalp which was eventually used for source localization. In al1 patients the 3D location of the epileptic focus was in agreement with the lesions as identified by MRI. 172. Analsis of paroxysmal EEG activities in epileptic negative myo- clonus. - G. Rubboli, L. Parmeggiani, R. Plasmati, P. Rlguzzi, R. Rizzi, A.M. Borghi, R. Michelucci and C.A. Tassinari (De- partment of Neurology, Bellaria Hospital, University of Bologna, Bologna) Epileptic negative myoclonus-related spikes (ENM-rS) were studied and compared to ENM-unrelated spikes (ENM-US) in a patient with ENM, as described by Guerrini et al. (1993). ENM was observed mainly in the right upper limb. Polygraphic data were collected in digital format. Topographic mapping was used to analyze spike voltage distribution. ENM-EEG correlation was investigated using back averaging of rectified EMG recorded from the right deltoid. ENM consisted of a brief (range: 80-630 msec) muscular atonia, preceded (from 50 to 120 msec) in the EEG by a negative focal spike with highest amplitude over the C3 electrode. ENM-US showed maxima1 amplitudes over F3, F7, T3, T5 and C3. ENM-US peaking over C3 differed from ENM-rS in being faster (respectively 92 1_ 21 and 128 k 27 msec; P < 0.011, without statistically significant differences in amplitude. In conclusion, ENM-rS and ENM-US show morphological and topographical differences, suggesting that dis- tinct physiopathogenetic mechanisms are involved in their origin. 173. A comparative study between dipole localization methods (DLM) and stereo-EEG @EEG) applied to the analysis of focal epileptic spikes. - G. Rubboli, S. Fraucione ‘, L. Parmeggiani, JJ. Carboneli, L. Tassi ‘, P. Kahane ‘, C.A. Tassinari and C. Mu- nari ’ (Dept. of Neurology, Bellaria Hospital, Univ. of Bologna, Bologna, and ’ Dept. of Neurosciences, Grenoble, France)