Communications orales/Oral communications 15S

041 NEUROPHYSIOLOGICAL AND METABOLIC ASSESSMENT OF CORTICAL VISUAL AREAS IN ALZHEIMER'S DISEASE. T. Loca te l l i , V. Mar t ine l l i , C. Lia, C. Fornara, M. France- schi, F. Fazio, D. Perani, G. Comi. I ns t i t u te H San Raffaele, Milan, I t a l y .

Neuropathological features of Alzheimer's Disease (AD) pr imar i ly a f fec t tempora l -par ie ta l -occ ip i ta l cor t ices with sparing the primary visual cortex. In th is study the topographic mapping of pattern reversal VEPs and 18F-FDG Positron Emission Tomography (PET) have been performed in I0 patients with c l i n i c a l l y probable AD in order to corre la te neurophysiological and metabolic functions of visual areas. AD patients and I0 age-matched normal controls underwent binocular VEP st imulat ion with 60' e 30' and 15' checks. Mean age of pat ients was 63 years (range 54-78 years). Recordings were made from 16 electrodes with l inked ears as reference. Topographic mapping of averages was performed using Nicolet Pathfinder equipment l inear rectangular in terpo la t ion was selected for map reconstruct ion. We did not f ind any s t a t i s t i c a l l y s ign i f i can t abnormality of amplitudes, latencies or topographic d is t r ibu t ions of N75 and P!O0 VEP components in AD group. These f indings well corre la te with the normal glucose consumption observed in the primary visual cortex of a l l our pat ients. B i la tera l temporo- par ietal and often also f ronta l hypometabolism has been found in most of AD patients. Patients with the most severe glucose metabolis reduction in the visual association areas had a s ign i f i can t amplitude decrease of the ~200 VEP component. Moreover the f ronta l negat iv i ty concomitant to the poster ior P200 usually present in normal subjects, was frequent ly absent in AD pat ients.

043 JEGENERATIVE INVOLVEMENT OF RETINAL DOPAMINERGIC SYSTEM IN PARKINSON'S DISEASE: A PERG STUDY IN PARKINSONIAN AND HEALTHY SUBJECTS. P.Stanzione, M.Tagliati and G.Bernardi, Clinics Neuro]ogica, II Universita' di Roma (ITALY).

Parkinson' s Disease (PD) is one of the most important degenerative disorders of the CNS . Its aetiology is still unknown, but aging is surely one of the principal risk factors . Although the characteristic lesion is the progressive cell loss in the substantia nigra of the midbrain, other neural systems have been found to be affected (e.g. locus coeruleus, frontal cortex), suggesting the hypothesis of a systemic cathecolaminergic failure . A decreased dopaminergic activity has been described also in zhe retina of PD patients. To directly monitor the retinal activity, we performed grating pattern electroretinograms (PERG) in a group of i0 PD patients before and during L-DOPA therapy, utilizing different spatial frequencies and contrast levels of the stimulus. Moreover, a dopaminergic failure was reproduced in 23 healthy subjects administering baloperidol . The dopaminergic precursor L-DOPA was tested in 5 normals to check its specificity in reversing the electrophysiologieal impairment in PD patients . The results show an increase of PERG latency in PD patients ( compared to an age-matched group ) , particularly revealed by low contrast stimuli . The mean delay was of 4.07 ms. (p=O.05) at 50% and of 12.88 ms. (p=O.Ol) at 10% of contrast. The deficit ' recovers during L-DOPA therapy, confirming the dopaminergic nature of the retinal impairment. The data from normal subjects treated with haloperidol repeat those observed in parkinsonians (mean delay of 7.4 ms., p=O.Ol), while L-DOrA is unable to affect a normal dopaminergic system. This last finding witnesses once more the involvement of retinal dopaminergic circuits in PD.

042 CORRELATION DE LA CARTOGRAPHIE DE L'EEG ET DE LA POLYSOMNO- GRAPHIE DANS LE VIEILLISSEMENT PHYSIOLOGIQUE AVEC LES TROUBLES DU SOMMEIL M.Mihajlovic, V.Dordevic,R.Mihajlovic,Clinic of Neurology, Military Medical Academy,Belgrade (Yougoslavie)

Pans ce travail nous avons choisi l'Electro-encEphalographie comme la seule mEthode de la presentation fonctionnelle rielle de l'activit6 c6r4brale car elle donne l'enregistre- ment precis et tr6s pr6coce des alterations Electrocortica- lea. Nous avons observe 30 sujets, b'encEphalographie a EtE faite par le syst6me ALVAR/KARTOVAR et MEDILOG 9000 Holter en estimant tousles crit~res de l'Electro-encEphalographie standard. L'enc~phalographie a 6tE faite avant le commence- ment de la thErapie et trois semaines apr6s la th6rapie Flormidal-Midazolam. Sur la cartographie de I'EEG, nous avons observe :

b) force relative exprim6e en pourcentages de ces 2 rigions c) index de ia vaste disposition en avant-en arri6re d) index de i'asym6trie A gauche - ~droite Sur la poiysomnographie, nous avons observ6 : ~7-f~i~{iB~-a~-~i{~f~5~-~B~-as-~3~il avant et apr~s ia prise du m6dieament b) frEquence des phases du sommeil au cours de diff~rents intervalles du sommeil.

Les r4sultats obtenus jusqu'~ present ont montrE la faible baisse de l'index alpha/t&ta avec le vieillissement, le dEplacement de l'activitE alpha vers les structures centra- lea. Le polysomnogramme indique l'augmentation signifiante de la phase I du sommeil, tandis que lea phases III et IV manquent presque. Apr~s la prise du m~dicament, l'augmentation du quantum des phases Iet II est Evidente particuli~rement dans la premiere p4riode du sommeil ainsi que le raccourcissement net de la phase de dEplacement du corps et de la vigilance. Dans notre Etude nous avons remarquE les dEplacements impor- tants de l'activit4 41ectrocorticale par rapport aux sujets sains. Ces donn4es nous donnent la possibilitE de commenter l'6tiologie et la nature de ces ph4nom~nes.