High-resolution CT scans of the brain and posterior fossa were performed on 106 phenytoin (PHT)treated epileptics, 28 de novo epileptics and 43 control subjects. A higher incidence of cerebellar and brainstem (CBS) atrophy was observed in chronic PHT-or PHT+ phenobarbital-treated epileptics compared to the two other groups. Some control subjects and de novo epileptics presented mild CBS atrophy, whereas moderate to severe atrophy was noted exclusively in chronically-treated patients. In attempting to delineate the etiology of CBS atrophy, epileptic patients were divided in three groups: 55 subjects with normal CT scans, 30 with both cerebral and CBS atrophy, and 49 with pure CBS atrophy. Their ages, length of illness, number of generalized seizures, number of other seizures, and amount of PHT received during their lifetime were assessed. Statistical analysis revealed that posterior fossa atrophy in epileptics was significantly correlated with both the length of the illness and the amount of PHT ingested during the patient's lifetime. The number of seizures appears to not be related to CBS atrophy. RESUME: L'atrophie cerebelleuse chez les epileptiques. On a pratique la tomodensitometrie du cerveau avec haute resolution pour la fosse posterieure chez 106 epileptiques chroniques traites a la phenytoine (PHT), chez 28 Epileptiques chroniques traites a la PHT, chez 28 epileptiques de novo et chez 43 sujets-controles. Nous avons retrouve une fr6quence significativement elevee de l'atrophie cerebelleuse et du tronc cerebral (ACTC) chez les epileptiques chroniques par rapport aux deux autres groupes. Certains sujets controles et epileptiques de novo ont presente une atrophic ponto-c6r£belleuse legere tandis que les atrophies moderees ou severes ont ete observees en exclusivite chez les epileptiques. En essayant de preciser retiologie de l'ACTC, 134 patients traites sur base externe ont ete divises en trois groupes: 55 sujets avec une tomodensitometrie du cerveau normale, 30 patients avec ACTC et avec atrophies cerebrales et 49 epileptiques avec des ACTC pures. Les parametres etudies ont ete l'age, la duree de la maladie, le nombre de crises de grand-mal, le nombre d'autres crises et la quantite de PHT ingeree pendant la vie du malade. Les analyses statistiques ont demontre que l'ACTC est correlee avec la duree de la maladie et avec la quantite totale de PHT ingeree pendant la vie du malade. Le nombre de crises n'etait pas apparemment relie avec la frequence de l'atrophie des formations de la fosse posterieure.

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The use of magnetic resonance imaging (MRI) enhanced the distinction between the normal residual pituitary parenchyma and sellar lesions and even made the differentiation of the neurohypophysis from the adenohypophysis possible.In plain T1-weighted MRI images, the neurohypophysis can be located as the "bright spot" (BS) by its spontaneous hyperintense appearance.1 , 2 Gadopentate-dimeglumine (Gd-D T PA) injection not only increases the sensitivity of the examination by an average of 15%, but also makes it possible to clearly delineate the lesion and the residual adenohypophysis (RAH).3-5 This is of special significance from a surgical point of ABSTRACT: Objective: This study was undertaken to assess the displacement patterns and shifts of the normal pituitary gland in sellar pathologies on MRI and to determine if the position of the bright spot (BS) represents a predicting factor for the position of the residual adenohypophysis (RAH) in pathological conditions. Methods: In a control group of 102 patients without any pituitary pathology, the presence of the BS was evaluated. In 100 patients with intra-or suprasellar pathologies, presence and respective topography of BS and RAH were scrutinized on MRI, according to lesion type, size, endocrine status and intra-operative findings in the surgical group. Results: The BS was visible in 91.2% of 102 cases in the control group, as compared to 75 of the 100 patients with sellar lesions. Location of RAH was identified in 58% of the patients, and RAH enhanced more than the lesion in all cases after contrast infusion. The RAH was identified in 65.3% of the 75 "BS positive" patients, as compared to 36% of the 25 "BS negative". The normal residual gland was visualized intra-operatively in 63.5% of the 52 operated patients: in 37 "BS positive" patients, it was visualized intra-operatively in 81.1% and in 28 "RAH positive" patients, it was identified in 82.1%. Conclusions: The BS can be identified in the majority and RAH in more than half of the cases with pituitary lesions on MRI. Positions of both the BS and RAH help predict the location of the normal residual gland during surgery and, therefore, may contribute to preserving the pituitary function. RÉSUMÉ: Distorsion des structures hypophysaires normales à l'IRM de pathologies de la selle turcique.Objectif : Le but de cette étude était d'évaluer les signes de distortion et de déplacement de l'hypophyse normale dans les pathologies de la selle turcique à l'IRM et de déterminer si la position de l'image en hyper signal, ou bright spot (BS), peut être considérée comme un facteur de prédiction de la position de l'adénohypophyse résiduelle (AHR) dans les états pathologiques. Méthodes : La présence du BS a été déterminée chez un groupe témoin composé de 102 patients sans pathologie hypophysaire. Chez 100 patients porteurs de pathologies intra ou suprasellaires, nous avons examiné minutieusement l'IRM pour détecter la présence et la topographie respective du BS et de l'AHR, selon le type de lésion, sa taille, le statut endocrinien e...