Among 527 MRI examinations of patients with a suspicion of epilepsy in 5 years, we found 32 cases of hippocampal malrotation (HIMAL). The characteristic features are: incomplete inversion of the hippocampus with and abnormally round shape; unilateral involvement of the whole hippocampus; normal signal intensity and size; blurred internal structure; an abnormal angle of collateral sulcus; abnormal position and size of the fornix; normal size of the temporal lobe; enlargement and particular configuration of the temporal horn, typical of corpus callosum agenesis; and a normal corpus callosum. In 7 cases (22%) HIMAL occurred together with developmental disorders. It was predominantly seen in men. The clinical features were varied. Based on some MRI features, the presence of developmental disorders, the male predominance, the frequently positive family history, and a review of the literature, we think HIMAL may be the consequence of a mild hemisphere developmental disorder. It is probably not the basic cause of epilepsy in such varied clinical setting, but may be a sign of a developmental disorder and can help in selecting patients for more meticulous investigation. It also may give some new understanding of brain development.

Summary:Purpose: Severe myoclonic epilepsy in infancy (SMEI; Dravet's syndrome) is a malignant epilepsy syndrome characterized by early prolonged febrile convulsions (PFCs) with secondary psychomotor delay and a variety of therapy-resistant seizures. Although the initial symptoms are repeated PFCs, the MRI performed at the onset of disease shows no hippocampal structural abnormalities. We aimed to assess clinical and serial MRI data of patients with SMEI with a special attention to the temporomedial structures. To our knowledge, this is the first systematic MRI study in this disease.Methods: Clinical and MRI data of all SMEI patients treated in our hospitals between 1996 and 2004 were reviewed.Results: Twenty-eight MRIs from 14 children (one to four images/patient) were included. Age at disease onset was between 3 and 9 months; age at initial MRI was 5 months to 13 years. Ten of 14 patients showed hippocampal sclerosis (HS) during the course of the disease (nine unilateral, one bilateral). Six of these 10 had a normal initial MRI. Age at the first verified HS was between 14 months and 13 years. Neither complex partial seizures nor anterior temporal irritative zone was recorded in these children.Conclusions: After initially normal structures, in most patients with SMEI, HS develops several months or years after the first PFC. These data support the hypothesis that PFC might be responsible for HS, but other factors and individual sensitivity should play a role in this process. Key Words: Severe myoclonic epilepsy in infancy-Prolonged febrile convulsionHippocampal sclerosis-Retrospective MRI study-Children.Severe myoclonic epilepsy in infancy (SMEI) is a malignant epilepsy syndrome described initially by Dravet (1). Patients with SMEI show normal development during infancy, until developing prolonged unilateral or generalized tonic-clonic febrile seizures (1-6). Psychomotor delay becomes evident from the second year of life, and subsequently patients manifest new-usually drug resistantseizure types, including atypical absence, myoclonic, and complex partial seizures. Abnormal neurologic signs include ataxia and pyramidal tract damage. EEGs are usually normal in the early course of the disease; however, generalized interictal epileptiform discharges appear in the second year of life (4). Earlier reviews on SMEI reported no characteristic MRI abnormality of this condition (3,7).During the last decade, the association of childhood prolonged febrile convulsions (PFCs) and the development of hippocampal sclerosis (HS) was debated (8-10). As PFC is a typical early manifestation of SMEI, we aimed to assess

Concomitant structural and functional neuroimaging provide possibly complementary information in the early noninvasive workup of RE and may facilitate the early diagnosis of this rare disorder.

Patients with catastrophic epilepsy due to bilateral epileptogenic lesions but without a high risk of additional postsurgical deficit may be good candidates for epilepsy surgery.

Concomitant structural and functional neuroimaging provide possibly complementary information in the early noninvasive workup of RE and may facilitate the early diagnosis of this rare disorder.