BRAIN DISTORTIONS IN PATIENTS WITH PRIMARILY GENERALIZED TONIC-CLONICSEIZURES

Purpose: A precondition for the diagnosis of primarily generalized epi lepsy with tonic-clonic seizures (GTCS) is absence of brain pathology. This definition, based on normal findings on computed tomography (CT) and magnetic resonance imaging (MRI) is challenged however, by observ ation of microscopic migrational disturbances in patients with GTCS. i n the present study, we examined whether hitherto undiscovered gross m anifestations of the reported migrational disturbances may be detected by analysis of CT and MRI scans with a computerized anatomic brain at las. Methods: The atlas program permitted group comparisons of size, i ntrinsic proportion, and shape of the brain. Healthy men (n = 20), pat ients with partial seizures (n = 8), secondarily generalized partial s eizures (n = 8), and patients with GTCS (n = 10) were studied. The con tours of the brain of the computerized atlas were first transformed an d adjusted to the contours, central structures, and ventricles of each subject's MRI scans. During this process, the specific parameters for the shape, size, and proportion of the brain were determined, resulti ng in a set of values for each subject. These values were then applied for comparisons between the four investigated groups. Results: In rel ation to the controls, patients with GTCS had brains significantly fla ttened in the craniocaudal direction (p = 0.002), with a disproportion ally small caudal part. The anterior portion of their brain was also, relatively elongated as compared with the posterior portion (p = 0.04) . Similar systematic abnormalities were not observed in patients with partial epilepsy. Conclusions: The observed deformations are compatibl e with previously reported findings of Purkinje cell degeneration and frontal lobe microdysgenesis in GTCS. The study suggests a new approac h to identify effects of morphologic abnormalities in the brain when r esults of conventional structural neuroimaging are normal.