Gyral disorders represent the morphological marker of cortical malformations of different types and severity. They are probably the most frequent malformative finding found on MRI in patients with syntomatic epilepsy. All diffuse forms are neuronal migration disorders. Agyria, pachygyria, band heterotopia with diffuse cortical dysplasia and Aicardi syndrome are constantly accompanied by epilepsy which is often intractable and has quite distinctive electroclinical features, although varying within a spectrum. Congenital bilateral perisylvian syndrome is a bilateral microgyria of the insular and opercolar regions. The associated clinical syndrome is quite homogeneous, but not all patients have epilepsy and EEG findings, seizure types and severity may vary considerably. Hemimegalencephaly is a disorder of neuronal proliferation involving one hemisphere associated with early epileptic encephalopathy in typical cases. Hemispherectomy may prevent the healthy hemisphere from the deleterious effect of transmitted epileptiform activity. Focal cortical dysplasia of Taylor's type is a localized disorder of neuronal migration accompanied by focal epilepsy and focal EEG abnormalities. Unilateral microgyria is infrequently a discrete lesion: in spite of apparently localized MR changes, electroclinical and pathological findings suggest widespread cortical involvement. However, in all gyral disorders, as in other malformations, the severity and type of epilepsy are not necessarily correlated with the extent of the lesion.
|Number of pages||11|
|Journal||Rivista di Neuroradiologia|
|Publication status||Published - 1994|
ASJC Scopus subject areas
- Clinical Neurology
- Radiology Nuclear Medicine and imaging
- Radiological and Ultrasound Technology