[Clinical and electroencephalographic studies in children with hemimegalencephaly].

Clinical and electroencephalographic (EEG) studies were performed in two children with hemimegalencephaly. The ages of seizure onset were 44 hours after birth in one infant and 33 days of postnatal life in the other patient. In both children, infantile spasms (IS) associated with hemihypsarrhythmia, developed at 1.5 months and 4 months, respectively. The subsequent clinical courses in these children were notable for frequent, intractable seizures. The seizures consisted of either generalized or partial seizures which originated from not only the hemimegalic hemisphere but also the contralateral one. Later, the clinical and EEG findings in one child indicated the development of Lennox-Gastaut syndrome (LGS). These findings suggested that the lesions of epileptogenesis in patients with hemimegalencephaly involved not only the pathological hemisphere, but also the contralateral hemisphere and subcortical structures. A detailed neurophysiological investigation in hemimegalencephaly could help the elucidation of the pathophysiology of intractable epilepsies, such as IS or LGS.