Objectives - Widespread use of MRI now gives us increased insights into the
different expressions of malformations of cortical development (MCD). The
heterogeneity of these disorders are reflected by their varied clinical and
neuroimaging features. Characteristic and intense scalp EEG abnormalities
have been described in some patients. Material and methods - We report the
MRI and clinical findings of 3 adult patients (age 32-36) with a peculiar E
EG pattern of distinct, localized, fast, continuous spiking. These patients
represent all patients with such EEG findings that have been recognized by
the first author during 9 years. Results - MRI showed MCDs in all, respect
ively hemimegalencephaly, a subcortical heterotopion, and a focal cortical
dysgenesis. The EEG findings had been stable since childhood and were poste
riorly located. Two patients had fairly well controlled epilepsy in adult a
ge. The third patient was incapacitated by persistent seizures and was trea
ted with surgery. Histologically cortical dysplasia with neuronal clusters
was found in this patient. Variable degrees of cognitive dysfunction were p
resent in all. Conclusion - Focal, continuous, fast spiking is an unusual s
calp EEG pattern. It is not an inevitable sign of severe epilepsy. It may s
uggest an MCD. It is not yet clear to what extent such findings are predict
ive of a dysgenetic etiology of epilepsy.