Frontal lobe epilepsy associated with tuberous sclerosis: electroencephalographic-magnetic resonance image fusioning.

We studied the topographic relationships between cortical and subcortical lesions shown on magnetic resonance images (MRI) and sources of epileptiform activity in a series of nine children with intractable epilepsy and tuberous sclerosis complex. Although video-electroencephalographic (EEG) monitoring was suggestive of a frontal seizure onset, interictal EEG was, in seven of nine cases, in the form of apparently bisynchronous discharges. In all cases, the use of a short time lag estimation procedure based on a nonlinear correlation function between surface recorded EEG signals allowed the detection of a lateralized onset of EEG paroxysmal activity. Furthermore, a computerized method based on a source localization EEG-MRI image fusioning procedure, has revealed a topographic concordance between well-defined frontal cortical lesions shown on MRI and site of onset of paroxysmal discharges. Lennox-like EEG patterns frequently reported in children with tuberous sclerosis complex could be the result of the tendency of frontal tubers to induce secondary bilateral synchrony, with implications in the medical and eventually surgical management of the often drug-resistant associated seizures.