Analysis of ictal EEGs of epilepsy associated with tuberous sclerosis

To investigate the significance of cortical pathology of tonic spasms in patients with tuberous sclerosis.

The subjects were 38 patients with epilepsy associated with tuberous sclerosis. We analyzed ictal EEGs of tonic spasms and partial seizures by means of video-EEG monitoring for a total of 763 tonic spasms in 20 patients and 107 partial seizures in 15 patients. We also investigated the relation between partial seizures and magnetic resonance imaging (MRI) findings of these patients.

Ictal EEG patterns of tonic spasms were divided into generalized and focal patterns. Thirteen patients had only generalized patterns, whereas seven had both patterns. In five patients who had focal ictal patterns of tonic spasms and partial seizures, the location of focal patterns corresponded with the location of onset of partial seizures. Focal discharges were seen immediately before, after, and in the middle of tonic spasms in series in 13 patients. The location of focal discharges also corresponded with the location of the onset of partial seizures in 10 of the 13 patients. Regarding partial seizures, four patients had multiple active epileptogenic foci during the same period, and two others had shifting epileptogenic foci with increasing age.

These findings indicate that cortical pathology plays an important role in the occurrence not only of partial seizures but also of tonic spasms in patients with tuberous sclerosis.