Surgical treatment of delayed epilepsy in hemiconvulsion-hemiplegia-epilepsy syndrome

Hemiconvulsion-hemiplegia-epilepsy (HHE) syndrome is an uncommon consequence of prolonged febrile convulsive seizures in infancy and early childhood. Delayed epilepsy in HHE syndrome is frequently intractable to medical treatment. The present study evaluated the role and prognosis of surgical treatment in patients with delayed epilepsy of HHE syndrome.

We included 26 consecutive patients who were diagnosed with HHE syndrome and underwent surgical treatment for delayed epilepsy at Seoul National University Hospital. The multidisciplinary presurgical evaluations included brain MRI, video-EEG monitoring, FDG-PET, and ictal SPECT. Anterior temporal lobectomy (ATL), cortical resection, functional hemispherectomy, and callosotomy were performed according to the results of presurgical evaluations.

Patients were grouped into either the temporal lobe epilepsy (TLE) group (n = 12) or the neocortical/multifocal epilepsy group (n = 14) according to the results of presurgical evaluations. Patients were included in the TLE group if there was strong evidence that the mesial temporal lobe was the only ictal-onset area. The other patients were included in the neocortical/multifocal group. There were no significant differences in demographic characteristics between the two groups. All patients in the TLE group became seizure-free after ATL, but only four patients became seizure-free, and additional two patients showed improvement after various surgical procedures in the neocortical/multifocal group (p = 0.002).

Surgical intervention may be helpful in patients with delayed epilepsy in hemiconvulsion-hemiplegia-epilepsy (HHE) syndrome, especially if the mesial temporal lobe appears to be the only epileptogenic area, regardless of the presence of additional abnormalities seen with neuroimaging. Therefore, surgical treatment should be considered for selected patients with delayed epilepsy in HHE syndrome.