Long-term outcome of epilepsy in patients with Prader–Willi syndrome

Prader–Willi syndrome is a multisystemic genetic disorder that can be associated with epilepsy. There is insufficient information concerning the clinical and electroencephalographic characteristics of epilepsy and the long-term outcome of these patients. The aim of this study is to describe seizure types, electroencephalographic patterns and long-term seizure outcome in Prader–Willi syndrome patients suffering from epilepsy. We retrospectively studied 38 patients with Prader–Willi syndrome and seizures. Results of neuroimaging studies were obtained for 35 individuals. We subdivided these patients into two groups: group A, 24 patients, without brain lesions; and group B, 11 patients, with brain abnormalities. All patients were re-evaluated after a period of at least 10 years. Twenty-one patients (55.2 %) were affected by generalized epilepsy and 17 patients (44.8 %) presented focal epilepsy. The most common seizure type was generalized tonic–clonic seizure. The mean age at seizure onset was 4.5 years (ranged from 1 month to 14 years). In the follow-up period, seizure freedom was achieved in 32 patients (84.2 %). Seizure freedom was associated with electroencephalographic normalization, while the six children presenting drug-resistant epilepsy showed persistence of electroencephalographic abnormalities. Group B patients showed a higher prevalence of drug-resistant epilepsy. Patients with Prader–Willi syndrome were frequently affected by generalized seizures. Most of the patients had a favorable evolution, although, patients with brain abnormalities presented a worse outcome, suggesting that the presence of these lesions can influence the response to antiepileptic therapy.