Abstracts

Rationale: Hypothalamic hamartomas (HH) are an uncommon malformation of the ventral hypothalamus associated with treatment-resistant epilepsy. Since February 2003, our institution has evaluated and treated a substantial number of HH patients. We sought to determine the spectrum of EEG and ictal video EEG (VEEG) abnormalities in this patient population.Methods: Institutional Review Board approval and patient informed consent was obtained for prospective database entry to include medical history and prior diagnostic studies. We correlated prior EEG and VEEG findings with clinical features.Results: One hundred and forty-three charts were reviewed. Ten patients were excluded: for lacking a history of epileptic seizures (n=4) or due to a lack of clinical data (n=6). Data was collected and analyzed on the remaining one hundred and thirty-three patients. Mean age at time of data analysis was 15.8 years (range 1 to 59 years). There were 79 males (59%). At evaluation, 77% of patients had gelastic seizures, 58% of patients had complex partial seizures (CPS), and 21% had generalized tonic-clonic seizures. All other seizure types were seen in less than 10% of patients. Available data for routine EEG consisted of 102 EEGs on 73 patients. Sixty-eight percent of these EEGs were abnormal. Generalized background slowing was seen in 47% of these abnormal records, and focal slowing in 41%. Epileptiform features were seen in 79% of these abnormal EEGs (26% generalized, 43% focal and 30% multifocal). Most epileptiform abnormalities were noted in the temporal (37%) and frontal lobes (32%). Seventy of the 133 (53%) patients underwent VEEG for a mean of 55.2 hours (range <1 hour to 192 hours). A total of 82 VEEG sessions were available for review. Ten VEEG sessions failed to capture an event. Events were reviewed in the other 72 VEEG sessions on 61 patients. The majority of events were of either a gelastic (61.4%) or CPS phenotype (16.8%). There were 591 gelastic events. No ictal change was noted in 439 (74%). An ictal change was noted in 152 gelastic events (26%). Similar percentages of gelastic events were generalized (54%) or focal (44%) and a minority were multifocal (2%). Localization data was available on 69 of these 152 gelastic events and 54 (78%) localized to the frontotemporal head regions. There were 162 CPS events. No ictal change was noted in 69 events (43%). In the 93 events where an ictal change was noted, 67 events were focal (72%), 25 events were generalized (27%) and 1 event (1%) was multifocal. Localization data was available on 69 of these 93 CPS events and 65 events (94%) localized to the frontotemporal head regions. Conclusions: There is a diversity of EEG features in the HH patient population. A significant percentage of seizure events fail to demonstrate any appreciable change in background EEG with standard visual analysis. The lack of EEG change with many clinical seizures, and the wide spectrum of abnormalities in the ictal EEG (when they do occur), suggest that scalp EEG and VEEG have limited utility in the pre-surgical evaluation of these patients.