Abstracts

Hypothalamic hamartomas (HHs) are rare developmental abnormalities that cause various types of seizures including gelastic seizures. These seizures are often refractory to medical treatment, and patients undergo extensive evaluations in order to identify definite seizure foci. Surgical resection of HH has proven to be highly effective, especially when the lesion is completely disconnected from the attached hypothalamus. It is also found that the HHs are predominantly attached to one side of hypothalamus. Thus, it is important to identify the location of hamartomas in order to achieve successful seizure control with HH surgery. Ictal EEG data on patients with HHs was reviewed in order to determine whether video-EEG monitoring can reliably predict the attachment side of HHs. From our database, 41 patients with HH who previously underwent surgical treatment were reviewed. Among these patients, data on presurgical video-EEG monitoring and brain MRI scans were evaluated when available. Information on ictal EEG changes, seizure localization, seizure outcome, and location of the HH was reviewed retrospectively. Twenty-three of 41 patients had previous video-EEG monitoring and all 41 patients had brain MRI scans. Detailed monitoring reports were available in 20 patients. Of these cases, 12 hamartomas were attached to the left hypothalamus and eight to the right. Ictal onset was infrequently lateralized to the same side of HH attachment (10 %), and majority of seizures were non-lateralizing (75 %). The remaining 15 % had alternating sides of ictal onset. No difference in seizure outcome was noted regardless of HH location or seizure lateralization. Scalp video-EEG monitoring does not provide useful information in the presurgical evaluation of HH resection. Our study indicates that in 90 % of the cases, ictal onset was either non-lateralizing or falsely lateralizing. Thus, ictal video-EEG monitoring has limited utility and should not influence the side of surgical resection and/or disconnection of the HH.