Abstracts

RATIONALE: Hypothalamic hamartomas and gelastic seizures (HHGS) is a well recognized developmental epileptic syndrome characterized by intractable epilepsy, cognitive decline and behavioral changes. EEG is usually non-localizing but preliminary ictal SPECT studies have demonstrated perfusion changes in the hamartomas. We describe the perfusion patterns observed in patients with HHGS.
METHODS: Interictal and ictal SPECT studies with Tc-HMPAO were carried out in 12 patients with HHGS. Ictal studies were obtained during EEG-Video monitoring. Repeat ictal studies were obtained in 3 patients. Interictal and ictal studies were co-registered to MRI and ictal blood flow was substracted from interictal scans. Regions of interest were analyzed using previously validated methods.
RESULTS: Interictal studies revealed relatively normal perfusion compared to cortical areas. Ictal studies were obtained in all patients within 8 seconds of ictal onset. Increased ictal perfusion was observed from the hamartoma in 10/12 patients with associated increase perfusion in thalamic and hypothalamic areas. One patient had frontal cortical activation. Substraction and co-registration revealed well localized hypothalamic activation in 9/12 patients. In the three patients without activation, diffuse areas of activation or no activation were observed. Confirmation of ictal onset by depth electrode recordings were obtained in 10 of 12 patients.
CONCLUSIONS: Ictal/interictal substraction SPECT studies are reliable in demonstrating ictal activation of hamartoma in patients with HHGS. However, not all patients demonstrated definitive activation raising the possibility of other areas as seizure generators. In addition, activation was not observed in one patient who demonstrated ictal onset by depth recordings. These findings need further investigations