Abstracts

Rationale: Hypothalamic Hamartomas (HH) are intrinsically epileptogenic lesions associate to medically intractable focal epilepsy mainly characterized by gelastic and focal seizures. Intralesional recording with deep electrodes have been documented the presence of the ictal discharge arising inside the lesion. Nevertheless interictal and ictal scalp EEG is poorly informative and non-localizing in a great deal of cases. HH disconnection leads to seizure remission in most cases. Aim of this tudy is ​ to describe the intralesional EEG recordings and to compare them with concomitant scalp EEG and with the previous cases reported in literature. Methods: We reviewed the medical records of 17 children affected by drug resistant focal epilepsy associated to HH. We recorded intralesional electrical activity during stereo-endoscopic disconnection in three cases and during Deep Brain Stimulation (DBS) implantation in one. We also correlated it with the simultaneous scalp-EEG recording. Results: Acute intralesional recordings in our cases confirmed the presence of epileptiform abnormalities intermingled with low-voltage activity, mostly on the same side of the HH attachment. Paroxysmal activity recorded inside the HH was always evident. Figure 1. Pre-operative brain MR of patients #2, #3, #4 (A-C). Scalp and contemporary intra-hamartoma EEG recordings (D-F). Patients were anesthetized during the operation A. Brain MR in patient #2: coronal IR sequence showing type 2 hypothalamic hamartoma. B. Brain MR in patient #3: coronal T2-weighted sequence showing type 4 hypothalamic hamartoma. C. Brain MR in patient #4: coronal T2-weighted sequence showing type 2 hypothalamic hamartoma. D. Recording in patient #2: scalp EEG shows slow wave superimposed by fast activity, intra-hamartoma recording shows rare paroxysms of sharp waves with few spikes, on a background of beta activity. E. Recording in patient #3: scalp EEG shows intermittent right central and temporal high amplitude slow waves intermingled with low voltage theta waves, intra-hamartoma recording shows continuous fast activity with very few medium amplitude sharp waves, in brief trains. F. Recording in patient #4: scalp EEG shows theta-beta activity intermingled with infrequent slow waves, intra-hamartoma recording shows recurrent high amplitude sharp waves, intermingled with numerous spikes, on a very low amplitude background activity. Conclusions: Mapping of HH epileptogenic activity could be useful to confirm the usefulness of disconnection procedure: recording abnormalities and then disconnecting.