Functional brain mapping of ictal activity in gelastic epilepsy associated with hypothalamic hamartoma: A case report

Abstract

SUMMARYHypothalamic hamartomas (HHs) have been demonstrated as the cause of gelastic epilepsy, both by intracranial electrodes and functional imaging. The neocortex becomes secondarily involved, through poorly characterized propagation pathways. The detailed dynamics of seizure spread have not yet been demonstrated, owing to the limited spatial-temporal resolution of available functional mapping. We studied a patient with epilepsy associated with HH and gelastic epilepsy. Simultaneous electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) of several seizure events were obtained, with blood oxygen level dependent (BOLD) activation of the hamartoma, and left hemisphere hypothalamus, hippocampus, parietal-occipital area, cingulate gyrus, and dorsal-lateral frontal area. Integration of regional BOLD kinetics and EEG power dynamics strongly suggests propagation of the epileptic activity from the HH through the left fornix to the temporal lobe, and later through the cingulate fasciculus to the left frontal lobe. The EEG ⁄ fMRI method has the spatial-temporal resolution to study the dynamics of seizure activity, with detailed demonstration of origin and propagation pathways.

Hypothalamic hamartomas. Part 1. Clinical, neuroimaging, and neurophysiological characteristics

“…Interestingly, after onset in the hamartoma, the blood oxygen level-dependent response involved the left hippocampus and occipital lobe, and later the left cingulate gyrus and dorsal-lateral frontal lobe. 69 Ictal EEG showed an early cortical activation of the left occipital-temporal area and later spread to the left frontal lobe. Such EEG-fMRI recordings may help to further characterize the dynamic model of seizure propagation pathways in patients with HHs.…”

“…In a very elegant paper, Leal and colleagues 69 performed simultaneous EEG and fMRI recording in a 2-year-old boy with medically refractory gelastic seizures related to an HH. Interictal EEG showed multifocal spikes predominantly over the frontal and occipital-temporal regions in the left hemisphere.…”

The diagnosis and management of hypothalamic hamartomas in children

“…These data indicate that GS originates in the HH, and propagates to the hypothalamus and afterward to the neocortex. With the development of EEG and functional MRI, Someone reported that propagation of epileptic activity from the HH through the left fornix of the temporal lobe, and later through the cingulate fasciculus to the left frontal lobe [19]. The possibility of controlling seizures appears to In general, GS is pharmacoresistant and ends as a severe epileptic encephalopathy and catastrophic epilepsy of childhood [15,20,21].…”

“…Neocortical seizure propagation and secondary epileptogenesis are deemed to be significant. Several studies of HH children with GS have reported a restricted participation of neocortical areas in epileptic activity [45,46], with epileptic spikes involving predominantly the frontal or temporal areas, most often in a single hemisphere [3]. Intra-hamartoma spikes and slow waves were detected on depth electrode recordings.…”

“…The prevalence of epilepsy associated with hypothalamic hamartoma is estimated at 1 in 200,000 [2]. Recent functional MRI and intracranial electroencephalography (EEG) recordings have provided the proof that seizures originate in the hamartomas [3]. But some reports indicated another independent epileptogenesis [4], which is facilitated by the plethora of connections between the hypothalamus and the temporalfrontal lobe.…”