T01. Role of hypothalamic hamartoma in non-gelastic seizures: An exploration of the brain network

Abstract

Patients having a hypothalamic hamartoma frequently present epileptic attacks of laughter, and they later experience multiple additional seizure types. Because of these types of seizures, hypothalamic hamartomas are considered to be a type of pharmacoresistant epilepsy. Gelastic seizures are associated with hypothalamic hamartomas, but the relationship between hypothalamic hamartomas and other non-gelastic seizures is unknown. Deep electrodes were placed in the hypothalamic hamartoma (anterior, superior, medial aspect), bilateral anterior nuclei of the thalamus, bilateral cingulate gyri, bilateral hippocampi, and bilateral hippocampal sides of the hypothalamic hamartoma under stereotactic guidance. Clinical manifestations and electroencephalograms (EEG) were collected during intermittent and acute stages. The seizure generator zone was located. Seizures in adult patients with hypothalamic hamartomas usually consist of the following types: generalized tonic-clonic seizures; partial tonic seizures; excessive body movements (hip swing and automotor seizures); and evolving seizures (generalized tonic-clonic seizures evolving to excessive body movements or excessive body movements evolving to brief generalized tonic-clonic seizures). The clinical manifestations usually occur later than the discharges in the hypothalamic hamartoma. Seizures originating from the anterior, superior, medial aspect of the hypothalamic hamartoma propagate first to the anterior nucleus of the thalamus. Symptoms are generated in the bilateral cingulate gyri and prefrontal cortex, especially in the cingulate gyri. As the seizures continue to propagate, ictal onset is triggered in the hippocampus, which leads to generalized tonic-clonic seizures. The amygdala and hippocampus are the regions of single cell discharges; no apparent discharges were observed in the amygdala-hippocampal side of the hypothalamic hamartoma. Through stereotactic electrode implantation, we confirmed that the conducting pathway of seizures from a hypothalamic hamartoma is the hypothalamus-anterior nucleus of the thalamus-cingulate gyrus-prefrontal cortex. Ictal symptoms disappeared post-operatively, which further proved the “running down” phenomenon. After removing the persistent effect of the hypothalamic hamartoma on the frontal (mammillary body-mammillothalamic fasciculus- anterior nucleus of the thalamus-cingulate gyrus-frontal lobe) and temporal lobes (connections between the hypothalamus and amygdala or the fornix-medial temporal lobe), epileptiform discharges in the temporal and frontal lobes improved. This finding indicated that neocortical temporal lobe epilepsy originates from the hypothalamic hamartoma. These results provide guidance for the treatment of seizures in patients with hamartomas and contribute to an understanding of the brain network.