Abstract
Gelastic seizure (GS) is a cardinal symptom of patients with hypothalamic hamartoma (HH). It is always non-mirthful rather than mirthful GS with temporal lobe epilepsy. There were also several case reports of frontal lobe epilepsy or parietal lobe epilepsy associated with non-mirthful GS. We elucidated the pathophysiological network of GS based on the series of 80 patients with HH. We disclosed that ictogenesis resided within the interface zone of HH itself and propagation network as symptomatogenesis was implicated in mediodorsal (MD) nucleus of the thalamus, facial nuclei of pons, and cerebellum on study of ictal single-photon emission computed tomography. Amygdala is implicated in the center of emotion and MD nucleus of the thalamus is implicated in the center of laughing motion. Only unidirectional connection between amygdala to MD nucleus affects GS without mirth. Hemifacial hyper-expression on GS is likely to be one of the lateralizing sign. Furthermore, MD nucleus of the thalamus is also implicated in memory and behavior because this nucleus is chronically bombarded with epileptic propagation. This is main reason why epileptic encephalopathy associated with HH is treatable after surgery.
