The pivotal role of the supplementary motor area in startle epilepsy as demonstrated by SEEG epileptogenicity maps.

Startle seizures belong to reflex epilepsy syndromes. They usually occur in patients with mental deficiency and showing widely extended cortical lesions, often involving the sensorimotor area. Here we report three cases who did not fulfill these criteria, and in whom stereotactic electroencephalography (SEEG) recordings demonstrated the prominent involvement of the supplementary motor area (SMA). Visual analysis was complemented by time-frequency analysis of SEEG signals using a neuroimaging approach (Epileptogenicity Maps), which showed at seizure onset a significant increase of high frequency oscillations (HFOs, 60-100 Hz) over the premotor and prefrontal areas. Critically, in all cases, the SMA showed ictal HFOs at seizure onset and was included in the surgical resection. All patients became seizure-free after surgery, and histopathological examinations showed no specific lesion. These cases suggest the prominent but not exclusive role of SMA in startle seizures, and highlight the fact that surgery can be considered even in the absence of any magnetic resonance imaging (MRI) lesion.