Purpose: To study the mechanisms of startle-induced supplementary sensorimotor area (SSMA) seizures.
Methods: We present a patient investigated with indwelling subdural grid electrodes covering both the SSMA and the dorsolateral frontal lobe.
Results: We found a simultaneous seizure onset in the right dorsolateral premotor cortex and the right SSMA. High-resolution magnetic resonance imaging (MRI) showed a small subcortical lesion adjacent to the right SSMA. The patient became seizure free after resection of the lesion and the ictal-onset zone.
Conclusions: We conclude that an extended region of abnormally excitable tissue within the frontal lobe could facilitate the generation of startle-induced seizures. We speculate that a widespread epileptogenic zone could help to explain why some patients with SSMA or dorsolateral frontal lobe seizures are more likely to have startle-induced seizures.