Startle Epilepsy: Clinical Characteristics in 8 Patients

ABSTRACT

BACKGROUND: The focus of this paper was to determine the clinical characteristics of startle epilepsy characterized by reflex partial seizures of the sensorimotor cortex. METHODS: Eight patients with startle epilepsy were evaluated for their clinical seizure history, neurologic examination, MRI, routine EEG, video-EEG monitoring, and ictal SPECT. RESULTS: Etiologies were perinatal injury (4 patients), kernicterus following hemorrhage during infancy (1), near-drowning at age 4 (1), and unknown (2). The age of seizure onset varied from several months to 16 years. All patients had spontaneous as well as reflex seizures. Effective triggers included several sensory modalities, typically proprioceptive and auditory. The stimuli should be sudden and unexpected. Seizures usually occurred daily and were medically intractable. Neurological examination was abnormal in 6 patients. Five had mental retardation, and 4 with motor deficit. MRI was abnormal in 6 patients, generally showing large encephalomalatic changes involving cortical and sub-cortical structures. Five had bilateral lesions. The semiology was characterized by unilateral or generalized tonic posture. Scalp interictal and ictal EEGs had limited value to lateralize the epileptogenic focus. Intracranial EEG in 1 patient who underwent surgery showed ictal onset on the lateral sensorimotor cortex. CONCLUSIONS: Startle epilepsy is a rare but distinctive epileptic syndrome characterized by reflex seizures triggered by unexpected sensory stimuli. Some clinical findings including etiologic events (kernicterus following hemorrhage, near-drowning), high incidence of bilat-eral lesions, ictal onset on lateral sensorimotor cortex without involvement of medial cortex, and ictal SPECT findings have not been reported or were different from previous studies.