Startle epilepsy is a type of reflex epilepsy in which seizures are provoked by loud noises or sudden surprises. Most patients with startle epilepsy are only sensitive to one sensory modality (i.e. temperature, taste, sound, pressure). However, it is the unexpected nature of the stimulus rather than the sensory modality that characterizes startle epilepsy.
Patients with startle epilepsy usually have static cerebral lesions and developmental delay. Many of the patients are hemiparetic, meaning half of the body is partially paralyzed, and it is the weak side of the body that is primarily involved in the startle seizures. Startle epilepsy is often associated with disorders such as infantile hemiplegia, Down syndrome, anoxic encephalopathy, and cortical dysplastic lesions.
These seizures usually last less than 30 seconds. The seizure begins with a startle response, followed by a brief tonic phase. Patients sometimes fall to the ground and experience clonic jerks. Responsiveness to the stimulus decreases as a result of repeated exposure to the stimulus. Spontaneous seizures also occur in patients with startle epilepsy, but are infrequent in most cases.
Carbamazepine, clonazepam, clobazam, and lamotrigine are sometimes prescribed for patients with startle epilepsy. Surgery has been reported to control startle epilepsy associated with infantile hemiplegia, but startle epilepsy is typically intractable. Patients can usually only achieve incomplete or temporary seizure control.