Startle epilepsy associated with gait-induced seizures: Pathomechanism analysis using EEG, MEG, and PET studies.

We describe herein a girl who has had startle-induced seizures since she was 3 years old. These seizures were refractory to antiepileptic medications and worsened when the patient was 9 years old, following termination of phenytoin administration because of adverse effects. During this period she could walk only a few steps with support, and sudden drop attacks inevitably occurred. Interictal electroencephalography (EEG) revealed abundant spike-wave activity at the centroparietal midline areas, and ictal EEG of poststartle and gait-induced seizures revealed initial voltage attenuation followed by recruitment of vertex activity, which preceded a tonic or myoclonic-atonic phase. Magnetic resonance imaging (MRI) results were unremarkable, but magnetoencephalography (MEG) and positron emission tomography (PET) suggested the presence of an extensive epileptogenic zone in the bilateral pericentral gyri, and the bilateral paracentral and left precuneus lobules, including the primary motor, supplementary motor, and supplementary sensory areas. The pathophysiologic significance of these structures is discussed.