Startle seizures are characterized by a bilateral tonic contraction, predominating on the paretic side when asymmetric, and comprising head and trunk flexion, rising of flexed or extended upper limbs, extension of lower limbs, eye closure, and facial contraction. Startle seizures are observed in various diseases and in a wide spectrum of cerebral lesions from an area of dysplasia to widespread bilateral cortico-subcortical lesions. Given the multiplicity of causes, multiple mechanisms are possible. In cases of widespread cerebral lesions, motor reactions triggered by an unexpected but not intense stimulus frequently occur without following seizures. Seizures elicited by cutaneous stimulation of a trigger zone start with localized paresthesiae such as tingling sensations. Startle epilepsies and other reflex epilepsies with seizures evoked by sensorimotor stimuli are not defined by their etiologies but rather by the mode of triggering of their seizures.