Skip to Content
Find MS events and support groups near you! Get started >>
Medical Term:


Pronunciation: hī′pĕr-ek-plek′sē-ă

Definition: A hereditary disorder in which there are pathologic startle responses, protective reactions to unanticipated, potentially threatening, stimuli of any type, particularly auditory; the stimuli induce often widespread and violent sudden contractions of the head, neck, spinal, and sometimes, limb musculature, resulting in involuntary shouting, jerking, jumping, and falling; autosomal dominant and recessive inheritance forms, with the responsible gene localized to chromosome 5q; probably the result of lack of inhibitory neurotransmitters, glycine, or GABA.

Synonym(s): kok disease, startle disease

[hyper- + G. ekplēxia, sudden shock, fr. ekplēssō, to startle]