Chapter 30 Hyperekplexia

Abstract

Hyperekplexia, or startle disease, is derived from the Greek. The abnormal startle consists of an exaggerated response to unexpected stimuli, particularly sounds. The classification of the startle disorders has hitherto largely relied on electrophysiological criteria, and its clinical utility has therefore been limited. This chapter gives a clinical classification of the abnormal startle. In this, patients are separated according to whether the clinical picture is dominated by brief body jerks that clinically seem to follow the stimulus almost immediately or by spasms that are of visibly longer latency and last a second or more. Often these spasms follow a normal or exaggerated jerk to the stimulus. This chapter discusses the one cause of short latency body jerks following unexpected stimuli; hyperekplexia, which may be hereditary or sporadic. Upon examination, the hallmark of hyperekplexia is a brief body jerk of short latency following unexpected stimuli. Such stimuli may be visual, auditory, or somesthetic. Somesthetic stimuli are most effective when applied to the mantle area, particularly the face, when the response that results is sometimes termed a head retraction reflex.