Definition of Hyperexplexia Hyperexplexia: A rare genetic
disorder inherited in an autosomal dominant manner in which
babies have an exaggerated startle reflex. Symptoms at birth may
include muscle stiffness (hypertonia), an exaggerated response
to being startled, and strong brain stem reflexes (especially
head-retraction reflex). The startle reflex is sometimes
accompanied by sudden stiffness (acute generalized hypertonia),
which can cause the affected person to fall to the ground like a
log. Treatment is via medications. Also known as exaggerated
startle disease, hyperekplexia, Kok disease, startle disease,
and stiff baby syndrome. Last Editorial Review: 3/19/2012 Back
to MedTerms online medical dictionary A-Z List Need help
identifying pills and medications? Get the latest health and
medical information delivered direct to your inbox FREE!