Neonatal hyperekplexia ("startle disease") is a rare hereditary disorder which can be easily misdiagnosed.


Synonym: stiff baby syndrome, neonatal startle disease


Inheritance: autosomal dominant


Clinical features:

(1) generalized rigidity in a neonate after being startled or touched, with sustained tonic spasms

(2) exaggerated startle response with eye blinking, facial grimacing, head flexion, shoulder elevation, flexion of extremities and trunk

(3) there is usually a family history, with a parent or sibling affected


A bedside test is to trigger an episode by light glabellar tapping.


An attack can be relieved by forced knee-chest position or oral clonazepam



(1) apneic episodes


Differential diagnosis:

(1) neonatal tetanus

(2) neonatal seizures

(3) drug toxicity

(4) cerebral palsy


A description of the syndrome and its genetic basis is in Chapter 17.


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