The August 1992 issue of Ped Neur Briefs included 3 articles on hyperekplexia. An additional report from the Hammersmith Hospital, London illustrates the difficulties of clinical diagnosis of startle disease (hyperekplexia). At 1 hour after birth the infant had generalized jerks diagnosed as convulsions and treated with phenobarbitone. She had pronounced truncal hypotonia, but on day 3 she developed hypertonia in the limbs, exaggerated tendon reflexes, and jitteriness. The hypertonia diminished during sleep but increased when she was touched. Jerks and stiffening were precipitated by handling, tapping, and especially by turning to the prone position. Pyridoxine and phenobarbitone reduced the frequency and severity of the attacks but did not relieve the touch-induced myoclonus. Clonazepam introduced on day 28 controlled the symptoms. Forcible flexion of the infant also stopped the jerks and stiffening. The measurement of CSF GABA concentration may be helpful in the diagnosis. [1]

COMMENT. I am startled by the unexplained rash of recent articles on hyperekplexia! Ryan SG et al. have studied 4 large clonazepam-responsive families with a hereditary hyperekplexia, using a panel of chromosome 5q polymorphic DNA markers. “Multilocus linkage analysis in each family confirms the previous chromosomal assignment of hyperekplexia to chromosome 5q. The hypothesis that a mutation in a GABA-receptor subunit causes hyperekplexia is particularly attractive in view of the long term benzodiazepine responsiveness of the disorder.”