Periodic nocturnal myoclonus in a patient with hyperexplexia (startle disease).

The periodic nocturnal myoclonus of a patient with hyperexplexia has been studied. Evidence has been given that the jerks are spontaneous arousal reactions. The temporal characteristics of the jerks have been analysed. The jerks appear to be correlated with the respiratory rhythm and the data suggest a correlation of the jerks with circulatory and respiratory higher order waves. The results are discussed with relation to the literature concerning spontaneous sleep jerks.