PERIODIC LIMB MOVEMENT IN SLEEP IN CHILDREN WITH WILLIAMS-SYNDROME

Objective: Williams syndrome (WS) is associated with neurobehavioral a bnormalities that include irritability and attention-deficit/hyperacti vity disorder. Parents often report children having difficulties initi ating and maintaining sleep because of restlessness and arousals. Ther efore we evaluated a group of children with WS for the presence of a m ovement arousal sleep disorder. Methods: Twenty-eight families of chil dren with WS participated in a telephone survey aimed to screen for a movement arousal disorder. Of the 16 children identified as having suc h a disorder, 7 (mean age, 3.9 +/- 2.2 Sears) underwent polysomnograph y. Their studies were compared with those of 10 matched control subjec ts (mean age, 5.3 +/- 2.0 years). Results: The 7 subjects with WS who were screened by the sun ey had sleep latency, total sleep time, arous als, and awakenings that were similar to those of control subjects. Ho wever, they presented with a disorder of periodic limb movement in sle ep (PLMS). The PLMS index in the subjects with WS was 14.9 +/- 6.2 ver sus 2.8 +/- 1.9 in control subjects (P <.0001). In addition, arousal a nd awakening in subjects with WS were strongly associated with PLMS. M oreover, children with WS spend more time awake during sleep periods t han control subjects (10.0% +/- 7.0% vs 4.4% +/- 4.7%; P <.05). Five c hildren were treated with clonazepam, and in 4 a significant clinical response was noted. Conclusion: We report an association between WS an d PLMS. Clonazepam may reduce the clinical symptoms of PLMS in some of these children.