Sleep abnormalities in children with Dravet syndrome

Background: Mutations in the voltage-gated sodium channel SCN1A gene are responsible for the majority of Dravet syndrome cases. There is evidence that the Nav1.1 channel coded by the SCN1A gene is involved in sleep regulation. We evaluated sleep abnormalities in children with Dravet syndrome using nocturnal polysomnography.

Methods: We identified six children at our institution with genetically confirmed Dravet syndrome who had also undergone formal sleep consultation with nocturnal polysomnography. Indications for polysomnography were parental concern of daytime fatigue or sleepiness, hyperactivity, inattention, disruptive behavior, nighttime awakenings, or nocturnal seizures. Sleep studies were scored according to guidelines of the American Academy of Sleep Medicine and non-rapid eye movement cyclic alternating pattern was visually identified and scored according to established methods.

Results: The mean age of the subjects at the time of polysomnography was 6 years. Standard polysomnography did not show any consistent abnormalities in the obstructive or central apnea index, arousal index, sleep efficiency, or architecture. Cyclic alternating pattern analysis on five patients showed an increased mean rate of 50.3% (vs 31% to 34% in neurological normal children) with a mild increase in A1 subtype of 89.4% (vs 84.5%). A2/A3 subtype (5.3% vs 7.3%) and B phase duration (22.4 vs 24.7 seconds) were similar to previously reported findings in neurologically normal children.

Conclusion: Despite parental concerns for sleep disturbance in patients with Dravet syndrome, we could not identify abnormalities in sleep macroarchitecture. Non-rapid eye movement sleep microarchitecture was, however, abnormal, with increased A1 subtype, somewhat resembling a tracé alternant pattern of neonates and possibly suggestive of cortical synaptic immaturity in Dravet syndrome. Larger studies are needed to replicate these results.