Sleep spindle alterations in patients with malformations of cortical development

Malformations of cortical development are disorders of altered brain anatomy and architecture that arise from abnormalities in the usual processes of cerebral cortical development. Although they often lead to epilepsy, cognitive delay, and motor impairment, little is known about their effect on sleep. Since malformations may anatomically or functionally disrupt the cerebral circuits that mediate sleep spindles, we hypothesized that these disorders would be associated with abnormal spindle characteristics. We analyzed the density, maximum frequency, laterality and distribution of sleep spindles seen in routine and long-term electroencephalographic recordings performed in ten brain malformation subjects and ten matched controls. There were no significant differences in spindle density or maximum frequency between the two groups, but malformation subjects had a significantly lower proportion of bilateral spindles and a significantly higher proportion of anterior and diffuse spindles compared to controls. In addition, unilateral malformations appeared to be associated with a skewing of unilateral spindles toward the contralateral side. Our findings suggest that brain malformations disrupt the thalamocortical circuits responsible for sleep spindle generation, and support the need for further studies on the relationships between cortical maldevelopment and sleep.