Beyond a motor disorder: a prospective evaluation of sleep quality in cervical dystonia

Little is known about sleep disturbances in cervical dystonia (CD), particularly the relationship to motoric symptoms. It is critical to clarify these points given the impact on quality of life.

Primary CD patients receiving botulinum toxin (BoNT) injections and age- and gender- matched healthy controls were included. In both groups, sleep quality and daytime sleepiness were assessed. In CD, these assessments were repeated following BoNT injections. CD severity, mood symptoms, and health impact of CD were also assessed.

54 CD patients and 55 controls were included. Impaired sleep quality was more frequent in CD compared to controls (t = 4.82, p < 0.0005), even when controlling for the effects of depression, anxiety, and benzodiazepineuse (F = 5.62, p = 0.020). Excessive daytime sleepiness was not significantly different between groups (t = 1.67, p = 0.1). 48 patients received BoNT and returned for follow-up. There was no improvement in sleep quality (t = 0.834, p = 0.41) or daytime somnolence (t = 1.77, p = 0.083) despite improvement in CD severity (t = 4.77, p < 0.0005) with BoNT. There was a small improvement in health impact (t = 2.10, p = 0.04).

Sleep quality was more impaired in CD patients, compared to healthy subjects, and did not improve following BoNT treatment, despite a robust improvement in CD severity. This dichotomy suggests that sleep aberrations in CD require separate focus for effective treatment and cannot be viewed as secondary complications of the motor elements of this condition.