Background and purpose: To assess the prevalence of vigilance disorders in Parkinson's disease patients, relate the observed phenomena to potential causes and confirm these troubles with polysomnographic analysis.
Patients and methods: A questionnaire was used to gather information on demographic data, previous and current treatments, disease characteristics, sleep and vigilance troubles. Somnolence was measured using the Epworth Sleepiness Scale (ESS). Nocturnal polysomnography (PSG) and multiple sleep latency tests (MSLT) were performed for a sample of parkinsonian patients.
Results: Two hundred twenty-two parkinsonian patients completed the questionnaire, and 36 patients had objective analyses. Of the patients, 43.2% had an ESS score >10, and 28.4% reported somnolence in the hour after taking dopaminergic drugs, whereas 6.8% reported unintended sleep episodes. In view of questionnaire data, these vigilance disorders may be partly explained not only by the impact of nocturnal sleep disorders (e.g. sleep apnea syndromes) but also by dopaminergic therapy (especially with dopaminergic agonists). With PSG and MSLT results, we have shown a significant correlation between mean sleep latency and ESS score. Patients with unintended sleep episodes have severe sleepiness in MSLT compared with others patients.
Conclusions: Vigilance disorders are frequently observed in Parkinson's disease. We recommend informing patients of the risk of occurrence of such conditions, notably for patients with unintended sleep episodes and with sleepiness in the hour after taking dopaminergic drugs.