Clinical usefulness of the Parkinson's disease sleep scale.

Objective: To test the usefulness of the Parkinson's disease sleep scale (PDSS) in identifying sleep disorders in the clinical practice setting.

Methods: Sixty-two PD patients were evaluated with the PDSS and the Epworth sleepiness scale (ESS). A cut-off of less than five for each PDSS item as an indicator of substantial sleep disturbance was chosen. If the ESS was equal to or greater than eight, patients were referred to a sleep disorder specialist and possible polysomnography.

Results: The mean total PDSS score was 104.7+/-21.5,which correlated with the mean Hoehn and Yahr score (1.9+/-0.9) as well as the mean ESS score (9.7+/-4.7). A significant correlation was also found between the ESS score and several items of the PDSS.

Conclusions: The PDSS was useful in identifying sleep disturbances which were not previously diagnosed, such as sleep maintenance insomnia and excessive daytime sleepiness. Problems with the PDSS include ambiguities of some questions, lack of quantification and an inability to identify specific sleep disturbances such as sleep apnea.