Reader response: Clinical outcomes of asleep vs awake deep brain stimulation for Parkinson disease.

Abstract

Brodsky et al.1 compared verbal fluency, aspects of cognition, and quality of life after asleep and awake deep brain stimulation (DBS) in Parkinson disease. Awake DBS is associated with significant perioperative discomfort in 40% or more of patients.2 It is possible that anticipated discomfort contributes to the reluctance to undergo surgery expressed by 50% of patients (who are not referred for surgery despite appropriateness of DBS).3 Although good motor outcomes are attainable by asleep DBS,4 little is known about differences between the 2 methods in cognitive and quality of life outcomes.5 Brodsky et al.1 reported that verbal fluency improved after asleep DBS and that speech and quality of life outcomes were superior after asleep vs awake DBS. Only the change scores were presented for each group and then compared. It would be helpful to know the preoperative and postoperative scores of the groups, as well as the effect size associated with the interaction terms between group and time. Such data would better allow consideration of potential preoperative differences between the groups and whether these differences are accentuated after surgery. In addition, the clinical significance of fluency data is difficult to interpret as change is measured in points. Do these points refer to the number of words or a standardized score? Furthermore, were the verbal fluency changes correlated with change in the 39-item Parkinson's Disease Questionnaire cognition and communication scores? Why might the fluency changes not have manifested in Dementia Rating Scale total score changes, which are heavily influenced by fluency (20 of 144 points)?