To the Editor: In their randomized controlled trial, Dr Weaver and colleagues1 reported a significant improvement in the motor function of participants with advanced Parkinson disease (PD) treated with bilateral deep brain stimulation, compared with best medical therapy. Dementia is often cited as a contraindication to deep brain stimulation on practical grounds. This is particularly (but not exclusively) true when it is felt that the patient will be unable to cooperate during surgery.2 Indeed, participants with Mini-Mental State Examination (MMSE) scores of 24 or less were excluded from the trial. The prevalence of dementia in advanced PD may be greater than 70%.3 Therefore, treatment with deep brain stimulation may only be offered to a minority of patients with severe motor symptoms.
The sensitivity of MMSE in detecting dementia in PD has been questioned. Although a score of less than 25 is likely to indicate cognitive impairment, a higher score may not be reassuring. In this study, the baseline neurocognitive tests for both groups showed mean scores below 50 (the authors' stated normal mean) for phonemic fluency, Hopkins Verbal Learning Test, Wisconsin Card Sorting Test perseverative response, and Brief Visuospatial Memory Test scores. The standard deviations of these data suggest a wider range of cognitive function than may have been inferred from the MMSE score alone, raising a question of the suitability of MMSE in the preoperative screening process.
This trial brings significant new evidence of the efficacy of deep brain stimulation but not of the assumption that dementia is a contraindication. Given the prevalence of neuropsychiatric disorders in advanced PD, this assumption requires further examination. Should potentially cooperative patients who meet the diagnostic criteria for dementia be considered for this treatment? The question of how demented is too demented for deep brain stimulation will remain until there is trial evidence.
Financial Disclosures: None reported.
Country-Specific Mortality and Growth Failure in Infancy and Yound Children and Association With Material Stature
Use interactive graphics and maps to view and sort country-specific infant and early dhildhood mortality and growth failure data and their association with maternal
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