Neuropsychological and quality of life outcomes 12 months after unilateral thalamic stimulation for essential tremor

OBJECTIVES: To evaluate the one year cognitive, mood state, and quality of life (QoL) outcomes of unilateral thalamic deep brain stimulation (DBS) for essential tremor (ET). METHODS: 40 patients diagnosed with ET completed comprehensive neuropsychological assessments about one month before and three and 12 months after DBS electrode implantation. Data were subjected to multivariate analyses, and significant results were further analysed using univariate techniques. RESULTS: Analyses revealed statistically significant improvements on a cognitive screening measure and in aspects of fine visuomotor and visuoperceptual functions, verbal memory, mood state, and QoL. No group-wise declines in cognition were observed, but more patients showed declines than improvements on language and visual memory tests. Semantic verbal fluency declined significantly in four (10%) of the patients. In these four patients, diminished lexical verbal fluency was present at baseline. CONCLUSION: Cognitive, mood, and QoL outcomes after one year of DBS for ET are favourable; there were no overall deleterious effects on cognition, and DBS was accompanied by a significant reduction in anxiety and improvements in quality of life. However, preoperative verbal fluency diminution may predispose to further fluency declines after DBS.