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Bilateral deep brain stimulation (DBS) of the globus pallidus internus (GPi) alleviates symptoms in patients with dystonia but its effects on cognition, neuropsychiatric status, and quality of life have not been examined. This is a case series report of 15 consecutive patients with different forms of dystonia who underwent bilateral implantation of DBS electrodes in the GPi. The patients were evaluated preoperatively and after 3-12 months of DBS with tests of cognition (Mattis Dementia Rating Scale, Stroop Test, Trail Making Test, Phonemic and Category Word Fluency, Digit Span, Rey Auditory Verbal Learning Test, Tonic and Phasic Alertness), neuropsychiatric status (Beck Depression and Anxiety Inventories, Montgomery Asberg Depression Rating Scale, Snaith-Hamilton Pleasure Scale, Brief Psychiatric Rating Scale), quality of life, and motor functions. GPi DBS significantly improved dystonic symptoms, functional abilities, and quality of life allowing for a significant reduction of antidystonic medications. No deterioration was observed in cognitive scores and neuropsychiatric measures. The present case series report thus provides preliminary evidence for the safety of GPi DBS regarding cognitive and neuropsychiatric functions in patients with dystonia.

A 70 year old woman presented with a 6 year history of medically refractory severe tardive dystonia. After informed consent, a bilateral stereotactic electrode placement targeting the ventral intermediate thalamic nucleus (VIM) and the globus pallidus internus (GPi) was performed. After bilateral stimulation of the GPi, the patient showed a clear and stable improvement of the painful dystonic syndrome within hours. Stimulation of the VIM did not improve the hyperkinetic movements and simultaneous stimulation of both the GPi and the VIM did not result in any additional benefit. The possible pathophysiological mechanisms are discussed.