title: Thalamic stimulation for tremor. Subtle changes in episodic memory are related to stimulation per se and not to a microthalamotomy effect.
abstract: The aim of this study was to investigate the impact of unilateral deep brain stimulation (DBS) of the ventrointermediate (Vim) thalamic nucleus on neuropsychological functioning comparing stimulation-on with stimulation-off conditions. Nine patients [five patients with Parkinson's Disease (PD), two patients with essential tremor (ET) and 2 patients with multiple sclerosis (MS)] underwent comprehensive neuropsychological testing for cognitive functions, including general mental impairment, aphasia, agnosia, executive and constructional abilities, learning, memory, cognitive processing speed and attention as well as depression. The neuropsychological assessments were performed at least 6 months postoperatively (mean 9 months). Testing in the stimulation-on and stimulation-off condition was obtained within a period of 3 to 4 weeks. Unilateral DBS resulted in improvement of tremor in all patients. There were no significant differences between the stimulation-on and the stimulation-off condition with the exception of a decrement of word-recall in the short delay free-recall subtest of the Rey Auditory-Verbal Learning Test (RAVLT). Subgroup analysis indicated that the impairment in word-recall was related to left-sided thalamic stimulation. Our study confirms that chronic unilateral DBS is a safe method with regard to cognitive function. The subtle changes in episodic memory are related to stimulation per se and not to a microthalamotomy effect.
authors.affiliation: Department of Neurology, University of Berne, Inselspital, Switzerland.
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Loher
authors.forename: Klemens
authors.initials: K
authors.lastname: Gutbrod
authors.forename: Nina L
authors.initials: NL
authors.lastname: Fravi
authors.forename: Thomas
authors.initials: T
authors.lastname: Pohle
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Burgunder
authors.forename: Joachim K
authors.initials: JK
authors.lastname: Krauss
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000377:Agnosia; D001037:Aphasia; D001288:Attention; D003071:Cognition; D003863:Depression; D004558:Electric Stimulation; D004599:Electric Stimulation Therapy / Q000379:methods*; D020329:Essential Tremor / Q000628:therapy; D005260:Female; D005500:Follow-Up Studies; D007839:Functional Laterality; D006801:Humans; D008297:Male; D008570:Memory, Short-Term; D008609:Mental Status Schedule; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000628:therapy; D009483:Neuropsychological Tests; D010300:Parkinson Disease / Q000628:therapy; D011597:Psychomotor Performance; D018709:Statistics, Nonparametric; D013788:Thalamus / Q000033:anatomy & histology / Q000502:physiology*; D016896:Treatment Outcome; D014202:Tremor / Q000628:therapy*; D014706:Verbal Learning