Thalamic stimulation for tremorSubtle 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.

Effects on cognition and quality of life with unilateral magnetic resonance–guided focused ultrasound thalamotomy for essential tremor

“…7,38 Interestingly, there has been a report of a subtle diminution in verbal memory in the DBS-on state versus the DBS-off state. 27 In the present study, we demonstrated that postoperative cognitive decline could be minimized by thalamic lesioning with MRgFUS. Only 5 patients manifested worsened cognitive function, but most of them (4 patients) already had cognitive impairment as a predisposing factor before surgery.…”

Effects of Deep Brain Stimulation on Cognition, Mood and Behaviour in Parkinson’s Disease

“…Four studies [9][10][11][12] have observed no widespread or significant changes in cognition, mood or behaviour after unilateral thalamic DBS, although one study suggested that statistically (but not necessarily clinically) significant declines in verbal memory are associated with left thalamic DBS. Few studies have examined mood after thalamic DBS, but one study 9 found an improvement in depressive symptoms four to 10 days after surgery.…”

Comment on the Article by Ledermann et al. Entitled ‘Effects of Cerebellothalamic Tractotomy on Cognitive and Emotional Functioning in Essential Tremor: A Preliminary Study in 5 Essential Tremor Patients'

“…The former have been speculated to be attributable to microlesional/oedema effects and the latter to permanent changes to neuroanatomical structures. One difference between the two studies relates to stimulation effects, which were absent in the study of Ledermann et al With thalamic DBS for ET, effects of stimulation have been postulated to account for postoperative memory [6] and verbal fluency [7] changes. Conclusions regarding stimulation effects on cognition in PSA-DBS ET patients are limited to one study at present which only analysed verbal fluency outcomes in 17 patients 3 days and 1 year after zona inserta DBS surgery [5].…”