Objective: To evaluate what intraoperative factors contribute to impairment after deep brain stimulation (DBS) surgery in patients with essential tremor (ET) and Parkinson’s disease (PD).

Background: DBS is the standard treatment for medically refractory tremor disorders including PD and ET.   Although cognitive decline is a well-known risk of PD, there is evidence that such changes are worse in patients following DBS. Transient cognitive decline has also been observed in ET patients undergoing DBS.  While the motor benefits of DBS have been the subject of extensive research, less is known about what surgical factors may impact cognitive outcomes.  

Methods: All PD and ET patients aged 18 and older undergoing DBS at Duke University Medical Center from 2000 to 2015 were eligible for analysis. Baseline characteristics and intraoperative factors of patients who were noted to have post DBS confusion on follow-up in movement disorders were compared to those with no cognitive changes.  Continuous demographic variables (age, duration of disease) were compared using a two-tailed student’s t-test. Categorical demographic variables were compared using contingency analysis, specifically the chi-square statistic.

Results: The initial results of our examination includes 12 patients in the analysis group vs. 25 patients in the control group. Subjects were equally matched for age (68.9 +/- 5.2 years vs. 64.5 +/- 10.5 years, p=0.175), disease duration (17.3 +/- 18.5 years vs. 13.1 +/- 12.5 years, p=0.429), sex (female 8/12 vs 13/25, p=0.399), and disease (PD 8/12 vs. 16/25, p=0.874).  Patients who experienced post-operative cognitive impairment were more likely to receive sevoflurane (9/12 vs. 6/25, p=0.003) and dexmedetomidine (9/12 vs. 9/25, p=0.026) during surgery.  Additionally, patients who experienced post-DBS confusion were more likely to have undergone a two-stage surgery, and had a longer total duration of anesthesia.

Conclusions: Anesthetic choice during DBS surgery may influence the risk of post-operative cognitive impairment. A staged surgery for both DBS lead and battery placement may be less preferable to a single surgery.  Further scrutiny of each disease population separately, an expanded population analysis, and a prospective study using objective measurements of pre- and postoperative cognitive function may better define intraoperative risk factors for cognitive impairments following deep brain stimulation surgery. 

References: Hickey P, Stacy M. Deep Brain Stimulation: A Paradigm Shifting Approach to Treat Parkinson’s Disease. Front Neurosci. 2016 Apr 28;10:173.

Carlson JD, Neumiller JJ, Swain LD, Mark J, McLeod P, Hirschauer J.  Postoperative delirium in Parkinson’s disease patients following deep brain stimulation surgery. J Clin Neurosci. 2014 Jul;21(7):1192-5.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/postoperative-cognitive-impairment-following-deep-brain-stimulation-surgery/