Objective: Excessive daytime sleepiness is a relatively common feature in PD. However, it has not been reported as a side effect of STN DBS. We describe a case of acute, severe, reversible somnolence linked to specific STN DBS parameters in a subject with PD.

Background: 54 year old man diagnosed with PD at the age of 42, developed levodopa motor complications leading to implantation of bilateral STN DBS at the age of 49 with marked improvement in motor scores and reduction in PD medications. At age of 45, he developed excessive daytime sleepiness (EDS). Overnight polysomnogram followed by multiple sleep latency testing was performed at age 48. NPSG: mild OSA. MSLT: hypersomnolence, with short sleep latency of 1 minute, but no sleep onset REM.

Methods: Hypersomnia was reported during initial programming: somnolence started and ended abruptly at specific thresholds on both sides.

The patient described a sense of sleepiness, and an urge to close the eyes. He becomes quiet, and uncharacteristically withdrawn. Below the amplitude threshold, symptoms promptly resolve.
At 4 years, reassessment confirmed the same acute transient somnolence in the absence of other side effects more typically seen at higher charge densities such as paresthesias, muscular contractions, dysarthria or ocular disturbances.

Results: video link: https://goo.gl/photos/KpsaaNVyfpukJL1DA

Conclusions: To our knowledge, there are no reports of acute drowsiness as a reversible STN DBS stimulation effect. There is one report of severe somnolence lasting several hours immediately following bilateral DBS electrode insertion into the prelemniscal radiation, but somnolence was not present with chronic stimulation.
Somnolence may be induced by current spread to fibers linked to the ascending reticular formation, mesencephalic tegmentum and mammillothalamic tract. No imaging is available to provide an anatomic correlate, but the patient has otherwise responded in a typical robust manner to STN DBS.
These data suggest high frequency stimulation can, in rare cases, lead to nonmotor side effects not typically anticipated based on the known topographical distribution of fibers surrounding the subthalamic nucleus. In this case, somnolence was achieved independently on either side, suggesting this is not simply an issue of aberrant lead placement. More studies are needed to determine the true incidence of this phenomenon.

References: Carrillo-Ruiz, Josè D et al. “Bilateral electrical stimulation of prelemniscal radiations in the treatment of advanced Parkinson’s disease.” Neurosurgery 62.2 (2008): 347-359

Bejjani, Boulos-Paul et al. “Transient acute depression induced by high-frequency deep-brain stimulation.” New England Journal of Medicine 340.19 (1999): 1476-1480

« Back to 2017 International Congress

MDS Abstracts - https://www.mdsabstracts.org/abstract/somnolence-as-untoward-stimulation-effect-in-subthalamic-deep-brain-stimulation-stn-dbs-for-parkinsons-disease-pd/