Non-motor Adverse Effects Avoided by Directional Stimulation in Parkinson's Disease: A Case Report

Abstract

IntroductionDeep brain stimulation (DBS) is widely used for treatment of advanced, medication-refractory Parkinson's disease (PD). However, a significant proportion of patients may suffer adverse effects; up to 10% will present one or more transient or permanent neurobehavioral events.Patient and MethodsIn our case study, a 44-year-old woman diagnosed with PD 6 years previously who was suffering from motor fluctuations, dyskinesia, and freezing of gait episodes was submitted for DBS and implanted with directional electrodes. Intraoperative local field potentials (LFPs) were recorded. After surgery, conventional monopolar revision was performed. Preoperative 3T MRI studies and postoperative 3D and X-ray data were integrated using the Guide DTI software application (Brainlab), and diffusion tensor imaging tractography traced from cortical areas to each subthalamic nucleus (STN) using Elements software (Brainlab).ResultsWe observed that left STN stimulation in the ring mode significantly improved motor symptoms, but the patient presented uncontrollable mirthful laughter. Stimulation was then switched to the directional mode; laughter remained when using the more posteromedial contact (3-C+) but not 2-C+ or 4-C+ at the same parameters. Interestingly, LFP recordings showed the highest beta-band activity over contacts 4 and 2, and very scarce beta power over contact 3. The orientation of the directional leads was selected based on the 3D postoperative X-rays. Associative fibers showed the shortest distance to contact number 3.ConclusionStimulation of the STN can affect motor and associative loops. The use of directional electrodes is a good option to avoid not only undesirable capsular or lemniscal effects, but also limbic/associative events. Oscillatory activity in the beta range that preferentially takes place over the somatomotor STN region and is closely related to motor improvement, provides a reliable guide for optimizing the DBS programming. The importance of the exact location of electrical stimulation to determine the non-motor symptoms such as mood, apathy, attention, and memory, as well as the usefulness of biological markers such as LFP for optimal programming, is discussed in relation to this case.

Case report: Left gaze and facial nerve palsies after ventral intermediate thalamic nucleus deep brain stimulation implantation

“…For globus pallidus internus (GPi) DBS, mental status/behavioral changes are also the highest reported followed by speech disturbances (10). Complications can be further derived from stimulation, such as electrical flow expanding through association regions and causing non-motor symptoms including laughter and hypomania (11).…”

Surgical Therapies for Parkinson Disease

“…6 Neuropsychiatric effects of STN-DBS include potential worsening of depression and anxiety and impulse control disorders. 12 Despite stable improvements in global outcomes of DBS, patients can have worsening of gait impairment and speech disturbances, as well as persistent levodopa-resistant freezing of gait. 13 Overall, many studies show that no significant differences are found in long-term control of motor symptoms between the two sites.…”

“…The STN target is thought to be associated with increased medication reduction compared with the globus pallidus internus (GPi) target, while the GPi target is thought to be better at addressing dyskinesias 6 . Neuropsychiatric effects of STN-DBS include potential worsening of depression and anxiety and impulse control disorders 12 . Despite stable improvements in global outcomes of DBS, patients can have worsening of gait impairment and speech disturbances, as well as persistent levodopa-resistant freezing of gait 13 .…”

A Retrospective Comparison of Multiple Approaches to Anatomically Informed Contact Selection in Subthalamic Deep Brain Stimulation for Parkinson’s Disease

“…Especially since the advent of directional leads, contact selection can be employed for selective current distribution to improve stimulation response [6][7][8]. Consequently, the practice of meticulously testing acute stimulation effects for each contact to determine optimal stimulation response, the monopolar review (MPR), has become even more tedious and time-consuming.…”