Subthalamus stimulation in Parkinson disease: Accounting for the bilaterality of contacts

Abstract

Background:Deep brain stimulation (DBS) in Parkinson's disease uses bi-hemispheric high-frequency stimulation within the subthalamus, however, the specific impacts of bilaterality of DBS are still not clear. Thus, we aimed to study the individual-level clinical impact of locations of right-left contact pair-up accounting for each subthalamic nucleus (STN) anatomy.Methods:Contact locations and effects at 1 year were studied retrospectively in an unselected series of 53 patients operated between 2004 and 2010. Location of contacts was defined relatively to the main axis of STN used to map longitudinal and transversal positions, and STN membership (out meaning out-of-STN). Contact pairings were described via three methods: (i) Unified contact location (UCL) collapsing DBS into an all-in-one contact; (ii) balance of contact pair-up (BCPU), defined as symmetric or asymmetric regardless of laterality; (iii) hemisphere-wise most frequent contact pair-up (MFCP) regardless of BCPU. Clinical data were: mean levodopa equivalent dose, Unified Parkinson's Disease Rating Scale (UPDRS) motor score III without medication, UPDRS II and III speech sub-scores, UPDRS II freezing sub-score, 1 year versus preoperative values, with and without levodopa. Ad-hoc two-sided tests were used for statistical analysis.Results:Worsening speech, was more frequent for UCL_out patients and when the left MFCP contact was rear and/or superolateral, however, it less frequent for BCPU-asymmetric patients. Worsening freezing was more frequent when the right MFCP contact was rear and superolateral.Conclusions:These results point to strategies for minimizing dysarthria and freezing as adverse effects of DBS.

Anatomical predictors of cognitive decline after subthalamic stimulation in Parkinson’s disease

“…The surgical procedure for bilateral STN implantation was carried out according to preoperative magnetic resonance imaging (MRI), anatomic mapping, intraoperative microrecordings and clinical assessment, as reported previously (Lemaire et al 2007). The final effective contact location was identified 1-year after implantation on postoperative CT scans co-registered with pre-operative MRI (Lemaire et al 2016) and determined regarding the compromise between substantial clinical improvement, adverse effects and optimized dopatherapy. As the anterior/ventral location of DBS contact (within the associative or limbic part of STN) is known to impair cognitive functions (Welter et al 2014;Tsai et al 2007), we assessed the contact location mainly in the antero-posterior axis.…”

“…As the anterior/ventral location of DBS contact (within the associative or limbic part of STN) is known to impair cognitive functions (Welter et al 2014;Tsai et al 2007), we assessed the contact location mainly in the antero-posterior axis. Then, the main axis of STN was subdivided into four longitudinal antero-posterior subdivisions [as previously described (Lemaire et al 2016)]. We identified patients with an "anterior" location of contact if at least one effective contact on one side was situated in the most anterior quarter of the STN.…”