Subthalamic deep brain stimulation for Parkinson’s disease outcome
Suboptimal targeting within the STN can give rise to intolerable sensorimotor side effects, such as dysarthria, contractions and paresthesias 2) 3) 4). eye movement perturbations, and psychiatric symptoms 5) 6) 7), limiting the management of motor symptoms. The small size of the STN motor territory and the consequences of spreading current to immediately adjacent structures obligate precise targeting. Neurosurgeons therefore rely on a combination of imaging, electrophysiology, kinesthetic responses, and stimulation testing to accurately place the DBS lead into the sensorimotor domain of STN 8) 9) 10).
High frequency subthalamic nucleus (STN) deep brain stimulation (DBS) improves the cardinal motor signs of Parkinson’s disease (PD) and attenuates STN alpha/beta band neural synchrony in a voltage-dependent manner. While there is a growing interest in the behavioral effects of lower frequency (60 Hz) DBS, little is known about its effect on STN neural synchrony.
Low-frequency stimulation of the subthalamic nucleus via the optimal contacts is effective in improving overall motor function of patients with Parkinson Disease 12). In Parkinson’s disease significantly improved important aspects of QoL as measured by PDQ-39. The improvements were maintained at 2 years follow-up except for social support and communication. Sobstyl et al., demonstrated a positive correlation between changes in the off condition of motor UPDRS scores and Unified Dyskinesia Rating Scale in several PDQ-39 dimensions, whereas fluctuation UPDRS scores were negatively correlated with PDQ-39 mobility scores 13).
The degree of clinical improvement achieved by deep brain stimulation (DBS) is largely dependent on the accuracy of lead placement.
A study reports on the evaluation of intraoperative MRI (iMRI) for adjusting deviated electrodes to the accurate anatomical position during DBS surgery and acute intracranial changes 14).
Although dementia is a contraindication in deep brain stimulation for Parkinson’s disease, the concept is supported by little scientific evidence. Moreover, it is unclear whether PD with mild cognitive impairment (PD-MCI) or domain-specific cognitive impairments affect the outcome of DBS in non-demented PD patients.
Baseline cognitive levels of patients with PD who underwent DBS were classified into PD with dementia (PDD) (n = 15), PD-MCI (n = 210), and normal cognition (PD-NC) (n = 79). The impact of the cognitive level on key DBS outcome measures [mortality, nursing home admission, progression to Hoehn&Yahr (HY) stage 5 and progression to PDD] were analyzed using Cox regression models. Park et al. also investigated whether impairment of a specific cognitive domain could predict these outcomes in non-demented patients.
Results: Patients with PDD showed a substantially higher risk of nursing home admission and progression to HY stage 5 compared with patients with PD-MCI [hazard ratio (HR) 4.20, P = .002; HR = 5.29, P < .001] and PD-NC (HR 7.50, P < .001; HR = 7.93, P < .001). MCI did not alter the prognosis in patients without dementia, but those with visuospatial impairment showed poorer outcomes for nursing home admission (P = .015), progression to HY stage 5 (P = .027) and PDD (P = .006).
Conclusions: Cognitive profiles may stratify the pre-operative risk and predict long-term outcomes of DBS in PD 15).