Deep brain stimulation for movement disorders.

Deep Brain Stimulation (DBS) was introduced into clinical practice nearly four decades ago and is currently the standard of care for patients with Parkinson's disease experiencing motor complications. Apart from this, it has several other established and emerging applications in movement disorders. The exact mechanisms by which DBS provides relief in movement disorders are still unclear; disruption of pathological neuronal synchrony and abnormal information flow through the neuronal circuits involved, are the most likely underlying mechanisms. DBS has been established to be a relatively safe procedure if patients are carefully selected and followed up by experienced multidisciplinary teams. Alternatives to the traditional stereotactic frame based techniques of lead implantation are emerging, and these, along with the other recent technological advances, are likely to extend the availability of this therapy to an increasing number of patients in the future.

The decade after subthalamic stimulation in advanced Parkinson's disease: A balancing act.

AIM: The duration of improvement in quality of life after subthalamic nucleus deep brain stimulation (STN DBS) for Parkinson's disease (PD) and the presurgical identification of factors predicting sustained clinical benefits have implications in patient selection and timing of surgery. These aspects were assessed in patients who underwent yearly assessment for at least 7 years after surgery. MATERIALS AND METHODS: The quality of life, motor and cognitive outcomes of 25 patients who completed the 7-year assessment, and 12 patients who completed the 10-year assessment, were analyzed. RESULTS: The improvement in quality of life was sustained only for 5 years, while the severity of motor signs and motor fluctuations remained reduced at 7 and 10 years. Tremor and rigidity showed more enduring reduction than bradykinesia and axial signs. The dose reduction in medications could be maintained until 7 years, by which time, the axial scores were worse than that seen at the pre-DBS levels. At 10 years, a higher levodopa requirement and recurrence of dyskinesias were noted. Patients with greater pre-DBS levodopa-responsive motor signs had greater long-term motor improvement. CONCLUSIONS: STN DBS performed in patients with advanced motor fluctuations and severe dyskinesias provide only an average of 5 years of quality of life improvement. STN DBS in patients with motor signs that are less responsive to levodopa results in shorter duration of clinical benefits. The improvements in the severity of motor fluctuations, rigidity, and tremor are the most enduring benefits of STN DBS that last a decade . However, these are offset by worsening axial and cognitive functions, bradykinesia, a higher levodopa requirement, and recurrence of dyskinesias by the end of the decade.

Predictors of dementia-free survival after bilateral subthalamic deep brain stimulation for Parkinson's disease.

OBJECTIVE: Bilateral subthalamic nucleus deep brain stimulation (STN DBS) improves motor complications and quality of life (QOL) in patients with Parkinson's disease (PD). However, it does not delay or prevent the occurrence of dementia. The deleterious effects of dementia on QOL and activities of daily living (ADL) underscore the importance of identifying predictors of dementia-free survival in PD patients considered for STN DBS. AIMS AND METHODS: The baseline clinical and neuropsychological data and the occurrence of dementia recorded during the longitudinal follow-up of a cohort of patients with PD with at least 2 years follow-up after bilateral STN DBS, were reviewed. RESULTS: One hundred and sixteen patients operated between 1999 to 2014 satisfied the inclusion criteria. Their mean age was 56.5 (±10) years and the mean duration of PD at surgery was 11.2 (±4.2) years. During the 542 person-years of follow-up, 30 patients developed dementia. The mean dementia-free survival after surgery was 8.7 [95% confidence interval (CI): 7.8-9.6] years. In univariate analysis, the baseline factors of older age, longer disease duration, past history of depression or psychosis, freezing of gait in OFF phase, worse ADL scores in ON phase, lower levodopa response of the Unified Parkinson's Disease Rating Scale (UPDRS) III axial sub-scores, and poor performances in the Addenbrooke's Cognitive Examination and Wisconsin Card Sorting Test (WCST) were associated with a shorter dementia-free survival. Among these, only freezing of gait and poor performance in WCST were independent predictors. CONCLUSION: Presence of freezing of gait in the drug OFF state and executive dysfunction predict the occurrence of earlier dementia in PD patients who otherwise qualify for bilateral STN DBS.

Surgical Treatment of Levodopa-induced Dyskinesia in Parkinson's Disease.

The treatment of motor manifestations of Parkinson's disease (PD) is essentially a trade-off between adequate relief of motor symptoms and prevention and control of motor complications, particularly levodopa-induced dyskinesia (LID). Progression of PD is paralleled by a progressive difficulty in achieving the balance. Functional neurosurgical procedures provide sustained relief of LID in carefully selected patients when further tailoring of medical therapy fails to achieve this goal. Though deep brain stimulation (DBS) has superseded lesioning surgeries, pallidotomy still has a role in those patients in whom DBS is not feasible for financial or other reasons.