The effect of deep brain stimulation on motor and cognitive symptoms of Parkinson's disease: A literature review.

Flavia Amaral Machado,Caroline Tozzi Reppold

doi:10.1590/s1980-57642015dn91000005

Flavia Amaral Machado, Caroline Tozzi Reppold

Open Access

https://doi.org/10.1590/s1980-57642015dn91000005

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Abstract

Deep brain stimulator (DBS) implant surgery is considered a breakthrough in the treatment of Parkinson's disease, especially in cases where motor symptoms cannot be controlled through conventional drug treatment. Its benefits have been studied extensively in the literature, particularly in relation to motor symptoms. However, the disease's cognitive aspects have been studied to a lesser extent.ObjectiveThis systematic review aims to assess the effects of DBS surgery on motor and cognitive symptoms in patients with Parkinson's disease.MethodsThe search strategy included MEDLINE, LILACs, SCIELO and the Cochrane Library. Randomized clinical trials with DBS surgical intervention and Parkinson's disease were included. Of the 178 studies identified, 19 met the eligibility criteria. These studies were descriptively analyzed as regards to their results.ResultsControl of motor symptoms, as assessed by the UPDRS Part III scale, was found in all of the studies, pointing to great interest in this outcome and demonstrating an advantage of DBS over conventional drug treatment. Regarding cognitive aspects, heterogeneity in the choice of subjects studied and the use of different assessment tools for each was evident, hampering comparisons and leading to inconclusive results.ConclusionThis review provides a broad overview of the effects of DBS on Parkinson's disease symptoms. However, it is suggested that future studies be conducted to establish a gold-standard protocol for neuropsychological assessment, thereby enabling data comparison and more consistent conclusions.

Highlights

Parkinson’s disease (PD), first described by the English doctor James Parkinson in 1817, is considered a neurodegenerative disease, highly prevalent in the elderly population worldwide, whose incidence tends to increase with the population aging observed in recent years
Increased control of motor symptoms proved similar between the two implant groups, as the studies found no significant differences and the results showed an improvement ranging from 26% to 40% for subthalamic nuclei (STN) and 28% to 40% for globus pallidus (GPi).[20,31,32]
The improvement in motor conditions in PD patients who underwent deep brain stimulator implant surgery is well established in the literature

Summary

Introduction

Parkinson’s disease (PD), first described by the English doctor James Parkinson in 1817, is considered a neurodegenerative disease, highly prevalent in the elderly population worldwide, whose incidence tends to increase with the population aging observed in recent years. Non-motor symptoms affect the individual and are responsible for limitations and disabilities that impair the quality of life in these individuals.[1,2]. The neuropathology of PD involves the degeneration of dopaminergic neurons located in the brain’s substantia nigra. It is a process in which neurons are lost in the region called the pars compacta and results from the accumulation of proteins (mainly alpha-synuclein) in this region. The loss of dopaminergic terminals leads to a decrease in dopamine transporter (DAT) density. This reduction in DAT density can reach 90% of normal levels.[3,4,5]

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