Deep Brain Stimulation in Parkinson's Disease: Motor and Functional Outcomes

Condition(s) studied

Investigational drug(s) / intervention(s)

Deep Brain Stimulation: Deep Brain Stimulation (DBS) is a stereotactic surgical technique used for the control and management of motor complications arising from L-dopa treatment. DBS consists of neural modulation through implanted electrodes connected to a neurostimulator (SHARMA et al., 2020). The fundamental criterion for surgical indication is refractoriness to conservative treatment. Of the four cardinal manifestations presented, three are suitable for surgical treatment: tremor, rigidity, and bradykinesia. The levodopa challenge test allows for an approximate assessment of the improvement that can be achieved with surgery; the ideal candidate is one who is severely impaired in the 'off' state and presents motor complications related to levodopa treatment or refractory tremor (HAMANI et al., 2008; FONOFF, 2012).

Study summary

Introduction: Parkinson's Disease (PD) is a progressive neurodegenerative condition characterized by classic motor symptoms, such as bradykinesia, rigidity, resting tremor, and postural instability, which directly compromise the mobility and autonomy of individuals with PD. Furthermore, non-motor manifestations, including autonomic, cognitive, and emotional changes, impact the quality of life of individuals with PD. Deep Brain Stimulation (DBS) surgery is a well-established treatment to assist in improving the primary motor symptoms of PD; however, literature is scarce in describing specific results regarding physiotherapeutic aspects, such as the motor symptoms that determine better quality of life and social participation for individuals with PD. Determining whether factors amenable to improvement prior to surgery-such as bradykinesia, muscle strength, and balance-are related to better motor and functional outcomes in individuals with PD post-DBS is of great importance to ensure a better result from the surgical intervention.

Objective: To compare motor outcomes (gait speed, balance, freezing of gait, fear of falling, muscle strength, functional capacity, and physical activity level) of individuals with PD after undergoing DBS, relative to the motor status previously observed in the preoperative period.

Methods: This is an uncontrolled clinical trial, with data collection conducted at the Neurovida private multidisciplinary clinic and the Hospital Santa Casa in Belo Horizonte. This study will be registered at www.clinicalTrials.gov and conducted according to the Consolidated Standards of Reporting Trials (CONSORT) recommendations. The present study will be submitted to the Research Ethics Committee of the Federal University of Minas Gerais (COEP) and will only commence after proper approval. All necessary consents for the development of the study have been obtained. The sample consists of individuals with idiopathic PD selected by a clinical neurologist specializing in movement disorders. The inclusion criteria for the present study are: having idiopathic PD diagnosed for more than five years, being under treatment with a neurologist specializing in movement disorders, and having an indication for DBS. Descriptive statistics and normality tests will be performed for all study variables. Selected variables will be compared in terms of mean difference between post- and pre-surgery measurements, considering a 95% CI. In all analyses, a significance level of α=0.05 will be considered, using the SPSS statistical package version 15.0 for Windows.

Eligibility

Primary outcome measure(s)

• Gait Speed — Participants will be evaluated prior to Deep Brain Stimulation and at three- and six-month postoperative follow-ups
  Gait speed will be assessed using the 6-Meter Walk Test (6MWT). The 6MWT is a simple, low-cost, and reliable test, performed on a flat surface without the use of sophisticated equipment, and it does not require specialized training on the part of the evaluator. In individuals with Parkinson's disease (PD), this test has been used to assess gait speed (Canning et al., 2006). During the test, the individual is instructed to walk at their usual speed for six meters along the walkway. The total time taken to complete the test will be recorded (Lam et al., 2010; Lyons et al., 2015). The literature indicates that there is no need to include acceleration and deceleration phases in the assessment of individuals with PD, nor to perform repeated measurements (Lindholm et al., 2018).
• Balance — Participants will be evaluated prior to Deep Brain Stimulation and at three- and six-month postoperative follow-ups
  Balance will be assessed using the Mini-BESTest (Franchignoni et al., 2010), which includes sections 4 to 6 of the BESTest (anticipatory postural adjustment, postural responses, sensory orientation, and gait stability) (King et al., 2012). It consists of 14 items, each scored from zero to two, with a maximum score of 28 and a minimum of zero, where a higher score indicates better balance.
• Freezing of gait — Participants will be evaluated prior to Deep Brain Stimulation and at three- and six-month postoperative follow-ups
  For the assessment of freezing of gait (FOG), the Freezing of Gait Questionnaire (FOG-Q) (APPENDIX B) will be administered. Freezing typically occurs at gait initiation, during turning, when passing through narrow spaces, and/or immediately before reaching a destination (Baggio et al., 2012). Freezing of gait, which is a type of akinesia, is a phenomenon of unknown origin and is considered the most disabling motor symptom of Parkinson's disease (PD), as well as a significant predictor of falls (Kerr et al., 2010). The FOG-Q is a questionnaire designed to assess and quantify the degree of difficulty in walking directly related to freezing of gait. It consists of 6 items, each scored on a 5-point scale ranging from 0 (absence of symptoms) to 4 (most severe stage). The total score ranges from 0 to 24 points, with higher scores indicating greater severity. The questionnaire should be administered during the "on" medication phase.
• Fear of falling — Participants will be evaluated prior to Deep Brain Stimulation and at three- and six-month postoperative follow-ups.
  In 1990, Tinetti, Richman, and Powell developed the first scale to assess falls, called the Falls Efficacy Scale (FES). Based on this scale, the European falls prevention network developed a modified version, the Falls Efficacy Scale International (FES-I), which includes six additional items. The FES-I is a scale used to assess fear of falling and demonstrates excellent test-retest reliability (ICC = 0.96) and internal consistency (Cronbach's alpha = 0.96) (Camargos et al., 2010; Jonasson et al., 2017; Fasano et al., 2017).
• Muscle strength — Participants will be evaluated prior to Deep Brain Stimulation and at three- and six-month postoperative follow-ups.
  Muscle strength will be assessed using a Hand-Held Dynamometer test. The following muscle groups will be measured: trunk extensors, bilateral quadriceps, and bilateral plantar flexors. The hand-held dynamometer is essential for the functional assessment of individuals and is widely used in clinical practice for various purposes, including functional diagnosis to monitor improvement or deterioration over time, as well as a predictive or prognostic measure for the occurrence of falls and limitations in activities of daily living (Bohannon, 1986; Andrews et al., 1996). The device must always be stabilized by the same examiner at the appropriate location for applying resistance for each muscle group test. After stabilization, the individual will be verbally encouraged by the examiner, using a standardized verbal command, to perform a maximal isometric contraction for 5 seconds while the examiner resists the movement, keeping the segment static. A rest period of 15 seconds will be allowed.
• Functional capacity — Participants will be evaluated prior to Deep Brain Stimulation and at three- and six-month postoperative follow-ups.
  Functional capacity will be assessed using the Duke Activity Status Index (DASI) (APPENDIX B), a questionnaire originally developed in English (Hlatky et al., 1989) and translated into Portuguese (Coutinho-Myrrha et al., 2014), with the aim of evaluating metabolic cost capacity (METs) in individuals with cardiovascular diseases. The final score ranges from 0 to 58.2 points, with higher scores indicating better functional capacity.
• Physical activity level — Participants will be evaluated prior to Deep Brain Stimulation and at three- and six-month postoperative follow-ups.
  The level of physical activity will be assessed using the Human Activity Profile (HAP). It has previously been used (Goulart et al., 2004) as a measure of functional performance and physical activity level in individuals with Parkinson's disease (PD) in stages 1 to 3 of the Hoehn and Yahr (HY) scale. The results indicated that individuals in the early to moderate stages of PD tend to reduce their level of physical activity more rapidly than asymptomatic individuals of the same age. In addition, it was shown that low physical fitness is present in the early and moderate stages of the disease, and not only in the advanced stage (Goulart et al., 2004).

Trial sites (1)

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