The Effects of Thalamic Deep Brain Stimulation on Gait in Essential Tremor: a Kinematic Study.
Paola Testini1, Johnathan McKay2, Richa Tripathi1, Imari Genias3, Grey Skelton3, Douglas Bernhard1, Svjetlana Miocinovic1, Pratibha Aia1, Cathrin Buetefisch1, Lenora Higginbotham1, Laura Scorr1, Shirley Triche1, Stewart Factor1, Christine Esper1
1Jean & Paul Amos PD & Movement Disorders Program, Department of Neurology, Emory University School of Medicine, 2Department of Biomedical Informatics and Jean & Paul Amos PD & Movement Disorders Program, Department of Neurology, Emory University School of Medicine, 3Rollins School of Public Health
Objective:
To determine the effect of ventral intermediate thalamic nucleus (VIM) deep brain stimulation (DBS) on gait parameters in patients with essential tremor (ET).
Background:
DBS is an established treatment for medication-refractory ET. ET can be associated with primary gait impairment; additionally, the effect of VIM-DBS on gait is currently debated, with reports ranging from a more frequently observed worsening to an improvement with therapeutic stimulation. Determining VIM-DBS effects on gait is pivotal to determine patient candidacy for this treatment.
Design/Methods:
Database review from our kinematics laboratory identified 27 patients (women, 15; men, 12) with ET who underwent VIM-DBS (bilateral, 5; unilateral, 22) and pre- and post-DBS quantitative gait kinematics analysis with a 3D commercial motion analysis (MA) system. Post-DBS assessments were performed on stimulation. Changes in gait outcomes from pre- to post- were expressed as effect sizes (Cohen’s d) and categorized as “small,” “medium,” or “large” using established cutoff values. Post-DBS Tremor Research Group Essential Tremor Rating Scale motor scores on and off stimulation were retrospectively reviewed and available for 22 patients; percent change of on versus off stimulation was calculated and scores were compared with paired samples t-tests.
Results:
Patients underwent DBS at a mean age of 69.4±8.5 years (Table 1). The average percent reduction of the contralateral upper limb tremor scores on versus off stimulation was 80.4±13.2 (p<0.001), 9.7±3.3 months after surgery. Postoperative MA was performed 9.2±3.2 months after surgery. Small worsening effects were observed in gait speed (d=-0.32), cadence (d=-0.39), and step length (d=-0.24), which were not statistically significant (Figure 4). No changes were observed in step width.
Conclusions:
Thalamic DBS improved tremor scores, but we observed a small, non-statistically significant, worsening trend of some gait parameters. Further study is required to clarify the observed effect of VIM-DBS on gait and identify pre-DBS gait features predictive of poor gait outcomes.