title: Brain-controlled functional electrical stimulation therapy for gait rehabilitation after stroke: a safety study.
abstract: BACKGROUND
  Many stroke survivors have significant long-term gait impairment, often involving foot drop. Current physiotherapies provide limited recovery. Orthoses substitute for ankle strength, but they provide no lasting therapeutic effect. Brain-computer interface (BCI)-controlled functional electrical stimulation (FES) is a novel rehabilitative approach that may generate permanent neurological improvements. This study explores the safety and feasibility of a foot-drop-targeted BCI-FES physiotherapy in chronic stroke survivors.
  
  
  METHODS
  Subjects (n = 9) operated an electroencephalogram-based BCI-FES system for foot dorsiflexion in 12 one-hour sessions over four weeks. Gait speed, dorsiflexion active range of motion (AROM), six-minute walk distance (6MWD), and Fugl-Meyer leg motor (FM-LM) scores were assessed before, during, and after therapy. The primary safety outcome measure was the proportion of subjects that deteriorated in gait speed by ≥0.16 m/s at one week or four weeks post-therapy. The secondary outcome measures were the proportion of subjects that experienced a clinically relevant decrease in dorsiflexion AROM (≥2.5°), 6MWD (≥20 %), and FM-LM score (≥10 %) at either post-therapy assessment.
  
  
  RESULTS
  No subjects (0/9) experienced a clinically significant deterioration in gait speed, dorsiflexion AROM, 6MWT distance, or FM-LM score at either post-therapy assessment. Five subjects demonstrated a detectable increase (≥0.06 m/s) in gait speed, three subjects demonstrated a detectable increase (≥2.5°) in dorsiflexion AROM, five subjects demonstrated a detectable increase (≥10 %) in 6MWD, and three subjects demonstrated a detectable increase (≥10 %) in FM-LM. Five of the six subjects that exhibited a detectable increase in either post-therapy gait speed or 6MWD also exhibited significant (p < 0.01 using a Mann-Whitney U test) increases in electroencephalogram event-related synchronization/desynchronization. Additionally, two subjects experienced a clinically important increase (≥0.16 m/s) in gait speed, and four subjects experienced a clinically important increase (≥20 %) in 6MWD. Linear mixed models of gait speed, dorsiflexion AROM, 6MWD, and FM-LM scores suggest that BCI-FES therapy is associated with an increase in lower motor performance at a statistically, yet not clinically, significant level.
  
  
  CONCLUSIONS
  BCI-FES therapy is safe. If it is shown to improve post-stroke gait function in future studies, it could provide a new gait rehabilitation option for severely impaired patients. Formal clinical trials are warranted.
authors.affiliation: Department of Biomedical Engineering, University of California, Irvine, CA, 92697, USA. cmccrimm@uci.edu.
authors.forename: Colin M
authors.initials: CM
authors.lastname: McCrimmon
authors.affiliation: Department of Biomedical Engineering, University of California, Irvine, CA, 92697, USA.
authors.forename: Christine E
authors.initials: CE
authors.lastname: King
authors.affiliation: Department of Biomedical Engineering, University of California, Irvine, CA, 92697, USA.
authors.forename: Po T
authors.initials: PT
authors.lastname: Wang
authors.affiliation: Department of Neurology, University of California, Irvine, Orange, CA, 92868, USA.|Department of Anatomy & Neurology, University of California, Irvine, CA, 92697, USA.|Department of Physical Medicine & Rehabilitation, University of California, Irvine, Orange, CA, 92868, USA.
authors.forename: Steven C
authors.initials: SC
authors.lastname: Cramer
authors.affiliation: Department of Biomedical Engineering, University of California, Irvine, CA, 92697, USA. znenadic@uci.edu.|Department of Electrical Engineering and Computer Science, University of California, Irvine, CA, 92697, USA. znenadic@uci.edu.
authors.forename: Zoran
authors.initials: Z
authors.lastname: Nenadic
authors.affiliation: Department of Neurology, University of California, Irvine, Orange, CA, 92868, USA.
authors.forename: An H
authors.initials: AH
authors.lastname: Do
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D062207:Brain-Computer Interfaces; D002908:Chronic Disease; D004599:Electric Stimulation Therapy / Q000295:instrumentation / Q000379:methods*; D004569:Electroencephalography; D005240:Feasibility Studies; D005260:Female; D005528:Foot / Q000503:physiopathology; D020233:Gait Disorders, Neurologic / Q000209:etiology* / Q000534:rehabilitation*; D006801:Humans; D008297:Male; D008875:Middle Aged; D061214:Patient Safety; D026741:Physical Therapy Modalities / Q000009:adverse effects* / Q000295:instrumentation*; D016059:Range of Motion, Articular; D015203:Reproducibility of Results; D020521:Stroke / Q000150:complications*; D000071939:Stroke Rehabilitation; D016896:Treatment Outcome; D016138:Walking