Physiotherapy for central vestibular dysfunction in poststroke patients in the sub-acute phase

Abstract

Background Vestibular dysfunction arising from the central components of the vestibular system are associated with impaired balance. Due to decreased spontaneous recovery of the central vestibular system post-stroke, patients may develop maladaptive sensory strategies in the early months post-stroke in response to the absence of specific management to address vestibular dysfunction following a stroke. Methods A phase 1 cross-sectional survey was conducted to determine the prevalence of clinical features and activity limitations associated with central vestibular dysfunction in patients who are in the sub-acute phase post-stroke (N=102). A phase 2 singleblind cluster randomised controlled trial (RCT) was conducted to determine the effect of vestibular rehabilitation therapy (VRT) integrated with task-specific activities received by patients in the experimental group, compared to patients who received task-specific activities alone in the control group. After central vestibular dysfunction was diagnosed based on the outcome of the assessment of smooth pursuit or saccadic eye movement using videonystagmography (VNG) or the assessment of vestibulo-ocular reflex (VOR)-gain using video head impulse test (vHIT) during the cross-sectional survey, 60 patients were randomly allocated to either an experimental group (N=30) or control group (N=30). Patients in the experimental group received a combination of VRT integrated with task-specific activities as part of the treatment as an “add-on” intervention compared to patients in the control group who received taskspecific activities alone during the two-week intervention period. Results A high prevalence of clinical features associated with central vestibular dysfunction, including impairment of smooth pursuit eye movement (97.1%-99.0%), utricle and superior vestibular nerve function (97.1%) and higher vestibular function (97.1%), were observed. A high prevalence of activity limitations associated with central vestibular dysfunction, including impaired functional ability (98.0%), ability to modify gait in response to changing task demands (97.1%) and functional balance (87.3%), were also observed in the current study. Findings of the single-blind cluster RCT demonstrated that between-group comparison based on logistic regression adjusted for age, gender and race, patients in the experimental group that received VRT integrated with task-specific activities improved significantly more in oculomotor function, specifically saccadic movement (velocity and accuracy), level of depression and functional ability, compared to patients in the control group who received task-specific activities alone. Conclusion The high prevalence of clinical features and activity limitations associated with central vestibular dysfunction on body structure and function, as well as activity level in patients post-stroke, may suggest that the measurement of these clinical features and activity limitations associated with central vestibular dysfunction might be a robust biomarker that may be applied in the guidance and interpretation of treatment outcomes post-stroke. Findings of the study adds to an increasing body of evidence that the CNS has the capability to compensate for central vestibular dysfunction and re-weight sensory inputs post-stroke. Input from the visual system may compensate for the loss of vestibular information and is thus a substitute as a reference for earth vertical in controlling posture and trunk stability. Implication Vestibular rehabilitation therapy integrated with task-specific activities are a low cost, safe and effective complement to standard treatment of stroke patients.