The video head impulse test predicts the ability to reweight vestibular information during stance in patients with vestibular disorders

INTRODUCTION: During stance, vestibular information is used and weighted based on its reliability. Vestibular deficits affect the reliability of vestibular information and therefore affect the ability to reweight vestibular information during stance. Vestibular information during stance mainly consists of frequencies up to 5 Hz. However, vestibular-ocular reflex (VOR) tests designed to detect vestibular deficits mainly operate in restricted frequency ranges such as 0.002 - 0.004 Hz for the caloric test, 0.1 - 1 Hz for the rotational chair test and 1 - 6 Hz for the head impulse test. In this study we investigated how these three VOR tests are related to the ability to reweight vestibular information under different sensory disturbance conditions in patients with vestibular disorders. METHODS: 11 Patients (5 female) with vestibular disorders (mean ± SD age: 59.3 ± 9.9 years) were included. All patients underwent VOR examination using videonystagmography during bilateral cold caloric test, the rotational chair test at horizontal harmonic oscillations of the chair at 0.4 Hz and the head impulse test. In addition, balance control experiments were conducted using continuous support surface rotations (SS) which followed a pseudo-random ternary sequence (PRTS). Patients stood with their eyes closed during two SS conditions: 1) 0.5 degrees peak-to-peak amplitude and 2) 1.0 degrees peak-to-peak amplitude. System identification and parameter estimation were used to estimate balance control model parameters, including the vestibular weight Wv which indicates how much patients relied on vestibular information in each condition. Spearman correlation coefficients were calculated to establish the relation between VOR tests (caloric test, rotational chair test and head impulse test) and the difference in the vestibular weight (Wv_diff) between 0.5 and 1.0 degrees peak-to-peak amplitude. RESULTS: Only the head impulse test was significantly related to Wv_diff (ρ = -0.67, p = 0.033), indicating that patients who showed more asymmetric ocular responses to left and right head impulses showed less sensory reweighting between SS conditions during balance control. DISCUSSION: Our results suggest that out of the three VOR tests included in this study the video head impulse test is most predictive of a reduced ability to reweight vestibular information during stance in patients with vestibular disorders. The video head impulse test mainly operates in the 1-6 Hz frequency range, which is comparable to the frequency range of joint torque and body sway oscillations and could therefore explain this high association

Technology-assisted training of arm-hand skills in stroke: concepts on reacquisition of motor control and therapist guidelines for rehabilitation technology design

<p>Abstract</p> <p>Background</p> <p>It is the purpose of this article to identify and review criteria that rehabilitation technology should meet in order to offer arm-hand training to stroke patients, based on recent principles of motor learning.</p> <p>Methods</p> <p>A literature search was conducted in PubMed, MEDLINE, CINAHL, and EMBASE (1997–2007).</p> <p>Results</p> <p>One hundred and eighty seven scientific papers/book references were identified as being relevant. Rehabilitation approaches for upper limb training after stroke show to have shifted in the last decade from being analytical towards being focussed on environmentally contextual skill training (task-oriented training). Training programmes for enhancing motor skills use patient and goal-tailored exercise schedules and individual feedback on exercise performance. Therapist criteria for upper limb rehabilitation technology are suggested which are used to evaluate the strengths and weaknesses of a number of current technological systems.</p> <p>Conclusion</p> <p>This review shows that technology for supporting upper limb training after stroke needs to align with the evolution in rehabilitation training approaches of the last decade. A major challenge for related technological developments is to provide engaging patient-tailored task oriented arm-hand training in natural environments with patient-tailored feedback to support (re) learning of motor skills.</p

Recovery of the paretic upper limb early after stroke: restitution or substitution of motor control?

promotiedatum: 12-11-2014 � prom-id: 970

Impact of Time on Quality of Motor Control of the Paretic Upper Limb After Stroke

Objective To establish the time course of recovery regarding smoothness of upper limb movements in the first 6 months poststroke. Design Cohort study with 3-dimensional kinematic measurements in weeks 1, 2, 3, 4, 5, 8, 12, and 26 poststroke. Setting Onsite 3-dimensional kinematic measurements in stroke units, rehabilitation centers, nursing homes, and patients' homes. Participants Patients (N=44; 19 women, 25 men; mean age ± SD, 58±12y) with a first-ever unilateral ischemic stroke and incomplete upper limb paresis (27 left sided, 17 right sided) were included. Interventions Not applicable. Main Outcome Measures In each measurement, an electromagnetic motion tracker acquired hand and finger trajectories during a reach-to-grasp task. Movement duration was determined, and smoothness of hand transport and grasp aperture was quantified by normalized jerk. With the use of random coefficient analysis, the effect of progress of time on smoothness of hand transport and grasp aperture was investigated. Results During the first 5 weeks poststroke, there was a significant contribution of progress of time to reductions in movement duration and normalized jerk of hand transport and grasp aperture (P<.01). Conclusions The present longitudinal 3-dimensional kinematic study showed that smoothness of paretic upper limb movements improves in the first 8 weeks poststroke. This improvement suggests that motor control normalizes in the first 8 weeks poststroke and can be mostly explained by spontaneous neurologic recovery that occurs typically in the first weeks poststroke. Future 3-dimensional kinematic studies should investigate whether therapies starting early after stroke can improve the quality of motor control beyond spontaneous neurologic recovery. © 2014 by the American Congress of Rehabilitation Medicine

Understanding Adaptive Motor Control of the Paretic Upper Limb Early Poststroke: The EXPLICIT-stroke Program

Background. During upper limb motor recovery after stroke, the greatest improvements occur typically in the first 5 weeks poststroke. It is unclear what patients learn during this early phase of recovery. Objective. To investigate the hypothesis that, early poststroke, patients learn to master the degrees of freedom in the paretic upper limb as reflected by dissociated shoulder and elbow movements during reach-to-grasp. Methods. Thirty-one patients with a first-ever ischemic stroke were included. Repeated 3-dimensional kinematic measurements were conducted at 14, 25, 38, 57, 92, and 189 days poststroke. Trunk, shoulder, elbow, and wrist rotations were measured during a reach-to-grasp task. Using principal component analysis the longitudinal changes in dissociated upper limb movements during reach-to-grasp were investigated. Twelve healthy subjects were included for comparison. Results. The main coordination pattern during reach-to-grasp in patients with stroke and healthy subjects consisted mostly of horizontal shoulder adduction and elbow extension. The standard deviation of this main pattern increased over time, with the largest increase in the first 5 weeks poststroke (F = 5.5, P <.001), but remained smaller than in healthy individuals. The standard deviation increased by 0.46 per day between 14 and 38 days and tapered off to 0.05 per day between 38 and 189 days poststroke. Conclusions. Our results suggest that restitution of motor control by dissociation of shoulder and elbow movements occurs mainly early poststroke. However, compared with healthy adults, most patients did not achieve fully dissociated upper limb movements at 26 weeks poststroke, suggesting that upper limb motor control after stroke remains adaptive. © The Author(s) 2013