Valerie M. Pomeroy

Motor Imagery A Backdoor to the Motor System After Stroke

Background and Purpose— Understanding brain plasticity after stroke is important in developing rehabilitation strategies. Active movement therapies show considerable promise but depend on motor performance, excluding many otherwise eligible patients. Motor imagery is widely used in sport to improve performance, which raises the possibility of applying it both as a rehabilitation method and to access the motor network independently of recovery. Specifically, whether the primary motor cortex (M1), considered a prime target of poststroke rehabilitation, is involved in motor imagery is unresolved. Summary of Review— We review methodological considerations when applying motor imagery to healthy subjects and in patients with stroke, which may disrupt the motor imagery network. We then review firstly the motor imagery training literature focusing on upper-limb recovery, and secondly the functional imaging literature in healthy subjects and in patients with stroke. Conclusions— The review highlights the difficulty in addressing cognitive screening and compliance in motor imagery studies, particularly with regards to patients with stroke. Despite this, the literature suggests the encouraging effect of motor imagery training on motor recovery after stroke. Based on the available literature in healthy volunteers, robust activation of the nonprimary motor structures, but only weak and inconsistent activation of M1, occurs during motor imagery. In patients with stroke, the cortical activation patterns are essentially unexplored as is the underlying mechanism of motor imagery training. Provided appropriate methodology is implemented, motor imagery may provide a valuable tool to access the motor network and improve outcome after stroke.

Taking healthcare interventions from trial to practice

The results of thousands of trials are never acted on because their published reports do not describe the interventions in enough detail. How can we improve the reporting?

The effects of increased dose of exercise-based therapies to enhance motor recovery after stroke: a systematic review and meta-analysis

BackgroundExercise-based therapy is known to enhance motor recovery after stroke but the most appropriate amount, i.e. the dose, of therapy is unknown. To determine the strength of current evidence for provision of a higher dose of the same types of exercise-based therapy to enhance motor recovery after stroke.MethodsAn electronic search of: MEDLINE, EMBASE, CINHAL, AMED, and CENTRAL was undertaken. Two independent reviewers selected studies using predetermined inclusion criteria: randomised or quasi randomised controlled trials with or without blinding of assessors; adults, 18+ years, with a clinical diagnosis of stroke; experimental and control group interventions identical except for dose; exercise-based interventions investigated; and outcome measures of motor impairment, movement control or functional activity. Two reviewers independently extracted outcome and follow-up data. Effect sizes and 95% confidence intervals were interpreted with reference to risk of bias in included studies.Results9 papers reporting 7 studies were included. Only 3 of the 7 included studies had all design elements assessed as low risk of bias. Intensity of the control intervention ranged from a mean of 9 to 28 hours over a maximum of 20 weeks. Experimental groups received between 14 and 92 hours of therapy over a maximum of 20 weeks. The included studies were heterogeneous with respect to types of therapy, outcome measures and time-points for outcome and follow-up. Consequently, most effect sizes relate to one study only. Single study effect sizes suggest a trend for better recovery with increased dose at the end of therapy but this trend was less evident at follow-up Meta-analysis was possible at outcome for: hand-grip strength, -10.1 [-19.1,-1.2] (2 studies, 97 participants); Action Research Arm Test (ARAT), 0.1 [-5.7,6.0] (3 studies, 126 participants); and comfortable walking speed, 0.3 [0.1,0.5] (2 studies, 58 participants). At follow-up, between 12 and 26 weeks after start of therapy, meta-analysis findings were: Motricity Arm, 10.7 [1.7,19.8] (2 studies, 83 participants); ARAT, 2.2 [-6.0,10.4] (2 studies, 83 participants); Rivermead Mobility, 1.0 [-0.6, 2.5] (2 studies, 83 participants); and comfortable walking speed, 0.2 [0.0,0.4] (2 studies, 60 participants).ConclusionsCurrent evidence provides some, but limited, support for the hypothesis that a higher dose of the same type of exercised-based therapy enhances motor recovery after stroke. Prospective dose-finding studies are required.

Neuroimaging in Stroke Recovery: A Position Paper from the First International Workshop on Neuroimaging and Stroke Recovery

Baron, Jean-Claude*Black, Sandra E.Butler, Andrew J.Carey, JamesChollet, FrancoisCohen, Leonardo G.*Corbetta, MaurizioCramer, Steven C.*Dobkin, Bruce H.*Frackowiak, RichardHeiss, W.D.Johansen-Berg, Heidi*Krakauer, John W.Lazar, Ronald M.Lennihan, Laura L.Loubinoux, Isabelle*Marshall, Randolph S.*Matthews, PaulMohr, J.P.Nelles, GereonPascual-Leone, AlvaroPomeroy, ValerieRijntjes, MichelRossini, Paolo MariaRothwell, John C.Seitz, Rudiger J.Small, Steven L.Sunderland, AlanWard, N.S.*Weiller, CorneliusWise, Richard J.S.IntroductionThe First International Workshop on Neuroimagingand Stroke Recovery was convened in February, 2004 inNew York City. The purpose of the workshop was to de-scribe the state of the field with regard to technical andanalytical methods, to discuss the use of complementaryimaging modalities, and to assess the current potential toapply functional neuroimaging to the development of ratio-nal treatment strategies for enhanced stroke recovery.Presented herein is a summary statement of topics dis-cussed at the workshop. These included (i) the clinical rel-evance of functional imaging changes after stroke for themotor and language systems; (ii) the technical challengesfaced in moving towards establishing functional neuro-imaging as a clinically useful tool; (iii) the contributions ofneurophysiological probes such as transcranial magnet-ic stimulation (TMS) to improve understanding of themechanisms underlying brain reorganization after stroke;and (iv) the potential role of neuroimaging in the assess-ment and development of rational pharmacological andbehavioral therapies.Clinical RelevanceFunctional recovery commonly occurs in survivingstroke patients in the weeks and months following theinjury. There is evidence from animal models that cere-bral reorganization underlies at least some of this recov-ery and it is hoped that an understanding of the neuro-physiological processes underlying this reorganization inthe human brain will lead to a rational approach to thetreatment of impairment. In animal models, focal braindamage triggers a number of changes at the molecular, cel-lular, and systems level, some of which alter the potentialfor cerebral reorganization and consequent functionalrecovery. Although the same techniques are not availableto study the working human brain, functional brain imag-ing has provided insights into how the human brainresponds to focal injury.

Motor Imagery After Subcortical Stroke A Functional Magnetic Resonance Imaging Study

Background and Purpose— In recovered subcortical stroke, the pattern of motor network activation during motor execution can appear normal or not, depending on the task. Whether this applies to other aspects of motor function is unknown. We used functional MRI to assess motor imagery (MI), a promising new approach to improve motor function after stroke, and contrasted it to motor execution. Methods— Twenty well-recovered patients with hemiparetic subcortical stroke (14 males; mean age, 66.5 years) and 17 aged-matched control subjects were studied. Extensive behavioral screening excluded 8 patients and 4 control subjects due to impaired MI abilities. Subjects performed MI and motor execution of a paced finger–thumb opposition sequence using a functional MRI paradigm that monitored compliance. Activation within the primary motor cortex (BA4a and 4p), dorsal premotor, and supplementary motor areas was examined. Results— The pattern of activation during affected-hand motor execution was not different from control subjects. Affected-hand MI activation was also largely similar to control subjects, including involvement of BA4, but with important differences: (1) unlike control subjects and the nonaffected hand, activation in BA4a and dorsal premotor was not lower during MI as compared with motor execution; (2) the hemispheric balance of BA4p activation was significantly less lateralized than control subjects; and (3) ipsilesional BA4p activation positively correlated with motor performance. Conclusions— In well-recovered subcortical stroke, the motor system, including ipsilesional BA4, is activated during MI despite the lesion. It, however, remains disorganized in proportion to residual motor impairment. Thus, components of movement upstream from execution appear differentially affected after stroke and could be targeted by rehabilitation in more severely affected patients.

The Potential for Utilizing the “Mirror Neurone System” to Enhance Recovery of the Severely Affected Upper Limb Early after Stroke: A Review and Hypothesis

Recovery of upper limb movement control after stroke might be enhanced by repetitive goal-directed functional activities. Providing such activity is challenging in the presence of severe paresis. A possible new approach is based on the discovery of mirror neurons in the monkey cortical area F5, which are active both in observing and executing a movement. Indirect evidence for a comparable human “mirror neurone system” is provided by functional imaging. The primary motor cortex, the premotor cortex, other brain areas, and muscles appropriate for the action being observed are probably activated in healthy volunteers observing another’s movement. These findings raise the hypothesis that observation of another’s movement might train the movement execution system of stroke patients who have severe paresis to bring them to the point at which they could actively participate in rehabilitation consisting of goal-directed activities. The point of providing an observation therapy would be to facilitate the voluntary production of movement; therefore, the condition of interest would be observation with intent to imitate. However, there is as yet insufficient evidence to enable the testing of this hypothesis in stroke patients. Studies in normal subjects are needed to determine which brain sites are activated in response to observation with intent to imitate. Studies in stroke subjects are needed to determine how activation is affected after damage to different brain areas. The information from such studies should aid identification of those stroke patients who might be most likely to benefit from observation to imitate and therefore guide phase I clinical studies.

Motor imagery to enhance recovery after subcortical stroke: who might benefit, daily dose, and potential effects.

Background. Motor imagery may enhance motor recovery after stroke. Objectives. To estimate the proportion of patients able to perform motor imagery, the feasibility of delivery of motor imagery training (MIT), and the effects of MIT on motor recovery in an exploratory study. Methods. An immediate pretreatment and posttreatment single-group design was used to study 10 patients after subcortical stroke with neuromuscular weakness in the upper limb. MIT that included upper limb activities reflecting everyday tasks was provided for 10 consecutive working days. Measures included assessment of chaotic motor imagery, patient report of tolerability of MIT, Motricity Index (MI), Nine Hole Peg Test (9HPT), and quality of movement (MAL-QOM). MIT dose was changed in response to patient feedback. Graphed motor function scores were inspected visually for clinically important changes. Results. Four of the 10 patients were unable to perform motor imagery. Patient opinion was positive about the content and shaped daily dose of MIT given in two 20-minute periods separated by a 10-minute rest. Clinically important changes in motor scores were found. Four patients increased MI score (range 8-16), 3 patients increased 9HPT score (range 0.02-0.04 pegs/second), and 4 patients increased MAL-QOM score (range 0.63-1.29). Conclusions. MIT was received positively by patients, but 40% were unable to perform imagery and interindividual variations were found on motor function.

Mobility and dementia: is physiotherapy treatment during respite care effective?

Mobility problems experienced by elderly people with a dementia are associated with falls, fractures and admission to long‐term care. A hospital respite care admission is therefore often seen as an opportunity to provide physiotherapy treatment.

Transcranial Magnetic Stimulation and Muscle Contraction to Enhance Stroke Recovery: A Randomized Proof-of-Principle and Feasibility Investigation

Objective. To explore the efficacy of repetitive transcranial magnetic stimulation (rTMS) and voluntary muscle contraction (VMC) to improve corticospinal transmission, muscle function, and purposeful movement early after stroke. Methods. Factorial 2 × 2 randomized single-blind trial. Subjects: n = 27, mean age 75 years, mean 27 days after middle cerebral artery infarct (24 subjects completed outcome measures). Procedure: after baseline measurement (day 1), subjects were randomized to 1 of 4 groups. Treatment was given for the next 8 working days, and outcome was measured on day 10. Interventions: (a) Real-rTMS + RealVMC, (b) Real-rTMS + PlaceboVMC, (c) Placebo-rTMS + RealVMC, and (d) Placebo-rTMS + PlaceboVMC. Real-rTMS consisted of 200 1-Hz stimuli at 120% motor threshold in 5 blocks of 40 separated by 3 minutes delivered to the lesioned hemisphere. Placebo-rTMS used a dummy coil. In RealVMC, the paretic elbow was repeatedly flexed/extended for 5 minutes. In PlaceboVMC, subjects viewed pairs of drawings of upper limbs and reported their likeness. Outcomes: frequency of motor-evoked potentials in biceps and triceps, muscle function (torque about elbow), and purposeful movement (Action Research Arm Test). Analysis: group mean changes (outcome — baseline) were compared. Results. In the Real-rTMS + RealVMC group, motor-evoked potential frequency increased 14% for biceps and 20% for triceps, whereas in the Placebo-rTMS + PlaceboVMC group, it decreased 12% for biceps and 6% for triceps. For other groups, there were changes of intermediate values. No meaningful differences were found for secondary outcomes. Conclusions . A positive trend for motor-evoked potential frequency was found for Real-rTMS + RealVMC, whereas a negative trend for motor-evoked potential frequency was found for Placebo-rTMS + PlaceboVMC.

Neurological Principles and Rehabilitation of Action Disorders: Rehabilitation Interventions

This third chapter discusses the evidence for the rehabilitation of the most common movement disorders of the upper extremity. The authors also present a framework, building on the computation, anatomy, and physiology (CAP) model, for incorporating some of the principles discussed in the 2 previous chapters by Frey et al and Sathian et al in the practice of rehabilitation and for discussing potentially helpful interventions based on emergent neuroscience principles.