New Developments in Stroke Rehabilitation Eugenio R
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New Developments in Stroke Rehabilitation Eugenio R. Rocksmith, MD, and Michael J. Reding, MD Address ment of common stroke complications, such as depression, Burke Rehabilitation Hospital, 785 Mamaroneck Avenue, dysphagia, venous thromboembolic complications, incon- White Plains, NY 10605-2523, USA. tinence, and spasticity. This article examines these develop- E-mail: [email protected] ments and their effects on rehabilitation following stroke. Current Atherosclerosis Reports 2002, 4:277–284 Current Science Inc. ISSN 1523–3804 Copyright © 2002 by Current Science Inc. Advances in Stroke Epidemiology The American Heart Association has recently increased its There is increasing evidence that environmental and neuro- estimate of the number of new strokes in the United pharmacologic treatments enhance stroke recovery. Func- States population from 500,000 to 600,000 per year (105 tional magnetic resonance imaging and transcranial magnetic to 139 cases per 100,000 population). Their estimate of stimulation have significantly broadened our understanding of the number of stroke survivors in the United States has the neuroanatomic relationships involved in recovery from also been increased from 3 million to 4 million. [1] These brain injury due to stroke. These tools have also demon- changes are due to the fact that previous estimates were strated the role for pharmacologic enhancement of cortical based on populations from white, middle class Rochester, plasticity coupled with behavioral interventions. Robot- Minnesota and Framingham, Massachusetts. The poor are assisted therapy and partial body weight-supported treadmill less likely to seek medical attention, and blacks are 2.4 gait training have demonstrated the role for technologic times more likely to have a stroke than whites [2]. Stroke intervention in the modern neuro-rehabilitation setting. Cur- remains the most common debilitating neurologic disor- rent research using hemi-field ocular prisms and patching der of adults in the United States. It is the third leading techniques suggest a role in the rehabilitation of hemianopsia cause of mortality and is one of the leading causes of and visual neglect. Finally, many advances have been made in long-term, severe disability. The cost of acute care plus the understanding of common stroke complications, such as rehabilitation services is estimated to total $30 billion per depression, dysphagia, venous thromboembolic disease, year. Of all patients surviving 3 months after their stroke, incontinence, and spasticity. approximately half will be alive in 5 years, and a third will survive 10 years. Approximately 60% recover inde- pendence with self-care, and 75% recover the ability to Introduction walk independently. Approximately 19% will require There is increasing evidence that environmental and neu- chronic institutional care. [3] ropharmacologic treatments enhance stroke recovery. Func- tional magnetic resonance imaging (fMRI) has allowed us to study the role of ipsilateral and contralateral primary, Advances in Neuroimaging secondary, and tertiary motor control systems in the motor Within the past decade, the neuroscience community has recovery process. Magnetic coil stimulation has been used made tremendous strides in understanding the complex- to study primary and secondary motor cortex responsive- ities of the human brain. Positron emission tomography ness to stimulation before versus after passive manipula- (PET) imaging became available in the late 1980s. It tion of the paretic limb, or to drug versus placebo requires administration of a radioactive tracer, which is intervention. Behavioral interventions, such as forced use of used to measure regional cerebral glucose metabolism the paretic limb by constraining the normal hand and par- both at rest and while performing cognitive or behav- tial body weight-supported treadmill gait training of the ioral tasks. Comparisons of rest with activation images hemiplegic patient, have a solid experimental base and are provide information about the role of specific neuroana- becoming standard rehabilitation techniques for selected tomic structures in performance of the cognitive or patients. Use of hemi-field ocular prisms or patching tech- behavioral tasks. Its application in behavioral research is niques is being studied for their effects on treating visual limited by the short half-life of the radioactive tracers hemi-neglect following stroke. Important advances have used and by the total dosage of radiation that can be also been made in the prevention, recognition, and treat- safely administered. 278 Cardiovascular Disease and Stroke Functional MRI is a significant advance in neurobehav- retrieve food pellets with gross four-finger grasp, then with ioral research that became available in the mid 1990s. It does successively more precise finger movements. not require radiation exposure. fMRI is based upon the con- Several studies have shown efficacy of CI rehabilitation cept that increased neuronal activity is coupled to increased techniques of the upper extremity (UE) in selected patients local blood flow. For example, flexion and extension of the following stroke. Patients must have some residual volun- right elbow is associated with increased blood flow in the tary wrist and hand movement (20 degrees of wrist exten- region of the left primary motor cortex devoted to elbow sion and 10 degrees of finger extension). CI therapy control. With the use of fMRI, it has been shown that bilat- improvements have led to functional and lasting gains as eral motor cortices and their association areas are recruited in measured by improved performance of self-care activities learning a novel motor task. In addition, the greater the [8•,9–11]. amount of force generated, the larger the area of bilateral Brain imaging and TMS studies in stroke victims have activation. [4] As performance of the motor task is perfected shown that CI therapy causes use-dependent cortical reor- through repetition, the recruitment area becomes smaller ganization. This is evidenced by an increase in the area of and includes only contralateral primary motor cortex. cortex involved in the control of movement of the affected Functional MRI has also revealed that the same pattern UE [12]. In a study by Levy et al. [13], two subjects who of recruitment occurs initially in some patients who have had already undergone traditional therapy had a baseline sustained a stroke. As with learning a novel task, a patient fMRI performed that revealed minimal ipsilateral posterior with a subcortical stroke relearning how to grasp an object parietal activation. After 2 weeks of CI therapy for 6 hours with the paretic hand initially activates bilateral motor cor- per day, follow-up fMRI in one subject demonstrated acti- tices, posterior parietal regions, and prefrontal regions. As vation bordering the lesion, bilateral activation in associa- the ability to perform the task is refined, ipsilateral motor tion motor cortices, and ipsilateral activation in the cortex activity decreases and contralateral activity increases primary motor cortex. In the second subject, activation was [5••]. There is evidence that this neural plasticity can be demonstrated adjacent to the lesion site. Additionally, enhanced through various techniques used in the neurore- these increases in areas of activation correlated with habilitation setting. increased strength and performance time [13]. TMS has also been used to map the region of the primary motor cor- tex involved in controlling the affected arm movements in Modulation of Neural Plasticity hemiparetic patients. As the magnetic coil is applied to Constraint-induced (CI) therapy for motor recovery is specific regions of the motor strip, muscle activity is based on research in monkeys and demonstrates that deaf- detected in the affected hand via electromyelogram (EMG). ferentation of a limb results in either no movement or very After a trial of CI therapy, an enlargement of the cortical clumsy nonproductive movements. Through negative rein- region producing hand movements is noted, implying that forcement, the monkeys learn not to use the affected limb. cortical reorganization has occurred [14]. They develop compensatory strategies using their intact limb to achieve their goals. Forcing the animals to use their deafferented limb by restraining the intact upper extremity Robot-assisted Neurorehabilitation improves motor performance in the affected limb. CI ther- At the dawn of the 21st century, we have achieved a num- apy was first studied in stroke survivors in 1981 [6]. Within ber of technologic advances that have been applied to the past several years, fMRI and transcranial magnetic stim- stroke rehabilitation. Our multimedia environment pro- ulation (TMS) have enabled research neuroscientists to vides us with new techniques to increase patient motiva- visualize the changes that take place in the brain as a result tion and participation in their therapy programs. of CI therapy. The data support two effects of CI therapy: Technology may also be used to reduce the cost of in- cortical reorganization via use-dependent plasticity, and patient rehabilitation by more efficient use of therapist reversal of learned nonuse of the paretic limb. time and skills. Robot-aided sensorimotor training, a varia- Intracortical microstimulation studies of monkeys with tion of CI rehabilitation, can deliver a quantifiable amount a surgically induced ischemic infarct in a portion of the of patient therapy and can simultaneously