I don't see how anything here helps
survivors recover but since I'm stroke addled I shouldn't speak truth to
stroke medical 'professionals'. Useless.
Parthasarathy Thirumala, Daniel B. Hier and Pratik Patel Departments of Bioengineeringand Neurology and Rehabilitation, The University of Illinois at Chicago, Chicago, IL, USA
Several theories have been proposed to explain recovery from stroke. Functional brain imaging offers an opportunity to evaluate these theories and visualize recovery after stroke. Functional brain imaging has proven to be an effective tool to map brain areas activated during a specifc task. This paradigm can extend our understanding of the mechanisms of motor recovery after stroke. Functional brain imaging tools such as functional MRI, PET, transcranial Doppler ultrasonography, and transcranial magnetic stimulation can be used to evaluate motor activation after stroke. Functional imaging is proving useful in identifying areas, pathways and mechanisms involved in motor recovery after stroke. Studies have shown changes in motor organization with rehabilitation. Functional brain imaging may assist in the selection of rehabilitation methods that best foster recovery. [Neurol Res 2002; 24: 453–458] Keywords: Motor recovery; theories of recovery; stroke rehabilitation; functional brain imaging INTRODUCTION Stroke is the third leading cause of death and the leading cause of disability in the United States. There are multiple etiologies of stroke (atherosclerosis, cerebral embolism, in situ thrombosis, small artery occlusion, and hemorrhage). Strokes differ in vascular territory affected, size, severity, and laterality. Some strokes are cortical, some subcortical, and some both. Strokes may affect primary cortex (e.g. motor or sensory), association cortex (visual, auditory, etc.) or cortex involved in higher cortical functioning. Strokes differ in outcome. Some show a rapid improvement; others show scant improvement. In one study
1 of unselected strokes, 19% were rated very severe, 14% severe, 26% moderate, and 41% mild. In patients surviving the stroke, neurologic impairment after rehabilitation was rated severe or very severe in 11%, moderate in 11%, and mild in 47%. About 31% achieved normal neurologic functioning. In another study
2 , only 45% of stroke survivors were functionally independent at six months. Motor deficits remain a major cause of long-term disability after stroke. Although motor recovery occurs after stroke, it is often incomplete. The most important predictor of recovery is initial severity. After rehabilitation, the group with moderate and severe disability is reduced from 50% to 25% and the group with mild or no disability is increased from 50% to 75%. One third of the survivors in the mild group are discharged back to their homes with little disability
1
. The mechanism by which motor recovery occurs is uncertain. Functional MRI and other functional brain imaging techniques are revealing how motor recovery occurs after stroke. HOW DOES MOTOR RECOVERY OCCUR? A variety of theories have been advanced to explain motor recovery after stroke
3 . These theories are not mutually exclusive and motor recovery may occur by several mechanisms. Some initial motor recovery occurs because of the resolution of initial metabolic disturbances related to ischemia and anoxia. Restitution of cerebral blood flow with resolution of acute anoxia, edema, ischemia, and acidosis correlates with improved neuronal functioning and return of some lost motor function in brain areas that have not undergone frank infarction. Similarly, some early recovery may be due to the resolution of diaschisis. With diaschisis, there may be functional changes in neuronal activity at sites distant from areas of brain injury. Brain areas may become temporarily and reversibly dysfunctional if connected to ischemic areas. The resolution of diaschisis may explain some motor recovery. Nonetheless, functional reorganization must be important to much of the recovery that after stroke. This reorganization can occur around the lesion itself, elsewhere in the same hemisphere, or in the hemisphere contralateral to the stroke
4,5 . The mechanisms of functional reorganization include perilesional remapping (reorganization of motor functions around the site of the stroke), use of collateral pathways in the same hemisphere, or use of collateral pathways in the opposite hemisphere. Functional MRI and other functional brain imaging techniques can show how these mechanisms, either individually, in sequence, or in concert promotes motor recovery after stroke.
No comments:
Post a Comment