Researchers have been interested in the changes associated with motor function in humans
after suffering a stroke. Presently, the mechanism by which a person recovers motor
function following a stroke is poorly understood. There is little information available
about the areas of the brain involved in the recovery of limb function.
Recently, a new set of techniques have been developed that may be useful for reducing the
physical impairment often associated with strokes.
The best way to identify the areas of the brain associated with regaining function is to
test patients before, during, and after function is regained.
This study will compare two therapies and determine which is better at improving recovery of
motor function. The first technique involves immobilizing the functional limb and actively
training the affected dysfunctional limb. The second technique involves no immobilization,
and passive movement of the affected limb.
Results from this study will indicate which of the two therapies is better at improving
motor function. Additional diagnostic tests will help to identify changes in brain function
associated with recovered use of affected limbs.
We have been interested in the study of plastic changes associated with recovery of motor
function in humans after a variety of lesions in the central (spinal cord injury) and
peripheral nervous system (amputation, reversible deafferentation) and motor learning. At
present, mechanisms underlying recovery of motor function after stroke are poorly
understood. Little and inconsistent information is available about the specific brain
regions newly recruited in patients with chronic ischemic subcortical stroke after
reacquisition of use of the affected limb.
Recently, a new set of techniques proposed to be useful for reducing the chronic
incapacitating motor impairment often associated with stroke has been developed. In
essence, it consists of prolonged restraint of the unaffected upper extremity and practice
in using the affected arm. These techniques increased significantly the use of the affected
arm in daily activities in the two trials reported. The beneficial effect, once produced,
appeared to last for years after the intervention.
The best way to identify the brain regions associated with reacquisition of motor function
after stroke is to test patients before, during and after reacquisition is accomplished. In
this case, we propose that patients be tested before, during and after one of two specific
interventions: one involving immobilization of healthy arm plus active training of affected
arm (test procedure) and the other involving no immobilization, and passive manipulations of
the affected arm. Results from this study will indicate which of the two therapies is
better at improving recovery of motor function. Comparison of neurophysiological and
imaging studies performed before, during and after the interventions will allow
identification of plastic changes in brain function associated specifically with the
recovery of use of the affected hand in patients with chronic ischemic subcortical stroke.
Methodologically, a multimodality approach will be used. Magnetic stimulation will allow
detailed analysis of maps of representation areas in the primary motor cortex and motor
thresholds and evaluation of central motor conduction. EEG and movement-related cortical
potentials will provide information about coherence and timing of activation of different
brain regions. PET scan will identify regions activated in association with performance of
motor tasks. Registration of this information onto MRI will allow precise identification of
brain regions associated with reacquisition of motor skills on the affected side after
We hypothesize that use of the affected arm associated with decreased use of the unaffected
arm are useful triggers of plasticity and reacquisition of motor function after stroke. We
expect to identify cortical and subcortical regions newly activated in each patient after
reacquisition of use of the affected arm, understand the coherence and timing of activation
of new brain regions recruited and quantify plastic changes in motor representation areas
targeting arm muscles in the affected and unaffected arm.
Patients with stroke more than 1 year before testing.
Patients with right cortico-subcortical strokes will be included.