Changes in proprioceptive systems activity during recovery from post-stroke hemiparesis.

OBJECTIVE: To investigate the activity of proprioceptive systems during early recovery of motor function after ischaemic stroke in a prospective, longitudinal, functional imaging study. METHODS: Ten patients with unilateral infarction of the posterior internal capsule were investigated using oxygen-15-water positron emission tomography during passive extension of the index finger. Patients were assessed initially after stroke (mean 4.7 days) and again after rehabilitation. Changes in brain activation patterns were analysed. RESULTS: All patients showed significant improvement in motor function of the paretic limb. During passive finger movement of the non-paretic index finger, significant increases in cerebral blood flow were observed in the somatosensory areas I and II (SI and SII) of the non-infarcted hemisphere. Additionally, significant activation of ipsilateral SII in the infarcted hemisphere was observed. After rehabilitation, ipsilateral SII activation vanished and the normal activation pattern was restored. During passive movement of the paretic index finger only SI and SII of the infarcted hemisphere were activated. During rehabilitation, additional recruitment of SII in the non-infarcted hemisphere occurred. CONCLUSION: Recovery from internal capsule infarction is accompanied by substantial changes in activity of proprioceptive systems of the paretic and non-paretic limb. These changes may reflect an inter-hemispheric shift of attention to proprioceptive stimuli associated with recovery.