Brain function early after stroke in relation to subsequent recovery.

Abstract

This study aimed to characterize brain activation and perfusion early after stroke within cortical regions that would later change activation during recovery. Patients were studied serially after stroke (mean t1, = 16 days after stroke, t2 = 3.5 months later) using perfusion-weighted imaging and functional magnetic resonance imaging during finger movement. Controls (n = 7) showed no significant change in regional activation volumes over time. Among stroke patients (n = 8), however, recovery was accompanied by several patterns of functional magnetic resonance imaging change, with increased activation volumes over time in five patients and decreased in two. Most regions increasing activation over time were in the stroke hemisphere. Of the five patients showing increased activation over time, specific activation foci enlarged at t2 were already activated at t1 in four patients, and at least one focus growing from t1 to t2 was in a different arterial distribution from the infarct in all five patients. Perfusion of sensorimotor cortex at t1 was generally not reduced in the stroke hemisphere (94% of noninfarcted hemisphere). Improved clinical outcome was related to increased activation within sensory cortices of both brain sides, including bilateral secondary somatosensory areas. Early after stroke, cortical activation that will later increase in parallel with recovery is often already identifiable, can be remote from the vascular territory of the infarct, and is not likely hindered by reduced perfusion. The findings may be useful for restorative interventions introduced during the weeks after a stroke.