Abstract
Near-infrared spectroscopy (NIRS), which allows non-invasive monitoring of cerebral activation, might be a useful tool to assess brain activity in stroke patients because it allows recording without imposing restraints on the subject’s posture. Previous NIRS studies on stroke patients have focused on brain activation in patients with mild impairment or full recovery, and there has been a lack of data on patients without recovery. In the present study, we compared the hand movement-related brain activation pattern and laterality balance of healthy subjects and of stroke patients with mild or moderate hemiparesis in the chronic phase. In normal subjects, predominantly contralateral activation was observed during unilateral hand grasping. Similar contralateral-predominant activation was observed during grasping with the unaffected hand in stroke patients, and during affected-hand grasping in patients with mild hemiparesis. However, abnormal activation patterns, i.e., bilaterally increased activation and ipsilateral-predominant activation, were observed during affected-hand grasping in patients with moderate hemiparesis. These findings suggest that differences in brain activation patterns in stroke patients are well detected by NIRS.
Highlights
Hemiparesis and hemiplegia are the most common disorders after stroke
Previous studies using functional magnetic resonance imaging, positron emission tomography, and electroencephalography demonstrated that abnormal activation patterns in motor-related areas, such as the primary sensorimotor cortex (SM1), premotor cortex (PM), supplementary motor areas (SMA), and the cerebellum, could be seen during unilateral finger or hand movement in stroke patients [2,3,4,5,6,7,8,9]
The cerebral activity of stroke patients who cannot tolerate the restraint needed for functional magnetic resonance imaging (fMRI) or PET scans can be measured by Near-infrared spectroscopy (NIRS) without difficulty
Summary
Hemiparesis and hemiplegia are the most common disorders after stroke. Motor functional recovery from the neurological deficit can occur, but the extent of recovery varies widely [1]. In two earlier studies using laterality index, including ours [24,25], the lateralization change from ipsilateral or bilateral to the contralateral hemisphere was accompanied by motor functional recovery. These previous studies mainly focused on well or fully recovered hemiparetic stroke patients. We used NIRS to record hand grasprelated activation in motor-related brain areas in 10 stroke patients who had persistent mild or moderate hemiparesis in the chronic phase (>3 months), and examined the relationship between cerebral laterality balance and degree of paralysis to further establish the usefulness of NIRS in the assessment of brain activation in stroke patients
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