Near-infrared spectroscopy and imaging for investigating stroke rehabilitation: test-retest reliability and review of the literature.

Abstract

To review the use of near-infrared spectroscopy (NIRS) in stroke rehabilitation and to evaluate NIRS test-retest reliability within-session on a motor control task commonly used in neuroimaging of stroke recovery. Cohort study. Hospital-based research laboratory. Nineteen healthy control subjects (age range, 22-55y). Subjects performed 2 experimental runs of a finger-opposition task in a block-design paradigm (finger opposition alternated with a fixation rest period) while undergoing multichannel NIRS and physiologic monitoring. Reliability coefficients (Pearson r) for oxyhemoglobin (O(2)Hb) and deoxyhemoglobin (HHb) correlated amplitude modulations across measurement channels during individual blocks and block averages. Correlations between single blocks (ie, 16-s slices of data) exhibited a correlation intercept of .33+/-.09 for O(2)Hb. This value was minimally decreased by increasing lag between compared blocks (slope, -.012; P=.019) but was substantially enhanced by averaging across blocks (within-run slope, .11; between-run slope, .044). Correlations using 64 seconds of data reached 0.6. Results for HHb were virtually identical. NIRS modulations were repeatable even when comparing very short segments of data. When averaging longer data segments, the test-retest correspondences compared favorably to neuroimaging using other modalities. This suggests that NIRS is a reliable tool for longitudinal stroke rehabilitation and recovery studies.