Near infrared spectroscopy (NIRS) measurements following subarachnoid hemorrhage (SAH): potential for the detection of vasospasm

Bilateral NIRS measurements of relative blood volume (BV) and oxygen saturation (DESAT) from frontal, temporal and parietal regions were acquired daily (n=42) in 4 SAH patients (supine and with the head elevated 30 degrees) and compared with subtraction angiography for the detection of vasospasm. Significant differences in NIRS signals were found exclusively in one patient who developed vasospasm. There were significant differences in DESAT (right versus left temporal region [supine], p=0.003); while head elevated data revealed side to side differences for individual wavelengths as well as for BV and DESAT in the temporal and frontal regions, respectively. Differences were also found between periods of spasm and non-spasm for BV in the left parietal (p=0.035) and left frontal (p=0.023) region. Angiographically confirmed vasospasm was confined to the internal carotid and middle cerebral arteries on the left side. NIRS showed differences only in the affected side, and although not able to identify the location of the spasm, the technique may prove useful in the routine, daily assessment of these patients