Near-Infrared Spectroscopy (NIRS) as a diagnostic tool in patients with
suspected stroke or brain injury
S. Goldberg, C. Lott, M. Ostermeyer, H.-J. Hennes
Absorption of Near-Infrared (NIR) light in the brain is mainly caused by hemoglobin. Superficial intracranial hematoma with a higher concentration of hemoglobin causes a higher absorption in NIRS. The existence of hemorrhage can be demonstrated by the difference of optical density, comparing identical measuring points at both hemispheres of the brain: absorption of NIR light is greater at the side of the hemorrhage, causing less reflection in NIRS.
In a prospective, blinded study, 100 patients who were scheduled for CCT-scan for brain injury or symptoms of stroke have been measured by NIRS. The measurement results were proved by the CCT-diagnosis.
A sensitivity of the NIR measurement of 65% and a specificity of 87% was achieved including all patients with any pathology, whereas the subgroup of 58 patients with suspected superficial hematoma and without other pathology showed pathologic findings by NIRS in all of 16 patients indicating superficial bleeding by CCT, pathology could be excluded by NIRS and CCT in 41 patients, one false positive and no false negative result. The results (sensitivity 98%, specificity 100%) support the hypothesis that NIRS is a reliable device for the detection of superficial intracranial hematoma.