Comparative studies of the diagnostic value of cerebrospinal fluid spectrophotometry and computed tomographic scanning in subarachnoid hemorrhage.

Serial spectrophotometric scans of cerebrospinal fluid (CSF) and computed tomographic (CT) scans of 99 patients with a subarachnoid hemorrhage (SAH) were examined. The xanthochromic index (i.e., the sum of the absorption values at 416 nm (oxyhemoglobin) and 460 nm (bilirubin)) yielded an accurate diagnosis in 82%, as did the CT scan. When both spectrophotometric and CT scans were used, the accuracy of SAH diagnosis increased to 96%. The xanthochromic index was valuable in estimating the date of hemorrhage and also correlated well with the clinical outcome of these patients. Only 42% of the recurrent hemorrhages were diagnosed by CSF spectrophotometry; in this capacity, its role seems less clear. However, a positive diagnosis of recurrent hemorrhage by CT scan was made in 83%.