Which pathology is specifically indicated by the presence of xanthochromic CSF?

Xanthochromic cerebrospinal fluid (CSF) refers to a yellowish discoloration of the fluid, which can occur due to the breakdown of red blood cells and the presence of bilirubin following a hemorrhagic event. In the context of subarachnoid hemorrhage, xanthochromia typically appears within 6-12 hours after the bleeding has occurred, and it may persist for weeks.

When blood enters the CSF due to rupture of a cerebral aneurysm or other vascular abnormalities, the red blood cells (RBCs) begin to lyse, resulting in the release of hemoglobin. The hemoglobin is subsequently metabolized to bilirubin, which imparts the characteristic yellow color seen in xanthochromic CSF. This finding is crucial for the diagnosis of subarachnoid hemorrhage, especially when the initial CSF sampling did not show an elevated red blood cell count but a suspicion of hemorrhage remains.

In contrast, other conditions like neurosyphilis, normal pressure hydrocephalus, and Guillain-Barré syndrome typically do not present with xanthochromic characteristics in the CSF. Neurosyphilis may show lymphocytic pleocytosis and elevated protein