L’esame liquorale nella diagnosi di emorragia subaracnoidea

AUTORI

ABSTRACT

Cerebrospinal fluid (CSF) examination for subarachnoid hemorrhage (SAH) diagnosis

SAH denotes a bleeding between the arachnoid membrane and the pia mater. In the first days following the event, the computed tomography (CT) recognises >95% of SAH; however, this high sensitivity decreases with time. In two-three weeks, the CSF examination for the presence of hemoglobin (or its catabolite, bilirubin) becomes the most sensitive test for SAH diagnosis. Since the presence of hemoglobin in the CSF can be caused by traumatic collection, special attention should be paid to preanalytical conditions. Bilirubin gives a yellow colouring to CSF that can be detected by visual inspection. However, this colouring, also named xantochromia, could not be accurately perceived by the human eye. The 2008 United Kingdom guidelines for SAH diagnosis are based on the spectrophotometric analysis of the CSF that represents at present the reference method. However, this procedure is complex, requires skilled specialists and a sufficient number of cases to maintain the competence. Furthermore, its availability as emergency test can be difficult. This is probably the reason why the vast majority of laboratories continue to evaluate the presence of xantochromia by visual inspection.
The automation of the bilirubin measurement on clinical chemistry analysers has been proposed. This method is certainly less accurate than spectrophotometric analysis; however, it can be performed on common analysers and made results available for emergency situations, with a short turnaround time.

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