Cerebrospinal fluid analyses for the diagnosis of subarachnoid haemorrhage and experience from a Swedish study. What method is preferable when diagnosing a subarachnoid haemorrhage?

Abstract

Subarachnoid haemorrhage (SAH) has a high mortality and morbidity rate. Early SAH diagnosis allows the early treatment of a ruptured cerebral aneurysm, which improves the prognosis. Diagnostic cerebrospinal fluid (CSF) analyses may be performed after a negative computed tomography scan, but the precise analytical methods to be used have been debated. Here, we summarize the scientific evidence for different CSF methods for SAH diagnosis and describe their implementation in different countries. The principle literature search was conducted using PubMed and Scopus with the search items "cerebrospinal fluid", "subarachnoid haemorrhage", and "diagnosis". CSF analyses for SAH include visual examination, red blood cell counts, spectrophotometry for oxyhaemoglobin or bilirubin determination, CSF cytology, and ferritin measurement. The methods vary in availability and performance. There is a consensus that spectrophotometry has the highest diagnostic performance, but both oxyhaemoglobin and bilirubin determinations are susceptible to important confounding factors. Visual inspection of CSF for xanthochromia is still frequently used for diagnosis of SAH, but it is advised against because spectrophotometry has a superior diagnostic accuracy. A positive finding of CSF bilirubin is a strong indicator of an intracranial bleeding, whereas a positive finding of CSF oxyhaemoglobin may indicate an intracranial bleeding or a traumatic tap. Where spectrophotometry is not available, the combination of CSF cytology for erythrophages or siderophages and ferritin is a promising alternative.

Flow cytometry for the microscopy of body fluids in patients with suspected infection

“…Although for body fluids there are no diagnostic cut-off values for RBCs, the reporting of high numbers of RBCs may confirm the visual impression of a body fluid and would provide a record of this finding; if this is required, then all that is needed is the ability to count RBCs down to 6000×10 6 /L, as this is the lowest count giving a grossly haemorrhagic appearance 3. Even for CSFs the detection of RBCs is of limited value because the number of RBCs in CSF associated with traumatic taps is variable and there are no acknowledged reliable cut-off values to differentiate traumatic taps from intracranial bleeding 15. For SAH imaging is the key diagnostic strategy and CT has a very high sensitivity if performed during the first 6–12 h with newer generation CT scans 15 61.…”

Clinical course of nontraumatic nonaneurysmal subarachnoid hemorrhage: a single institution experience over 10 years and review of the contemporary literature

“…inspection of the supernatant in the seven patients with negative initial CT-scan. Recent publications underlined the importance of the utility of spectrophotometry, bilirubin and oxyhaemoglobin determination, CSF cytology and ferritin measurement for more reliable detection of the xanthochromia (46). According to the national guidelines spectrophotometry is routinely used in United Kingdom, whereas its usage varies in the rest of Europe and it is not used in North America (12).…”

Clinical and diagnostic findings in patients with elevated cerebrospinal bilirubin

“…Although there is controversy about the methodology for detecting SAH blood in CSF,12 ranging from visual inspection, CSF ferritin and non-clearing of erythrocytosis, the UKNEQAS guidelines13 probably have the most scientific evidence as an objective measurement of CSF bilirubin 24. As with our study, higher CSF red cell counts have been recognised in patients with aneurysmal SAH compared with non-aneurysmal SAH, but CSF red cell count alone is not sufficiently discriminatory 25.…”

“…Visual inspection of CSF for xanthochromia, automated measurement of CSF ferritin, detection of non-clearing of erythrocytosis and spectrophotometry are methods used to identify SAH after lumbar puncture 12. In the UK, CSF spectrophotometry is used to identify SAH in CT-negative patients who present with a thunderclap headache.…”