Spectrophotometry of cerebrospinal fluid for xanthochromia is a sensitive and specific test for subarachnoid bleeding but adds little to computed tomography

Abstract

Subarachnoid hemorrhage (SAH) is a serious neurological event associated with high morbidity and mortality. Computed tomography of the cerebrum (CTC) is the diagnostic method of choice, but in case of negative CTC but strong suspicion of SAH, lumbar puncture with spectrophotometric analysis of cerebrospinal fluid (CSF) for xanthochromia is performed. We wanted to examine the diagnostic properties of CSF spectrophotometry for xanthochromia testing. We performed a retrospective study of the diagnostic properties of CSF analysis for xanthochromia using spectrophotometry in the diagnosis of SAH. A total of 489 CSF samples were analyzed for xanthochromia, according to international guidelines, from 2009 until 2014 and for 411 of these the patient files were retrieved and examined for final clinical diagnosis and result of CTC. One patient with SAH did not have a positive spectrophotometry report and another patient with SAH had an equivocal report. In four patients did initial CTC not correctly identify SAH. For patients with a negative CTC within six hours of symptom onset spectrophotometry for xanthochromia in the CSF had a diagnostic sensitivity of 100% and a diagnostic specificity of 98.5%. The positive predictive value was 16.7% and the negative predictive value 100%. We conclude that spectrophotometry of CSF for xanthochromia is a sensitive and specific test for diagnosing SAH. However, it seems that an initial CTC identifies almost all patients with SAH. This suggests that in our and similar diagnostic settings, lumbar puncture and testing for xanthochromia might only be relevant in very few cases, if not obsolete.

Keywords:

• Subarachnoid hemorrhage
• cerebrospinal fluid
• diagnostic tests
• spinal puncture
• sensitivity and specificity

Acknowledgements

The expert technical assistance of senior technologist Lone Saelsen is gratefully acknowledged.

Ethical approval

The access to individual patient data was approved by the Danish National Board of Health (file.nr. 3-3013-713/1/1).

Author contributions

A.B.W. and L.M.H. contributed to the concept and design of the study as well as the acquisition of data. A.B.W. drafted the manuscript and performed the analysis of the data. A.B.W, J.L.S.H, and L.M.H. all contributed to interpretation of the data and revised the manuscript critically for intellectual content as well as approved the version to be published.

Disclosure statement

A.B.W. has received consultancy honoraria from Roche. Other authors had no potential conflicts of interest.

Guarantor

A.B.W. had full access to all the data in the study and takes responsibility for its integrity and the data analysis.