How valuable is a lumbar puncture in the management of patients with suspected subarachnoid haemorrhage?
OBJECTIVE
The aim of the study was to determine the range of cerebrospinal fluid findings associated with emergency department disposition and treatment of patients with headache suspicious of subarachnoid haemorrhage but a negative or equivocal computed tomography head scan, in particular the role of xanthochromic index.


METHODS
A retrospective review of medical records of 196 adult patients who underwent cerebrospinal fluid examination for red cell count and xanthochromia for suspected subarachnoid haemorrhage but had a normal or equivocal computed tomography scan.


RESULTS
Included in the study were 196 patients. Only one patient out of 189 with a negative computed tomography scan was found to have a subarachnoid haemorrhage caused by a ruptured aneurysm (0.5%; 95% confidence intervals 0-2.9%). Three other patients were diagnosed with benign subarachnoid haemorrhage. Ninety-one patients were stratified into the lowest possible risk group for subarachnoid haemorrhage and discharged home from the emergency department. All patients with equivocal computed tomography head scans and a positive xanthochromic index were admitted for cerebral angiography. In many cases, cerebrospinal fluid findings did not appear to influence clinical decision-making.


CONCLUSIONS
In the study institution, cerebrospinal fluid results appeared to have a variable influence on clinical decision-making for patients with suspected subarachnoid haemorrhage and a non-diagnostic computed tomography head scan. Of particular concern is the lack of validation of the tests used in this investigative approach, the frequency of patients having a lumbar puncture where the results did not influence their management, the inconsistency in the laboratory's technique for performing tests on cerebrospinal fluid and the very low yield of detecting patients with subarachnoid haemorrhage and a potentially treatable causative lesion.
Foot
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Emergency Department, Princess Alexandra Hospital, Brisbane, Queensland, Australia.
Staib
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D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002533:Cerebral Angiography; D003937:Diagnosis, Differential; D004632:Emergency Medical Services; D004909:Erythrocyte Indices; D005260:Female; D005500:Follow-Up Studies; D006261:Headache / Q000175:diagnosis / Q000000981:diagnostic imaging; D006801:Humans; D008297:Male; D008875:Middle Aged; D019635:Neurosurgical Procedures; D010343:Patient Admission; D010351:Patient Discharge; D012189:Retrospective Studies; D013053:Spectrophotometry; D013129:Spinal Puncture; D013345:Subarachnoid Hemorrhage / Q000134:cerebrospinal fluid* / Q000175:diagnosis* / Q000000981:diagnostic imaging; D013997:Time Factors; D015898:Tomography Scanners, X-Ray Computed