title: Benefit of cerebrospinal fluid spectrophotometry in the assessment of CT scan negative suspected subarachnoid haemorrhage: a diagnostic accuracy study.
abstract: This study aimed to determine if performing cerebrospinal fluid spectrophotometry in addition to visual inspection detects more ruptured cerebral aneurysms than performing cerebrospinal fluid visual inspection alone in patients with a normal head CT scan but suspected of suffering an aneurysmal subarachnoid haemorrhage (SAH). We performed a single-centre retrospective study of patients presenting to the emergency department of a tertiary hospital who underwent both head CT scan and lumbar puncture to exclude SAH. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of an approach utilising both spectrophotometry and visual inspection (combined approach) was compared to visual inspection alone. A total of 409 patients (mean age 37.8 years, 56.2% female) were recruited and six (1.5%) had a cerebral aneurysm on angiography. The sensitivity of visual inspection was 50% (95% confidence interval [CI]: 12.4-82.6%), specificity was 99% (95% CI: 97.5-99.7%), PPV was 42.9% (95% CI: 10.4-81.3%) and NPV was 99.2% (95% CI: 97.8-99.8%). The combined approach had a sensitivity of 100% (95% CI: 54.1-100%), specificity of 79.7% (95% CI: 75.4-83.5%), PPV of 6.8% (95% CI: 2.6-14.3%) and a NPV of 100% (95% CI: 98.8-100%). The sensitivity of the combined approach was not significantly different to that of visual inspection alone (p=0.25). Visual inspection had a significantly higher specificity than the combined approach (p<0.01). The combined approach detected more cases of aneurysmal SAH than visual inspection alone, however the difference in sensitivity was not statistically significant. Visual xanthochromia should prompt angiography because of a superior specificity and PPV. Due to its reduced sensitivity, caution should be applied when using only visual inspection of the supernatant.
authors.affiliation: School of Medicine, University of Queensland, Herston, QLD, Australia; The Prince Charles Hospital, Chermside, QLD, Australia. Electronic address: angus.hann@uqconnect.edu.au.
authors.forename: Angus
authors.initials: A
authors.lastname: Hann
authors.affiliation: School of Medicine, University of Queensland, Herston, QLD, Australia; Department of Emergency Medicine, Royal Brisbane and Women's Hospital, Herston, QLD, Australia.
authors.forename: Kevin
authors.initials: K
authors.lastname: Chu
authors.affiliation: School of Medicine, University of Queensland, Herston, QLD, Australia; Department of Emergency Medicine, Royal Brisbane and Women's Hospital, Herston, QLD, Australia.
authors.forename: Jaimi
authors.initials: J
authors.lastname: Greenslade
authors.affiliation: School of Medicine, University of Queensland, Herston, QLD, Australia; Department of Emergency Medicine, Royal Brisbane and Women's Hospital, Herston, QLD, Australia.
authors.forename: Julian
authors.initials: J
authors.lastname: Williams
authors.affiliation: School of Medicine, University of Queensland, Herston, QLD, Australia; Department of Emergency Medicine, Royal Brisbane and Women's Hospital, Herston, QLD, Australia.
authors.forename: Anthony
authors.initials: A
authors.lastname: Brown
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000792:Angiography; D004632:Emergency Medical Services; D005260:Female; D006261:Headache / Q000175:diagnosis / Q000209:etiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012015:Reference Standards; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013053:Spectrophotometry; D013129:Spinal Puncture; D013345:Subarachnoid Hemorrhage / Q000134:cerebrospinal fluid* / Q000175:diagnosis*; D014057:Tomography, X-Ray Computed; D055815:Young Adult
keywords: Headache; Spectrophotometry; Spinal puncture; Subarachnoid haemorrhage