Sensitivity and specificity of funduscopy in determining the need for brain computed tomography in patients presenting with new-onset headache

Steyn, Elizabeth C.
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Introduction: Headache is a highly prevalent debilitating disorder. Computerized tomography of the brain (CTB) is commonly requested in patients with new-onset headache. This places a tremendous burden on the public health system. Our study aims to describe new-onset headache, its relationship to funduscopy and then relate the likelihood of finding an abnormality on CTB scan. Methods: This was a prospective study of adult patients presenting with new-onset headache. History of comorbidities was noted. A full neurological examination was done to ascertain if focal signs were present. Funduscopy was performed and radiological data collected. Fisher’s exact test was used to assess significant associations between funduscopy, focal signs and CTB scan. A p-value of <0.05 was considered significant. Cohen’s Kappa test was done to assess if the probability of agreement of fundoscopy and CT findings are by chance alone. A value of less than 0.40 was considered a fair agreement. Results: One-hundred and eight patients were included in this study. Forty-six (43%) had abnormal CTB scan findings. The most common abnormalities were focal brain lesions and cerebrovascular incidents. Twenty-five patients (23%) had abnormal funduscopy findings of which papilloedema and retinopathy were the most common. The sensitivity of fundoscopy in detecting abnormalities on CTB scans prior to stratification into “focal- and no focal signs” groups, was low (36%) but the specificity was high (87%). In patients with focal signs the sensitivity was still low (44%) but specificity was 100%. In the group with no focal signs the sensitivity was extremely low (16%), but the specificity was high (71%). Conclusions: In patients with new-onset headache, abnormalities on funduscopy with or without focal signs have high a specificity but a low sensitivity in predicting abnormalities on CTB scan and cannot be recommended as effective screening tools in our setting.
A research report submitted in partial fulfilment for the degree of Master of Medicine in the division of Neurology to the Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, 2020