Cranial ultrasound as a diagnostic tool for infant meningitis in a low-or middle income setting: “sensitivity and specificity"

Background: Cerebrospinal fluid (CSF) analysis remains the gold standard for diagnosing meningitis but it requires technique and time. In infants, open fontanels allow ultrasound visualization, making cranial ultrasound a low-cost, point-of-care diagnostic tool for suspected meningitis. This study aimed to develop a standardized cranial ultrasound checklist, and to assess the sensitivity and specificity of cranial ultrasound as a diagnostic tool for infants with meningitis compared with the gold standard cerebrospinal fluid (CSF) analysis. Materials and methods: This diagnostic tool validation study compared cranial ultrasound with the gold standard cerebrospinal fluid (CSF) analysis for meningitis using consecutive sampling. Infants under 12 months of age with patent fontanelles presenting to the Aga Khan University Hospital with suspected meningitis were allowed to participate. Results: Overall, 79 patients with suspected meningitis were enrolled. The mean age of the patients was 52.68 ± 82.27 days, and males were predominant (68.35%). The sensitivity, specificity, PPV, NPV, and accuracy of ultrasound were 46.81%, 56.25%, 61.11%, 41.86%, and 50.63%, respectively. The significant finding was thickened echogenic sulci 25 (31.64%), followed by meningeal thickening 23 (29.11%), white matter abnormalities 14 (17.71%), brain edema 12 (15.18%), ventricular system dilatation 6 (7.59%), and elevated CSF echogenicity 7 (8.86%). Conclusion: Cranial ultrasound showed low diagnostic accuracy for infant meningitis in this study. However, it may be used as a front-line imaging modality in the initial diagnosis and monitoring of infants with acute meningitis. It holds potential as a point-of-care diagnostic tool, and its utility may be enhanced by additional scanning approaches and Doppler techniques.