SIGNIFICANCE OF CONTRAST-ENHANCED CT BRAIN VS LUMBAR PUNCTURE FOR PATIENTS POST PRESENTING WITH SUSPECTED MENINGITIS IN THE EMERGENCY DEPARTMENT

Abstract

: The routine use of contrast-enhanced computed tomography (CECT) prior to lumbar puncture (LP) in patients with suspected meningitis may delay definitive diagnosis and timely initiation of antimicrobial therapy. Evidence supporting the incremental diagnostic value of CECT over LP in emergency settings, particularly in low- and middle-income countries, remains limited. Objective: To compare the diagnostic significance of contrast-enhanced CT brain and lumbar puncture in adults presenting with suspected meningitis to the emergency department of a tertiary care hospital in Pakistan. Study Design: Prospective observational study. Settings: Emergency Department of Shifa International Hospital, Islamabad. Duration of Study: From March 2024 to August 2024. Methods: Ninety consecutive adult patients presenting with clinical features suggestive of acute meningitis were enrolled. In accordance with institutional protocol, all patients underwent a contrast-enhanced CT of the brain prior to lumbar puncture. CT findings were evaluated for parenchymal abnormalities and radiological contraindications to LP. Cerebrospinal fluid (CSF) analysis served as the reference standard for confirming and etiologically classifying meningitis. Diagnostic performance indices of CECT were calculated against CSF findings. Post-stratification analysis assessed associations between CT abnormalities, presenting clinical features, and in-hospital outcomes. Statistical analysis was performed using SPSS version 26, with p < 0.05 considered statistically significant. Results: The mean age of participants was 34.8 ± 15.6 years, with a male predominance (56.7%). CSF analysis confirmed meningitis in 84.4% of cases. The predominant etiologies were bacterial (41.1%), viral (31.1%), and tuberculous meningitis (12.2%). CECT demonstrated abnormalities in 35.6% of patients and identified radiological contraindications to LP in 8.9% of cases. Using CSF as the reference standard, CECT showed limited sensitivity (42.1%) and moderate specificity (83.3%) for meningitis-related abnormalities. CT abnormalities were significantly associated with altered level of consciousness, seizures, and papilledema (p < 0.05). Patients with abnormal CT findings experienced higher rates of intensive care unit admission, mechanical ventilation, neurological sequelae, and in-hospital mortality (all p < 0.05). Emergency department length of stay was significantly prolonged among patients undergoing CT prior to LP. Conclusion: Contrast-enhanced CT of the brain demonstrates limited sensitivity for confirming meningitis but remains valuable for identifying contraindications to lumbar puncture and stratifying patients at risk of severe outcomes. Lumbar puncture with CSF analysis remains the definitive diagnostic modality. Selective, guideline-directed use of pre-LP neuroimaging may reduce diagnostic delays and improve outcomes in resource-constrained emergency care settings.