The Clinical Manifestations, Risk Factors, Etiologies, and Outcomes of Adult Patients with Infectious Meningitis and Encephalitis: Single Center Experience

Abstract

(1) Background: Central nervous system (CNS) infections, including meningitis and encephalitis, are serious conditions which are associated with high morbidity and mortality. This study aims to identify the clinical manifestations, etiologies, and outcomes of meningitis and encephalitis in adult patients in Saudi Arabia, addressing the current gap in understanding these conditions within this population. (2) Methods: This is a single-center retrospective study which included all adult patients diagnosed with meningitis and encephalitis from March 2016 to May 2022. (3) Results: This study found that most cases of meningitis and encephalitis occurred due to unknown pathogens. Pretreatment with antibiotics prior to lumbar puncture (LP) was found in 71.2% of patients with meningitis. Altered mental status and seizures were common presenting symptoms among patients with encephalitis while altered mental status and fever were common among patients with meningitis. (4) Conclusions: Adherence to guidelines in treating meningitis and encephalitis and performing LPs in a timely manner are important. Establishing national biobanks with biological samples from patients suspected of having meningitis or encephalitis will significantly enhance our understanding of these conditions in Saudi Arabia.

Keywords: bacterial meningitis; central nervous system infection; encephalitis; meningitis; viral encephalitis; viral meningitis.

Figure 1

Case of meningitis secondary to Klebsiella pneumoniae. (a) Axial FLAIR post-gadolinium image reveals enhancing leptomeninges over the frontoparietal regions and scattered parenchymal edema (arrows). (b,c) Axial and coronal T1 post-gadolinium images show thick, intense leptomeningeal enhancement (yellow arrows) and pachymeningeal enhancement (white arrows).

Figure 2

Case of complicated meningoencephalitis with ventriculitis and empyema secondary to Salmonella enterica. Axial FLAIR post-gad (a), DWI, and ADC map (b,c) show abnormal parenchymal hyperintensities and diffusion restriction in the medulla oblongata and bilateral cerebellar hemispheres, consistent with encephalitis. Furthermore, note the restricted diffusion in the prepontine cistern, consistent with empyema. Axial T1 post-gadolinium (d), DWI, and ADC map (e,f) show intense ventricular ependymal surface enhancement related to ventriculitis and intraventricular diffusion restriction due to intra-ventricular empyema, with a pus fluid level indicated by white arrows. On the sagittal post-gadolinium image (g), leptomeningeal enhancement is visible on the ventral pons, medulla oblongata, and inferior vermis, indicating meningitis (white arrows). The axial post-gadolinium images show leptomeningeal enhancement along the bilateral trigeminal nerves (h), bilateral facial and vestibulocochlear nerves (white arrows), and the left abducent nerve (yellow arrow) (i).