Epidemiological and clinical characteristics of central nervous system infections in a tertiary center: A retrospective study

Abstract Background and Aims Central nervous system (CNS) infection is one of the most common causes of morbidity, mortality, and hospital admission worldwide. The natural history of CNS infection is quite fatal. Early diagnosis and treatment have been proven to have a crucial role in patients' survival. The aim of this study was to identify the epidemiological and clinical patterns of patients diagnosed with CNS infections. Methods This study is a retrospective study conducted in a tertiary level hospital in Nepal in which patient diagnosed with CNS infections (September 2019 to 2021) were included. Data were collected and analyzed in SPSS. Results The mean age of the 95 patients included in the study was 45.18 ± 19.56. Meningoencephalitis (n = 44, 46.30%) was the most common infection diagnosed. Patients belonging to the age group 30−60 years had a higher frequency of focal neurological deficit, and other classical clinical features. All the patients who died during the treatment had associated comorbidities but no concurrent infections. Altered sensorium, fever, and headache were the common presenting symptoms in all the recovered patients. Conclusion To ensure optimum disease outcome, early diagnosis and prompt management are crucial. For this, recognizing the local disease patterns in terms of disease distribution, commonly implicated aetiologies, presenting symptoms, and prognostic factors is of utmost importance.

sensorium, focal neurologic deficit, and blurring of vision. However, clinical manifestation varies according to different etiology and brain tissue involvement. The natural history of CNS infection is quite fatal.
Early diagnosis and treatment have been proven to have a crucial role in patients' survival. 1 It is usually diagnosed through the clinical presentation, blood tests, blood culture, and electroencephalography and confirmed by There has been significant geographical variation in distribution, clinical presentation, and outcome. One of the few studies from Nepal has shown Japanese Encephalitis (JE) and enterovirus as the most common cause of CNS infection in adults while S. pneumoniae and N. meningitidis still stand as the most common bacterial etiology causing CNS infection, tubercular meningitis is also the common diagnosis. 3 Results of different studies from different parts of the world do not correlate with each other and vary significantly. 5,6 Despite the high prevalence and burden in developing countries like Nepal and other South Asian countries, there are limited articles on epidemiological aspects of CNS infection. Thus, a retrospective study to observe the various epidemiological characteristics of a CNS infection patient was conducted in one of the largest tertiary centers in Nepal.

| Study design
The study was conducted in a retrospective design, in Tribhuvan University Teaching Hospital. Our institution is a major referral and tertiary level hospital in Nepal with high patient flow.

| Inclusion criteria
Patients with diagnosis of meningitis, meningoencephalitis, encephalitis, and parasitic infection of the brain and under the care of the neurology department of Tribhuvan University Teaching Hospital from September 1, 2019 to September 1, 2021 were included in the study.

| Exclusion criteria
All those patients whose diagnosis was uncertain and inconclusive were excluded from the study. Patients with incomplete or missing data were also excluded from the study.

| Sampling
A non-probability, convenience sampling was done for the sample size selection of our study. We reviewed the charts of the hospital's neurology department from September 2019 to 2021. The data were collected based on a pre designed proforma sheet manually. The data were categorized into the domains of demography, clinical presentation, investigation, diagnosis, treatment, and outcome. The first set of data included age, sex, address (based on provincial division of country), marital status, comorbidities, concurrent infections, previous treatment/surgery history, and placement of invasive devices.
The second set of data included clinical features (fever, vomiting, seizures, headache, altered mental status, focal neurologic deficit, and others), signs (neck stiffness, Brudzinski sign, Kernig sign, papilledema), investigations (lumbar puncture, imaging), and outcomes of the patient.

| Statistical analysis
The raw data were entered and maintained in Microsoft Excel (Ver 2016). The analysis of the data was done using SPSS 21 (IBM Corp. Released 2012. IBM SPSS Statistics for Windows; Version 21.0; IBM Corp.). Initially, a descriptive analysis of the data was done.
Categorical data was presented in terms of frequency and percentage. Continuous data were presented as mean and median. A p-value of 0.05 or less has been considered statistically significant.

| Ethical consideration
Ethical clearance was obtained from the Institutional Review Board of our institution, before commencing with the data collection (Reference Number: 188 [6][7][8][9][10][11] E2/078/079). There were no human harm or direct contact with the patient. The data collection was done in such a manner that no identifying characteristics of the patient had been recorded in the excel sheets.

| RESULT
After a retrospective review of the chart of patients with CNS infection admitted to our hospital (September 1, 2019 to September 1, 2021), a total of 120 patients were identified but only 95 patients were included in the study. Twenty-five patients were excluded due to incomplete data. The mean age group of the patients was T A B L E 1 Age-wise detailed characteristics of study population (n = 95).  Table 2.
The most common diagnosis in the recovered patient was meningoencephalitis (n = 20). All the patients who died during the treatment had associated comorbidities but no concurrent infections.
Altered sensorium, fever, and headache were the common presenting symptoms in all the recovered patients. Five patients each in a resolved and improving group had their EEG done (Table 3).

| DISCUSSION
Infections involving the brain, spinal cord, optic nerves, and  The most common etiology in the age group of 10−30 years was also tubercular (12 out of 27 patients) followed by viral, bacterial, and autoimmune in decreasing order. According to a study done in Vietnam, the most commonly implicated organism of CNS infections in patients under the age of 14 was JEV, which was not the case in our study. 15 Interestingly, the number of CNS viral infections were equal to tubercular in the 30−60 age group.
The age-disaggregated data of our study shows that 75% (n = 3, supervision.

CONFLICT OF INTEREST STATEMENT
The authors declare no conflict of interest.

TRANSPARENCY STATEMENT
The lead author Subarna Giri affirms that this manuscript is an honest, accurate, and transparent account of the study being reported; that no important aspects of the study have been omitted; and that any discrepancies from the study as planned (and, if relevant, registered) have been explained.

DATA AVAILABILITY STATEMENT
The data that support the findings of the present study are available on reasonable request. However, they are not publicly available due to privacy and ethical restrictions.