Meningitis refers to inflammation of the membranous covering of the brain called meninges. There are acute and chronic forms of meningitis with varied etiology and constitute a neurological emergency with significant morbidity and mortality. Infectious causes of meningitis along with associated clinical syndromes such as encephalitis represent an important clinical and socioeconomic challenge in developing nations like India.
Early recognition, etiological diagnosis and appropriate empirical followed by specific antimicrobial therapy are crucial in reducing mortality and morbidity which continues to be high especially in children and the elderly.
Broad Classification into infectious (bacterial, tubercular, viral, fungal) and non-infectious causes (malignancy, autoimmune disorders, trauma, chemical agents) is useful from an etiological perspective. Common bacterial pathogens include Streptococcus pneumonia, Neisseria meningitides, Haemophilus influenza, Listeria monocytogenes, and Staphylococcus aureus.1
Tuberculosis is a major cause of subacute and chronic meningitis in India. Among the viral infections, the common causative organisms include the enterovirus (especially the Coxsackie virus), and the Herpes simplex virus.2
Fungal meningitis is relatively uncommon and is classically seen in immunocompromised individuals.
Data on the overall incidence and prevalence of meningitis in India is scarce. The Global Burden of Diseases, Injuries, and Risk Factors (GBD) 2016 study estimated meningitis incidence between 60-80/100,000, with an estimated 60,000 deaths due to the illness in the year 2016 alone.3 A single tertiary hospital-based retrospective study in 2017 found that Viral Meningitis was the most common followed by bacterial and tuberculous meningitis.2 A systematic review of etiology of bacterial meningitis showed that N. meningitides, S. pneumonia, and H. influenza were the predominant pathogens that caused bacterial meningitis in most age groups.4
The common causes of viral encephalitis reported from India are Japanese encephalitis, which is a major public health problem because of large endemic areas in the country, the high case fatality rate (20-30%) and frequent residual neuropsychiatric damage (50-70%); followed by Enteroviruses (especially EV 71), Chandipura virus, Dengue virus and Chikungunya virus.5
The classic clinical triad of meningitis is fever, headache, and neck stiffness, but these classic symptoms may be absent in a significant number of patients. A decreased level of consciousness occurs in >75% of patients and can vary from lethargy to coma. Fever, headache, stiff neck, or an altered level of consciousness will be present in nearly every patient with bacterial meningitis. Nausea, vomiting, photophobia and seizures are also common complaints.
The following table lists the investigations in brief:
|Blood||Complete Blood Count, Random Blood Sugar, Urea, Creatinine, Serum
Electrolytes, liver function tests
and Coagulation Profile
C-Reactive Protein, ESR, Procalcitonin
Meningococcal and Pneumococcal PCR(Serum Sample)
|CSF||Opening Pressure, Cell count, Cell type, Cell cytology, Culture
Gram Stain, AFB, ADA
Protein, Glucose, Chloride
PCR for Menigococcus, Pneumococcus, Enterovirus, HSV1,2, VZV
Gene Xpert for TB
Cryptococcal Antigen, India Ink for Cryptococcus, Fungal Culture
|Throat swab for Enterovirus/Stool for Enterovirus PCR
CSF PCR for other viruses as directed by history
16S rDNA/RNA PCR on CSF or Blood
Treatment for bacterial meningitis is antibiotics, with or without steroids. Early initiation of therapy is critical for a good outcome. The choice of antibiotics is a three-stage process: an initial empirically chosen antibiotic based on clinical suspicion, followed by changes in therapy following review of microscopy results, and review again when culture or PCR results are available.
Despite appropriate therapy, a mortality rate of about 15% is seen in adults, with a significant amount of residual morbidity among those who have recovered. 7 These further emphasize the need for a high degree of suspicion for early diagnosis and rapid intervention among patients with suspected meningitis.
HOD & Consultant - Neurology, Epileptology, Sleep Medicine Specialist
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