Viral meningitis overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Ahmed Elsaiey, MBBCH [2]
Overview
Viral meningitis is a condition in which the layers lining of the brain, or meninges, become inflamed due to a viral infection. Meningitis is diagnosed on a history of characteristic symptoms and certain examination findings (e.g. Kernig's sign). Investigations should show an increase in the number of leukocytes present in the cerebrospinal fluid (CSF), obtained via lumbar puncture.
Historical Perspective
Meningitis was first discovered by the hippocrats. Wallgren described aseptic meningitis in 1924 and defined it as a disease with acute onset that had typical systematic symptoms of meningeal involvement, in association with a cerebrospinal fluid (CSF) typical of meningitis (typically with a mononuclear cell predominance). Additionally, there was absence of bacteria on stain and culture and there was no identifiable parameningeal infection.[1]
Classification
There is no specific classification to the viral meningitis. However, it may be classified based on the age into child and adult viral meningitis. It may be also according to the causative virus like enterovirus, arbovirus, mumps and herpes simplex viruses.
Pathophysiology
Viral meningitis pathophysiology differs from virus to another and depends on many factors like age, immune status and gene expression. Invasion into the meninges by a pathogen can set up a local inflammatory response. The clinical signs are due to this meningeal irritation - for example, Kernig's sign is due to pain produced by stretching of the inflamed meninges.
Causes
Viral meningitis is caused by many viruses. The most important and the most common virus group that causes meningitis is Enteroviruses group. There are other viruses cause meningitis as Arbovirus and herpes simplex virus groups but not common as the enteroviruses.[1][2][3]
Differential diagnosis
The differential diagnosis of viral meningitis includes two step approach. First is differentiating bacterial meningitis from other diseases which have similar clinical presentation as viral meningitis such as encephalitis, brain abscess, subarachnoid hemorrage, and brain tumour. Second step involves CSF examination and differentiating bacterial meningitis from bacterial, fungal and other causes of meningitis
Epidemiology and demographics
Viral meningitis affect around 26.000 to 42.000 individual annualy with incidence 11 per 100.000 population. There is no gender or racial predilection.
Risk Factors
Viral meningitis risk factors rely particularly on the exposure to the infection itself and the route of transmission like respiratory droplet and feco-oral transmission. However, there are people at risk to be infected by the disease as children less than 5 years and immunocompromised patients.[4]
Natural History, Complications and Prognosis
Viral meningitis is a self resolved disease if left untreated. It takes around 10 days to be resolved. Seizures and loss of consiousness are the most important complications that may appear in the infants younger than 3 months. It has an excellent prognosis.
Medical Therapy
Treatment is needed for fungal or mycobacterial causes of aseptic meningitis. Herpesvirus or varicella (chickenpox) virus may be treated with antiviral medicines. Treatment for noninfectious causes consists of pain medications and managing complications, if they occur. No specific treatment is available for enteroviral or most other viral forms of aseptic meningitis.
References
- ↑ Logan SA, MacMahon E (2008). "Viral meningitis". BMJ. 336 (7634): 36–40. doi:10.1136/bmj.39409.673657.AE. PMC 2174764. PMID 18174598.
- ↑ Rotbart HA (2000). "Viral meningitis". Semin Neurol. 20 (3): 277–92. doi:10.1055/s-2000-9427. PMID 11051293.
- ↑ Yi EJ, Shin YJ, Kim JH, Kim TG, Chang SY (2017). "Enterovirus 71 infection and vaccines". Clin Exp Vaccine Res. 6 (1): 4–14. doi:10.7774/cevr.2017.6.1.4. PMC 5292356. PMID 28168168.
- ↑ CDC https://www.cdc.gov/meningitis/viral.html Accessed on April 10, 2017