Patient Presentation: 31-year-old Caucasian male with Viral Meningitis
Introduction to Meningitis:
Viral meningitis is inflammation of the leptomeninges associated with central nervous
system infection. ‘Viral’ names the causative agent, and the term ‘meningitis’ implies lack of
parenchymal and spinal cord involvement. Viral meningitis is also often referred to as aseptic
meningitis.
More than 10,000 cases of viral meningitis are reported annually, but the actual
incidence may be as high as 75,000. Lack of reporting is due to the uneventful clinical outcome
of most cases and the inability of some viral agents to grow in culture. According to reports
from the CDC, inpatient hospitalizations resulting from viral meningitis range from 25,000-
50,000 each year. An incidence of 11 per 100,000 people per year has been estimated in most
reports.
Clinical presentation of viral meningitis:
Symptoms include fever, headache, irritability, nausea, vomiting, stiff neck, rash, or
fatigue within the previous 36 hours. Constitutional symptoms of vomiting, diarrhea, cough,
and muscle pain appear in over 50% of patients. Headache is virtually always present in
patients with viral meningitis and is often described as severe. History of fever occurs in over
75% of patients who come to medical attention. A common pattern is low-grade fever in the
prodromal stage and higher temperature elevations at the onset of neurological signs, later on
in the disease progression.
Nuchal rigidity and other signs of meningeal irritation may be seen in over 50% of
patients, but these symptoms are generally less severe than they are in bacterial meningitis.
Irritability, disorientation, and altered mentation may be neurological deficits present. Severe
lethargy is a sign of increased intracranial pressure but may remain absent in most cases.
Photophobia is relatively common but may be mild. Phonophobia may also be present, less
commonly than photophobia.
Diagnosis:
Lumbar puncture is the hallmark procedure used in the diagnosis of viral meningitis. A
CT scan is usually performed prior to LP to rule out syndromes that would contradict an LP such
as an intracranial mass. The LP itself may provide symptomatic relief of the headache. LP should
be performed sterilely, and the CSF opening pressure should be measured. The order of testing
after the LP depends on the patient’s current condition and on suggestive factors in the history
and physical. For example, most cases of viral meningitis do not require PCR testing for HIV. A
high WBC count in the CSF, a high protein level, and a low glucose level should suggest a
diagnosis of a bacterial meningitis, although some viral pathogens may produce similar CSF
profiles. Coagulopathy is a relative contraindication to LP.
Due to the low mortality rate associated with acute viral meningitis, pathologic features
other than lymphocytic response within the CSF are generally not seen. The leptomeninges
undergo inflammation with PMNs and mononuclear cells in the acute phase of the disease.
Perivascular cuffing, neuronophagia, and an increased number of microglial cells have been
noted in brain biopsy specimens from patients who died of viral encephalitis.
Differential diagnosis of viral meningitis- Haemophilus Meningitis, Staph Meningitis, TB
Meningitis, Acute Disseminated Encephalomyelitis, CNS Lupus, Stroke, TIA.
Management:
Treatment for viral meningitis is mostly supportive. Rest, hydration, antipyretics, and
pain medication may be given as needed. The most important action is to initiate antimicrobial
therapy empirically for bacterial meningitis while waiting for the cause to be identified.
Intravenous antibiotics should be administered promptly if bacterial meningitis is suspected.
Broad-spectrum coverage is attained with vancomycin and a third-generation cephalosporin.
Aminoglycosides are used in severe infections in neonates or children.
No surgery is usually indicated in patients with viral meningitis. In rare patients in whom
viral meningitis is complicated by hydrocephalus, a CSF diversion procedure may be required.
Patients with signs of meningoencephalitis should receive acyclovir early to combat HSV
encephalitis. Therapy can be changed as the results of the LP become available. Patients in
unstable condition need critical care unit admission for airway protection, neurologic checks,
and the prevention of continuing complications.
Acyclovir should be used in cases suspicious for HSV and is usually used empirically in
more severe-presenting cases. Anti-HIV therapy is initiated when the patient’s history suggests
the possibility of HIV infection or if confirmatory tests have proven that an infection exists.
Ganciclovir for CMV-related infections is reserved for severe cases with positive CMV culture or
congenital infection, or for immunocompromised patients.
Prognosis:
Most people who have viral meningitis recover in a few weeks without issue. Those with
more severe infections caused by HIV or West Nile will require ongoing hospitalization and
antiviral therapy to avoid complication.