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Presents as fever, headache, and meningeal irritation associated with a CSF lymphocytic pleocytosis. Fever may be accompanied by malaise, myalgia, anorexia, nausea and vomiting, abdominal pain, and/or diarrhea. A mild degree of lethargy or drowsiness may occur; however, a more profound alteration in consciousness should prompt consideration of alternative diagnoses, including encephalitis.

Etiology !!navigator!!

Using a variety of diagnostic techniques, including CSF PCR, culture, and serology, a specific viral cause can be found in 60-90% of cases. The most important agents are enteroviruses, VZV, HSV type 2, HIV, and arboviruses (Table 191-4). The incidence of enteroviral and arboviral infections is greatly increased during the summer.

Diagnosis !!navigator!!

Most important test is examination of the CSF. The typical profile is a lymphocytic pleocytosis (25-500 cells/µL), a normal or slightly elevated protein concentration [0.2-0.8 g/L (20-80 mg/dL)], a normal glucose concentration, and a normal or mildly elevated opening pressure (100-350 mmH2O). Organisms are not seen on Gram or acid-fast stained smears or india ink preparations of CSF. Rarely, polymorphonuclear leukocytes (PMN) predominate in the first 48 h of illness, especially with echovirus 9, West Nile virus (WNV), eastern equine encephalitis virus, or mumps. The total CSF cell count in viral meningitis is typically 25-500/µL. As a general rule, a lymphocytic pleocytosis with a low glucose concentration should suggest fungal, listerial, or tuberculous meningitis or noninfectious disorders (e.g., sarcoid, neoplastic meningitis).

CSF PCR testing is the procedure of choice for rapid, sensitive, and specific identification of enteroviruses, HSV, EBV, varicella zoster virus (VZV), human herpes virus 6 (HHV-6), and CMV. Attempts should also be made to culture virus from CSF and other sites and body fluids including blood, throat swabs, stool, and urine, although sensitivity of cultures is generally poor. Serologic studies, including those utilizing paired CSF and serum specimens, may be helpful for retrospective diagnosis; they are particularly important for diagnosis of WNV and other arbovirus etiologies.

Differential Diagnosis !!navigator!!

Consider bacterial, fungal, tuberculous, spirochetal, and other infectious causes of meningitis; parameningeal infections; partially treated bacterial meningitis; neoplastic meningitis; noninfectious inflammatory diseases including sarcoid and Behçet's disease.

Treatment: Viral Meningitis

  • Supportive or symptomatic therapy is usually sufficient, and hospitalization is not required.
  • The elderly and immunocompromised pts should be hospitalized, as should individuals in whom the diagnosis is uncertain or those with significant alterations in consciousness, seizures, or focal neurologic signs or symptoms.
  • Severe cases of meningitis due to HSV, EBV, and VZV can be treated with IV acyclovir (5-10 mg/kg every 8 h), followed by an oral drug (acyclovir (800 mg, five times daily; famciclovir 500 mg tid; or valacyclovir 1000 mg tid) for a total course of 7-14 days; for mildly affected patients, an oral course of antivirals alone may be appropriate.
  • Additional supportive therapy can include analgesics and antipyretics.
  • Prognosis for full recovery is excellent.
  • Vaccination is an effective method of preventing meningitis and other neurologic complications associated with poliovirus, mumps, rubella, measles, and VZV infection.

Outline

Outline ⬆

Section 14. Neurology