History
Upon presentation, most patients report fever, headache, irritability, nausea, vomiting, stiff neck, rash, or fatigue within the previous 18-36 hours. Constitutional symptoms of vomiting, diarrhea, cough, and myalgias appear in more than 50% of patients.
For several weeks or longer, children may experience irritability, incoordination, and an inability to concentrate.
Headache is almost always present in patients with viral meningitis and is often reported as severe. However, the classic description of abrupt onset of the "worst headache of my life," attributable to aneurysmal subarachnoid hemorrhage, is uncommon.
History of temperature elevation occurs in 76-100% 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.
Younger children may not report headache and may simply be irritable.
Newborns may present with poor feeding and lethargy.
Some viruses cause rapid onset of the above symptoms, while others manifest as nonspecific viral prodromes, such as malaise, myalgia, and upper respiratory symptoms. In many cases, symptoms have a biphasic pattern; the nonspecific flu-like symptoms and low-grade fever precede neurologic symptoms by approximately 48 hours. With the onset of neck stiffness and headache, the fever usually returns.
Meticulous history taking is essential and must include evaluation of exposure to ill contacts, mosquitoes, ticks, outdoor activity in areas of endemic Lyme disease, travel history with possible exposure to tuberculosis, as well as history of medication use, intravenous drug use, and sexually transmitted disease risk.
An important part of the history is prior antibiotic use, which may alter the clinical picture of bacterial meningitis.
Physical Examination
Some general physical findings in viral meningitis are common to all causative agents.
The classically taught triad of meningitis consists of fever, nuchal rigidity, and altered mental status, but not all patients have all 3 symptoms.
Fever is common (80-100% of cases) and usually ranges from 38°-40°C.
Nuchal rigidity or other signs of meningeal irritation (Brudzinski or Kernig sign) may be seen in more than half of patients, but these symptoms are generally less severe than they are in bacterial meningitis. Pediatric patients, especially neonates, tend not to exhibit nuchal rigidity on examination.
Irritability, disorientation, and altered mentation may be seen.
Severe lethargy or bulging fontanelle in neonates is a sign of increased intracranial pressure but may be absent in more than half of all cases. The neonate may exhibit hypotonia, irritability, and poor feeding. The clinical picture can mimic neonatal bacterial septicemia accompanied by multiple organ system involvement.
Headache is common and is characteristically severe.
Photophobia is relatively common but may be mild. Phonophobia may also be present.
Seizures occur occasionally and are usually a result of the fever, although the involvement of brain parenchyma (encephalitis) should be considered.
Global encephalopathy and focal neurologic deficits are rare but can be present. Deep tendon reflexes are usually normal but may be brisk.
Various signs of specific viral infection can aid in diagnosis. These include the following:
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Pharyngitis and pleurodynia in enteroviral infections
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Skin manifestations, such as zoster eruption from VZV, maculopapular rash from measles and enteroviruses, vesicular eruption from herpes simplex, and herpangina from coxsackievirus A infections
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Pharyngitis, lymphadenopathy, and splenomegaly, which suggest EBV infection
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Immunodeficiency and pneumonia, which should suggest adenovirus, CMV, or HIV as the causative agent
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Parotitis and orchitis, from mumps
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Gastroenteritis and rash, which occur with most enteroviral infections
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T1-weighted MRI of brain demonstrates diffuse enhancement of the meninges in viral meningoencephalitis.
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This rash consists of an enlarging annular plaque. Image courtesy of Lyme Disease Network (http://www.lymenet.org/).
