Encephalitis

Symptoms:

• a sudden fever
• a headache
• vomiting
• light hurts the eyes (photophobia)
• a stiff neck and back (occasionally)
• confusion, disorientation
• drowsiness
• clumsiness, unsteady gait
• irritability or poor temper control

Emergency symptoms:

• loss of consciousness
• poor responsiveness, stupor, coma
• seizures
• muscle weakness or paralysis
• sudden severe dementia
  • memory loss (amnesia), impaired short-term memory or impaired long-term memory
  • little or no observable change in mood, or mood is inappropriate for the situation
  • diminished interest in daily activities
  • inflexibility, self-centeredness, indecisiveness, or withdrawal from social interaction
  • impaired judgment

Signs and tests:

Various symptoms resembling gastroenteritis or meningitis may be present, or symptoms may mimic subdural hematoma or brain abscess. An examination may show signs of meningeal irritation or increased intracranial pressure, or other neurologic symptoms such as muscle weakness or changes in sensation.

• A lumbar puncture test and cerebrospinal fluid (CSF) examination show clear fluid, high pressure, high white-blood cell and protein levels, and normal glucose. Blood may be present in the CSF.
• Viral cultures of CSF or blood that reveal any type of virus will confirm the diagnosis of encephalitis, however, viral cultures are rarely useful. More often the health care provider also relies on serology tests to provide evidence of viral infection.
• EEG test results are abnormal.
• A cranial MRI or a CT scan of the head may be used to determine the presence or absence of internal bleeding or focal edema (swelling of a portion of the brain).