The evaluation of encephalitis begins with a medical history and physical examination.

Physical findings in someone with encephalitis may include:

• Brudzinski sign:
• Bending of the neck causes the hips and knees to bend
• Confusion
• Lethargy:
• Excessive sleepiness or drowsiness
• Fever
• Kernig sign:
• Extending the knees with the hips flexed causes pain and muscle spasms
• Papilledema:
• Increased pressure in the eyes
• Petechial rash:
• Meningococcal infection may cause a rash that looks like broken blood vessels.

Testing is necessary to determine the underlying cause for encephalitis.

Tests that may be used to evaluate encephalitis include:

• Spinal tap:
• This is the most important test to diagnose meningitis
• Encephalitis or meningitis may cause the spinal fluid to become cloudy
• The fluid can be rapidly tested for the presence of bacteria
• Blood cultures
• Complete blood count
• Serologic tests for bacteria, fungi and viruses

Less commonly used tests that may be used to evaluate encephalitis include:

• CT scan of the brain
• MRI scan of the brain

For more information:

• Arbovirus infection evaluation
• Bacterial meningitis evaluation
• Dengue fever evaluation
• Equine encephalitis evaluation
• Japanese encephalitis evaluation
• St Louis encephalitis evaluation
• Viral meningitis evaluation
• West Nile virus evaluation