In milder cases, symptoms may resemble the flu. In severe cases of encephalitis, symptoms may include some or all of the following:
Behavioral and personality changes Coma
Confusion or disorientation Difficulty swallowing or breathing
Extreme fatigue Fever
Headache Inability to emote
Lack of concentration Lethargy and reduced consciousness
Loss of consciousness Memory loss
Muscle weakness Partial paralysis
Rash Sensitivity to light
Seizures Speech, hearing and vision problems
Stiff neck and back Tingling and numbness
Encephalitis, regardless of its source, produces similar symptoms and is often difficult to differentiate. If a doctor suspects encephalitis, the antiviral acyclovir should be administered until the cause can be determined. Herpes simplex, one of the common causes of encephalitis, is responsive to acyclovir. With the other most common cause, the arboviruses, symptoms can be managed, but no treatment is available.
Blood tests – Blood tests may be used to test for arbovirus infections.
Brain biopsy – In rare cases, a doctor surgically removes tiny brain tissues to test for the presence of a virus. Rabies is the most common type of encephalitis that calls for brain biopsy.
Imaging – Scanning techniques, such as CTs or MRIs, are commonly the first step in diagnosis. Although not all patients’ scans will reveal the damage, many will show the extent of the inflammation in the brain. Most doctors choose an MRI over a CT because they are more reliable in differentiating if the source is the herpes virus.
An electroencephalogram (EEG) may reveal temporal lobe abnormalities. These also indicate herpes simplex encephalitis.
Spinal Tap – A spinal tap involves taking a sample of cerebrospinal fluid from the patient's lower back. Results from the fluid are helpful in determining the virus, including herpes simplex, Epstein-Barr, varicella-zoster, enteroviruses, Japanese encephalitis and West Nile.