Acute encephalitis is an inflammatory condition of the central nervous system. It is a complex and severe disease. Acute encephalitis can be caused by a wide variety of conditions, including bacterial or viral infection in the brain, ingestion of toxic substances, complication of an infectious disease or of an underlying malignancy. Many cases of encephalitis may go unnoticed because they result in only mild flu-like symptoms or even no symptoms. Severe cases of encephalitis, while relatively rare, can be life-threatening. Since the course of any single case of encephalitis is relatively unpredictable, it’s important to get timely diagnosis and treatment. Primary encephalitis occurs when a virus or other infectious agent directly infects the brain. The infection may be concentrated in one area or widespread. A primary infection may be a reactivation of a virus that had been inactive (latent) after a previous illness. Secondary (post-infectious) encephalitis is a faulty immune system reaction in response to an infection elsewhere in the body. This likely occurs when disease-fighting proteins enlisted to fight an infection mistakenly attack molecules in the brain. Secondary encephalitis often occurs two to three weeks after the initial infection.
Questions about symptoms, risk factors and medical history are important in making a diagnosis of encephalitis. Diagnostic tests that may be needed include a combination of physical examination, lab tests, imaging and spinal taps. If symptoms and patient history are suggestive of encephalitis, then brain imaging is often the starting point for confirming the diagnosis. For this techniques like MRI and CT scan are used (for details see Technology & procedures).
It involves medication to battle the infection, supportive care and follow-up therapy all of which is available at BRAINS. In addition to bed rest and plenty of fluids anti-inflammatory drugs such as acetaminophen and ibuprofen are used by doctors at BRAINS to relieve headaches and fever. More-serious cases of encephalitis are countered with aggressive antiviral treatments. Since the specific virus causing the infection may not be identified immediately or at all, treatment with acyclovir is often begun immediately. This drug can be effective against the herpes simplex virus, which can result in significant complications or death when not treated promptly.
Supportive care: Additional supportive care also is needed in the hospital for people with severe encephalitis. The care may include: Breathing assistance, as well as careful monitoring of heart function, intravenous fluids to ensure proper hydration and appropriate levels of essential minerals, anti-inflammatory drugs, such as corticosteroids, to help reduce swelling and pressure within the skull and anticonvulsant medications, such as phenytoin (Dilantin), to stop or prevent seizures.
Follow-up therapy: After the initial illness, it may be necessary to receive additional therapy depending on the type and severity of complications including physical therapy to improve strength, flexibility, balance, motor coordination and mobility, occupational therapy to develop everyday skills and to use adaptive products that help with everyday activities, speech therapy to relearn muscle control and coordination to produce speech.
- Brain imaging: Brain imaging is often the first test if symptoms and patient history suggest the possibility of encephalitis. The images may reveal swelling of the brain or another condition that may be causing the symptoms, such as a tumor. Technologies may include magnetic resonance imaging (MRI), which can produce detailed cross-sectional and 3-D images of the brain, or computerized tomography (CT), which produces cross-sectional images.
- Spinal tap (lumbar puncture): With a spinal tap, the doctor inserts a needle into the lower back to extract cerebrospinal fluid (CSF), the protective fluid that surrounds the brain and spinal column. A particular profile of blood cells and immune system proteins can indicate the presence of infection and inflammation in the brain. In some cases, samples of CSF can be tested in a laboratory to identify the causative virus or other infectious agent.
- Other lab tests: Your doctor or other members of the care team may take samples of blood, urine, or excretions from the back of the throat. These can be tested in the laboratory to identify some of the viruses or other infectious agents that can cause encephalitis.
- Electroencephalogram (EEG): Your doctor may order an electroencephalogram (EEG), a test in which a series of electrodes are affixed to the scalp. The EEG records the electrical activity of the brain. Certain abnormal patterns in this activity may be consistent with a diagnosis of encephalitis.
- Brain biopsy: Rarely, a procedure to remove a small sample of brain tissue (brain biopsy) is used if symptoms are worsening, treatments are having no effect, and there is no working diagnosis.