When an infectious agent such as a virus, a fungus, or a bacterium enters the body, the immune system usually sends white blood cells to fight off the infection. The result is often an inflammation in the affected area, characterized by pain, swelling, and redness. An inflammation that occurs in the brain tissues is generally called encephalitis, and when this affects the membrane covering the spinal cord and brain, it is referred to as meningitis. When meningitis and encephalitis are both present, the condition is frequently referred to as meningoencephalitis or sometimes, encephalomeningitis.
Meningoencephalitis is often associated with several other conditions. These include viral infections like measles, West Nile fever, and rabies. Measles is commonly seen in children and usually is characterized by rashes all over the body. Rabies is often transmitted through the bites of infected wild and domesticated animals. The West Nile fever is contracted through the bites of infected mosquitoes.
Examples of bacterial infections that may also result in meningoencephalitis are Lyme disease and Pontiac fever. Lyme disease is usually transmitted by the bite of infected ticks. The bacteria causing Pontiac fever often thrive in water sources such as pools and showers and may infect individuals exposed to these water sources.
Infection with the parasite Naegleria fowleri commonly leads to a condition known as primary amoebic meningoencephalitis (PAM). This is a rare, but often devastating, disease that causes death several days after exposure to the parasite. Prompt diagnosis and treatment is often necessary in the management of patients with PAM.
The symptoms of meningoencephalitis include fever, rigidity of the neck muscles, headache, and vomiting. Many patients have also experienced seizures, changes in behavior, alteration of consciousness, and memory loss during the infection. Some may present with partial paralysis of both the arms and the legs. In infants, there may be bulging of the fontanel, a soft area that can be felt in the infant's head.
Doctors usually diagnose their patients basing on their medical history, symptoms, and neurological and physical examination findings. Diagnostic tests may also be done, such as blood tests, urine test, and analysis of the cerebrospinal fluid (CSF), the fluid contained inside the spinal cord and brain. A computed tomography (CT) scan, as well as magnetic resonance imaging (MRI), may be done to detect inflammations in the brain.
Treatment often depends on the infectious agent causing meningoencephalitis. Antiviral drugs or antibiotics are usually given in cases of viral or bacterial infections, respectively. Other medications are also frequently given to relieve pain and swelling in the brain. Severe meningoencephalitis cases often need to be confined in the hospital for intravenous administration of drugs and monitoring of patients.