Our brain, the spinal cord, and its surrounding structures can become infected by a large spectrum of germs. Bacteria and viruses are the most common offenders. Parasites, fungi, and other organisms can infect the central nervous system, although more rarely. Depending on the location of the infection, different names are given to the diseases. Meningitis is the inflammation of the meninges, the surrounding three-layered membranes of the brain and spinal cord, and the fluid it is bathed in, called cerebrospinal fluid. Encephalitis is an inflammation of the brain itself. Myelitis actually means a spinal cord inflammation. Abscess is an accumulation of infectious material and offending microorganisms, and this can occur anywhere within the CNS.
Organisms may cause bacterial, viral, parasitic, fungal, or prion infections of the central nervous system. Usually, viral meningitis causes milder symptoms, requires no specific treatment, and goes away completely without complications. Viral infections are two to three times more common than bacterial infections. Bacterial meningitis is a very serious disease and may result in a learning disability, speech defects, hearing loss, seizures, and loss of extremity function, permanent brain damage, and even death. Three types of bacteria are the most common causes of meningitis in all age groups except newborn.
Various types of brain infections lead to many different symptoms, which can depend on the age of the person, the type of bacteria, the type of infection, and the acuteness of the disease. In general, people older than 2 years of age with acute bacterial infection develop high fever, severe headache, stiff neck, nausea, vomiting, and discomfort when looking into a bright light, sleepiness, and confusion. Seizures can be a late development of the disease. Severe forms of bacterial meningitis, particularly meningococcal, can cause shock with complete loss of consciousness and coma and bring about a spreading purplish rash. Someone with viral brain infections tends to appear somewhat less ill.
In bacterial infections antibiotics given through a vein, as well as medications for fever and headache, are used in the treatment of brain infections. Anyone in respiratory distress will receive oxygen and be closely observed. IV fluids and electrolyte replacement are given to those with continuing nausea and vomiting. Anticonvulsants are used to prevent or treat seizures. Irritable or restless people will receive mild sedation. If there is evidence of brain swelling, steroids will be given. Antibiotic therapy is similar to that of bacterial meningitis. Most viral infections go away naturally with complete recovery. They do not require any specific treatment. The only exception to this is the herpes viruses. Special antiviral drugs are used to treat brain infections caused by herpes.