Central Sleep Apnea : Causes

Central sleep apnea often occurs in people who are seriously ill. For example, it can develop in persons who have life-threatening problems with the brainstem. The brainstem controls breathing. As a result, any disease or injury affecting this are...

Encephalitis is irritation and swelling (inflammation) of the brain, usually due to infections. See also: Meningitis

Encephalitis is an inflammation of the brain, usually caused by a direct viral infection or a hypersensitivity reaction to a virus or foreign protein. Brain inflammation caused by a bacterial infection is sometimes called cerebritis. When both the brain and spinal cord are involved, the disorder is called encephalomyelitis. An inflammation of the brain's covering, or meninges, is called meningitis .

Detailed information on the most common types of encephalitis, including Japanese encephalitis, tickborne encephalitis, and arbovirus encephalitis

Although the word meningitis suggests an inflammation of the meninges only, there is always some involvement of the most superficial parts of the brain that are contiguous to the meninges. Often there are also alterations in the flow of cerebrospinal fluid (CSF).

Detailed information on encephalitis, including causes, symptoms, diagnosis, and treatment

Detailed information on encephalitis, including cause, symptoms, diagnosis, and treatment

Encephalitis is an acute inflammatory process that affects brain tissue and is almost always accompanied by inflammation of the adjacent meninges (tissues lining the brain). There are many types of encephalitis, most of which are caused by viral infections. Meningitis is an inflammation of the membranes (meninges) that surround the brain and spinal cord. Meningitis may be caused by many different viruses and bacteria, or by diseases that can cause inflammation of tissues of the body without infection (such as systemic lupus erythematosus). Viral meningitis is sometimes called aseptic meningitis to indicate it is not the result of a bacterial infection.

An inflammatory disease of the brain caused by a virus that either has invaded the brain, or a virus appearing elsewhere in the body that has caused a sensitivity reaction in the brain. Encephalitis infects the brain tissue itself and has serious consequences. Among the many forms of encephalitis are those that occur seasonally, those that affect animals, and a form that is carried by a mosquito. Viruses that have been directly implicated in causing encephalitis include the arbovirus, echovirus, poliovirus, and the herpes simplex virus. Encephalitis occurs as a complication of, for example, chicken pox, polio, and vaccinia, which is a cowpox virus used in smallpox vaccinations, as well as the common flu virus. Other implicated causes include the herpes simplex virus, responsible for the common cold sore, eczema, and genital herpes; the measles (rubeola) virus; some of the 31 types of echoviruses that also cause a paralytic disease or an infection of the heart muscle; the coxsackie virus responsible for infections of the heart and paralysis; the mumps virus; and the arboviruses that normally infect animals and can be spread by mosquito to humans. The virus responsible for encephalitis can invade the cranium and infect the brain via the circulatory system. The blood-brain barrier, a system that protects the brain from certain drugs and other toxins, is ineffective against viruses. Once it has gained entrance into the brain the virus infects the brain tissue. The immediate reaction is an inflammation that causes the brain to swell and activates the immune system. The tightly closed vault of the cranium leaves little room for the brain to enlarge, so when it does expand it is squeezed against the bony skull. This can result in loss of neurons, or nerve cells, which can result in permanent post-infection damage, depending upon the location of the damage. The individual who is developing encephalitis will have a fever, headache, and other symptoms that depend upon the affected area of the brain. He may fade in and out of consciousness and have seizures resembling epileptic seizures. He may also have rigidity in the back of the neck. Nausea, vomiting, weakness, and sore throat are common. Certain viruses may cause symptoms outside the nervous system as well. The mumps virus will cause inflammation of the parotid gland (parotitis), the spleen, and the pancreas as well as the brain, for example. An infection by the herpes virus can cause hallucinations and bizarre behavior. Treatment of encephalitis is difficult. It is important that the type of virus causing the infection be identified. Drugs are available to treat a herpes virus infection, but not others. The death rate can be as high as 50% among patients whose encephalitis is caused by the herpes virus. Infection by other viruses, such as the arbovirus, may have a mortality rate as low as 1%. Reduction of fever, as well as treatment for nausea and headache, is needed. Unfortunately, even those who survive viral encephalitis may have remaining neurologic defects and seizures. Reye's syndrome is a special form of encephalitis coupled with liver dysfunction seen in young children and adolescents. Invariably, children who develop Reye's syndrome have had an earlier viral infection from which they seemingly have recovered. Hours or days later, however, they will begin to develop symptoms such as vomiting, convulsions, delirium, and coma. A virus such as the influenza virus, varicella (measles), and coxsackie virus are responsible. For reasons unknown, giving a child aspirin tablets to reduce fever accompanying a cold or flu can trigger Reye's syndrome. At the time the nervous system begins to show signs of infection, the liver is also being affected. Fatty deposits begin to replace functional liver tissue, and similar fatty tissue can be found in the heart muscle and the kidneys. The relationship between the viral effects on the brain and the parallel liver damage is not known. Treatmen

Encephalitis is an inflammation of the brain, usually caused by a direct viral infection or a hypersensitivity reaction to a virus or foreign protein. Brain inflammation caused by a bacterial infection is sometimes called cerebritis. When both the brain and spinal cord are involved, the disorder is called encephalomyelitis. An inflammation of the brain's covering, or meninges, is called meningitis .