Chronic meningitis is slowly developing inflammation of the layers of tissue that cover the brain and spinal cord (meninges) and of the fluid-filled space between the meninges (subarachnoid space) when it lasts 4 weeks or longer (see Biology of the Nervous System: Viewing the Brain).
The subarachnoid space is located between the middle layer and the inner layer of the meninges, which cover the brain and spinal cord (see Biology of the Nervous System: Viewing the Brain). This space contains the cerebrospinal fluid.
Chronic meningitis develops slowly, over weeks or longer, and may last for months to years. Rarely, chronic meningitis causes only mild symptoms and resolves on its own.
Subacute meningitis develops over a longer period of time than acute meningitis and over a shorter period than chronic—over a few weeks. Its causes, symptoms, diagnosis, and treatment are similar to those of chronic meningitis. Bacterial meningitis may be subacute rather than acute.
Chronic meningitis is usually caused by an infection. Many microorganisms can cause chronic meningitis. Among the most important microorganisms are
The bacteria that cause Lyme disease do not typically cause acute bacterial meningitis.
The bacteria that cause tuberculosis cause a rapidly progressive form of chronic meningitis.
Cryptococcus neoformans is the most common cause of chronic meningitis in the Western hemisphere. These fungi are more likely to cause meningitis in people who have a weakened immune system due to disorders such as human immunodeficiency virus (HIV) infection or AIDS or who take drugs that suppress the immune system.
Less commonly, chronic meningitis is caused by other bacteria (such as those that cause syphilis), other fungi, or parasites such as the protozoa Toxoplasmosis gondii (usually in people with HIV infection or AIDS).
Viruses, such as HIV and enteroviruses, can also cause chronic meningitis. Chronic meningitis is common among people who have HIV infection.
Disorders that are not infections can cause chronic meningitis. They include sarcoidosis and certain disorders that cause inflammation, such as systemic lupus erythematosus (lupus), Behçet syndrome, and Sjögren syndrome. Chronic meningitis can also develop when leukemia, lymphoma, or cancer spreads to the meninges.
A few people have developed chronic meningitis after they were given methylprednisolone (a corticosteroid) as an injection into the space around the spinal cord (called an epidural injection) in the lower back (for example, to relieve sciatica). In all cases, the drug had not been prepared using sterile techniques. Symptoms include headache, confusion, nausea, and/or fever. Most people also have a stiff neck, but about one third do not. If people have any of these symptoms during the weeks or months after having a corticosteroid injection in their back, they should call their doctor.
The symptoms of chronic meningitis are similar to those of acute bacterial meningitis, except that they develop more slowly and gradually, usually over weeks rather than days. Also, fever is often less severe. Symptoms may last for years. Some people get better for a while, then worsen (relapse).
Headache, confusion, a stiff neck, and back pain are common. People may have difficulty walking. Weakness, pins-and-needles sensations, numbness, paralysis of the face, and double vision are also common. Paralysis of the face, double vision, and hearing loss develop when meningitis affects the cranial nerves (which go directly from the brain to various parts of the head, neck, and trunk).
Meningitis due to the bacteria that cause tuberculosis usually worsens fairly rapidly (over days to weeks) but may develop much more rapidly or gradually. It can have serious effects. Pressure within the skull may increase. Blood vessels may become inflamed, sometimes leading to stroke. Vision, hearing, facial muscles, and balance may be affected.
Doctors ask about factors that increase the risk of chronic meningitis, such as a weakened immune system (as may be caused by HIV infection or AIDS) and travel to areas where Lyme disease or certain fungal infections are common. Doctors also ask about and look for symptoms that may suggest a cause.
To confirm the diagnosis, doctors do magnetic resonance imaging (MRI) or, if MRI is not available, computed tomography (CT) of the head, followed by a spinal tap (lumbar puncture) to obtain a sample of cerebrospinal fluid.
The cerebrospinal fluid is sent to a laboratory to be examined and analyzed. The results can usually enable doctors to distinguish between chronic and acute meningitis. In chronic meningitis, the number of white blood cells in cerebrospinal fluid is higher than normal but is usually lower than that in acute bacterial meningitis. Also, the type of white cells that are most common is usually different. Some infectious organisms that cause chronic meningitis, such as the fungus Cryptococcus neoformans, are visible under a microscope, but many, such as the bacteria that cause tuberculosis, are difficult to detect.
The cerebrospinal fluid is also cultured. Organisms, if present, are grown so that they can be identified. However, culturing may take weeks. Special techniques, which may provide results more quickly, may be used to identify fungi and the bacteria that cause tuberculosis and syphilis. For example, the polymerase chain reaction (PCR) technique, which produces many copies of a gene, may identify the unique DNA sequence of the bacteria that cause tuberculosis.
Other tests on cerebrospinal fluid are done, depending on which disorders are suspected. For example, the fluid may be analyzed for cancer cells if cancer is suspected.
The cause of chronic meningitis may be difficult to determine, partly because detecting microorganisms in cerebrospinal fluid can be difficult. Thus, spinal taps may be repeated to obtain more cerebrospinal fluid for culture. Doctors may also need to culture samples of blood and urine or to biopsy infected meninges or other tissues, which are identified using MRI or CT. Even after extensive testing, the cause often cannot be determined.
Doctors focus on treating the cause. Depending on the cause, the following treatments are used:
Chronic meningitis due to Cryptococcus neoformans is commonly treated with amphotericin B plus flucytosine or fluconazole. When a fungal infection is particularly difficult to cure, amphotericin B is sometimes injected directly into the cerebrospinal fluid through an Ommaya reservoir. The Ommaya reservoir is a device that is placed under the scalp. The reservoir contains a large supply of drug, which it delivers slowly, over days or weeks, through a small tube running from the reservoir to the spaces within the brain.
The prognosis depends on what is the cause is and, in many cases, how strong the person's immune system is.
Syphilis and Lyme disease usually resolve after treatment. Meningitis due to fungal or parasitic infections is harder to treat and more likely to recur, especially in people with HIV infection. If meningitis is due to leukemia, lymphoma, or cancer, the prognosis is often poor. In such cases, meningitis can be fatal.
Last full review/revision February 2013 by John E. Greenlee, MD