Tuberculous meningitis

Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at November 1, 2016
StartDiseasesTuberculous meningitis

Tuberculous meningitis (TB meningitis) is a life-threatening infection that causes inflammation of the meninges, membranes that surround the brain and spinal cord. Symptoms usually develop slowly, and the disease is often advanced by the time a diagnosis is made and treatment is given. Though TB meningitis is life-threatening when left untreated, people can recover from the disease with proper treatment. Unfortunately, the disease is fatal for some individuals, and some people who recover from the condition will suffer after-effects, such as hearing loss and brain damage.

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Definition & Facts

Tuberculous meningitis is an infection that causes inflammation in the meninges, membranes that surround and protect the brain and spinal cord from infection and injury. TB meningitis is the most severe form of tuberculosis.

Symptoms & Complaints

Symptoms of TB meningitis are typically vague and progress slowly over time. Initial signs and symptoms of TB meningitis may include fever and chills, fatigue, loss of appetite, aches and pains, nausea and vomiting, and persistent headache. The initial symptoms of TB meningitis may be present for weeks as the disease develops.

Later signs and symptoms of the condition include photophobia (sensitivity to light), neck stiffness, severe headaches, seizures, and nerve palsy. Mental status changes, such as stupor, confusion, and disorientation may also occur.

In addition, agitation and opisthotonos, an unusual posture where the head and neck are arched backward, may occur in some cases. Children may complain of feeling poorly or may be irritable, and babies may suffer from bulging fontanelle, where the soft spot on an infant's head curves outward.

If left untreated, tuberculous meningitis can lead to some serious complications. Seizures, hearing loss, brain damage, and death can all occur when TB meningitis is left untreated. Additionally, subdural effusion, a build-up of fluid between the brain and skull, may occur. Hydrocephalus, the excess accumulation of cerebrospinal fluid in the brain, is another possible complication of TB meningitis.

Causes

TB meningitis is caused by the bacterium Mycobacterium tuberculosis. This bacterium is responsible for causing tuberculosis. The bacteria typically gets into the body through droplet inhalation. Specifically, the bacteria from someone's cough or sneeze is usually breathed in by another person. The bacteria then multiplies in the lungs, makes its way into the bloodstream, and travels to other areas in the body, such as the brain and spinal cord.

When the bacteria makes its way to the brain and spinal cord, small abscesses called tubercles are formed. These abscesses can burst and lead to tuberculous meningitis. This process can happen right away or several months or years after the initial tuberculosis infection. Only two percent of those infected with tuberculosis will develop TB meningitis.

Anyone can get tuberculous meningitis. However, those who live in areas where tuberculosis is prevalent are more likely to develop the condition. Africa, the Eastern Mediterranean, South East Asia, and the Western Pacific have the highest rates of tuberculosis. TB meningitis is very rare in the United States.

Most of the cases of TB meningitis in America are in individuals who have traveled from other countries. Those who live in poor conditions, such as the homeless, are at higher risk of developing TB meningitis as well. Additionally, individuals who have HIV/AIDS, a weakened immune system, pulmonary tuberculosis, and those who drink alcohol excessively also have a higher risk of developing the condition.

Diagnosis & Tests

Because the initial symptoms of TB meningitis are vague and develop slowly, it can be difficult to make a diagnosis. A lumbar puncture is an essential test for the diagnosis of tuberculous meningitis. In a lumbar puncture, a needle is inserted into the spine, and cerebrospinal fluid is collected for diagnostic purposes.

Other tests, such as chest X-rays, blood tests, gram stain, a skin test for tuberculosis, computed tomography (CT) scan, and analysis of the cerebrospinal fluid via lumbar puncture may also be ordered to help diagnose the condition.

Treatment & Therapy

Treatment for the condition typically lasts for at least 12 months. For the first two months, someone with TB meningitis will receive pyrazinamide, ethambutol, rifampicin, and isoniazid. This is followed by a 10-month course of rifampicin and isoniazid. This course of treatment helps reduce the risk of antibiotic-resistant TB meningitis from developing. If antibiotic-resistant TB meningitis develops, other antibiotics are utilized to treat the condition.

Despite receiving the best treatment, approximately 15-30% of individuals who develop TB meningitis will die. If treatment is given early and completed successfully, most people recover from the condition well.

However, some individuals will have after-effects of TB meningitis. These after-effects include hearing impairment or deafness, epilepsy, sight impairment or blindness, paralysis, and severe brain damage. Other individuals may experience temporary or permanent learning difficulties, memory loss, behavioral issues, depression, anxiety, and headaches after recovering from the condition.

Prevention & Prophylaxis

Individuals can prevent TB meningitis. A vaccine called the Bacillus Calmette-Guerin (BCG) vaccine, protects people from the most severe forms of tuberculosis, including TB meningitis. The vaccination is recommended for children and adults who are at higher risk of developing tuberculosis.

The vaccine is also recommended for infants who are from parts of the world where TB is prevalent. The BCG vaccine is never given to adults over the age of 35 because the vaccine doesn't work well in adults. Some adults who are at higher risk of TB meningitis through their occupations, such as some medical professionals, are given the vaccine before the age of 35.

The BCG vaccine is composed of a weakened strain of the TB bacteria. It causes the immune system to protect against tuberculosis without actually causing the disease. In children, the vaccine is 70-80% effectively in preventing severe forms of TB, such as TB meningitis. The vaccine is less effective in preventing respiratory TB, which is the most common form of tuberculosis in adults.

TB meningitis is a severe form of tuberculosis. The initial symptoms of TB meningitis are vague and develop slowly over time, which makes the condition challenging to diagnose. For this reason, the condition is often advanced before a diagnosis is made. When treatment is given early, many people recover from TB meningitis. The condition is fatal in some cases, however, and even when people recover from TB meningitis, they may suffer long-term after-effects.