Meningitis is an inflammation of the membranes (meninges) surrounding the brain and spinal cord. Tuberculous (TB) meningitis is the result of a bacterial infection invading the tissues and membranes around the brain and spinal cord. The infection is usually present in other locations; particularly the lungs, in the body and eventually spreads to the meninges through the bloodstream.
In some areas, the prevalence of tuberculosis is high and the risk of TB meningitis also increases particularly in young children. In some countries the incidence of TB meningitis is very low.
How Is Tuberculous Meningitis Caused?
TB meningitis is caused due to tuberculosis, which is a bacterial infection, the causative organism of which is Mycobacterium Tuberculosis. When there is tuberculosis of lungs or other sites in the body, the infection can spread to the brain and meninges.
Some persons who are at an increased risk of TB meningitis include
- Persons suffering from pulmonary tuberculosis (TB of lungs)
- Persons with weakened immune system due to certain drugs, surgeries, illnesses or other infections like AIDS.
- Excessive use of alcohol
How Does Tuberculosis Spread?
Tuberculosis is a contagious bacterial infection, which spreads through air. The infection particularly affects the lungs; respiratory or oral secretions of an infected person can spread the infection by common means. Tuberculosis of lungs or other sites in an infected person can lead to tuberculous meningitis, when the infection reaches the brain and meninges.
What Are The Symptoms Of Tuberculous Meningitis?
The initial presentation may have non-specific symptoms during the prodromal period and the person may have malaise, fever, fatigue and muscle pain. These symptoms can last for few days to few weeks. Meningitis specific signs and symptoms may develop with high fever and severe headache, neck stiffness, associated nausea or vomiting, increased sensitivity to light, altered mental status or confusion.
Some additional symptoms that may be noted include increased irritability, poor feeding or dislike for food, increased lethargy, altered consciousness and unusual body postures like arching of head and neck backwards may be seen. In babies, soft spot on the head or fontanels may be seen bulging.
Some presenting features, especially in infants and children that may need urgent medical attention include high-pitched cry, poor feeding, persistent fever and increased irritability or crying.
How Is Tuberculous Meningitis Diagnosed?
The physician thoroughly evaluates the symptoms and signs along with the clinical history. Clinical examination is done to note fever, neck stiffness and mental alertness.
Laboratory tests and blood culture may be ordered to determine the presence of the causative organism. Skin test and other investigations specific to tuberculosis may be ordered.
Lumbar puncture or spinal tap can be performed to collect cerebrospinal fluid (CSF), which is taken for detailed analysis. CSF examination includes various tests that detect certain parameters like protein, glucose and cell counts, which helps in confirming the exact diagnosis and cause of the infection.
Imaging studies like chest x-ray, CT scan of head is done. In some cases biopsy of brain or meninges may be required.
How is Tuberculous Meningitis Treated?
The tuberculous meningitis treatment approach needs to consider treating the infection, related symptoms and associated complications. Anti-microbial therapy is given to treat tuberculosis infection which includes drugs like Rifampicin (RIF), Isoniazid (INH), Pyrizinamide (PZA) and Streptomycin (SM). These are of particular importance in treating Tuberculous meningitis or TB meningitis because they can enter into the cerebrospinal fluid (CSF) and help in treating meningeal inflammation.
Sometimes, corticosteroids may also be used, depending on the severity of the infection and associated problems like focal neurological findings, altered consciousness, increased intracranial pressure or tuberculous encephalopathy.
For certain complicated cases like obstructive hydrocephalus or neurological problems, drainage or shunt placement may be considered.
What Are The After-Effects Or Complications Of Tuberculous Meningitis?
The complications of Tuberculous meningitis or TB meningitis can be serious and need to be managed appropriately. Some of the after effects include brain damage, fluid build-up between brain and skull or subdural effusion, hydrocephalus, seizures or hearing loss. Sometimes the infection can cause increased intracranial pressure, which can lead to permanent and irreversible damage to the brain.
Prevention of Tuberculous Meningitis
Tuberculous meningitis or TB meningitis can be prevented by controlling tuberculosis infection. BCG vaccine can offer protection against some forms of tuberculosis and help in TB meningitis. For children living in areas where this infection is more common, BCG vaccine is an important vaccine in the recommended immunization schedule.
Another important factor in preventing tuberculous meningitis or TB meningitis is to control the spread of tuberculosis from infected persons. As tuberculosis is contagious, the necessary preventive measures should be taken. Personal hygiene like covering nose and mouth should be followed; proper ventilation of rooms should be ensured and in some cases isolation of the infected person may be required.
Treating persons with non-active tuberculous infection is equally important. Such cases should be identified in time and appropriate treatment should be started in addition to other preventive measures. For all persons under treatment of tuberculosis it is important to complete the prescribed course of treatment, for which patient education and awareness programs should be considered.