Tuberculous Meningitis - Causes, Symptoms, Diagnosis, and Treatment

Introduction

Tuberculosis is an airborne lung infection caused by Mycobacterium tuberculosis. It is a serious health issue and is a common condition worldwide. Tuberculosis starts in the lungs, and if left untreated, it spreads into the bloodstream; if it reaches the meninges, it leads to tuberculous meningitis. The most dangerous and lethal manifestation of tuberculosis is tuberculous meningitis.

What Is Tuberculous Meningitis?

Tuberculous meningitis is a condition that is characterized by the inflammation of the meninges (membrane covering that protects the brain and spinal cord) around the brain and spinal cord. It is caused by Mycobacterium tuberculosis and is either a sole manifestation of tuberculosis or happens along with a lung infection. It has a high mortality rate, especially in children and HIV (human immunodeficiency virus)-infected individuals.

What Causes Tuberculous Meningitis?

Tuberculosis (TB) is caused by a bacterium called Mycobacterium tuberculosis, which is spread from person to person through inhaling the droplets containing the bacterium. It usually starts as a lung infection, but if not treated immediately, it may spread to other body parts through the bloodstream. When it reaches the meninges, it causes small abscess formation, which later bursts into tuberculous meningitis. This could cause a rise in pressure within the skull in nerve and brain tissue damage.

What Are the Risk Factors?

Tuberculous meningitis is often seen in children aged one to five, although it may develop in adults of all ages. However, people with certain health conditions are more prone to the disease.

Risk factors include:

• AIDS (acquired immunodeficiency syndrome).

• Diabetes mellitus.

• Excessive use of alcohol.

• Impaired or weakened immune system.

• TB of the lungs.

What Are the Signs and Symptoms of Tuberculous Meningitis?

The presentation of symptoms may range from day one to nine months.

The initial symptoms include:

• Persistent headache.

• Low-grade fever.

• Malaise.

• Loss of appetite.

• Fatigue.

• Vomiting.

• Behavioral changes.

These symptoms may persist for several weeks. If untreated, the disease progresses, and more specific symptoms appear. These include:

• Severe headache.

• Dislike toward a bright light.

• Neck stiffness.

• Irritability.

• Lethargy.

• Confusion.

• Unconsciousness.

• Fever and chills.

Other symptoms may include:

• Agitation.

• Unusual posture, usually seen in infants below the age of three months, head and neck arched backward.

• Poor feeding and irritability in children.

• Decreased consciousness.

What Are the Complications of Tuberculous Meningitis?

Tuberculous meningitis is a serious condition and could be life-threatening. The complications of tuberculous meningitis include:

• Seizures.

• Hearing loss.

• Brain damage and infarction (dead tissue due to the failure of blood supply).

• Hyponatremia (it is the low level of sodium in the blood).

• Ischemia (a condition where blood flow to different body parts is reduced or restricted).

• Stroke.

• Death.

Unlike most forms of bacterial meningitis, tuberculous meningitis occurs at the base of the skull. Resulting in frequent dysfunction of cranial nerves and obstructive hydrocephalus (blockage in the flow of the cerebrospinal fluid).

How Is Tuberculosis Meningitis Diagnosed?

Unlike most types of bacterial meningitis, diagnosing tuberculous meningitis is difficult as the initial symptoms are non-specific, and symptoms like neck stiffness are not seen in the early phases of the condition. The doctor would take a complete medical history and ask for all the associated symptoms. Then, they will perform a physical examination to check for fast heart rate, neck stiffness, mental status changes, and fever.

The doctor may also advise a spinal tap or a lumbar puncture; the spinal fluid is collected and tested to confirm the condition.

Other tests include:

• Biopsy of the brain and meninges.

• Blood culture.

• Chest X-ray.

• CT (computer tomography) scan of the head.

• CSF (cerebrospinal fluid) examination for glucose, protein, and cell count.

• CSF culture.

• Polymerase chain reaction (PCR) of the CSF.

• Skin test to diagnose TB-PPD (tuberculosis-purified protein derivative) test.

How Is Tuberculous Meningitis Treated?

The multidrug antitubercular antibiotics used for tuberculosis are considered the mainstay of treatment for tubercular meningitis. However, the duration of treatment and the efficacy of the drugs are unclear as most drugs do not penetrate the CSF.

The four drugs used to treat TB include Isoniazid, Rifampin, Pyrazinamide, and Ethambutol. Ethambutol does not penetrate the lining of the brain; instead, a fluoroquinolone, such as Moxifloxacin or Levofloxacin, is used. In the case of drug-resistant tuberculous meningitis, long courses of treatment may be required with alternative medications.

The doctor may also prescribe corticosteroids along with the regimen. Depending on the severity of the illness, the treatment may last as long as 12 months. One must take the whole course of treatment and medications to avoid re-infection.

In certain severe conditions, hospitalization and close monitoring of the patient may be required.

How Can Tuberculous Meningitis Be Prevented?

The best preventive measure is to prevent TB.

• BCG Vaccine: The bacillus Calmette-Guérin (BCG) vaccine is used in many countries where TB is common to prevent TB, especially in young children.

• Vaccine for healthcare workers who work in close relation to TB patients.

• Taking appropriate treatment in the early stages of TB prevents further complications.

• Treating people with non-active or dormant TB: People who test positive for TB but show no symptoms.

• The primary contacts of the patient should be investigated for Mycobacterium tuberculosis as well to prevent further spread.

• If a person with TB refuses treatment, then a mandatory quarantine is required to avoid the spread.

What Is the Long-Term Outlook for Tuberculous Meningitis?

The long-term outlook of tuberculous meningitis would depend on the severity of the illness. Early detection and proper treatment can have a good outlook. However, once complications like brain damage or stroke have occurred, the outlook would be bad as these conditions are permanent and can not be reversed. Taking proper treatment and the complete course of medication can also determine the outlook of the illness. If proper treatment is not taken, the infection may present again.

Tuberculous meningitis is a severe condition that can be fatal if left untreated. Even with treatment, TBM still carries a mortality rate ranging from 20 to 67 percent. Individuals at increased risk of mortality include young children, older adults, people living with HIV, those with drug-resistant tuberculosis, and individuals with compromised immune systems.

When to Seek Medical Care?

Tuberculosis is a serious condition, and its form is tuberculous meningitis. Without treatment, TB has a mortality rate exceeding 50 percent, so individuals experiencing symptoms of TB or TBM should promptly contact their doctor.

Guidelines for Parents and Caregivers -

Young children are particularly vulnerable to developing TBM. Therefore, parents and caregivers should promptly seek medical advice if a child shows signs or symptoms of TB or TBM.

Common TBM symptoms that may affect children more frequently include:

• Mood changes like irritability and apathy.

• Headaches.

• Stiff neck.

• Light sensitivity.

• Nausea.

• Vomiting.

• Eye movement difficulties.

• Muscle weakness or loss of control.

Conclusion

Tuberculous meningitis is a severe life-threatening condition caused by Mycobacterium tuberculosis. It usually starts as a TB of the lung and later spreads to the meninges of the brain and spinal cord and causes tuberculous meningitis. Common symptoms include neck stiffness, severe headaches, and light sensitivity. Untreated tuberculous meningitis can have major complications, including brain damage and death. However, early detection and appropriate treatment are said to have a good outlook.