Nervous system tuberculosis (NS tuberculosis) is a serious infectious disease affecting the central nervous system (CNS) caused by the Mycobacterium tuberculosis complex. This infection is considered one of the most serious forms of tuberculosis (TB) and is especially common in immunocompromised individuals (HIV/ AIDS patients, diabetics, the elderly, etc.). Nervous system tuberculosis can present in various clinical forms such as meningitis, tuberculoma, spinal tuberculosis (Pott's disease), and brain abscess. This disease has high morbidity and mortality rates if not diagnosed and treated early.

History and Epidemiology

Tuberculosis is one of the oldest diseases in human history. Nervous system tuberculosis was first described in the 19th century. Robert Koch discovered Mycobacterium tuberculosis in 1882, and this discovery was a major turning point in understanding the pathogenesis of tuberculosis. Nervous system involvement showed that tuberculosis is a systemic disease and can affect any organ in the body.

Nervous system tuberculosis is more common in areas where tuberculosis is endemic. HIV/AIDS patients, children, the elderly, and immunocompromised individuals are particularly at risk. According to the World Health Organization (WHO), tuberculosis is a major cause of morbidity and mortality worldwide. Nervous system involvement accounts for approximately 1-5% of all tuberculosis cases, but the mortality rate is high in cases of delay in diagnosis and treatment.

Microbiology and Pathogenesis

Mycobacterium tuberculosis is an acid-fast, nonmotile, aerobic bacterium. CNS tuberculosis usually results from hematogenous spread from a primary infection in the lungs. The bacteria cross the blood-brain barrier to the CNS, where they cause granulomatous lesions in the meninges, brain parenchyma, or spinal cord. Tuberculous meningitis is the most common form of CNS tuberculosis and is characterized by an intense inflammatory response, usually in the basal meninges.

Pathological Process

In nervous system tuberculosis, granulomatous inflammation begins when bacteria reach the CNS. During this process, macrophages, lymphocytes, and other immune cells attempt to phagocytose the bacteria. However, Mycobacterium tuberculosis can survive and multiply within macrophages. This leads to caseation necrosis and granuloma formation. In the form of meningitis, an intense exudative reaction is seen in the basal meninges, which can cause complications such as hydrocephalus and cranial nerve palsies.

Clinical Findings

Tuberculosis of the nervous system manifests itself with different symptoms depending on its clinical form:

Tuberculous Meningitis: Tuberculous meningitis is the most common form of nervous system tuberculosis. It is characterized by headache, fever, changes in consciousness, neck stiffness, vomiting, and cranial nerve palsies (especially optic nerve). Complications such as hydrocephalus and vasculitis may develop. The disease usually has a subacute course and can be fatal if left untreated.
Tuberculoma: Tuberculomas present as granulomatous lesions in the brain parenchyma. Headache, seizures, and focal neurological deficits may be present. Tuberculomas usually present as single lesions, but multiple lesions may also be seen. Magnetic resonance imaging (MRI) is very helpful in the diagnosis of tuberculomas.
Spinal Tuberculosis (Pott's Disease): Spinal tuberculosis affects the spine and spinal cord. It can lead to serious complications such as back pain, neurological deficits, and paraplegia. Spinal deformities and nerve root compression are characteristic features of this form. Radiological imaging may show findings such as vertebral collapse and paravertebral abscess.
Tuberculous Brain Abscess: Tuberculous brain abscess is a rare form. It causes symptoms of mass effect and increased intracranial pressure. Abscesses are usually multiple and may require surgical drainage.

Diagnosis

The diagnosis of nervous system tuberculosis is made by clinical findings, imaging methods and laboratory tests:

Imaging Methods: Magnetic resonance imaging (MRI) and computed tomography (CT) are helpful in demonstrating meningitis, tuberculoma, or spinal involvement. MRI is particularly superior in demonstrating inflammation of the basal meninges and hydrocephalus.
CSF Examination: Analysis of cerebrospinal fluid (CSF) obtained by lumbar puncture shows lymphocytic pleocytosis, high protein, and low glucose levels. Acid-fast bacilli (AFB) staining and culture confirm the diagnosis. Molecular methods such as PCR can also be used to detect Mycobacterium tuberculosis DNA in CSF.
Histopathological Examination: Caseous necrosis and granulomas may be seen in biopsy specimens. These findings are pathognomonic features of nervous system tuberculosis.

Treatment

Treatment of tuberculosis of the nervous system includes long-term antimycobacterial therapy and supportive therapy:

Antimycobacterial Therapy: Standard treatment includes a combination of isoniazid (INH), rifampin, pyrazinamide, and ethambutol. The duration of treatment is usually 9 to 12 months. Steroids (prednisone) are used to reduce inflammation and prevent complications.
Supportive Therapy: In case of hydrocephalus, shunt placement, antiepileptic drugs for seizures, and fluid-electrolyte balance are important. In severe cases, intensive care support may be required.

Protection and Control

Prevention of tuberculosis of the nervous system depends on general tuberculosis control measures:

BCG Vaccine: It is especially applied to children in endemic areas. The BCG vaccine provides partial protection against tuberculous meningitis.
Early Diagnosis and Treatment: Early diagnosis and treatment of patients with pulmonary tuberculosis can prevent nervous system involvement. Rapid diagnostic tests should be used in patients with suspected tuberculosis.
Hygiene and Isolation: It is important to avoid contact with infectious patients and to take appropriate hygiene measures. Healthcare workers, in particular, should use protective equipment when in contact with TB patients.

Nervous System Tuberculosis