Introduction
Contrast-enhanced computed tomography (CT) scan in a patient with tuberculous meningitis demonstrating marked enhancement in the basal cistern and meninges, with dilatation of the ventricles.
Petechial hemorrhages in the subcortical white matter of the brain as a result of tuberculous meningitis–associated vasculitis.
T1-weighted gadolinium-enhanced magnetic resonance image in a child with a tuberculous abscess in the left parietal region. Note the enhancing thick-walled abscess.
Background
Tuberculosis (TB) of the central nervous system (CNS) is a granulomatous infection caused by Mycobacterium tuberculosis. The disease predominantly involves the brain and meninges, but occasionally, it affects the spinal cord. Clinical diagnosis can be difficult; therefore, imaging has an important role in establishing the diagnosis.
For excellent patient education resources, visit eMedicine's Bacterial and Viral Infections Center and Brain and Nervous System Center. See also eMedicine's patient education articles Tuberculosis and Brain Infection.
Tuberculosis (Infectious Diseases)
Tuberculosis (Pediatrics: General Medicine)
Tuberculosis (Emergency Medicine)
Spinal Cord Infections
Spinal Infections (Orthopedic Surgery)
Frequency
United States
The incidence of tuberculosis (TB) is 8 cases per 100,000 person-years. However, in a study in New York City, the incidence in patients receiving welfare was 744 cases per 100,000 person-years.1 The prevalence is especially high in people infected with human immunodeficiency virus (HIV), those who abuse drugs and alcohol, immigrants, and homeless persons.2
International
The rates of tuberculosis (TB) and tuberculous meningitis (TBM) have increased globally, especially in developing countries of Africa and Asia that are affected by the HIV pandemic.2 The incidence is 544 and 757 new patients per 100,000 population in Africa and India, respectively. Extensively drug-resistant TB (XDR TB) is becoming a public health problem in Africa.
Mortality/Morbidity
In 2005, mortality in the Americas for all tuberculosis (TB) patients was 5.5 deaths per 100,000 persons.3 The major causes of morbidity and mortality of CNS TB are the resulting complications of TBM, especially in pediatric patients. Primary complications include communicating hydrocephalus, vasculitis with resulting infarction, and ventriculitis.
- Hydrocephalus occurs in most patients who survive the first 4-8 weeks. Hydrocephalus may be communicating due to obstruction of the arachnoid granulations, or it may result from obstruction of the cerebral aqueduct or fourth ventricular foramina by tuberculous exudate in the acute phase and by pachymeningitis in the chronic phase of the disease.
- Infarction is common (>50% of patients) in the acute phase and results from a vasculitis that involves the pontine perforator, lenticulostriate, and thalamoperforating arteries. Small infarcts are common in the basal ganglia and brainstem, where they are responsible for the morbidity associated with the disease. These infarcts can lead to mental retardation, stroke, and blindness.
- Ventriculitis is a common complication and a major cause of morbidity, resulting in hydrocephalus.
Race
Tuberculosis is a disease of poverty, and the racial distribution varies with the socioeconomic status of the country.
Sex
The male-to-female ratio of tuberculosis is 1:1.
Age
All forms of tuberculosis, especially those with CNS involvement, are common in children and older persons because their immune systems are less robust than those of adults. In many developing countries, TB meningitis (TBM) is especially common in patients younger than 5 years.
Presentation
Natural history and presentation
Tuberculosis meningitis (TBM) preferentially involves the meninges and basal cisterns of the brain and spinal cord. Infection of the brain parenchyma and spinal cord also occurs and can result in tuberculous granulomas, tuberculous abscesses, or cerebritis.
CNS TB affects the brain and meninges. Infection is hematogenously spread from a primary focus, usually in the lung. Infection starts in a subpial or subependymal cortical focus (ie, Rich focus), resulting in a granuloma that erodes into the subarachnoid space, causing basal leptomeningitis. The meningitis usually causes communicating hydrocephalus, but it may also cause obstruction of the foramina of Luschka and Magendie, resulting in obstructive hydrocephalus. Vasculitis involving the lenticulostriate and thalamoperforatoring arteries may occur and cause small infarcts in the deep gray-matter nuclei and deep white matter.4
Other manifestations of TB are focal parenchymal granulomas (eg, tuberculomas), tuberculous abscesses, tuberculous cerebritis, and pachymeningitis. Spinal cord infection is less common; it results in either arachnoiditis or, rarely, focal intramedullary tuberculomas.
Clinical diagnosis of TBM can be difficult, especially in low-prevalence regions of the world. TBM should be considered in the differential diagnosis if the patient has persistent low-grade fever, headache, and confusion. TBM is more common in patients who are immunosuppressed, such as older persons, young children, patients with HIV or diabetes, and patients taking steroids or cytotoxic drugs.5Patients with parenchymal tuberculomas often present with focal seizures.
In cases of spiral TB, radiologic interventions are usually limited to biopsy under ultrasonographic or fluoroscopic guidance.
Preferred Examination
Magnetic resonance imaging (MRI) with gadolinium enhancement is the preferred method of initial investigation. MRI is the most sensitive test for detecting the extent of leptomeningeal disease and is superior to computed tomography (CT) scanning in detecting parenchymal abnormalities, such as tuberculomas, abscesses, and infarctions. MRI also readily depicts hydrocephalus.6,7,8
Cerebrospinal fluid (CSF) analysis is usually used to detect a decreased glucose level, elevated protein levels, and a slight pleocytosis. Results of CSF polymerase chain reaction (PCR) assays may be diagnostic.
Limitations of Techniques
Conventional MRI may cause early meningitis and early infarcts to be missed, and no MRI findings are pathognomonic for TBM. Diffusion-weighted imaging, if available, depicts infarctions in the hyperacute stage.
Differential Diagnoses
Other Problems to Be Considered
Sarcoidosis
Carcinomatous meningitis
More on Tuberculosis, CNS |
 Overview: Tuberculosis, CNS |
| Imaging: Tuberculosis, CNS |
| Follow-up: Tuberculosis, CNS |
| Multimedia: Tuberculosis, CNS |
| References |
| Further Reading |
| Next Page » |
References
Friedman LN, Williams MT, Singh TP, Frieden TR. Tuberculosis, AIDS, and death among substance abusers on welfare in New York City. N Engl J Med. Mar 28 1996;334(13):828-33. [Medline].
Corbett EL, Watt CJ, Walker N, et al. The growing burden of tuberculosis: global trends and interactions with the HIV epidemic. Arch Intern Med. May 12 2003;163(9):1009-21. [Medline].
World Health Organization. Global Tuberculosis Control: Surveillance, Planning, Financing. Geneva: WHO Press; 2007. [Full Text].
Rock RB, Olin M, Baker CA, Molitor TW, Peterson PK. Central nervous system tuberculosis: pathogenesis and clinical aspects. Clin Microbiol Rev. Apr 2008;21(2):243-61, table of contents. [Medline].
Rafi W, Venkataswamy MM, Ravi V, et al. Rapid diagnosis of tuberculous meningitis: a comparative evaluation of in-house PCR assays involving three mycobacterial DNA sequences, IS6110, MPB-64 and 65 kDa antigen. J Neurol Sci. Jan 31 2007;252(2):163-8. [Medline].
Srikanth SG, Taly AB, Nagarajan K, et al. Clinicoradiological features of tuberculous meningitis in patients over 50 years of age. J Neurol Neurosurg Psychiatry. May 2007;78(5):536-8. [Medline].
Smith AB, Smirniotopoulos JG, Rushing EJ. From the archives of the AFIP: central nervous system infections associated with human immunodeficiency virus infection: radiologic-pathologic correlation. Radiographics. Nov-Dec 2008;28(7):2033-58. [Medline].
Semlali S, El Kharras A, Mahi M, Hsaini Y, Benameur M, Aziz N, et al. [Imaging features of CNS tuberculosis]. J Radiol. Feb 2008;89(2):209-20. [Medline].
Janse van Rensburg P, Andronikou S, van Toorn R, Pienaar M. Magnetic resonance imaging of miliary tuberculosis of the central nervous system in children with tuberculous meningitis. Pediatr Radiol. Dec 2008;38(12):1306-13. [Medline].
Appenzeller S, Faria AV, Zanardi VA, Fernandes SR, Costallat LT, Cendes F. Vascular involvement of the central nervous system and systemic diseases: etiologies and MRI findings. Rheumatol Int. Oct 2008;28(12):1229-37. [Medline].
Garg RK. Tuberculosis of the central nervous system. Postgrad Med J. Mar 1999;75(881):133-40. [Medline].
Osborn AG. Diagnostic Neuroradiology. St Louis, Mo: Mosby; 1994.
Shah GV. Central nervous system tuberculosis: imaging manifestations. Neuroimaging Clin N Am. May 2000;10(2):355-74. [Medline].
Zimmerman RA, Gibby WA, Carmody RF, eds. Neuroimaging: Clinical and Physical Principles. New York, NY: Springer-Verlag; 1999.
Keywords
tuberculosis of the central nervous system, TB, Mycobacterium tuberculosis, cerebral tuberculosis, cerebral granulomas, tuberculomas, tuberculous granulomas, tuberculous abscesses, granulomatous meningitis, granulomatous infection, tuberculous meningitis, TBM
