Imaging meningo-encephalic tuberculosis

https://doi.org/10.1016/j.ejrad.2005.04.017Get rights and content

Abstract

Tuberculosis is becoming an increasingly troublesome public health problem mostly because of incomplete therapy of existing cases giving rise to multi-drug resistant strains and because of increase in immunodeficiency states from various causes. The disease affects preferentially economically underprivileged individuals. In this paper, we review the pathogenesis and radiological findings of meningo-encephalic tuberculosis. Imaging manifestations are very pleomorphic and can mimic parenchymal cerebral mass lesions or meningeal processes of different nature. Although imaging findings are generally non-specific, modern imaging plays a key role in the diagnosis. A high index of suspicion in the appropriate clinical and laboratorial setting may promote rapid diagnosis and institution of therapeutic measures that avoid death or serious neurological consequences.

Introduction

Tuberculosis (TB) is a disease caused by bacteria belonging to the Mycobacterium tuberculosis complex. First observed thousands of years ago, the infectious etiology of tuberculosis was debated until Robert Koch's discovery of the tubercle bacillus in 1882.

Improvement of socio-economic conditions, isolation of patients and the advent of anti-mycobacterial drugs led to a marked decrease in incidence. However, the disease has been returning since the mid 1980s partly because of incomplete therapy of existing cases and also because of increase in immunodeficiency states from various causes, including organ transplantation, treatment of certain malignant diseases and acquired immunodeficiency syndrome (AIDS). Thus, TB is becoming an increasingly troublesome public health problem. The rise in multi-drug resistant strains also makes the subject of tuberculosis one of universal concern. In 1993, it was declared a “global emergency” by the World Health Organization who stressed that almost one-third of the world population is infected with Mycobacterium tuberculosis [1].

Central nervous system (CNS) involvement occurs in 2–5% of all TB patients and in up to 15% of AIDS patients [2]. Coexistent pulmonary TB is often present [3], [4], seen in 25–83% of cases of CNS TB. Adult TB is most often a postprimary infection whereas most cases in children are due to primary infection [5]. The bacilli reach the CNS in most cases by hematogeneous spread, usually from a pulmonary focus but also from a gastrointestinal or genitourinary source. CNS infection causes a granulomatous inflammatory reaction that involves the meninges and/or brain parenchyma. In this paper, we review the contribution of modern neuroradiology to the diagnosis of meningo-encephalic tuberculosis.

Section snippets

Leptomeningeal TB

Considering all age groups meningitis is the most common manifestation of CNS TB [2], often developing in protein-calorie malnutrition in children or prolonged dysnutrition in adults, and affecting mostly economically underprivileged societies [6]. It remains a condition with high mortality due in part to the long duration of the process before therapy is started [7]. CSF studies typically reveal pleocytosis with low glucose and elevated protein. It is important to obtain PCR for TB and to

Parenchymal TB

Parenchymal lesions of TB occur anywhere in the brain parenchyma, with or without coexistent meningitis.

Tuberculous granuloma (tuberculoma) is the most common form of parenchymal lesion. They may be solitary, multiple or miliary in distribution. Tuberculomas may be secondary to hematogenous spread of systemic disease or may evolve from extension of CSF infection into the adjacent parenchyma via cortical veins or small penetrating arteries. They originate as a conglomerate of microgranulomata in

Other locations of cranial-encephalic TB

Other locations of cranial-encephalic tuberculosis such as epidural tuberculoma or empyema [40], [41], or subdural empyema [42] are rare. Epidural empyema may be associated with skull osteitis (Fig. 6).

Summary

Contrast-enhanced MR imaging is generally considered the modality of choice in the detection and assessment of meningo-encephalic tuberculosis. Imaging manifestations are very pleomorphic and can mimic parenchymal cerebral mass lesions or meningeal processes of different nature. Although imaging findings are generally non-specific, modern imaging plays a key role in the diagnoses. Magnetization transfer MR imaging and chemical analysis with in vivo MR spectroscopy may improve diagnostic

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