Tuberculous rhombencephalitis

Tuberculous rhombencephalitis is a particular form of neurotuberculosis that affects primarily the hindbrain (brainstem and cerebellum) and usually is manifested as a tuberculoma.

Please refer to the article on rhombencephalitis for a general discussion of that entity.

Studies have shown that in the USA ~5% of all TB cases involve CNS, and this percentage rises to ~25% (range 15-40%) in patients with AIDS 2. Brainstem involvement is rare, corresponding only to ~5% (range 2.5-8%) of CNS tuberculomas 1

Brainstem tuberculomas are usually focal lesions causing focal neurological symptoms related to the involvement of a cranial nerve nuclei. 

Tubercular meningitis is commonly associated in a tuberculous rhombencephalitis.

Hydrocephalus could be present when it causes obstruction to CSF flow.

CSF study 2:

  • increased leukocyte count 
  • increased protein 
  • normal or low glucose levels

Diagnosis sometimes is challenging and made by the combination of clinical presentation, imaging, laboratory and treatment response. 

Aetiology

Mycobacterium tuberculosis, also know as Koch's bacillus. 

Beam-hardening artifacts limit the visualization of the brainstem on CT images and MRI is the imaging modality of choice for the assessment of patients with suspected pathology in that anatomic location. Protocols, both on CT as on MRI, should include contrast. 

As systemic tuberculosis is present in ~ 55% of brainstem tuberculomas 1, further investigation such as chest radiography should be considered. 

CT  

Tuberculomas are usually presented as ring-enhancing lesions with a central hypointense area (necrotic center: solid caseous, fibrotic material, and macrophages).

MRI
  • T1
    • isointense to grey-matter 3
    • may have central region of hyperintensity representing caseation
  • T2
    • isointense to grey-matter
    • may have central region of hypointensity representing gliosis and abundant monocyte infiltration 3
    • lesions are surrounded by vasogenic oedema
  • T1 C+ (Gd)
    • usually appears as ring-enhancement
    • may appear as a conglomerate enhancing mass
  • MR spectroscopy
    • decrease in NAA/Cr
    • slight decrease in NAA/Cho
    • lipid-lactate peaks are usually elevated (86%) 4
Nuclear Medicine

Positive emission tomography (PET) scan can be used to help distinguishing between a tumour (e.g. brainstem gliomas or lymphomas) and tuberculomas.

Treatment of CNS tuberculosis is based on an anti-tubercular treatment regimen. However, multi-drug resistant tuberculosis remains a major hurdle in treatment.

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Article Information

rID: 32697
Section: Pathology
Tags: cases, refs
Synonyms or Alternate Spellings:
  • Brainstem tuberculoma
  • Pons tuberculoma
  • Brainstem tuberculosis
  • Tuberculous rhomboencephalitis

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