Case of the Week

Background:

• Tuberculous meningitis with leptomeningeal exudates in the basal cisterns may be associated with vasculitis that leads to acute infarcts.
• Tuberculous myelitis is associated with tuberculous meningitis or tuberculous arachnoiditis. It can be short or long segment (as in our case). It most commonly affects the thoracic or cervical cord. Pathophysiology of transverse myelitis in the setting of tuberculosis infection is caused by an abnormal immune reaction against the mycobacterial antigen. It may also be due to direct infection by the bacillus or due to drug toxicity.

Clinical Presentation:

• Patients with vasculitis and acute infarcts present with motor or sensory deficits, and potentially hemiplegia / hemiparesis.
• Patients with myelitis present with motor, sensory, and bladder complaints.

Key Diagnostic Features:

• Acute infarct and tuberculous vasculitis
  • Focal restricted diffusion in a vascular territory (typically lenticulostriate)
  • Irregularity and narrowing of the vessels (most commonly MCA M1 and M2 segments)
  • Enhancement in the basal cisterns (including the Sylvian cisterns)

• Myelitis/myelopathy
  • T2 hyperintense signal in the central cord parenchyma – short or long segment
  • Enhancement along the cord surface or along the nerve roots of the cauda equina (arachnoiditis)

Differential Diagnoses:

• Other causes of basilar meningitis: other infective etiologies such as pyogenic and fungal infections, inflammatory etiologies such as sarcoidosis, and neoplastic etiologies such as carcinomatous meningitis. Tuberculous meningitis is the most likely cause of basal meningitis in the endemic setting in an immunocompetent child without any other history of malignancy.
• Other causes of infarcts like primary CNS vasculitis: the features of meningitis and ring-enhancing lesions (granulomas) are a clue indicating tuberculosis.
• Other causes of longitudinally extensive transverse myelitis such as NMO, sarcoidosis: The features of meningitis and ring-enhancing lesions (granulomas) are a clue indicating tuberculosis.

Treatment:

• Antituberculous treatment, 6–8 weeks of steroids