Patient is a known C/O pulmonary tuberculosis(is on
anti-tuberculous line of treatment since late 1996 - Lymph Node biopsy was suggestive of
tuberculous lymphadenitis).
In mid 1998 patient presented with an altered mental state (meningeal signs +).
A sliver which is near isointense to brain parenchyma on the T1W images is
seen to overlie the left fronto-temporal lobes with erosion of the adjacent bone. This
lesion is hypointense on the T2W images and enhances intensely on the post-contrast
images.
The left sylvian fissure is obliterated and shows areas of enhancement on the
post-contrast images.This would suggest a leptomeningeal pathology/exudates.
This patient also had involvement of the atlanto-axial region.
Pathogenesis: |
Rupture of subependymal/subpial granulomata into the CSF.
Penetration of the meningeal vessel walls(by hematogenous spread - GI/Pulmonary).
As a result the basal meninges are involved and thick exudates are found in the basal cisterns. Coursing arteries(especially the MCA and it's branches) get involved directly or by reactive endarteritis obliterans. As a result spasm and intimal changes ending in thrombosis and infarction ensue.
Patients may present with fever, headaches, altered mental status and meningeal signs.
On MRI: |
Enhancement of the meninges, especially in the basal cisterns.
Obliteration of the cisterns/sulcal spaces by exudates on the non-enhanced scans.
Communicating hydrocephalus(occasionally-obstructive, due to parenchymal lesions or granulomatous ependymitis).
May find infarcts-especially in the basal ganglia.
Meningeal disease and non-enhancing lesions are commonly encountered in HIV positive patients.
| Differential Diagnosis: |
Leptomeningeal carcinomatosis.
Sarcoid.
Lymphoma/Leukemia.