Central nervous system disorders

III./3.3.: Granulomatous meningitis – special form of meningitides

III./3.3.1.General features

It is characterized by perivascular inflammation, granulomatous tissue growth, large amount of exsudative fluid collection, followed by reactive fibrosis. Basilar tuberculous meningitis is caused by a primary tuberculous inflammation or it develops as part of the generalised miliary tuberculosis (infants, babies). Sarcoid meningitis is also a granulomatous form. Intracerebral sarcoidosis occurs also often (simple or multiple). Fungal meningitis belongs also here as a non purulent inflammation (candidiasis, cryptococcosis, coccidiomycosis, actinomycosis, aspergillosis) and its outcome can be acute, fatal, and also indolent (e.g. steroid therapy – aspergillosis). Cerebritis, hydrocephalus and abscess can be also a consequence of granulomatous meningitides.

III./3.3.2.: CT examination

Unenhanced CT examination demonstrates that the basal and suprasellar cisterns, and the Sylvius sulci are filled and isodense, and the normal hypodensity of the liquor (compared to the cerebrum) is not visible in them. Contrast enhanced CT examination demonstrates a strong subarachnoid enhancement following contrast administration in the above mentioned localisations, however, not only the meninges but also the gyri take part in the enhancement.

Later, calcification can develop on the meninges, and hypodensity of the white matter can be observed.

III./3.3.3.: MR examination

On T2 weighted images, signal intensity of the inflammatory-granulomatous tissue is also high in the basal cisterns similarly to one of the liquor – therefore, it is not enough to demonstrate the presence of granulomatous tissue. Contrast enhanced examination (Gadolinium – Gd) identifies the strong enhancement of the granulomatous-inflammatory tissue. Same as in purulent meningitides, obstruction of basal cisterns and that the granulomatous tissue coats the cerebral surface quasi glazewise inhibiting the liquor circulation and absorption, the process leads to hydrocephalus. Through arteritides, cerebral infarctions can develop here as well.