Isolated CNS vasculitis

AKA isolated angiitis of the CNS. Rare (≈ 20 cases reported32 as of 1983); limited to vessels of CNS. Small vessel vasculitis is ≈ always present → segmental inflammation and necrosis of small leptomeningeal and parenchymal blood vessels with surrounding tissue ischemia or hemorrhage.

Combinations of H/A, confusion, dementia, and lethargy. Occasionally seizures. Focal and multifocal brain disturbance occurs in > 80%. Visual symptoms are frequent (secondary either to involvement of choroidal and retinal arteries, or to involvement of visual cortex → visual hallucinations). Evaluation ESR & WBC count are usually normal. CSF may be normal or have pleocytosis and/or elevated pro- tein. CT may show enhancing areas of low density. Angiography (required for diagnosis): characteristically shows multiple areas of symmetrical nar- rowing (“string of pearls” configuration). If normal, it does not exclude diagnosis. Histological diagnosis (recommended): all biopsy material should be cultured. Brain parenchyma biopsy infrequently shows vasculitis. Leptomeningeal biopsy invariably shows involvement.

Reportedly fatal if untreated, but may smolder for years. Rarity of this condition makes treatment uncertain. Recommended: cyclophosphamide (Cytoxan®) 2 mg/kg/d and prednisone 1 mg/kg/d qod therapy. NB: this condition is thought to be T-cell mediated, but prednisone causes more B-cell suppres- sion, therefore breakthrough during prednisone therapy is not uncommon.