Primary Angiitis of the Central Nervous System - Diagnosis and Management

Primary angiitis of central nervous system (PACNS) is a rare idiopathic disorder affecting blood vessels of brain, spinal cord, and meninges, consequently leading to infarct and less frequently hemorrhage. CNS vasculitis can also occur as part of systemic vasculitis or secondary to autoimmune diseases or infections. The clinical manifestations of PACNS are non-specific and no single laboratory investigation or neuroimaging finding can reliably diagnose this condition. Histopathological evidence of transmural inflammation of blood vessels of CNS is the gold standard, but is generally pursued subsequent to conventional angiogram (CA) because of its invasive nature. The differentials of PACNS are exhaustive and include systemic vasculitis, secondary vasculitis, non-inflammatory intracranial vasculopathies, demyelination, and neoplasm. These alternative conditions can often be distinguished by history, examination, immunological testing, cerebrospinal fluid analysis, and neuroimaging. CA can detect vasculitic changes in the large to medium cerebral arteries but the specificity is low. Recent advancements in vessel wall imaging techniques have further enabled the distinction of various intracranial vasculopathies from CNS vasculitis. The disease has considerable morbidity and fatality unless timely treatment with immunosuppressive agents is initiated. Induction therapy with glucocorticoids and cyclophosphamide followed by azathioprine, mycophenolate mofetil, or methotrexate as maintenance therapy is the cornerstone of management. Biological agents such as rituximab and anti-tumour necrosis factor alpha inhibitors (infliximab and etanercept) may be used in refractory cases. This review discusses the approach to the diagnosis, determinants of outcome, and management.