Clinical Spectrum and One-Year Outcomes of Central Nervous System Vasculitis Secondary to Systemic Autoimmune Disorders: A Retrospective Cohort Study.

Introduction Central nervous system (CNS) vasculitis (CNSV) is a rare but serious complication of systemic autoimmune disorders, including systemic lupus erythematosus, antineutrophil cytoplasmic antibodies (ANCA)-associated vasculitis, rheumatoid arthritis, polyarteritis nodosa, Sjögren's syndrome, and mixed connective tissue disease. Existing literature predominantly addresses primary CNSV, with limited systematic follow-up of secondary CNS involvement. This study aimed to describe the clinical spectrum, laboratory and imaging features, treatment strategies, and one-year outcomes of CNSV secondary to autoimmune diseases, while identifying predictors of prognosis. Methods This retrospective cohort study was conducted at Madras Medical College, Chennai, India, between May 2024 and May 2025. Consecutive adult patients with established systemic autoimmune disorders who developed CNS manifestations consistent with vasculitis were included. Patients with primary CNSV or infectious, neoplastic, or metabolic mimics were excluded. Clinical features, laboratory data, and neuroimaging findings were extracted from records using a structured proforma. Treatments were categorized as corticosteroids alone, steroids plus conventional immunosuppressants, or steroids plus biologics. Patients were followed for 12 months, with functional outcome assessed by modified Rankin Scale (mRS); a favorable outcome was defined as mRS 0-2. Relapse was defined as a new deficit after stabilization with radiological confirmation.  Results A total of 150 patients were studied (mean age 42.6 ± 12.4 years; 54.7% female). The most common underlying disease was lupus (70 patients, 46.7%), followed by ANCA-vasculitis (35 patients, 23.3%). Stroke-like presentations were seen in 70 patients (46.7%), seizures in 40 patients (26.7%), encephalopathy in 30 patients (20%), and focal motor/sensory deficits in 50 patients (33.3%), with 65 patients (43.3%) showing overlapping features. ANA was positive in 75 patients (50%), anti-dsDNA in 55 patients (36.7%), ANCA in 45 patients (30%), and multiple antibody positivity in 50 (33.3%). Very high antibody titers and elevated C-reactive protein (CRP) correlated with poor outcomes, while moderate titers did not. MRI abnormalities were present in 135 patients (90%), most often multiple-territory infarcts in 55 patients (36.7%), lacunar infarcts in 40 patients (26.7%), and white matter hyperintensities in 45 patients (30%). At one year, favorable outcomes increased from 70 patients (46.7%) at discharge to 85 patients (56.7%); relapse occurred in 30 patients (20%), recurrent admissions in 25 patients (16.7%), and mortality was seen in 20 patients (13.3%). Conclusion CNSV secondary to systemic autoimmune disease is clinically heterogeneous, with frequent systemic and neurological overlap, high inflammatory burden, and multifocal imaging abnormalities. Prognosis was significantly influenced by treatment timing, inflammatory markers, and antibody titers. Early initiation of immunosuppression and combination regimens were associated with better recovery, while delayed therapy and multiple antibody positivity predicted relapse and disability. Despite adherence to guideline-based therapy, mortality and relapse remained considerable, emphasizing the need for early recognition, aggressive therapy, and structured long-term follow-up.