Unraveling the Puzzle: A Case Report Questioning the Causal Relationship Between Subarachnoid Hemorrhage and Microscopic Polyangiitis.

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitides (AAV) are small-to-medium-vessel vasculitis, which includes granulomatosis with polyangiitis, microscopic polyangiitis (MPA), and eosinophilic granulomatosis with polyangiitis. MPA predominantly affects the kidneys and lungs. Subarachnoid hemorrhage (SAH), a life-threatening condition, rarely occurs with AAV. In this case, we present a 67-year-old female who presented with a sudden-onset headache after a recent diagnosis of ANCA-associated renal vasculitis. Kidney biopsy revealed pauci-immune glomerulonephritis, and serum was positive for ANCA along with myeloperoxidase antibody. A computed tomography scan of the head revealed both SAH and intraparenchymal hemorrhage. The patient was managed medically for SAH and intraparenchymal hemorrhage. ANCA vasculitis was treated with steroids and rituximab, and the patient showed improvement.