Cauda equina syndrome as a clinical presentation of primary angiitis of the central nervous system (PACNS)

Primary angiitis of the central nervous system (PACNS) is a form of vasculitis affecting the central nervous system (CNS) that is not associated with systemic disease or vasculitis outside the CNS. It is a rare disease with significant morbidity and mortality. Delay in diagnosis and treatment is common due to its nonspecific clinical symptoms and lack of efficient noninvasive diagnostic tests. The finding of vasculitis in the leptomeningeal and cortical biopsy sample has remained the gold standard for making the diagnosis of PACNS. We describe a patient whose clinical symptoms of cauda equina syndrome led to a nerve root biopsy that was consistent with PACNS despite prior extensive investigations including a brain biopsy. This report highlights the cauda equina syndrome as a clinical presentation of PACNS and emphasizes the need for awareness of this rare condition.