Primary CNS Vasculitis—Navigating the Diagnostic Challenge: A Case Report

Primary central nervous system vasculitis, also known as primary angiitis of the central nervous system (PACNS), is a rare inflammatory condition confined to the central nervous system vasculature, with an estimated incidence of approximately 2.4 cases per million person-years. 1 It is considered a diagnosis of exclusion, as clinical manifestations are diverse-ranging from focal neurological deficits to diffuse cognitive changes.Although its etiology remains uncertain, proposed associations include infections, connective tissue diseases, systemic vasculitides, and cerebral amyloid angiopathy.The absence of reliable biomarkers and overlapping features with other neurological disorders complicates recognition.2 case descrIptIon A 19-year-old female presented with two episodes of abnormal movements and irritability over three days.She had no significant medical history and was initially diagnosed with a dissociative disorder.On examination, she appeared drowsy and irritable, with no signs of systemic vasculitis or any other systemic diseases.Baseline laboratory investigations were unremarkable (Table 1).To establish the diagnosis, further evaluations were undertaken, including cerebrospinal fluid (CSF) analysis (Table 2), magnetic resonance imaging (MRI), computed tomography (CT) angiography, and electroencephalography (EEG) (Table 3).These investigations revealed vascular abnormalities, raising strong suspicion for PACNS.During the course of hospitalization, she later developed urinary incontinence and right-sided weakness, further supporting progressive central nervous involvement.After exclusion of infectious, systemic, and autoimmune causes, a working diagnosis of PACNS was established.Treatment was initiated with oral prednisolone and azathioprine, along with anticonvulsant, anticoagulant, and antiplatelet therapy.The patient demonstrated clinical improvement; however, follow-up neuroimaging revealed persistent lesions, indicating ongoing disease activity.