A Diagnostic Conundrum in Case of Primary Central Nervous System Vasculitis Presenting as Young Stroke

Primary Central Nervous System Vasculitis (PCNSV) is a rare inflammatory condition affecting the blood vessels in the brain and spinal cord, without signs of systemic vasculitis. The symptoms of PCNSV are typically non-specific and varied. This case involves a 16-year-old female who arrived at the emergency department with tingling and numbness in her left upper and lower extremities since waking up that morning. Within hours, she developed significant weakness in her left arm and leg. She had no significant medical history, comorbidities, or history of substance use. On examination, her vitals were stable, and she was fully conscious and oriented. Neurological examination revealed right-sided mouth deviation and decreased muscle power in her left limbs, while sensory function remained normal. Routine blood tests were normal, except for mildly elevated Erythrocyte Sedimentation Rate (ESR) and C-Reactive Protein (CRP). Autoimmune markers and complement levels were within normal limits. Cerebrospinal Fluid (CSF) analysis showed lymphocytic pleocytosis and mildly elevated protein levels. Magnetic Resonance Imaging (MRI) brain imaging revealed multiple small, acute, non-haemorrhagic infarcts in the right frontoparietal and temporo-occipital regions. MR angiography indicated thrombosis in the right internal carotid artery, with extensive thickening and constriction in various segments, consistent with PCNSV. She was treated with dual antiplatelet therapy, antiepileptics, methylprednisolone pulse therapy, and intravenous cyclophosphamide, followed by maintenance therapy with methotrexate and oral steroids. This case underscores the importance of early recognition and aggressive treatment of PCNSV to prevent long-term neurological deficits. Reporting this case is crucial as it highlights an atypical presentation in a young female, emphasising the need for awareness and comprehensive diagnostic approaches.