cPACNS is a challenging diagnosis to make. There are two types: (1) angiography-positive, which affects medium to large vessels and requires an abnormal angiography, and (2) angiography-negative, which affects small vessels and is confirmed via brain biopsy. There are no standardized treatment guidelines, but experts recommend early immunosuppressive therapy to optimize recovery.

This is a case report describing an adolescent female who presented with a few months history of dysphagia, sialorrhea, coughing, and gait imbalance. Neurology was consulted when she had an acute onset of hemisensorimotor deficits and multiple cranial neuropathies. The initial diagnosis included an inflammatory versus autoimmune condition. She had a rapid decline in her exam and our team started steroids, IVIG, and plasmapheresis prior to a definitive diagnosis. After extensive testing, she was found to have cPACNS. A systematic review of cPACNS was performed using PubMed.

Brain MRI was notable for multifocal cerebral encephalomalacia and heterogeneously enhancing lesions in the left midbrain and right temporal lobe. Angiography was negative, raising suspicion for small vessel vasculitis. Lesional brain biopsy was non-specific. Repeat brain MRI performed a month later for mental status decline showed a new active lesion, which was subsequently biopsied, showing vasculitis. Three months into her hospitalization, immunotherapy was started.

cPACNS is a rare disease that can present with subtle neurological findings. Early initiation of immunotherapy can improve outcome, therefore it is important to recognize cPACNS and know that proving angiography-negative cPACNS may require repeated brain biopsies (gold standard for diagnosis).