Case Presentation: A 51-year-old woman presented to the ER with acute altered mental status, left-sided weakness, and fever. Her medical history includes hypertension, hyperlipidemia, complex migraines, and strokes (2021, 2024). A stroke code was activated. Vital signs showed fever 40.6°C, HR 120, and BP 180/100 mmHg. Labs showed leukocytosis and lactic acidosis. Physical exam revealed mild dysarthria and left-sided neglect. Differential diagnosis included CNS infection, seizure, stroke, and complex migraine. Imaging showed chronic infarcts and mild vascular stenosis progression with no acute stroke. Continuous EEG (cEEG) had no epileptiform activity, and urine toxicology was negative. Empiric antimicrobials were started for possible CNS infection.The next morning she became obtunded; head CT was stable, but cEEG revealed seizure. Levetiracetam was initiated, and a lumbar puncture (LP) revealed no infection, so antibiotics were discontinued.Of note, in 2024, the patient was started on high-dose steroids for presumed primary central nervous system vasculitis (PCNSV) after recurrent strokes. The workup, including autoimmune testing, MRI, PET, LP, and skin biopsy, was inconclusive. Steroids were tapered off in July 2025 with plans for repeat testing. LP four days before her presentation was unremarkable.As the workup progressed, CNS vasculitis was again considered, and she received one dose of rituximab with improvement. On discharge, she had slowed responses/speech and minimal left-sided pronation without drift. Lacking insurance coverage, she could not receive additional rituximab outpatient and returned to the ER one month later with dysarthria, left-sided facial droop, and confusion.
Discussion: Cerebral vasculitis is the inflammation of blood vessels in the brain or spinal cord, classified as primary (idiopathic) or secondary (systemic) 1. Secondary CNS vasculitis results from conditions such as infections, autoimmune diseases, and malignancies, making diagnosis easier due to organ involvement and identifiable lab markers 1,2.In this case, high fever, recent LP, and neurological deficits raised initial concerns for CNS infection and stroke – common life-threatening diagnoses. Given the patient’s history, PCNSV should also be considered, as it can manifest with similar symptoms such as headaches, seizures, altered mental status, and focal neurological deficits 2,3. Although fever is atypical for PCNSV, it has been observed 3,4 . PCNSV is a rare condition with an incidence of 2.4 cases per million 5. Diagnosis is challenging due to the lack of definitive tests and the suboptimal sensitivity of available options 1,6. An exhaustive multidisciplinary workup is necessary to rule out mimics 6. Early immunosuppressive therapy, often with corticosteroids, cyclophosphamide, or rituximab, is essential 2,5. Serial MRI scans can help assess disease activity, especially during periods of altering medications 2. This patient received only one dose of rituximab but could not continue treatment, leading to readmission, illustrating how social determinants of health can impede disease control. Prognosis varies based on the extent of the disease and the timeliness of treatment, with prompt therapy improving outcomes 1,4.
Conclusions: PCNSV should be considered when evaluating a patient for acute or recurrent neurological symptoms. For a favorable prognosis, early identification and initiation of treatment are key. Corticosteroids and other immunosuppressants remain the treatment of choice.