Secondary polycythemia as a rare cause of ischemic stroke: A case report.

Polycythemia is a known but underrecognized risk factor for ischemic stroke, particularly in the setting of chronic hypoxia. We report a rare case of pontine infarction associated with secondary polycythemia in a patient with chronic respiratory failure. A 52-year-old middle-aged man with a history of hypertension, combined pulmonary fibrosis and emphysema syndrome, receiving long-term oxygen therapy as well as bronchodilator treatment, presented with sudden-onset left-sided hemiparesis. Neurological examination confirmed a pyramidal syndrome. Brain MRI revealed an acute infarct in the left pons. Laboratory findings showed a hematocrit of 62.5% and elevated hemoglobin (20.1 g/dL). Work-up excluded primary polycythemia and revealed an elevated erythropoietin level (78.2 mIU/mL), consistent with a secondary hypoxia-induced cause. Oxygen saturation on room air was 88%. No atherosclerotic or cardioembolic sources were found. The patient underwent 6 therapeutic phlebotomy sessions over 3 weeks, which reduced hematocrit to 48.7%. Neurological symptoms improved within 4 days, with a modified Rankin Score improving from 3 to 1 at discharge. This case highlights the importance of considering secondary polycythemia in patients presenting with cryptogenic stroke and underlying chronic hypoxia. Early diagnosis and targeted interventions, including phlebotomy and antiplatelet therapy, can prevent recurrence and improve outcomes.