Massive middle cerebral artery stroke in a young patient with a large Chiari network and possible patent foramen ovale: A case report.

The Chiari network is a congenital remnant in the right atrium, usually considered benign, but its presence may increase the risk of paradoxical embolism when associated with a patent foramen ovale (PFO), particularly in young patients. We report the case of a previously healthy 2-year-old male who presented with sudden-onset right-sided hemiparesis and aphasia. Brain MRI revealed an acute ischemic infarction in the left middle cerebral artery (MCA) territory, and echocardiography identified a Chiari network in the right atrium. Although a PFO was suspected, it could not be conclusively confirmed due to diagnostic limitations. The patient was treated with antiplatelet therapy and showed significant neurological recovery at 6-month follow-up without recurrence. This case highlights the potential role of a Chiari network in facilitating paradoxical embolism in pediatric cryptogenic stroke and emphasizes the need for comprehensive cardiac evaluation and individualized management. While the Chiari network is often a benign finding, its association with PFO and the potential for stroke necessitate careful assessment, particularly in cryptogenic cases, and interventional strategies should be considered on a case-by-case basis to reduce the risk of recurrence.