Alien Hand Syndrome as the Initial Presentation of Patent Foramen Ovale-Associated Stroke.

Alien Hand Syndrome (AHS) is a rare neurological condition characterized by involuntary, goal-directed movements of a limb without conscious control. It is most often associated with stroke in specific brain regions, including the medial frontal and parietal cortices. We report the case of a 33-year-old male with no previous medical history who presented with involuntary movements of the left upper limb, describing it as "moving on its own." Neurological examination was unremarkable, but MRI revealed multiple cortical infarcts in the right frontal and parietal lobes, with both acute and subacute features. Extensive workup ruled out vascular stenosis, dissection, and hypercoagulable states. Transthoracic echocardiography showed normal left ventricular function and a hypermobile interatrial septum. Transesophageal echocardiography confirmed the presence of a tunnel-shaped patent foramen ovale (PFO; 0.4 mm × 0.3 mm) without thrombus. No deep vein thrombosis or other embolic sources were found. A diagnosis of cardioembolic stroke due to paradoxical embolism through a PFO was established. The patient underwent successful percutaneous closure and started dual antiplatelet therapy. At follow-up, AHS symptoms improved significantly. This case highlights an atypical initial presentation of ischemic stroke in a young adult and emphasizes the need for early neuroimaging and comprehensive cardiac evaluation in cryptogenic strokes.