A previously healthy 33-year-old man went to an emergency department in Bogotá, Colombia, with an unusual complaint: his hand felt strange. For two hours, his left arm had been moving on its own and gave him the eerie sense that it did not belong to him.
It was not his first episode. About two weeks earlier, he had a brief bout of involuntary movements in the same arm that went away by itself. An MRI ordered to investigate that episode, done 48 hours before his emergency visit, had already shown small strokes on the right side of his brain.
Doctors diagnosed alien hand syndrome caused by stroke, and they traced the source to a common heart opening called a patent foramen ovale. Drixie D. Vargas and colleagues from Universidad El Bosque, Hospital Universitario Fundación Santa Fe de Bogotá, and other institutions described the case in August 2025 in Clinical Medicine Insights: Case Reports.
An Arm That Felt Like Someone Else’s
Alien hand syndrome is a rare condition in which a limb, usually a hand, makes involuntary movements that seem purposeful, often with the feeling that the limb is foreign. German neurologist Kurt Goldstein documented an early case in 1908, according to a 2025 review in the Orphanet Journal of Rare Diseases.
In the emergency department, the man’s standard neurological exam was surprisingly normal, which the authors attributed to his symptoms having fully resolved by then. His strength, reflexes, and sensation tested fine, including detailed touch tests. MRI showed multiple small infarcts in the right frontal and parietal lobes, with features of both new and slightly older damage.
The right side of the brain controls the left side of the body. Researchers describe several forms of the syndrome. According to a 2025 report in Frontiers in Human Neuroscience, the posterior form is linked to lesions in the non-dominant parietal lobe, thalamus or medial temporal lobe and features the sense of an alien hand with aimless movements. The Colombian authors did not assign their patient to a specific subtype.
Searching a Young Man’s Body for the Clot
Strokes in young, healthy adults set off a search for an unusual cause, because the usual culprits, such as high blood pressure and clogged arteries, are less likely. His neck and brain arteries showed no narrowing, tears, or plaque. His thyroid, cholesterol, and blood sugar were normal. Seven days of heart-rhythm monitoring found no atrial fibrillation; blood tests for clotting disorders were normal, and no clot was found in his leg veins.
The answer came from an ultrasound probe passed down his esophagus. It showed a small, tunnel-shaped patent foramen ovale, a flap-like opening between the heart’s upper chambers, along with an unusually mobile wall between those chambers. When he strained, blood crossed from the right side of the heart to the left.
That route matters. Normally, small clots from the veins travel to the lungs, which filter them out. A patent foramen ovale can let a clot skip the lungs and travel to the brain, a process called paradoxical embolism. The team concluded that this is what caused his strokes.
A Common Opening With Rare Consequences
Everyone has this opening before birth, and in most people it seals. When the FDA approved the Amplatzer PFO Occluder in October 2016, the agency said about 25% to 30% of people in the United States have a patent foramen ovale, which usually causes no problems and needs no treatment.
The approval was based on the RESPECT trial of 980 patients with a patent foramen ovale and a stroke of unknown cause. In that study, the FDA said the device combined with blood thinners was associated with about a 50% reduction in the rate of new strokes compared with blood thinners alone.
The Colombian team closed the man’s opening with an Amplatzer device placed through a catheter, citing his high-risk anatomy, including the tunnel shape and mobile septum, and the absence of any other cause. He went home on two antiplatelet drugs and a high-dose statin. By six months, his involuntary hand movements had resolved completely, and he had returned to work and driving.
Strange Symptoms Can Still Mean Stroke
The case is one patient, and the authors cannot prove the heart opening caused the stroke, only that other likely causes were ruled out after an extensive workup. PFO closure is not appropriate for everyone. The FDA advised that patients be carefully evaluated by both a neurologist and a cardiologist to rule out other causes before closure.
Alien hand syndrome after stroke often improves. A 2020 case report described a 45-year-old man whose symptoms from a very small stroke resolved within an hour, and the Frontiers authors described stroke-related cases as generally reversible.
The broader lesson is that stroke does not always look like the classic facial droop or slurred speech. A sudden sense that a limb is not one’s own, or that it is moving without permission, can be a sign of brain injury. Anyone who experiences sudden unexplained changes in movement, sensation, speech, or vision should call 911 immediately, even if the symptoms fade.
Key Questions Answered
What happened to the man?
His left arm felt foreign and moved involuntarily. MRI showed small strokes in the right frontal and parietal lobes.
What is alien hand syndrome?
A rare condition in which a limb makes involuntary, seemingly purposeful movements, often with a feeling that it belongs to someone else.
What caused his stroke?
Doctors concluded that a clot passed through a patent foramen ovale, a small opening between the heart’s upper chambers.
How common is a patent foramen ovale?
The FDA has said about 25% to 30% of Americans have one. Most never have problems.
How was he treated?
Doctors closed the opening with an implanted device and prescribed antiplatelet drugs and a statin. His symptoms resolved within six months.
When should someone call 911?
For any sudden change in movement, sensation, speech, or vision, including a limb that suddenly feels foreign or moves on its own.
Published by Medicaldaily.com
