Isolated Ischemic Inferior Rectus Paresis Related to Patent Foramen Ovale.

Isolated paresis of the inferior rectus muscle (IRM) represents a rare occurrence. This case report involves a young adult male who, abruptly during a Valsalva maneuver, encountered acute vertical diplopia due to right IRM paresis, resolving spontaneously within a few hours. The patient presented without identifiable risk factors, and magnetic resonance imaging revealed a minor left thalamic ischemic lesion. A cardiac study identified the presence of a patent foramen ovale, potentially associated with a paradoxical embolism, indicating its likely role in this transient ischemic event.