Inferior Oblique Muscle Paralysis-Associated Strabismus in Orbital Blowout Fracture: A case report

Abstract

　　Orbital blowout fractures often involve limitations in superior and inferior rotations due to inferior rectus muscle paralysis. However, strabismus caused by inferior oblique muscle paralysis is rarely reported as a primary symptom. We present the case of a 62-year-old man with an orbital blowout fracture and strabismus caused by inferior oblique muscle paralysis. The fracture line was proximal to the muscle’s origin, suggesting possible interference with the muscle and surrounding swollen tissue. Owing to severe diplopia, ocular motility disorder without improvement, and the unaffected ophthalmus overaction (identified on the preoperative Hess chart), we suspected inferior oblique muscle entrapment and performed orbital fracture surgery on the 9th day after the injury. The surgery successfully corrected the entrapment and improved the strabismus. Further studies are needed to clarify optimal indications and the timing of surgery in such cases.