Pulled-in-two syndrome: a multicenter survey of risk factors, management and outcomes

Background Pulled-in-two syndrome (PITS) is a serious complication of strabismus surgery that occurs when an extraocular muscle ruptures under tension. The purpose of this study was to establish a database of PITS patients to identify risk factors and management of PITS. Methods Strabismus surgeons from around the world contributed cases of PITS through an online survey. Risk factors, management, and outcomes were identified. Results A total of 40 cases of PITS from 29 physicians in 6 countries were collected. The most commonly involved muscles were the medial rectus (18/40 [45%]) and the inferior rectus (17/40 [43%]). The most commonly identified risk factors were previous ocular surgery (11/40 [28%]) and cranial nerve palsy (11/40 [28%]). Advanced age was also a significant risk factor, with 28/40 (70%) of reported patients being ≥50 years of age. In most cases the muscle was found and reattached to the globe (28/40 [70%]). The muscle was lost in 12 cases (30%). Half of these patients received a transposition surgery; the other half were followed by observation. Conclusions Our data suggests that strabismus surgeons might encounter one case of PITS approximately every 10 years. Major risk factors for PITS appear to be changes in the extraocular muscle due to cranial nerve palsy, prior surgery, and advancing age. The preferred management for PITS is surgical recovery and reattachment of the muscle; however, if the muscle is lost, transposition surgery or observation are common forms of management.