Traumatic Lysis of the Inferior Rectus Muscle

Background: The study aims to report a rare case of traumatic lysis of inferior rectus muscle after a traffic accident. Methods: This is a case report wherein the clinical features, computed tomographic findings, and surgical treatment were presented. Results: A 42-year-old woman complained of double vision and upward deviation of the left eye for 13 months after being involved in a traffic accident. The alternate prism and cover test both at distance and near testing showed an exotropia of 18 prism diopters (PD) and hypertropia of 50 PD of the left eye. The left eye had complete restriction of downward movement, and the forced duction test was negative. Computed tomography disclosed that the middle portion of the left inferior rectus muscle was absent. Diagnosis was traumatic lysis of left inferior rectus muscle. The deviation of the left eye was corrected by left superior rectus muscle recession and partial transposition of the medial and lateral rectus muscles. Six months after surgery, no deviation at the primary position both at distance and near testing was present; however, the left eye remained at a -3 restriction of downward movement. Conclusions: Paralysis of the inferior rectus muscle may have resulted from the traumatic lysis, a rare clinical feature that can be confirmed by computed tomography.