Lateral Rectus Muscle Entrapment in Complex Orbital Fracture in a Child.

A 6-year-old boy presented with a lateral rectus muscle entrapment in a complex orbital fracture sustained during bicycle riding. He was diagnosed with a skull-base fracture with pneumocephalus and zygomatic and inferior orbital wall fractures at another hospital. The zygomatic fracture and pneumocephalus were treated conservatively. Although a detailed ocular motility examination could not be performed due to pain and inability to open the eyelid, the inferior wall fracture was surgically repaired. Postoperatively, persistent extraocular movement limitation prompted a referral to the authors' clinic. Orbital CT imaging demonstrated a fracture at the greater wing of the sphenoid with a hypoattenuated area in the adjacent middle cranial fossa. Orbital MRI taken thereafter revealed lateral rectus and orbital fat prolapse into the middle cranial fossa, indicating entrapment of these structures through the lateral wall fracture. The incarcerated lateral rectus was released using an endoscopic transorbital approach via an upper lid crease, resulting in the recovery of extraocular movement.