Medial Orbital Wall Fracture with Associated Medial Rectus Entrapment and Retrobulbar Hematoma

Abstract

Sir: A 25-year-old Hispanic man presented after being struck in the right midface with a wooden bat. Examination revealed a large laceration over the right eye, 7 mm of right-sided proptosis, a dilated right pupil, subconjunctival hemorrhage, the inability to abduct the right eye, and bilateral decreased visual acuity. Intraocular pressures measured 17 mmHg in the right eye and 12 mmHg in the left eye (normal, 10 to 21 mmHg). A maxillofacial computed tomographic scan demonstrated a right medial orbital wall blowout fracture with 17 mm of edematous medial rectus herniating 7 mm through the lamina papyracea (Fig. 1), and a right-sided retrobulbar hematoma tracking along the optic nerve (Fig. 2, left).Fig. 1.: Maxillofacial computed tomographic (3-mm slice thickness) axial view (above) and coronal view (below) at patient presentation. There is a 17-mm defect in the medial orbital wall. The medial rectus is herniated through the wall into the ethmoid sinus and is clinically entrapped (see text). Compared with the contralateral medial rectus in other slices, the herniated muscle is enlarged and edematous. Also note the marked periorbital soft-tissue swelling.Fig. 2.: (Above) Maxillofacial computed tomographic axial view of the patient at presentation. The retrobulbar hematoma is visible as a collection of blood directly behind the globe. (Below) Maxillofacial computed tomographic axial view after operative repair of the medial orbital wall with a Silastic sheet and reduction of the medial rectus. The thin implant is visible layered over the remaining lamina papyracea.The clinical and radiographic evidence of medial rectus entrapment and retrobulbar hematoma warranted urgent surgical exploration and decompression. A lateral canthotomy with subsequent medial orbital wall repair using a Silastic sheet were performed. Postoperatively, forced duction testing was normal, and the patient was started on 5 days of 60 mg of prednisone. A postoperative maxillofacial computed tomographic scan showed good reduction of the medial rectus muscle (Fig. 2, right). After 1 week, the patient's extraocular movements resolved fully, showing no signs of muscle entrapment. Orbital fractures commonly occur with midface trauma and range from nondisplaced to complex fractures disrupting the orbit. Of the orbital walls, floor blowout fractures are most frequently seen, and medial wall (lamina papyracea) fractures follow in frequency, as a result of their inherently weak structures. The incidence of isolated medial wall fracture ranges from 0 to 10 percent of orbital fractures, and the incidence of concurrent medial wall and floor fractures ranges from 6.8 to 22 percent in larger case studies and up to 47 percent in one smaller case study.1–3 Medial orbital wall fractures are often difficult to diagnose, with findings including asymptomatic (termed “white eyed”) subconjunctival hemorrhage, abduction failure, adduction failure, combination extraocular movement deficit, globe retraction, or proptosis secondary to edema.1,4 Many case reports demonstrate that these fractures can cause medial rectus incarceration, ischemia, and permanent visual deficits.1,4 Potentially more serious, a retrobulbar hematoma may introduce an emergent threat of permanent blindness, and is also difficult to diagnose clinically.5 Retrobulbar hematomas are uncommon following craniofacial trauma, with reported incidences ranging from 0.45 to 0.6 percent in retrospective reviews of large facial trauma series.5 Clinical diagnosis of acute retrobulbar hematoma lies in assessment of painful proptosis, visual deficits, and loss of pupillary reflexes; however, thin-slice maxillofacial computed tomography is a standard diagnostic aid in orbital trauma. Visual deficits result from increased pressure within the orbit stretching the optic nerve. As in our case, an orbital fracture may decompress a hematoma, resulting in normal intraocular pressures. Although isolated medial orbital wall fractures and their combination with medial rectus incarceration and retrobulbar hemorrhage are rare events, they are important conditions for those managing trauma patients. Because medial orbital wall fracture and retrobulbar hematoma may be silent, early recognition of subtle examination findings, expeditious imaging studies, and rapid operative intervention are crucial for minimizing permanent visual impairment. Arthur Turko, B.S. Simon Talbot, M.D. Bohdan Pomahac, M.D. Division of Plastic Surgery Harvard Medical School, and Brigham and Women's Hospital Boston, Mass.