Incarceration of the inferior oblique muscle branch of the oculomotor nerve in patients with orbital floor trapdoor fracture.

PURPOSE

To examine the clinical characteristics of patients with concomitant incarceration of the inferior oblique muscle branch of the oculomotor nerve who had suffered from an orbital floor trapdoor fracture with orbital fat incarceration.

METHODS

Fifty-nine patients were retrospectively reviewed. Concomitant inferior oblique muscle branch incarceration was diagnosed by inferior oblique muscle underaction on the Hess chart and a missing inferior oblique muscle branch on computed tomographic images on baseline examination.

RESULTS

Eleven patients (18.6%) were diagnosed with concomitant branch incarceration. The patients with branch incarceration were all under 19 years of age, and were younger than those without branch incarceration (P = 0.026). There were no significant differences between the groups in terms of cause of injury, presence of concomitant medial wall fracture, hypoesthesia of the cheek region, or ocular and periocular complications (P > 0.050). All patients with branch incarceration underwent surgical reduction, whereas 16 of 48 patients without branch incarceration were observed without surgery (P = 0.021). Although preoperative binocular single vision field was smaller in patients with branch incarceration (P = 0.026), it improved after surgery, comparable to that of patients without branch incarceration (P = 0.079).

CONCLUSIONS

Concomitant incarceration of inferior oblique muscle branch of the oculomotor nerve occurred in 18.6% of patients who had suffered from an orbital floor trapdoor fracture with orbital fat incarceration. Patients with branch incarceration were all under 19 years of age. Branch incarceration resulted in a smaller binocular single vision field, which considerably improved after surgical reduction.