Thirty Cases of Front-orbital Fibrous Dysplasia: Intraoperative Optic Canal Localization with Three-bits Method and Outcomes Evaluation

Abstract

Objective To investigate the indications of optic canal decompression in the patients with front-orbital fibrous dysplasia and the methods of intraoperative optic canal localization and decompression. Methods We collected 30 cases of fibrous dysplasia. All patients had sufficient images assessment. Patients with symptoms underwent surgery, including front-orbital cranioplasty and optic canal decompression. The frontotemporal epidural approaches were used. If there was a proptosis, the approach was extended with the removal of superior orbital ridge. Six patients undertook intraoperative CT and MRI fusion navigation, assisting in confirming the trunk, orbital and cranial orifice of optic nerve. During the operation, the optic canals were decompressed by three-bits method, to confirm the position of optic nerve. Results There were 30 cases of optic canal decompression and one case of vision loss. The visual acuity and vision field of the remaining patients improved to varying degrees. The proptosis disappeared or alleviated after the operation. Thirteen cases were reconstructed with normal internal plate, five cases with titanium plate, nine cases without reconstruction, and two cases were paved with proliferative broken bone on the orbital top; one case recurred with exophthalmos again after five years, but the visual acuity did not decline. Conclusion For the patients with front-orbital fibrous dysplasia, active surgical treatment should be taken, optic canal decompression should be chosen for diminution of vision, craniofacial anaplasty and orbital decompression should be performed in patients with facial deformity. The epidural approach is a good option to locate the optic nerve from the orbital orifice or cranial orifice. Combined with the three-bits method, we can achieve safe and meticulous optic nerve decompression.

Keywords

• fibrous dysplasia
• visual acuity
• optic canal decompression
• intraoperative navigation
• extradural approach