Open and Endoscopic Treatment of Pediatric Fibrous Dysplasia Causing Blindness and Proptosis

Background Fibrous dysplasia causes normal bone marrow to be replaced by immature fibro-osseous tissue. This abnormal overgrowth of tissue has significant sequale, including disfiguring proptosis, ophthalmoplegia, and blindness. Although the literature suggests that the endoscopic endonasal approach (EEA) is a safe method for decompressing the orbit and neurovascular structures, its efficacy in visual outcomes is more uncertain in the pediatric population.

Case Description A 9-year-old girl with a history of fibrous dysplasia, initially presented with vision loss from her left eye. Her head CT revealed significant, circumferential optic nerve compression, as well as exophthalmos. Her ophthalmologist confirmed the presence of an afferent pupillary defect with significant deterioration in her visual acuity to 20/250 with temporal pallor and optic nerve thinning on optical coherence tomography (OCT). She subsequently underwent a left modified orbitozygomatic approach to decompress her orbit and optic nerve. One month following her surgery, her ophthalmologist noted improvement in her visual acuity. Approximately 6 months later, the patient noted continued visual improvement. One year following surgery, the patient began to notice new visual changes. The ophthalmologist noted at that time decreased visual acuity, increased optic nerve pallor, and a larger central scotoma in the left eye. Her most recent visual acuity is 20/600 for the left eye. Head CT revealed significant left optic nerve and orbit compression from the medial aspect of these structures. She is scheduled for an EEA to decompress her optic nerve and medial orbit.

Discussion Fibro-osseous tumors of the skull base can cause 360-degree compression of the optic nerve and orbit. Because of this phenomenon, once patients experience vision loss, the decision to decompress from an open or endoscopic approach can be challenging. In the pediatric population, there is a suggestion that the morbidity of an open approach should prompt the surgeon to manage this condition with an EEA. However, the authors proposed an initial open decompression because the optic canal can be opened 270 degrees from this approach. The patient now has worsening vision with significant disease burden medially. Although the second stage is not complete yet, the authors will complete a volumetric analysis subsequent to her EEA in conjunction with postoperative vision test to determine if the volume of osseous decompression was relevant to vision restoration.

Conclusion Circumferential compression of the optic nerve from fibrous dysplasia in a pediatric patient is a challenging condition. The authors believe that a combined approach is most likely necessary and should be advocated early in the management of these patients. Data regarding volumetric analysis are forthcoming and will provide additional information to clinicians facing this clinical dilemma.