Orbital Wall Reconstruction for Tumor-Associated Proptosis: Effect of Postoperative Orbital Volume on Final Eye Position

Background Surgical resection of sphenoid wing tumors and intraorbital pathology carries the dual goal of appropriately treating the target pathology as well as proptosis correction. Residual proptosis following surgery can lead to cosmetic and functional disability. When planning orbital wall reconstructions, surgeons have the option to rebuild a smaller orbit to compensate for fat necrosis from chronic compression, an anatomically normal orbit, or a slightly larger orbit to compensate for impaired orbital venous drainage through the superior orbital fissure. We sought to quantitatively assess the effect of orbital volume before and after reconstruction to determine the optimal strategy to achieve proptosis correction.

Methods All surgeries involving orbital wall reconstruction for orbital or intracranial pathology resulting in proptosis between January 1994 and May 2017 were reviewed. Age, sex, and tumor pathology were collected from the clinical record. The radiographic record was reviewed for cavernous sinus tumor invasion, superior orbital fissure tumor invasion, and pre- and postoperative orbital volumes. Proptosis was measured by the exophthalmos index (EI): the ratio of the distance of the anterior limit of each globe to a line drawn between the anterior limit of the frontal processes of the zygomas, comparing the pathological eye to the normal eye. Postoperative radiographic measurements were taken at least 60 days after surgery to allow surgical swelling to abate. The orbit contralateral to the pathology was used as an internal control for normal anatomic orbital volume. Cases with preoperative EI < 1.10, orbital exenteration, and enucleation were excluded. Values are reported as mean ± standard deviation, and significance was assumed for p < 0.05.

Results Twenty-three patients (16 females; 7 males) were treated surgically for proptosis, with a mean age of 43.6 ± 22.8 years. Nineteen patients harbored meningiomas (11 en-plaque; 8 sphenoid wing), and one patient each harbored an orbital schwannoma, glomangioma, arteriovenous malformation, and cavernous hemangioma. Preoperative EI averaged 1.27 ± 0.10 (range: 1.12–1.53). The only predictor of greater proptosis preoperatively was larger volume of soft-tissue tumor within the orbit (p < 0.01). Median time to postoperative imaging was 19 months. Postoperatively, the EI fell to a mean of 1.07 ± 0.09, an average reduction of 0.21 ± 0.14 (range: 0.03–0.54). Proptosis correction progressively increased as volume of the reconstructed orbit increased over that of the control contralateral orbit (p < 0.01). Larger volume of soft-tissue pathology was also associated with achieving greater proptosis correction (p < 0.01). Tumor invasion in the superior orbital fissure and cavernous sinus were not associated with degree of proptosis correction (p = 0.46 and p = 0.73, respectively). Residual exophthalmos (defined as EI > 1.10) was present in eight patients, while reconstruction in two patients resulted in enophthalmos (defined as EI < 0.95).

Conclusion Proptosis associated with intracranial and orbital pathology represents a surgical challenge. Orbital reconstruction resulting in volumes larger than that of the unaffected, contralateral orbit appears to result in greater proptosis correction in a linear fashion. Surgery also appears more successful when proptosis is caused by soft-tissue pathology within the orbit itself, rather than compression of the normal orbital contents.