A Case of Orbital Tumor Treated by Novel Endoscopic Transnasal Resection

Abstract

Recent advances in endoscopic technology and surgical instruments have expanded the indications of endoscopic endonasal surgery to include orbital tumors. Tumors located at the medial orbita, especially at the orbital apex, are considered to be appropriate for an endoscopic endonasal approach, although careful manipulation is required to avoid damage to visual function. Here, we report a case of an orbital tumor treated with novel endoscopic endonasal resection. A 45-year-old woman visited an ophthalmologist with a three-week history of blurred vision in the right eye. A CT scan showed a right orbital tumor located at the medial orbita outside the muscle cone. MRI indicated vascular malformation (cavernous hemangioma), with a diameter of 22 mm. Preoperative corrected visual acuity was (1.0) in the right eye and (1.2) in the left eye with a critical fusion frequency of 15 Hz in the right eye and 32 Hz in the left eye, indicating deterioration of right optic nerve function. The patient underwent radical resection of the tumor with an endoscopic endonasal approach to the orbit via the middle meatus, ethmoid sinus and lamina papyracea using an image-guided system. The tumor was adherent to the medial rectus muscle, but was carefully and successfully removed using fine instruments for otologic surgery and neurosurgery. The final histologic diagnosis was also vascular malformation (cavernous hemangioma). Postoperative corrected visual acuity was bilateral (1.5), and the critical fusion frequency was 35 Hz in the right eye and 39 Hz in the left eye, indicating improvement of right optic nerve function. Preoperative right blurred vision also disappeared with no ocular motility dysfunction. There were no adhesions in the sinonasal cavities and no other adverse events after surgery. Although an endoscopic endonasal approach is suitable for medial orbital resection, it is difficult due to the narrow surgical field and inconvenient operability. Therefore, there is a need to develop novel surgical techniques and instruments for safe and reliable treatment in a good surgical field.