The goal of this study was to investigate the safety and efficacy of multisession Gamma Knife surgery (GKS) in the treatment of benign orbital tumors.
Twenty-three patients who retained their vision despite having tumors touching their optic nerve were treated with multisession (4-fraction) GKS. The median tumor volume was 2800 mm(3) (range 211-10,800 mm(3)), and the median cumulative margin dose was 20 Gy (range 18-22 Gy).
The median clinical follow-up duration in these patients was 38 months (range 9-74 months). No patient experienced tumor progression in this study. In particular, a higher degree of tumor shrinkage was found in the 7 patients with cavernous hemangiomas than in patients with other types of lesions (p < 0.05). Of the 23 patients whose preoperative vision was preserved, 11 showed improvement in visual acuity and/or visual field and 12 showed stable visual acuity. No GKS-related adverse events were noted during or after treatment.
Multisession radiosurgery using the Gamma Knife may be a good strategy for tumors in direct contact with the optic nerve. A cumulative margin dose of up to 22 Gy delivered in 4 sessions is safe for preservation of visual function with a high probability of tumor control.
[Show abstract][Hide abstract] ABSTRACT: Schwannomas are typically benign tumors of the peripheral nervous system that originate from Schwann cells. It is well known that the optic nerves are myelinated by oligodendrocytes since their cell bodies arise centrally within the lateral geniculate nuclei. Because of this basic cellular anatomy, optic schwannomas should theoretically not exist. It is possible, however, these rare lesions stem from small sympathetic fibers that innervate the vasculature surrounding the optic nerve and its sheath.
The patient is a 46-year-old male with a one-year history of progressive right eye blurry vision. To our knowledge, there are only five known reported case of an optic nerve schwannoma. Additionally, because of its medial position relative to the optic nerve and within the orbital apex, it is the first such case to be resected via an endoscopic endonasal approach. The lesion was subtotally resected because of its adherence and continuity with the optic nerve and the patient's wish to preserve his vision. He was subsequently referred to radiation oncology for external beam radiation therapy.
Herein, we discuss the pertinent clinical findings of this rare lesion and review the literature relative to optic nerve and solitary orbital schwannomas.
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