"Round-the-Clock" Surgical Access to the Orbit

Abstract

Objective To describe an algorithm to guide surgeons in choosing the most appropriate approach to orbital pathology. Methods A review of 12 selected illustrative cases operated on at the neurosurgical department of University of Pittsburgh Medical Center over 3 years from 2009 to 2011 was performed. Preoperative coronal magnetic resonance imaging and/or computed tomography views were compared using a "clock model" of the orbit with its center at the optic nerve. The rationale for choosing an external, endoscopic, or combined approach is discussed for each case. Results Using the right orbit for demonstration of the clock model, the medial transconjunctival approach provides access to the anterior orbit from 1 to 6 o'clock; endoscopic endonasal approaches provide access to the mid and posterior orbit and orbital apex from 1 to 7 o'clock. The lateral micro-orbitotomy gives access to the orbit from 8 to 10 o'clock. The frontotemporal craniotomy with orbital osteotomy accesses the orbit from 9 to 1 o'clock; addition of a zygomatic osteotomy to this extends access from 6 to 8 o'clock. Conclusions Combined, the approaches described provide 360 degrees of access to the entire orbit with the choice of the optimal approach guided primarily by the avoidance of crossing the plane of the optic nerve.

Keywords: endonasal endoscopic approach; orbit; orbital tumors.

Fig. 1

Frontotemporal craniotomy with orbitozygomatic osteotomy. (A) Clock model showing the extent of the orbit that can be exposed through this approach. (B) The frontotemporal craniotomy (first piece) has been cut, the temporalis muscle dissected off its anterior attachment and retracted posteriorly, and a malleable retractor inserted between the orbital roof and the periorbita. (C) While protecting the orbit content on one side of the orbital roof and the frontal lobe on the other side with malleable retractors, the final cut over the orbital roof is made with a high-speed drill going laterally toward the inferior orbital fissure. (D) The “second piece” of the orbitozygomatic craniotomy is removed exposing (E) periorbita and periorbital fat. (F) After retraction of muscles and periorbital fat with cotton-tipped applicators, the tumor comes into view (photo taken with operative microscope).

Fig. 2

Lateral orbitotomy. (A) This approach is ideally suited for a lesion lateral to the optic nerve at the 8–10 o'clock position. (B) A small cantholysis incision is made with Steven scissors along a skin crease. (C) The temporalis muscle has been detached and retracted laterally; with adequate retraction it possible to expose the whole lateral wall of the orbit even with a relatively small incision. The osteotomy is performed with a reciprocating saw. (D) The lateral orbitotomy has been completed and the last fibers of the temporalis muscle cut with a monopolar knife. (E) The periorbita has been opened and the tumor completely removed. (F) A soft drain has been secured in place.

Fig. 3

Medial micro-orbitotomy. (A) This approach gives access to lesions located anterior and medial in the orbit. (B) An eyelid retractor is placed and local anesthetic injected where the peritomy will be performed. (C) After the conjunctiva is incised around the cornea and relaxing conjunctival incisions are made, the medial rectus muscle is detached and (D) retracted medially with a suture. (E) The eye globe is retracted laterally and the intraconal fat exposed. (F) After the lesion has been excised, the medial rectus muscle is reattached at its insertion site on the globe with a 6-0 absorbable suture, and the conjunctiva is closed with interrupted sutures.

Fig. 4

Endoscopic endonasal approach. (A) Clock model showing the extent of the orbit that can be exposed through this approach. (B) The insertions of the rectus muscles to the globe are identified and controlled with vessel loops. (C) Endoscopic view of the medial aspect of the orbital apex after a portion of the periorbita has been excised. The internal carotid artery (ICA) is visible medially. The window between medial and inferior rectus muscles is “closed.” (D) After external retraction on the medial and inferior rectus muscles by pulling the respective vessel loops, the surgical window in now “open” and the tumor is identified and (E) excised. (F) The periorbital defect is covered with a free mucosal graft harvested from the removed ipsilateral middle turbinate.

Fig. 5

Coronal preoperative magnetic resonance imaging and computed tomography scans of patients 1 to 6: 1, cavernous hemangioma; 2, foreign body; 3, foreign body; 4, angioleiomyoma; 5, orbital osteoma; 6, carcinoid metastasis.

Fig. 6

Coronal preoperative magnetic resonance imaging and computed tomography scans of patients 7 to 12: 7, melanocytoma; 8, cavernous angioma; 9, pleomorphic adenoma of the lacrimal gland; 10, Noninfectious inflammatory process; 11, recurrent nasal mucosal malignant melanoma; 12, neuroendocrine tumor.

Fig. 7

Clock model of the orbit summarizing how the different approaches fit together and overlap. ON, optic nerve.