20 Orbitocranial Approach
Abstract
The orbitocranial approach, also called transcranial orbital or orbitocranial approach, allows us to access lesions that are in the orbit, anterior and middle cranial fossa, and sellar or parasellar region. We divided the approach into three different extensions of bone removal according to the needs for each type of pathology, location, and dimensions. For example: A: The emphasis of the approach is centered in the orbit. B: Orbitocranial approach with frontal extension; this approach allows access to the sellar and parasellar regions. C: Orbitocranial approach with frontotemporal extension; this approach with the sylvian fissure dissection allows a wider extension to the parasellar region including the interpeduncular fossa. In this chapter the approach is carried out step by step and the extensions are exemplified with clinical cases for better understanding.
Keywords: Keywords: orbitofrontal, orbitocranial, transcranial orbital, anterior skull base, orbital osteotomy
20.1 Introduction
20.1.1 Historical Background
One of the first reports of orbitocranial surgery occurred in the early 20th century. In 1905, Fedor Krause,1 who is considered as the father of German neurosurgery, suggested a subfrontal approach to sellar tumors, unsuccessfully resected a tuberculum sellae meningioma and a pituitary adenoma in an acromegalic patient in 1908. Later, McArthur2 (1912) and Frazier3 (1913) performed orbitofrontal approaches removing the supraorbital arch for pituitary lesions. In 1982, Jane et al4 described the supraorbital approach which involved mobilizing the roof of the orbit and the rest of the frontal bone in one piece. They mentioned in their statement that it is “the approach of choice for all orbit lesions except those in the inferior portion”; with modification to the technique in 1987, Al-Mefty5 performed a pterional supraorbital approach which allowed access to multiple corridors, for example, subfrontal, transsylvian, and subtemporal.
20.1.2 Indications
The orbitocranial approach allows us to access lesions that are in the orbit, anterior and middle cranial fossa, and sellar or parasellar region. The removal of the orbital rim provides an angle of greater visibility, which gives less brain retraction and therefore better outcomes.
We divided the approach into three different extensions of bone work according to the needs for each type of pathology, location, and dimensions:
●A: Orbitocranial approach; in this case the emphasis of the approach is centered in the orbit.
●B: Orbitocranial approach with frontal extension; this approach allows access to the sellar and parasellar regions.
●C: Orbitocranial approach with frontotemporal extension; this approach with the sylvian fissure dissection allows a wider extension to the parasellar region including the interpeduncular fossa (Fig. 20.1).
Fig. 20.1 Endoscopic endonasal view of the sphenoid sinus exposing the landmarks in its posterior wall with the use of 0-degree endoscope. The planum, limbus, tuberculum (TS), and sella (4) are visualized in the midline after a large sphenoidotomy. The optic canals and clinoid segment of the internal carotid artery (cICA) are closely related; the lateral optico-carotid recess (LOCR), which corresponds to the optic strut, is located inferior and lateral to the optic canal and separates that structure from the superior orbital fissure. The lateral aspect of the tuberculum sellae is related with the medial optic carotid recess (MOCR) and it is named lateral tubercular strut. (Copyright Joao Paulo Almeida, MD.)
The group of pathologies that can be approached are6 , 7 , 8 , 9 , 10:
●Intraorbital tumors mainly found dorsal to the optic nerve (meningioma, glioma, and cavernomas)
●Carcinoma of the lacrimal gland
●Optic canal decompression with dural sheath release for tumors invading the optic canal
●Craniopharyngiomas
●Tuberculum sellae meningiomas
●Anterior communicating artery aneurysms
●Tumors that extend from the sellar region or anterior fossa to the orbit
The cranial orbital approach can be done in one or two pieces, even with variations extending to the lateral orbital wall or zygomatic arch.
In this chapter, we focus on the description of the bone work extension. The cranial orbital two-piece approach, in our experience, has less risk of injury to the periorbita and is technically easier.
20.2 Surgical Technique
20.2.1 Position
20.2.2 Skin Incision
The hair is minimally shaved 1 cm behind the hairline and a hemicoronal skin incision is planned and marked starting 1 cm anterior to the tragus and extended to the midline to facilitate exposure of the supraorbital foramen. The skin is prepared with chlorhexidine or iodine povidone solution. Once the surgical timeout is completed, the skin incision is performed, being careful to preserve the frontotemporal branches of the facial nerve and superficial temporal artery.
20.2.3 Scalp Elevation
The flap is reflected anteriorly temporarily with stitches or fish-hooks until the yellow fat pad of the temporal muscle and the supraorbital nerve become visible; the superficial temporal fascia is incised and dissection is continued anteriorly in the interfascial plane. The pericranium is preserved for later reconstruction. The temporalis muscle is carefully dissected preserving the deep temporalis fascia. Once the orbital rim is dissected it is important to carefully dissect the periorbital fascia from the orbital roof before performing craniotomy to prevent its laceration.
20.2.4 Craniotomy
The first burr hole corresponds to the keyhole placed behind frontozygomatic suture. The second burr hole is made at the medial aspect of the planned craniotomy. It is placed beyond the supraorbital nerve, immediately above the orbital rim. The two burr holes are then connected with a craniotome. If the frontal sinus is opened, cranialization of the frontal sinus and plugging is performed using pediculated pericranium.
20.2.5 Removal of the Orbital Rim
The periorbita is separated from the orbital bone and the dura mater is gently retracted. Superior and lateral orbital rim osteotomies are made with a craniotome: the first one at the level of the frontozygomatic suture and the second cut depends on the extension required for the surgery. The second cut can be lateral to the supraorbital nerve or it can be extended medially by dissecting the nerve. Next, the cut is extended toward the medial orbital roof and continued toward the optic canal.
20.2.6 Reconstruction
Once the surgery is completed, it is important to verify the integrity of the frontal sinus or cranialization should be done using pericranium. The orbital rim is fixed with miniplates and screws. The cranial bone flap is fixed with cranial fixation system while the muscle and the soft tissue are sutured.
20.3 Cases
20.3.1 Case 1
A 4-year-old female patient, with no important medical history, presented with 6 months of decreased visual acuity and eye movements impairments. MRI study showed a lesion in the optic nerve with gadolinium enhancement; a biopsy with a right orbitocranial approach in two-piece is planned (Fig. 20.2, Fig. 20.3, Fig. 20.4, Fig. 20.5, Fig. 20.6, Fig. 20.7, Fig. 20.8, Fig. 20.9).
