Chapter 51 Surgical Approaches to the Orbit
The surgical treatment of orbital processes presents a border area between different surgical specialties, including otorhinolaryngology, oral/maxillofacial surgery, ophthalmology, and neurosurgery. Neurosurgeons encounter more neural tumors such as meningiomas and optic pathway gliomas in contrast to ear, nose, and throat (ENT) or head and neck surgeons, who more often deal with secondary lesions such as mucoceles and paranasal sinus neoplasms. Patients treated by ophthalmologists have a greater incidence of thyroid-related orbitopathy and inflammatory pseudotumor. 1
History
The history of orbital approaches begins in the 19th century. Krönlein performed the first extracranial orbitotomy in 1889 and Berke in 1954. 2,3 Kennerdell and Maroon picked up this approach in 1988.4 Niho5 chose a transethmoidal approach in 1970, Colohan6 a frontal trans-sinusoidal path in 1985, and Hassler7 a transconjunctival approach in 1994.
Regarding the transcranial approaches, the subfrontal approaches published by Dandy8 in 1941 and Housepian9 in 1978 are well recognized. Naffziger10 chose a frontolateral pterional approach in 1948. In 1964 and 1975, Yasargil11 reported about experiences with the same approach. Kennerdell and Maroon4 also operated via this frontolateral approach. Seeger and Hassler used a pterional extradural approach in 1983 and 1985.12 Dolenc13,14 opened the orbit by unroofing it while operating on parasellar lesions and tracing them through the orbital roof directly or through the superior orbital fissure in 1983. Hassler15 described a contralateral pterional approach in 1994.
Choice of Surgical Approach
The choice of surgical approach is largely determined by the location, extension, and type of the lesion. The goals of the surgery such as biopsy, debulking, or gross-total resection have to be considered. The general guidelines recommend choosing the most direct approach, not to cross the optic nerve, and to avoid or hide skin incisions. In anterior locations, bone removal should be avoided. Today, there is a tendency towards less invasive approaches. Thus, the transcranial approaches are performed less frequently in favor of minimally invasive extracranial approaches. In most cases, the lateral orbitotomy and increasingly also the supraorbital orbitotomy are used to treat orbital pathologies. Anterior approaches without osteotomy such as superior or lower-eyelid incisions, sub-brow incision or inferior transconjunctival or subciliary incisions may be used for smaller anterior lesions.16
One of the more recently developed approaches, such as the transconjunctival, pterional (frontotemporal) contralateral, or pterional extradural approach, can be used as an alternative to a classic extracranial approach (lateral orbitotomy) or a more extensive transcranial approach.7,12,17,18 Some specialists may choose to operate through the neighboring paranasal sinuses (transethmoidal or transmaxillary approach).
Topographic Distribution
Certain types of lesions occur at certain locations (Table 51-1). Thus, the most common intraconal processes affecting the optic nerve are optic nerve glioma, optic sheath meningioma, and lymphoma. Other intraconal processes include cavernoma, neurinoma, and metastases. The intraconal space is delimited by the conus, which connects the four rectus muscles to each other. The extraconal compartment takes up only a small amount of space within the orbit, surrounding the muscular conus like a tube. The most common extraconal processes are dermoid tumor (dermoid cyst) and pleomorphic adenoma of the lacrimal gland. The subperiosteal compartment is defined as the potential space between the periosteum and the bony orbit. Mucoceles are the most common processes affecting this compartment. The bony orbit and the sphenoid wing can be the site of an osteoma, a malignant tumor, or fibrous dysplasia, but the most common process affecting these structures is a sphenoid wing meningioma. Meningiomas are often found at the orbital apex, the superior orbital fissure, and the cavernous sinus. The intracranial periorbital dura mater heading toward the optic nerve may be infiltrated by an optic sheath meningioma or by other types of meningioma of variable size and extent. Pleomorphic adenomas and carcinomas arise within the lacrimal gland and duct system. Lymphomas and infections can affect the preseptal segment or the lids.
| Intraconal (optic nerve) | Optic nerve glioma, optic nerve sheath meningioma |
| Intraconal | Cavernoma, schwannoma, metastases, lymphoma, lymphangioma |
| Extraconal | Dermoid cyst, pleomorphic adenoma of the lacrimal gland, pseudotumor |
| Subperiosteal | Mucocele |
| Sphenoid wing, bony orbit | Meningioma, osteoma, malignant tumor, fibrous dysplasia |
| Orbital apex, superior orbital fissure, cavernous sinus | Meningioma, cavernoma |
| Lacrimal gland, duct system | Pleomorphic adenoma, carcinoma |
| Muscles | Endocrine orbitopathy, rhabdomyosarcoma |
| Preseptal, lid | Lymphomas, infections, lipoma |
Surgical Techniques
Supraorbital Orbitotomy
The more lateralized supraorbital approach has been used by neurosurgeons for vascular lesions of the anterior segment of the Circle of Willis and some tumorous lesions from the intradural side during the last two decades (Fig. 51-1).19
Eyebrow incision may also be used for a transperiostal approach to the superior orbit (Table 51-2) (Fig. 51-1A).20,21 Lesions are approached by simple skin incisions of 4 cm along the orbital rim (Fig. 51-1A). After detachment of the periosteum, the supraorbital nerve is dissected and the periorbita is exposed. An osteotomy of the middle part of the supraorbital rim is performed using a reciprocating saw. Miniplates are fitted on both sides of the orbital rim (Fig. 51-1C to G). A small 2 × 3 cm frontobasal osteoclastic trepanation is carried out respecting the lateral border of the frontal sinus (Fig. 51-1C to E). In case of accidental opening of the frontal sinus, the mucous tissue is removed and the tear is closed with subcutaneous fat and fibrin glue. The basal dura of the frontal lobe is pushed away and the orbital roof is removed (Fig. 51-1F). The periorbita is opened and the levator palpebrae and superior rectus muscles are identified (Fig. 51-1E). In deeper intraconal lesions, three self-retaining retractors are positioned in the orbital fat; the tumor is exposed and removed. In extraconal tumors no spatula are necessary. There is no limitation of size of the tumor. The angle of approach allows tumor removal far behind the globe with minimal manipulation of brain and orbit. The surgical corridor is quite broad (3 to 3.5 cm). Finally, the periorbita is closed with sutures in intraconal lesions. In extraconal lesions the periorbita is partially resected and replaced by a dural patch, fixed with fibrin glue. The orbital rim is replaced and fixed by miniosteosynthesis (Fig. 51-1G). The frontobasal trepanation is filled with polymethyl-methacrylate. The orbital roof is not reconstructed. The muscular and subcutaneous layers are closed with interrupted sutures. A small suction drain is placed for 1 day and the skin is closed with a reabsorbable 6-0 suture. Two weeks postoperatively, the cosmetic result is good.
The supraorbital approach can be used in all kinds of intra- and extraconal pathologies that are located cranially to the optic nerve (Fig. 51-1B). It combines the extracranial approach in the eyebrow with the advantages of a frontobasal craniotomy. Thus, it is a mixed approach between the purely extracranial and transcranial approaches. The main advantages are only minimal orbital and brain retraction and it also is not limited by the size of the lesion. The only drawback consists in temporary hypaesthesia in the territory of the supraorbital nerve.
The eyelid crease approach (Fig. 51-1A) is useful for biopsies of lacrimal gland lesions, such as lymphoma, sarcoidosis, or pseudotumor.22 Superior extraconal lesions can be reached via a supraorbital or sub-brow incision. Larger extra- and intra-conal lesions require a superior supraorbital approach with an osteotomy as described above.
Lateral Orbitotomy
Lateral orbitotomy provides excellent exposure of the temporal compartment of the orbit and it is indicated for well defined periorbital and intraconal tumors which are located lateral, dorsal and basal to the optic nerve (Table 51-2) (Fig. 51-2B).20 It is useful for lacrimal gland tumors, retrobulbar lesions, such as cavernomas, and can be extended for posterior lesions.
In the past, the skin incision started superiorly and laterally in the eyebrow and was extended posteriorly along the zygomatic bone (Fig. 51-2A). Nowadays, the incision is usually smaller and runs along the lid crease towards the corner of the eye to the lateral canthus or even lateral to it (Fig. 51-2A). Then the temporalis fascia is incised, beginning at the midportion of the frontozygomatic bone and extending posteriorly the length of the skin incision. A reciprocating saw is used to incise the lateral rim of the orbit above the zygomaticofrontal suture line and inferiorly at the superior margin of the zygomatic arch (Fig. 51-2C and E). During the osteotomy the globe is protected with a retractor. The anterior edge of the greater wing of the sphenoid bone may be further reduced with rongeurs (Fig. 51-2D and F). The lateral orbit can be approached between the superior and lateral rectus muscles. Finally, a patch of artificial dura is placed to avoid a prolapse of the temporalis muscle into the orbit. Then the frontozygomatic bone is closed using plate and screw fixation. Alternatively, the bone may be held in position by nonabsorbable 4-0 nylon sutures. The periorbita and the slip of the temporalis muscle and periosteum are attached to the lateral orbital margin with 4-0 vicryl sutures.
There are numerous modifications of this lateral approach. The lateral canthothomy (Fig. 51-2A) presents the approach with the smallest incision, sufficient for lateral decompression in endocrine orbitopathy. An osteotomy is not required in all cases. Several anterior approaches through an eyelid crease incision, supraorbital or sub-brow incision are available to approach the anterior third of the orbit.22
Transconjunctival Approaches
The inferior transconjunctival approach17,23 is restricted to basal and medial intra- and extraconal tumors (Fig. 51-3A and B) (Table 51-2). Following antiseptic preparation, the eyelids held apart, the conjunctiva is incised inferiorly along the corneal edge and the flap created thereby is opened in a caudal direction (Fig. 51-3A and C). The inferior rectus muscle is hooked with a suture and retracted laterally, and the inferior oblique muscle is hooked and retracted caudally. After a superficial preparation and dissection of the layers of connective tissue and orbital fat, the lesion surface can be seen and approached. Due to the small access the tumor is removed piecemeal. After hemostasis, the inferior rectus muscle is released and the conjunctiva is closed with 8 to 10/0 suture (Fig. 51-3D). Limits of the transconjunctival approach are inability to deal with deep intraconal lesions and lesions of the apex (Fig. 51-3B). The advantage is that even masses larger than the eyeball can be removed transconjunctivally without bone destruction and without scars.
Subciliary and transcutaneous lower lid incisions are alternatives to access the inferior orbital rim and floor (Fig. 51-4). The medial transconjunctival approach with release of the insertion of the medial rectus muscle and readapt ion at its ends is used by our ophthalmologists to access the medial anterior orbit for biopsy or fenestration of the optic nerve sheath in pseudotumor cerebri. The transcaruncular approach is an alternative to reach the extraconal medial orbital wall and may be combined with the transconjunctival approach for repair of large medial orbital wall fractures.24
Transantral Approach
The transantral approach18 is performed by ENT surgeons to deal with basal intra- and extra-conal lesions in direct contact to the sinus (Table 51-2). The canine fossa is infiltrated for hemostasis and incised. The mucosa of the mouth is elevated from the anterior wall of the maxillary sinus. An osteotomy is made into the anterior wall with an osteotome and mallet. Using a Kerrison punch, the anterior wall is removed. Any manipulation of the infraorbital neurovascular bundle should be avoided. The bone can be removed up to the orbital rim to provide visualization. The medial orbital floor is removed under preservation of the infraorbital nerve. Then the medial wall and the inferior aspect of the orbital apex are removed. A longitudinal incision of the periorbita is made. Today, endoscopic endonasal approaches are used to approach the medial and inferomedial orbit.25
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