14 Transcranial Approaches to the Orbit

Nirmeen Zagzoog, Gmaan A. Alzhrani, Yair M. Gozal, and William T. Couldwell

The superior approach (usually performed through a transfrontal route, frontotemporal, or pterional approach), was first used by Dandy1 in 1941 and later by Naffziger² in 1948. Since then, it has been the most commonly utilized approach to the orbit by neurosurgeons. It is extremely versatile and was later adapted for lesions involving both the orbit and the cranial cavity by MacCarty and Brown³ in 1964, as well as by Housepian⁴ in 1978. Originally, this technique involved the removal of the frontotemporal bone and exposure of the orbital roof while preserving the orbital rim. Over the past century, however, it has evolved to its current three main forms: the subfrontal route, as proposed by Dandy¹ and Housepian,⁴ where the fronto-orbital bone is removed while the supraorbital rim is preserved; the supraorbital route, indicated for larger tumors with deep extension into the orbital apex or optic canal, which differs from the original route in that the rim is removed along with the frontal bone as a single unit⁵; and the pterional approach, utilized by Maroon and Hassler^{6 ,​ 7} among others, where, in its current form, the sphenoid wing is drilled as far down as the superior orbital fissure, thinning the orbital roof and opening the Sylvian fissure and basal cisterns.⁸ Lesions treated via these approaches include optic nerve gliomas, orbital meningiomas, or tumors located in the orbital apex, such as neurofibromas and osteomas.

The supraorbital approach is a minimally invasive approach to the superior orbit that was first described by Jane et al⁹ in 1982 and more recently by Hassler and Schick.¹⁰ It consists of an eyebrow incision with a small overlying osteotomy, minimal orbital rim resection, and small frontal craniotomy. Although it presents the advantage of minimal orbital and brain retraction, its main drawback is the more limited access to the more posterior portion of the orbit.¹¹

The lateral orbital approach was first described by Krönlein¹² in 1888 and was universally employed before the transfrontal route was proposed by Dandy.¹ Later, it was modified by Berke^{13 ,​ 14} in 1953, Maroon and Kennerdel⁷ in 1976, and Mourier et al¹⁵ in 1994. It is generally used to access lacrimal gland tumors and other lesions lateral to the optic nerve. The lateral orbital approach is described in detail in a different chapter of this book.

The superolateral orbital approach is a “hybrid” technique first described by Karagjozov in 1967 that adapted the superior approach by extending it to breach the lateral wall.¹⁶ This approach, slightly modified by Al-Mefty and Fox¹⁷ in 1985, allows a wide superior and lateral exposure of the contents of the orbit and is useful for the extirpation of large tumors. It provides access to most of the regions of the orbit, except the medial part below the optic nerve.¹⁶

14.2 Relevant Surgical Anatomy of the Orbit

A thorough understanding of orbital microanatomy is essential to avoid various complications that may arise after surgery in this complex region, such as blindness, impaired oculomotor function, and Bernard-Horner syndrome. Loss of visual acuity is often caused by injury to the optic nerve or the vessels supplying the retina. Ophthalmoparesis usually occurs as a result of direct damage to the muscular tissue from dissection or traumatic displacement. It may also derive from damage to the nerves innervating the ocular muscles, which is common when removing lesions near the orbital apex, the posterior third of the cone, or in the inferolateral part of the muscular cone near the inferior oblique muscle branch of the oculomotor nerve. Finally, Bernard-Horner syndrome may occur in the setting of injury to the ciliary ganglion or nerves during dissection close to the optic nerve, particularly when the inferior lateral route is taken.^{16 ,​ 18}

14.2.1 Structure of the Orbit

The orbits divide the mid-face from the upper facial skeleton. They are shaped like four-sided pyramids, although their walls, apex, and base are not straight but curvilinear. The orbit is approximately 35 mm in height and 40 mm in width when measured at the rims. Its volume is approximately 30 mL, of which 7 mL is occupied by the globe.¹⁹

The orbit itself is comprised of seven bones: the floor is formed by the sphenoid bone and the orbital processes of the maxillary and palatine bones; the roof is formed by the sphenoid and the frontal bones; the lateral wall is formed by the greater wing of the sphenoid bone, the frontal bone, and the zygomatic bone; and the medial wall is formed by the lesser wing of the sphenoid bone, the lacrimal bone, the ethmoid bone, and the frontal process of the maxillary bone (Fig. 14.1). The periosteum of these orbital bones, the periorbita or orbital fascia, surrounds the contents of the orbit. It is continuous with the cranial periosteum at the orbital rim and attaches to the optic canal and the superior orbital fissure at the apex of the orbit, where it gives rise to a tendinous ring called the annulus of Zinn.¹⁸

Fig. 14.1 Bone structure of the orbit. (Reproduced with permission. © Department of Neurosurgery, University of Utah.)

The ocular globe is suspended by tendons and ligaments within the periorbital and is covered by Tenon’s capsule, a two-layered fascia that separates it from the orbital fatty tissue. The ligaments that support the globe include the ligament of Lockwood, which traverses from lateral to medial at the bottom of the globe, Whitnall’s ligament, which extends from the trochlea at the orbital roof to the lateral orbit wall, and the medial and lateral check ligaments.18

14.2.2 Nerves of the Orbit

The superior orbital fissure serves as a conduit for several cranial nerves entering the orbit from the cranial fossa. Among other structures, its contents include the oculomotor nerve, the trochlear nerve, the abducens nerve, and the ophthalmic division of the trigeminal nerve. Similarly, the inferior orbital fissure transmits the infraorbital nerve (Fig. 14.2), and the optic nerve enters the orbit via the optic canal at the orbital apex.^{16 ,​ 18} Also located near the apex, the ciliary ganglion provides autonomic input and encompasses multiple branches, including a parasympathetic root from the oculomotor nerve, a sympathetic root derived from the carotid plexus, and a sensory root that rejoins the nasociliary nerve. Additionally, the ganglion has approximately 10 branches, referred to as short ciliary nerves, that are distributed to the iris and cornea around the optic nerve.¹⁶

Fig. 14.2 Fissures and foramina of the orbit. (Reproduced with permission. © Department of Neurosurgery, University of Utah.)

14.2.3 Blood Supply to the Orbit

Next to the optic nerve, the ophthalmic artery enters the orbit through the optic canal. The ophthalmic artery then gives rise to the supraorbital artery, the lacrimal artery, the ciliary arteries, and the anterior and posterior ethmoidal arteries, which exit the orbit through the anterior and posterior ethmoidal foramina at the junction of the frontal bone with the ethmoid bone (Fig. 14.3).^{16 ,​ 18} A branch of the middle meningeal artery enters the orbit through the cranio-orbital foramen, anterior to the superior orbital fissure, on the lateral orbital wall. A terminal branch of the internal maxillary artery enters through the inferior orbital fissure.¹⁶

The venous system of the orbit is organized around two ophthalmic veins: the superior and inferior ophthalmic veins. The superior ophthalmic vein collects blood from several veins, including the nasofrontal, the central retinal, and the ethmoidal veins. It subsequently exits the orbit through the superior orbital fissure, draining into the cavernous sinus. The inferior ophthalmic vein collects blood from the anterior and medial walls of the orbit, as well as the lacrimal sac, eyelids, and the inferior rectus and inferior oblique muscles. It then divides into two branches: the first joins the cavernous sinus through the superior orbital fissure, and the second communicates with the pterygoid plexus through the inferior orbital fissure (Fig. 14.4).^{18 ,​ 20}

Fig. 14.3 Superior view of the right orbit. The roof and orbital fat have been removed and the superior muscles with optic nerve were sectioned to show the optic nerve (ON) and the ophthalmic artery (OphA) and its branches situated under the ON (central artery of retina [CAR], long posterior ciliary artery [LPCA], muscle artery [MusA], lacrimal artery [LA], meningeal branch [MenB]). In this view, we can also see the nerve of the medial rectus muscle (MRN). (Reproduced with permission from Springer Nature: Hayek G, Mercier P, Fournier HD. Anatomy of the orbit and its surgical approach. Adv Tech Stand Neurosurg 2006;31:35–71.)

Fig. 14.4 Superior view of the right orbit after section of the superior muscles showing structures passing between these muscles and the optic nerve (ON). NCN, nasociliary nerve; OphA, ophthalmic artery; SOV, superior optic vein. (Reproduced with permission from Springer Nature: Hayek G, Mercier P, Fournier HD. Anatomy of the orbit and its surgical approach. Adv Tech Stand Neurosurg 2006;31:35–71.)

14.2.4 Muscles of the Orbit

The orbit contains seven ocular muscles that originate at the annulus of Zinn (except the inferior oblique) and are responsible for eye movement. The rectus muscles (superior, medial, inferior, and lateral) allow the globe to move in the direction indicated by the name of the muscle. These are innervated by the oculomotor nerve, except for the lateral rectus muscle, which is innervated by the abducens nerve. The superior oblique muscle attaches to the medial side of the roof of the orbit via the trochlea. Its tendon extends and inserts on the lateral side of the posterior globe, allowing the globe to rotate inferiorly. The inferior oblique muscle originates from the medial orbital rim and inserts into the globe medially behind its equator. These attachments allow the globe to move superiorly. Innervation to the superior oblique is derived from the trochlear nerve whereas the oculomotor nerve innervates the inferior oblique. Finally, the levator palpebrae superioris, also innervated by the oculomotor nerve, is involved in elevation of the upper eyelid rather than participating in ocular motility.^{16 ,​ 18}

14.2.5 Lacrimal Gland

The lacrimal gland is located in the superior lateral part of the orbit in the lacrimal recess of the roof of the orbit. It is innervated by the lacrimal branch of the first division of the trigeminal nerve and receives secretory parasympathetic fibers arising from the geniculate ganglion.

The transcranial approach is indicated for large posterior orbital tumors, as well as for tumors that traverse intracranially21; however, the indication of the specific route depends in large part on the precise location of the lesion. The subfrontal route is better suited for tumors medial to the apex or optic canal, including intraorbital optic nerve gliomas that grow into the cranial cavity, as well as tumors lateral to the optic nerve.¹⁰ The supraorbital approach is instead indicated for orbital roof tumors, such as meningiomas. It is also used as an alternative minimally invasive approach for purely intracranial lesions in the anterior cranial fossa or parasellar region.⁵ The frontolateral pterional route is ideal for tumors of the superior orbital fissure, the optic canal, and the orbital apex, whereas pterional approaches are well suited for tumors of the intraorbital optic nerve or lesions situated dorsal to the optic nerve. The pterional-extradural route is typically indicated for decompression of the optic nerve in the optic canal, resection of periorbital tumors, and any lesions near the cavernous sinus or superior and inferior orbital fissures.¹⁰ Finally, the superolateral approach provides a surgical corridor to lesions situated lateral to the optic nerve between the lateral rectus muscle and the superior muscles, giving access to most regions of the orbit.¹⁶ In cases where the surgical lesion is located in the lateral orbit, lateral and basal to the optic nerve, or in cases that involve the lacrimal gland, the lateral approach may provide a less invasive option than the transcranial approaches described above.^{10 ,​ 16}

14.4 Surgical Techniques

14.4.1 Preoperative Preparation

The patient is placed in a supine position, without any undue pressure points. These procedures may be prolonged, and proper positioning of the patient may help minimize postoperative morbidity. After the induction of general anesthesia, a Foley catheter is inserted, as well as an arterial line and large-bore intravenous lines. The head is secured in a three-point fixation head clamp and kept neutral or turned 15 to 30 degrees to the contralateral side, depending on the exact location of the lesion and the specific surgical route contemplated. The head is elevated 15 degrees above the level of the heart to facilitate venous drainage. The head may be hyperextended to passively distance the frontal lobe from the orbital roof. Prophylactic antibiotics, corticosteroids, osmotic diuretics, and antiepileptics are administered in accordance with the preferences of the surgical team.

14.4.2 The Subfrontal Route

The head is placed in neutral position with slight extension of the vertex. A unilateral curvilinear skin incision is made behind the hairline extending from just above the root of the zygoma toward the midline. Although it is typically ended at the widow’s peak, the skin incision can be extended across the midline, if necessary, to allow mobilization of the skin flap anteriorly to expose the superior orbital rim. The skin flap is elevated anteriorly without disruption of the temporalis fascia and muscle. Care must be taken not to injure the supraorbital neurovascular bundle at the supraorbital foramen. The frontal keyhole area is exposed by subperiosteal mobilization of the anterior aspect of the temporalis muscle inferiorly. One burr hole is made at the frontal keyhole to expose the frontal dura and anterior fossa floor. A second burr hole is then made posteriorly just inferior to the superior temporal line. A unilateral frontal craniotomy is made where the anterior cut is flush with the anterior skull base floor to minimize bone loss at this area. Alternatively, the superior orbital rim can be removed concurrently with the frontal bone flap as a single piece. Once the bone flap is elevated, the frontal dura can be elevated to expose the orbital roof all the way back to the planum sphenoidale and medially to the olfactory groove. The inner table of the frontal bone above the superior orbital rim can be drilled to increase exposure. Using a diamond drill bit, the roof of the orbit is removed as much as necessary to expose the periorbita. In cases where optic nerve decompression is needed, the optic canal can be unroofed through to the falciform ligament. It is not uncommon to open the ethmoidal or sphenoidal sinus during aggressive orbital roof removal; however, violation of the sinus mucosa is rare with judicious use of the diamond drill bit. In cases in which the sinus is exposed, it must be repaired with fascial or muscle graft. At this point, if the periorbita is not already opened by the lesion, it can be incised in line with the long axis of the orbit to avoid injury to the intraorbital contents. In some cases, the frontal branch of the ophthalmic nerve can be seen through the periorbita and can become an important landmark for periorbital opening.

Once the periorbita has been incised, the orbital contents and cone can be accessed via three routes described by Natori and Rhoton²²: lateral, central, and medial. The lateral route is directed between lateral rectus muscle and the superior rectus and levator palpebrae superioris muscles medially. This route allows visualization of lesions lateral to the optic nerve. A lesion may be approached medial or lateral to the superior ophthalmic vein depending on how easily the vein can be mobilized in either direction. Care must be taken not to injure this important vein. The lateral route also provides access to the ophthalmic artery and the nasociliary nerve, which cross laterally to medially superior to the optic nerve. The ophthalmic artery then gives rise to the ciliary arteries at its medial bend and the lacrimal artery laterally. The abducens nerve, which runs along the inner side of the lateral rectus muscle, and the oculomotor nerve branch destined for the inferior oblique muscle, can also be identified on the inferolateral side of the optic nerve. To expose the superior orbital fissure, the tendinous ring may be incised between the superior rectus and lateral rectus muscle.

The central route to the orbital contents is often used for limited surgery, such as biopsies. The levator palpebrae superioris muscle overlaps the medial side of the superior rectus muscle. This muscle may be retracted medially and the superior rectus laterally to open a surgical corridor. To allow a better view of the optic nerve at the level of the annular tendon, the frontal nerve is kept attached to the surface of the levator muscle and retracted medially. Alternatively, it can be dissected and retracted laterally with the superior rectus muscle. Once the muscles are retracted, the entire width of the middle intraorbital third of the optic nerve can be exposed by opening the fibrous septum extending along the inferior margin of the superior rectus muscle. The ophthalmic artery and the nasociliary nerve, which cross on the superior side of the optic nerve laterally to medially, will be immediately visualized. Moreover, the superior ophthalmic vein, the ciliary nerves and arteries, and the oculomotor branch to the levator and superior rectus muscles must be identified and preserved during this approach.

The subfrontal approach along with its variations provides direct access to the superior part of the orbit and is indicated for lesions with or without extension to the frontal lobe. It can be used also for lesions in the medial part of the orbital apex or the optic canal that are difficult to reach with less invasive techniques.16 It requires only minimal dissection of temporalis muscle to expose the frontal keyhole. However, some of the disadvantages of this approach include frontal lobe retraction, risk of frontal sinus violation, and potential difficulty in approaching posterior orbital lesion. Although uncommon, adverse outcomes such as temporary diplopia, enophthalmos, and decreased visual acuity may occur.²³

14.4.3 The Supraorbital Route

The patient is placed in supine position with the head rotated 15 to 30 degrees to the contralateral side. An incision is made just above the eyebrow from the supraorbital notch to the lateral aspect of the eyebrow, avoiding cutting across the hair follicles. The frontal skin flap is dissected subcutaneously and retracted upward. Again, care must be taken not to injure the supraorbital neurovascular bundle. The pericranium is cut in a C-shaped fashion based at the orbital rim and reflected downward. The frontal keyhole area is exposed by mobilizing a small portion of the temporalis muscle inferiorly. A burr hole is made in this region to expose the frontal dura, and a small frontal craniotomy is performed preserving the superior orbital rim. As with the subfrontal approach, the inner table of the frontal bone is drilled flush with the anterior skull base. The frontal dura is elevated and the orbital roof is removed. After opening the periorbita, the levator palpebrae superioris muscle and the superior rectus muscle are exposed. For deeper intraconal lesions, self-retaining retractors are positioned in the orbital fat to obtain exposure. At the completion of the intended procedure, any defects in the periorbita are closed with sutures or replaced by a dural patch. Although some surgeons do not reconstruct the orbital roof,¹⁰ bone fragments obtained from excision of the roof may be used for its reconstruction.²⁴ The reflected pericranium is sutured and the subcutaneous layer is closed with interrupted sutures.

Advantages and Disadvantages

The supraorbital approach is considered minimally invasive, requires minimal temporalis muscle dissection, and provides an excellent cosmetic result. It requires minimal brain retraction or orbital manipulation and carries a lower risk of injuring the superficial temporal artery. However, it provides a small corridor to access orbital lesions, particularly in the orbital apex, and increases the risk of injuring the supraorbital neurovascular bundle and the frontalis branches of the facial nerve. Moreover, this approach limits exposure of the pericranium, which restricts the use of a pericranial graft for reconstruction.²⁴ Some complications related to the approach include violation of the frontal sinus, frontal hypoesthesia, frontalis muscle weakness, cerebrospinal fluid (CSF) rhinorrhea, and cosmetic problems, such as visible scar or eyebrow alopecia.^{24 ,​ 25} The supraorbital approach is primarily reserved for small discrete lesions of the superior part of the orbit.

14.4.4 The Frontotemporal Approach

The patient is positioned supine with the head rotated 10 to 15 degrees to the contralateral side with slight extension to allow a straight trajectory to the optic canal and the superior orbital fissure. A curvilinear incision is performed 1 cm anterior to the tragus extending upward behind the hairline to the widow’s peak. The musculocutaneous flap is elevated as a single unit and reflected anteriorly. Typically, three burr holes are made: one at the frontal keyhole to expose the anterior fossa floor; one at the temporal keyhole just above the root of the zygoma to expose the middle fossa floor; and one posteriorly just inferior to the superior temporal line. A frontotemporal craniotomy is then completed by connecting the burr holes. The dura of the frontal and temporal lobe is elevated, and the sphenoid ridge is drilled down to the meningo-orbital band, a landmark for the lateral border of the superior orbital fissure. Next, the meningo-orbital band is cauterized and divided sharply. This allows the dura to be peeled posteriorly to expose the anterior clinoid, the superior orbital fissure, the lateral wall of the cavernous sinus, and the greater wing of the sphenoid. At this point, the orbital roof and lateral orbital wall can be drilled down just posterior to the superior and lateral orbital rim. Decompression of the optic nerve and the superior orbital fissure may be accomplished using a diamond drill with continuous irrigation to prevent thermal injury to these structures. An anterior clinoidectomy can be also performed in an extradural fashion by drilling down the optic strut, when indicated. The medial limit of the orbital bone removal is marked by the ethmoidal sinus medially, the optic nerve and the superior orbital fissure posteriorly, and the foramen rotundum inferolaterally. Although some authors advocate for the removal of the superior orbital margin and the zygomatic arch,²⁶ this maneuver may not significantly improve access to the posterior third of the orbit.²⁷ At the completion of bony drilling, the periorbita may be incised longitudinally and the orbit accessed as described above.

Advantages and Disadvantages

This approach provides wide access to the orbit contents as well as the frontal and temporal lobes and the cavernous sinus. It is especially useful for lesions located around the orbital apex. Moreover, lesions of the superior orbital fissure, inferior orbital fissure, superolateral aspect of the optic nerve, and superolateral and inferolateral orbital quadrants are excellent candidates for resection via this approach. These lesions can be approached with minimal brain retraction.27 One major complication of the frontotemporal approach is the development of orbital compartment syndrome (OCS). This condition is characterized by proptosis, ocular movement paresis, and visual loss, and occurs because of increased orbital pressure that may be caused by intraorbital hemorrhage or edema.²⁸

14.4.5 The Superolateral Approach

The superolateral approach is performed via either a standard frontotemporal skin incision or an eyebrow incision. After the frontal bone is exposed, the subperiosteal dissection is continued anteriorly to expose the superior orbital rim. About 1 cm posterior to the frontal process of the zygomatic bone, a small incision is made in the superficial temporalis fascia starting at the superior temporal line and extending inferior toward the root of the zygoma for 2 to 3 cm. Next, a subfascial or interfascial dissection is performed to expose the frontal process of the zygomatic bone, the upper half of the lateral orbital rim, and the frontozygomatic suture. The dissection is continued into the orbital cavity to separate the periorbita from the orbital roof and lateral wall. The temporalis muscle is dissected off the frontal keyhole area and the superior temporal line, leaving a small cuff of muscle along this line for reattachment at the end of the surgery. The muscle is then retracted inferiorly and posteriorly. The craniotomy can be performed using either one-piece bone flap¹⁵ or a two-piece bone flap.¹⁶ In the two-piece method, the first flap is a frontotemporal craniotomy and the second flap is an orbitotomy comprising the superior orbital rim, lateral orbital rim, part of the orbital roof, and lateral orbital wall.¹⁶ Because of the ease of reconstruction, the senior author prefers a one-piece bone flap method. For this craniotomy, a MacCarty burr hole is made in the frontal keyhole area, simultaneously exposing the frontal dura and the periorbita, and two other burr holes are made in the temporal bone as previously described for the frontotemporal approach. The frontal dura and the periorbita are dissected from the orbital roof through the burr hole. A craniotomy is fashioned by connecting the MacCarty burr hole to the temporal keyhole and then extending posteriorly to the posterior temporal burr hole. The frontal bone cut is made connecting the posterior burr hole to the superior orbital rim just medial to the supraorbital foramen. A thin drill bit (e.g., C1) can be used to cut the orbital rim toward the orbital roof. The next cut is made connecting the MacCarty burr hole to the lateral orbital rim just inferior to the frontozygomatic suture. This cut can be made with either the footplate attachment or an oscillating saw while protecting the orbital contents. At this point, the only remaining attachment of the bone flap is the orbital roof. A small osteotome may be used to complete the cut along the orbital roof. The osteotome cut is pointed toward the ipsilateral supraorbital notch to avoid injury to the optic nerve when fracturing the orbital roof posteriorly. Once the one-piece bone flap is removed, the remaining orbital roof and lateral wall may be drilled as far posteriorly as needed. Alternatively, a similar craniotomy may be made through a minimally invasive eyebrow incision. Notably, since in this modification much of the temporal bone is spared, the eyebrow approach is best suited for small discrete orbital lesions, parasellar masses, or anterior circulation aneurysms.¹⁵

Advantages and Disadvantages

The main advantage of the superolateral approach is the good access it confers into the superolateral orbital quadrant.¹⁶ Generally considered a minimally invasive approach when performed through an eyebrow incision, this approach provides limited access to the orbital apex and renders lesions located inferomedially to the optical nerve inaccessible.¹⁵

14.5 General Considerations to Avoid Postoperative Complications

14.5.1 Nasal Sinuses

The frontal sinus is at risk when performing any variation of the frontal craniotomy. In some cases, this sinus cannot be avoided during transcranial approaches for orbital lesions. When violated and the opening is large, the sinus should be cranialized by removing the posterior wall and mucosa. After the frontal ostium is plugged, the exposed sinus is covered with vascularized pericranial flap. When the opening into the sinus is small, it may be sealed with bone wax or a muscle plug prior to being covered with vascularized flap. Similarly, the ethmoid and the sphenoid sinuses are also at risk during removal of the orbital roof and in the setting of optic nerve decompression. If these are violated, careful attention should be paid to avoid concurrently injuring the underlying mucosa. In these situations, the opening into the sinus may be covered with a small muscle plug or local fascial graft.

14.5.2 Orbital Fat

Orbital fat is important for ocular movement, aesthetic appearance, and protection of the globe from trauma. To avoid postoperative enophthalmos, it is important to limit intraorbital fat manipulation such that it is mobilized only enough to allow access to the intraorbital lesion of interest. The fat may be dissected and retracted but generally not excised.¹⁶

14.5.3 Brain Retraction

One of the main risks of transcranial surgery of the orbit is inadvertent injury to the frontal or temporal lobe. This may often occur because of excessive retraction or when brain relaxation is insufficient.6 To minimize the risk of retraction injury, the head must be adequately hyperextended to allow the frontal lobe to passively fall away from the orbital bone. In cases where brain retraction is still needed, the use of dynamic retraction is preferred but may be supplemented by the use of a wide retractor blade.⁵

14.5.4 Reconstruction of Orbital Walls

To date, there is no clear consensus regarding the need for orbital wall reconstruction after a transcranial approach to the orbit. Some authors recommend orbital wall reconstruction whenever the orbital floor or more than one orbital wall is removed. Repair may be advocated to prevent occurrence of pulsatile enophthalmos or exophthalmos postoperatively when the periorbita is resected.^{16 ,​ 29} Because these complications are uncommon, in the senior author’s experience orbital reconstruction is unnecessary except in rare occasions when the orbital rim is removed.^{30 ,​ 31 ,​ 32 ,​ 33 ,​ 34} In fact, reconstruction of the orbit is routinely avoided if proptosis is one of the presenting signs. When orbital reconstruction is needed, the wall can be reconstructed using a titanium mesh, a piece of Medpor, dural substitute, or partial-thickness bone graft.

14.6 Illustrative Cases

14.6.1 Case 1: Cavernous Hemangioma of the Superomedial Orbital Quadrant

A 60-year-old woman presented with a 1 year history of progressive pressure-like headache associated with proptosis in the left eye. Physical examination revealed slight left proptosis and hypoglobus. On formal ophthalmologic examination, she was noted to have intact visual acuity and visual fields. MRI revealed an enhancing orbital lesion in the superolateral quadrant situated between the superior oblique muscle medially and the levator palpebrae superioris and superior rectus muscles laterally. The lesion eroded the orbital roof but without intracranial extension. The patient underwent an eventful left subfrontal approach through a frontal craniotomy with preservation of the orbital rim. A gross-total resection was achieved, and the patient was discharged to home on postoperative day 4. Proptosis and hypoglobus had resolved completely at her 4-week follow-up examination (Fig. 14.5).

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