Endonasal Transethmoidal Approach (Medial Orbitotomy)

H.-J. Welkoborsky

This is a classic rhinosurgical approach.

18.2.1 Indications

The indications for this approach are peribulbar and intraconal retrobulbar space-occupying masses, abscesses, aspergillomas, or vascular malformations medially to the eyeball or the optic nerve up to the orbital apex. ^{2,​ 3,​ 4,​ 5,​ 6}

18.2.2 Procedure

With transethmoidal medial orbitotomy, first of all an endoscopic or microscopic ethmoidectomy is performed with opening of the sphenoid sinus. It is important that the approach to the ethmoid bone is made laterally to the medial nasal concha. After that the lamina papyracea is exposed in its full extent from the orbit apex right through to anterior ⁷ ( ▶ Fig. 18.1a–c.; Video 18.1). When resecting the lamina papyracea, one should make sure that the periorbita still remains intact as, otherwise, sight and orientation are affected by the prolapsing of fat tissue. ⁸ After resection the lamina papyracea, the incision of the periorbita is made using a curved sickle knife. The orbital adipose tissue prolapses, and is prepared with a blunt preparation instrument (e.g., curved dissectors) until the medial rectus muscle is revealed. A light pressure on the globe leads to easier exposure of the pathologic process, which can then be removed using microsurgical dissectors with the aid of an angled endoscope or of an operating microscope. If indicated, additional decompression of the optic nerve can be carried out via the same approach. ⁷ In this event, the nerve canal in the lateral sphenoid wall is exposed and the covering bone shell is resected. A reconstruction of the medial orbital wall is usually not necessary. The operation is terminated by the insertion of packing into the nasal cavity.

Consistent rhinological follow-up treatment is important postoperatively. As a rule, the nasal packing can be removed on the first or second day postoperatively. Any scabs and crusts forming should be endonasally suctioned away daily. Nasal oils and ointments are suitable for caring for the mucous membrane and for supporting wound healing. The healing of the endonasal wound takes between 4 and 6 weeks.

18.2.3 Complications

Possible complications of endonasal transethmoidal endoscopic orbitotomy are:

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  Acute hemorrhage when the anterior or posterior ethmoid artery is injured. If the vessels run through the area of the operation without a covering of bone at the roof of the ethmoidal bone, they can be coagulated bipolarly or closed with a titanium clip to prevent bleeding.

  
  
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  Injury of the skull base with subsequent liquorrhea. If liquorrhea occurs, the defect is to be closed if possible without delay, for example, with a piece of temporalis fascia.

  
  
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  Injury of the optic nerve with amaurosis. This complication is rare and occurs in less than 1% of cases. To avoid damage to the nerve it is recommended to use a computerized navigation system and perform the operation with a magnifying angled endoscope or with an operating microscope. For preparation purposes it is recommended to use only blunt instruments or microinstruments that are sharp only on one side. Amaurosis caused by a nerve injury is irreversible in many cases.

  
  
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  Olfactory disorders when preparation goes too far medially in the olfactory region.

  
  
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  Displacement of the frontal sinus infundibulum by prolapsing orbital contents with the subsequent development of a chronic frontal sinusitis. In order to prevent this, the anterior ethmoidal cells should be opened up and resected, and a wider approach to the frontal sinus should be created.

  
  
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  Injury of the medial rectus muscle with eye globe motility disorders and double vision. This complication can be avoided if, during preparation, the muscle is pushed very carefully to the side or in a cranial or caudal direction, which is only possible under direct visual control. Here one should take note that the muscle, particularly in inflammatory diseases, can often be swollen with edema, which can make its identification difficult.

18.3 Transantral Approach

H.-J. Welkoborsky

18.3.1 Indications

The transantral or transmaxillary approach (syn. transmaxillary orbitotomy) is indicated for removal of pathological processes located caudally, mediolaterally and medio-inferiorly to the eyeball or optic nerve, and also for removing lacrimal sac tumors that infiltrate the orbit from medially. ^{9,​ 10} Via this approach the caudal intraconal sections of the orbit can be reached right up to the orbital apex. ^{6,​ 11}

18.3.2 Procedure

The anterior wall of the maxillary sinus is exposed via a sublabial incision in the oral vestibule mucosa. When pushing the soft tissue parts of the cheek away from the bone, one should be careful not to injure the infra-orbital nerve, which exits the infra-orbital foramen in the area of the infra-orbital rim. A large fragment is then temporally removed from the anterior wall of the maxillary sinus, which is replaced at the end of the operation (osteoplastic maxillotomy). Before cutting out the bone lid, it is advantageous to adjust the microplates with which the anterior wall of the maxillary sinus will be fixed later and to create the drill holes that are necessary to receive the osteosynthesis screws. The orbital floor is then exposed, freed of mucous membrane, and the infra-orbital nerve canal is also imaged. An osseous window should be inserted in the medial maxillary sinus wall to the nasal cavity so that secretion can drain and to ensure sufficient postoperative ventilation of the sinus, which is required for complete healing. The orbit floor is resected; the periorbita lying underneath this is left intact at this time ( ▶ Fig. 18.2). The size of the resection is based on the position and extent of the pathologic process in the orbit. One should make sure to preserve a bony bridge with the infra-orbital canal. Otherwise a downward displacement of the eyeball can occur, causing double vision. In practice this means that the orbital floor can be resected laterally and medially to the nerve canal without any sequelae. The periorbita is slit using a sickle knife. One should take care of the inferior rectus muscle as well as of the inferior oblique muscle. Using microsurgical dissectors the pathological process can now be prepared and removed. The orbit floor can, if necessary, be reconstructed, for example, with a piece of temporalis fascia, a PDS (polydioxanone) plate, or titanium mesh. The operation is concluded with the reinsertion of the temporarily removed anterior wall of the maxillary sinus, which is fixed in place with the previously adjusted microplates (one plate each on the medial and lateral edge of the bone lid is usually sufficient). The closure of the mucous membrane in the oral vestibule is done with absorbable sutures (Video 18.2).

18.3.3 Complications

Possible complications of transmaxillary orbitotomy are determined by the anatomical characteristics, particularly the course of the nerves supplying the extraocular muscles ¹²:

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  A separation of the infra-orbital nerve or tensile or compressive stress on it, either in the course of its canal in the orbit floor or after its exit from the infra-orbital foramen, causes a hypoesthesia in the area of the cheek, the lateral nose, and the maxillary anterior teeth. For this reason too, when using retractors or isolators, one should make sure that the nerve is not touched by the instrument.

  
  
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  Injury to the nerves supplying the extraocular muscles (inferior rectus, inferior oblique, possibly medial and lateral rectus muscles) results in paresis of these muscles with resulting double vision. According to anatomical investigations, nerve fibers mainly enter the muscles in the central third of the muscle belly ¹² so that particular care is required during preparation. The same applies with processes located posteriorly close to the superior orbital fissure

Further complications of this approach can include:

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  Hemorrhage upon injury to the infra-orbital artery or, with processes located posteriorly, to the ophthalmic artery with its infra-orbital branches.

  
  
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  Enophthalmus with consequent double vision. This complication can be expected if the entire orbit floor—that is, including the infra-orbital nerve canal—has been resected. Leaving the strip of bone with the nerve canal avoids this complication.

18.4 Lateral Orbitotomy

H.-J. Welkoborsky

Lateral orbitotomy was first described by Krönlein in 1888 and since then has undergone some modifications. This is an external approach to the lateral, laterocranial and latero-inferior orbital sections.

18.4.1 Indications

Indications for a lateral orbitotomy are the removal of pathologic processes laterally to the eyeball and the optic nerve, in the region of the lacrimal glands and in the latero-inferior as well as in the laterocranial parts of the orbit, and also in the context of orbital decompression in patients with Graves’s orbitopathy (balanced decompression, see Chapter ▶ 7.4.3). ^{3,​ 8,​ 13,​ 14,​ 15,​ 16} Further indications are orbit reconstructions for fractures of the lateral orbital rim and wall. ¹⁷ However, processes in the area of the orbital apex are more difficult to reach via this approach due to the massive greater wing of the sphenoid bone, which represents the dorsal resection limit. ^{18,​ 19}

18.4.2 Procedure

There are two possibilities available for the skin incision: an incision in the area of the lateral orbital rim, or an incision in, or dorsally, to the hairline (pterional incision). The latter has the advantage that the incision is not visible and so causes no cosmetic problem. The disadvantage of the orbital rim incision is the possibility of injury to the ramus frontalis and ramus ocularis of the facial nerve, which run through the area being operated on. If one decides on this incision, neuromonitoring of the facial nerve is recommended. Recently, methods of lateral orbitotomy via a transconjunctival endoscopic approach have been described, but this does give a significantly more restricted overview of the area of the operation compared to the external transcutaneous approaches. ^{20,​ 21}

With a pterional incision, after separation of the skin and subcutaneous tissue, a skin–soft tissue flap (scalp flap) is formed and prepared far anteriorly until the lateral orbital rim is exposed ( ▶ Fig. 18.3; Video 18.3). One should take care to preserve the lateral palpebral ligament as, otherwise, the lateral lid angle can be obliterated. The very strong temporalis muscle overlies the lateral orbital wall and is attached by its fibers to the temporal bone. It is cranially incised and bluntly pushed away from the bony lateral orbit wall. Microplates are needed for the reconstruction later of the lateral orbital rim. It is advantageous to fit these plates and to drill the holes necessary for taking the osteosynthesis screws in this phase of the operation. This will facilitate the later reconstruction with a perfect fit. With an oscillating saw the bone at the lateral orbital rim is now separated. Two cuts by the saw at a sagittal distance of at least 2 cm are required to temporarily separate a correspondingly large fragment temporarily. In doing this, the bone resections are arranged in a V-shape, which facilitates the later reconstruction ( ▶ Fig. 18.3; Video 18.3). One should make sure that the lateral palpebral ligament is preserved and remains attached to the bone. The sagittal distance of at least 2 cm should be adhered to as, otherwise, there will not be sufficient space for preparation in the orbit. The relatively thin lateral orbital wall can be separated with the oscillating saw parallel to the orbital roof and floor. The inferior boundary is represented by the greater sphenoid wing. At this preparation stage the periorbita remains intact. After temporary removal of the lateral orbital wall the periorbita is incised with a sickle knife. The pathologic process can now be prepared and removed using microsurgical dissectors and microscissors. One should pay attention to the lateral rectus muscle which, when the pathologic process has an intraconal site, must be displaced in the cranial or caudal direction. The periorbita can be sutured with a thin absorbable suturing material following complete resection of the pathologic process. For reconstruction of the lateral orbital wall and of the lateral orbital rim, the temporarily separated bone shell is repositioned and fixed in place by means of the already fitted microplates. The temporalis muscle is moved back and fixed. The operation is concluded with the insertion of an Easyflow drainage (alternatively, Redon drainage) and closure layer by layer of the scalp and skin layers.

18.4.3 Complications

The specific complications of the lateral approach to the orbit can be divided into intraorbital and extraorbital complications. ^{16,​ 18}

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  Intraorbital complications

  
  
  
  
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    Detachment of the lateral palpebral ligament from the lateral orbit rim with subsequent blunt shape of the lateral canthus. This complication can be avoided by making sure to preserve the lateral palpebral ligament on its osseous attachment.

    
    
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    Injury to the lateral rectus muscle and/or the inferior rectus muscle with impairment of eye globe motility and double vision. In this connection one should once again point out the importance of conducting the operation with the aid of magnifying endoscopes or of an operation microscope. One must also take care during preparation not to exert too much pressure on the muscles and, when the site of the pathologic process being removed is located intraconally, to push the muscles very carefully in the cranial or caudal direction.

    
    
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    With very extensive medial preparation there exists the risk of injuring the ciliary ganglion, located laterally to the optic nerve, with subsequent anisocoria.

  
  
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  Extraorbital complications

  
  
  
  
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    Injury to the ramus frontalis or the ramus orbitalis of the facial nerve with subsequent disorder of the mimetic musculature through to an inability to close the eyelids. In order to avoid this, precedence should be given to the course of the pterional incision behind the hairline and the operation should be conducted with neuromonitoring of the facial nerve.

    
    
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    An incomplete repositioning of the temporalis muscle can result in the sinking of the tissue above the zygomatic arch.

18.5 Anterior Orbitotomy

B. Wiechens

In contrast to the approaches to the orbit described above, in this following section those approaches are described that can be summarized as “anterior orbitotomy.” The majority of these approaches are used for biopsies and the removal of lesions that are palpable through the eyelids. However, processes lying deeper can also be reached via an anterior orbitotomy. The choice of which approach is appropriate is determined mainly by the location of the disease. With malignant tumors the radicality of the excision always depends on the individual case, taking into account the prognosis as well as the quality of life to be anticipated for the patient. The possibility of a complete tumor excision via an anterior orbitotomy depends considerably on how far the process extends behind the equator of the eye globe. Where necessary more invasive approaches or combinations might be recommended.

Anterior orbitotomy can be differentiated in transpalpebral and transconjunctival approaches ( ▶ Fig. 18.4).

Basically many interventions on small, subcutaneously located lesions in the anterior part of the orbit can easily be performed under local anesthesia. If preoperative diagnostic imaging has been inconclusive and/or if the feasibility of the operation under local anesthesia is questionable, general anesthesia is preferable as long as there are no objections due to the general situation of the patient. Thus, the operation, if necessary, can be extended without any problem, which is not possible or only to a limited extent in local anesthesia.

18.5.1 Transpalpebral Approach

When contemplating transcutaneous or transpalpebral approaches, the visibility of postoperative scars and the complication profile should also be considered. Thus, if possible, an approach should be chosen that will enable the best aesthetic result to be achieved. This manner of proceeding will of course be subject to limitations, especially in malignant conditions, with regard to the approachability of the tumor and the planned radicality.

Tumors or pathologic conditions in the upper space of the orbit can be reached either via a lateral orbitotomy in the area of the eyebrow or transpalpebrally via an incision in the upper lid groove, if necessary with lateral extension. Depending on localization, some specific potential complications should be considered: (1) injury of the trochlea superiomedially, with impairment of the levator complex and subsequent ptosis in the medial lid area; (2) damage to the lacrimal gland and its drainage system in the lateral lid area; (3) chronic edema and paresthesias following lateral extension of the incision; and (4) lesions of the lacrimal sac or lacrimal duct with medial approaches. ²²

Common tumors in the upper space of the orbit are dermoid cysts, hemangiomas, and mucoceles. Particularly with the latter, bony erosions in the area of the medial orbital wall and the orbital roof can be expected. Accordingly, careful preoperative diagnostic imaging and, where necessary, an interdisciplinary operation for resecting the tumor are recommended. Approaches to the superior orbit bear the risk of injuring in particular the supra-orbital nerve and the nerves in the medial and lateral lid angle. Thus patients must be informed preoperatively about the possibility of these complications with subsequent paresthesias/anesthesias or other functional limitations.

Preoperative assessment and marking up of the course of the incision in an erect position of the patient is necessary for all approaches. This is particularly important as anatomical conditions change in supine position of the patient. Preoperative and intraoperative photographic documentation of the findings is also recommended. In addition to the protection of anatomical structures, accurate hemostasis is important in order to reduce the risk of a postoperative orbital hematoma. Another principle is to spend as long as possible on the preparation in the extraperiorbital space until the lesion can be conclusively identified. This mode of procedure during the exploration significantly reduces the risk of postoperative orbital morbidity.

Upper Anterior Orbitotomy

Approaches for upper anterior orbitomy include the following.

Lateral Eyebrow Incision

Basically the approach to the superior lateral orbit via this incision is very limited due to the fact that the skin in the area of the eyebrow is very thick, the route for access to the superior lateral orbit by this approach is rather long, and the overlaying skin is not very mobile. A lateral extension of the incision, which is occasionally needed, is often associated with scarring; in contrast, an extension of the incision downward traverses important sensory nerve pathways and the relaxed skin tension lines (RSTL).

Approach via the Upper Lid Crease

This incision provides good access to the upper and lateral orbital rim and to the entire area of the upper orbit. In addition, the lid crease obscures later scar formation (AO Foundation). If necessary, this incision can be extended into the lateral canthus. After the skin incision, the approach passes through the orbicularis oculi muscle, whereby the orbital septum remains intact and, together with the orbital fat located here, protects deeper lying structures during preparation. The incision is done in a bow shape in the area of the lid crease, comparable to blepharoplasty of the upper lid, that is, ~10 mm above the lid margin medially and ~7 mm in the area of the lateral upper lid. Extraconal lesions in the upper orbit, even if they extend intraconally in part, can be reached by this approach. In the next step the orbital septum is separated. The closing of the wound is performed layer by layer (periosteum, muscle, and skin sutures) to achieve favorable cosmetic results (Video 18.4).

Inferior Anterior Orbitotomy

Many orbital conditions such as trauma, tumors, or transmitted infections occur in the inferior area of the orbit. These lesions are frequently located far anterior and so are palpable from outside. The affected regions can be easily reached via an inferior orbitotomy ( ▶ Fig. 18.5). Orbital processes located extraconally can usually be displayed well through this approach. Intraconal lesions can be reached through a preparation between the inferior rectus muscle and the lateral rectus muscle. Here one should pay attention to the identification and protection of the inferior oblique muscle. The medial inferior approach is more difficult due to the anatomical conditions.

Essentially, three transpalpebral incisions are possible in the area of the lower lid ( ▶ Fig. 18.6). Modifications to these are common and are used depending on the localization of the process and the surgical strategy.

Infra-orbital Incision

The infra-orbital incision is positioned in a transverse skin fold at the level of the infra-orbital margin. The infra-orbital rim is then exposed by means of blunt preparation between the orbicularis oculi muscle and the orbital septum, followed by a subperiostal preparation. After incision of the periosteum at the infra-orbital rim, the orbital floor is exposed subperiostally.

This approach is the shortest one to get access to the inferior orbit. However it is done in the transitional zone between the thin eyelid skin and the thicker skin of the cheek. Due to the lymph drainage pathways, this area is predisposed to postoperative edema and visible scars (AO Foundation). Because of these considerable complications, to date the infra-orbital incision is employed only in limited cases.

Subtarsal Incision

The incision is performed directly underneath the lower tarsus, medially ~2–3 mm underneath the lid rim and coursing slightly laterocaudally. After dissection of the orbicularis oculi muscle along the muscle fibers, the infra-orbital rim can finally be exposed while protecting the orbital septum. After separation of the orbital septum, a further preparation into the deeper orbit layers is also possible. Finally, the wound is closed layer by layer (first closure of the periosteum, followed by closure of the orbicularis oculi muscle, and then placement of skin suture).

Subciliary Approach

For the subciliary approach an incision is made directly under the eyelash row of the lower lid. From here there are three different surgical options to obtain access to the orbit ( ▶ Fig. 18.7):

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  Subcutaneous preparation (anterior to the orbicularis oculi muscle).

  
  
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  Direct deep preparation (behind the orbicularis oculi muscle).

  
  
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  Preparation layer by layer (through the orbicularis oculi muscle).

  
  
  
  

  

  
  

  Fig. 18.7 Subciliary approach and repositioning of a zygomatic bone fracture. ²³ (a) Possibilities for preseptal preparation routes: violet line, anterior to the orbicularis muscle; orange line, direct approach through all layers of the orbicularis muscle; red line, preparation layer-by-layer. (b) Subciliary approach for repositioning of a zygomatic bone fracture. The subciliary incision line is marked with a surgical pen. (c) The orbicularis muscle is exposed. (d) The orbital adipose tissue comes to the fore once the muscle is dissected. (e) The bony infra-orbital rim can now be exposed. (f) The fracture is repositioned and stabilized with an osteosynthesis plate. (g) This photograph shows the wound closure after the procedure has been terminated.

The subcutaneous preparation anterior to the orbicularis oculi muscle results in a very thin skin flap, which tends to scarring and thus predisposes to lid malpositioning (in particular lower lid ectropion) ( ▶ Fig. 18.8).

Direct deep preparation with incision through the orbicularis muscle and subsequent preparation anterior to the orbital septum results in a combined skin–muscle flap, which postoperatively carries the risk of reduced lower lid tone with subsequent lid malposition.

Preparation in layers begins with a skin flap with subsequent horizontal separation of the orbicularis oculi muscle layer by layer.

The last two options in particular require surgical skills to ensure that the orbital septum is not injured. If preparation is inaccurate, there is risk of a postoperative contraction of the lower lid retractors with subsequent lid malposition. ²³

Basically it is possible to expose the infra-orbital rim with all three types of preparation without opening the orbital septum. If the pathological processes are located deeper in the orbit, extended preparation can take place after separation of the orbital septum.

Comparative Studies

Due to its potential complications (lower lid ectropion or lower lid retraction as well as long-lasting lid edema) the infra-orbital approach is rarely used. In this subsection only the subtarsal and subciliary approaches are discussed.

Proponents of both approaches argue that the lower orbital rim and lower orbit can be reached in its entirety. ²⁴ Although a visible scar is created in both approaches, this can be concealed either underneath the eyelash row or in the lower lid groove—particularly in older people—and is therefore only minimally visible. One disadvantage of the inferior transpalpebral approaches is the risk of expanded eye opening in a downward direction (scleral show) or lower lid ectropion. For this reason several studies were conducted comparing the complication rates of transpalpebral (transcutaneous) approaches. The risk of lower lid retraction or ectropion with a subciliary approach lies between 12.5 and 42%, ^{25,​ 26} while it is only 2.7 to 7.7% for the subtarsal approach. ²⁶ Factors that inherently predispose to a lower lid retraction or a lower lid ectropion include the occurrence of hematomas, lid edemas, adhesions of the orbital septum, and scar contractions following treatment of an orbital floor fracture ²⁷ ( ▶ Fig. 18.12). Higher rates of visibility of the scar are reported for the subtarsal incision compared with the subciliary incision (2.2 versus 0%). ²⁸

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