Ординатура / Офтальмология / Английские материалы / Applied Pathology for Ophthalmic Microsurgeons_Naumann, Holbach, Kruse_2008

3.2.3.3

External Dacryocystorhinostomy with Bypass Tube Insertion

The principle is an insertion of a bypass tube passed from the medial canthus through the soft tissues and the bony rhinostomy into the nasal cavity.

Indications include canalicular obstructions with less than 8 mm of patent canaliculus, a failed canalicu- lo-dacryocystorhinostomy and a functional lacrimal obstruction not helped by a routine dacryocystorhinostomy (as in a complete facial palsy).

Bypass tube surgery requires long-term aftercare by the ophthalmologist as well as the patient themselves, because complications such as migration, malposition or obstruction of the tube and granuloma formation may occur.

In addition to the external approach, endonasal dacryocystorhinostomy is widely in use. The nasal mucosa and lower lacrimal sac are approached via the nose using an endoscope for magnification and illumination. The mucosa is incised and surgically excised or laser ablated. The rhinostomy is usually smaller than that of external dacryocystorhinostomy. There are no sutured flaps. Tubes are usually used. Indications for endonasal (intranasal, transnasal) dacryocystorhinostomy include obstructions in the lower lacrimal sac and inferior to it.

References (see also page 379)

Busse H: Classical lacrimal apparatus surgery from the ophthalmological viewpoint [in German]. Ophthalmologe 2001; 98:602 – 6.

Emmerich KH, Busse H, Meyer-Rüsenberg HW: Dacryocystorhinostomia externa. Technique, indications and results (in German). Ophthalmologe 1994; 91:395 – 398

Font RL: Eyelids and lacrimal drainage system. In: Spencer WH (ed): Ophthalmic pathology. Vol. 4. Philadelphia, London, Tokyo: WB Saunders; 1996:2412 – 27

Hurwitz JJ (ed): The lacrimal system. Philadelphia: LippincottRaven; 1996

Iro H, Waldfahrer F: Endonasal lacrimal apparatus surgery from ENT specialist viewpoint (in German). Ophthalmologe 2001; 98: 613 – 616

Kottler UB et al: Epiphora und Konjunktivitis seit 6 Jahren. Ophthalmologe 2004;101:730 – 2

McNab AA: Manual of orbital and lacrimal surgery. Edinburgh: Churchill Livingstone; 1994

Olver J: Colour atlas of lacrimal surgery. London, ButterworthHeinemann, 2002

Rose GE: The lacrimal paradox: toward a greater understanding of success in lacrimal surgery. Ophthal Plast Reconstr Surg 2004;20:262 – 5.

Struck HG, Weidlich R: Indications and prognosis of dacryocystorhinostomy in childhood. A clinical study 1970 – 2000. Ophthalmologe 2001;98:560 – 3

Thale A et al. Functional anatomy of the human efferent tear ducts: a new theory of tear outflow mechanism. Graefes Arch Clin Exp Ophthalmol 1998; 236:674 – 8

L.M. Holbach, L.M. Heindl, R.F. Guthoff

3.3.1

Surgical Anatomy

In the upper eyelid the first structure encountered behind the septum is the pre-aponeurotic fat pad, which lies in the space between the septum and the levator aponeurosis. This is similar in the lower eyelid.

The bony orbital walls are of particular importance in relation to their adjacent structures (Fig. 3.3.1). The bony roof of the orbit has the anterior cranial fossa and the frontal sinus above. The medial bony wall has the ethmoid sinuses and posteriorly part of the sphenoid sinus lying medial to it. The maxillary sinus lies below the bony orbital floor. The anterior lateral wall has the temporal fossa with the temporalis muscle within it. More posteriorly, the lateral wall lies in front of the middle cranial fossa.

The medial wall of the orbit has the thin lamina papyracea, separating the ethmoid sinus from the orbit. The fossa lacrimalis lies anteriorly in the medial wall. It houses the lacrimal sac and is bounded anteriorly by the anterior lacrimal crest, posteriorly by the posterior lacrimal crest. The orbital floor is also very thin, in particular medially. The suture between the ethmoid and maxillary sinus forms the inferior border of the medial wall. This marks a thick strut of bone providing sup-

port for the inferomedial orbit. This maxilloethmoidal strut often remains intact following orbital trauma. It should be left intact anteriorly during inferomedial orbital decompression. The lateral wall has a thinner portion in its middle third between the orbital rim and the thicker bone of the greater wing of the sphenoid.

The orbit can be divided into three surgical spaces:

1.Extraperiosteal

2.Extraconal

3.Intraconal

The extraperiosteal space exists only when opened surgically or filled by a pathologic process. It provides surgical access in an easily dissected plane, and may harbor pathologic tissue such as blood and pus. The periosteum is an important barrier confining many pathologic lesions. To reach the extraperiosteal space, the periosteum is incised and elevated over the orbital rim where it is firmly adherent. Within the orbital walls, it strips from the bone more easily. It follows the contours of the bony orbital walls. There are, however, a number of structures passing through it which are encountered when dissecting this plane, e.g., during orbital exenteration or bony decompression of the lateral wall. These include the zygomaticofacial nerve and artery occurring a variable but short distance inside the rim closer

to the floor than the roof. Inferiorly, on the lateral wall, the lower edge of the greater wing and the smooth posterior wall of the maxillary sinus form the inferior orbital fissure, which does not contain as many important structures as the superior orbital fissure so that dissection after bipolar cautery, for instance in lateral decompression surgery, is justified. The origin of the inferior oblique muscle is on the medial part of the floor, just inside the orbital rim and lateral to the nasolacrimal duct. The anterior and posterior ethmoidal vessels and nerves are a useful landmark for the upper limit of the medial wall and the lower limit of the roof during bony decompression of the medial wall. The larger anterior ethmoidal bundle is found one-third to one-half the way back from the rim, and the posterior a variable distance behind, sometimes quite close to the orbital apex. The supraorbital neurovascular bundle may pass through a bony canal and pierce the periorbita anteriorly. It may also remain within the periorbita as it leaves the orbit in a notch. It is located along the superior orbital rim at the junction of its medial one-third. The zygomaticofrontal suture is on the lateral orbital rim at its superior onefourth junction. It is a point of firm periosteal attachment and the most common location for dermoid cysts. The superior orbital fissure, which is located at the junction of the roof and lateral walls posteriorly, contains many important structures such as the oculomotor nerve with its superior and inferior divisions, the trochlear and abducens nerve, the first division of the trigeminal nerve, sympathetic fibers and veins connecting the orbit and the cavernous sinus. The orbital apex located between the roof and the medial wall contains the optic foramen with the optic nerve and ophthalmic artery.

The extraconal space contains the lacrimal gland and the extraocular muscles. The lacrimal gland lies in a bony fossa inside the orbital rim in the superotemporal quadrant. The larger orbital lobe of the lacrimal gland is only separated from the bone by the periorbita. It lies partly on the lateral horn of the levator aponeurosis. The palpebral lobe of the lacrimal gland lies laterally between the lateral horn of the levator aponeurosis and the conjunctiva. Lacrimal ductules from the orbital lobe pass through or around the palpebral lobe to empty into the lateral conjunctival fornix 4 – 5 mm superior to the tarsal border. The extraocular muscles provide a very obvious anatomic landmark as one dissects through the orbital fat. It may be helpful to use a traction suture through the lateral rectus muscle transconjunctivally in order to identify its course after lateral orbital wall removal. The four recti, superior oblique and levator palpebrae arise in the orbital apex (annulus of Zinn) and insert anteriorly on the globe (spiral of Tillaux) and eyelid.

The superior oblique tendon passes through the trochlea residing in a small bony fossa in the superomedial orbit inside the orbital rim. The trochlea can be safely lifted out of its fossa in extraperiosteal dissec-

tion. The recti and levator muscle receive their innervation from nerves entering the muscle bellies at the junction of the posterior and middle thirds. The trochlear nerve, however, enters the muscle belly on the superior surface of its posterior third. The inferior oblique muscle arises from the periosteum of the inferior orbital rim just lateral to the opening of the nasolacrimal canal. It passes beneath the inferior rectus towards the posterolateral aspect of the globe.

The intraconal space contains the orbital fat, which is structured by septa, as described by Koornneef (1979). These elements, partly forming pulleys, are leading to the sheath of the eye muscles, stabilizing and guiding their course during action. The ophthalmic artery and the optic nerve enter the orbit through the optic foramen. The first branch of the ophthalmic artery is the central retinal artery which arises near the orbital apex and runs forward beneath the optic nerve to pierce its dura about 10 mm behind the globe. The long posterior ciliary arteries (two to three) run forward within the adventitia surrounding the optic nerve and pierce the sclera laterally and medially to provide blood supply to the anterior segment of the eye. Fifteen to 20 short posterior ciliary vessels arise from the long posterior vessels in a ring around the optic nerve to supply the choroid and optic nerve head.

3.3.2

Surgical Pathology

3.3.2.1

Orbital Tumors

Clinical history (symptoms, duration) and examination findings (signs) are essential in the diagnosis of benign and malignant orbital lesions. Pain may be a prominent feature not only of inflammatory processes but also, e.g., adenoid-cystic carcinoma because of its tendency to infiltrate along sensory nerves. Imaging (orbital ultrasonography, computed tomography, magnetic resonance imaging) may provide additional information about location, size and extent of the mass, but allows no final diagnosis of tumor entity. Histopathologic examination is almost always necessary to confirm the clinical diagnosis in orbital diseases.

The following questions are to be addressed in a patient with an orbital tumor:

1.What is the most likely diagnosis? (benign versus malignant, infiltrative versus non-infiltrative)

2.Is an excisional or an incisional biopsy indicated?

3.What is the best surgical approach to the mass?

For clinical differential diagnosis the knowledge of the frequency of orbital lesions may be helpful (Tables 3.3.1, 3.3.2). The incidence varies with age. In childhood, dermoid cysts (Figs. 3.3.2, 3.3.3) and capil-

lary hemangiomas are the most common benign lesions. In adults, thyroid-associated orbitopathy (Figs. 3.3.18, 3.3.19) is predominant, and the commonest benign tumors of the orbit are cavernous hemangiomas (Figs. 3.3.8, 3.3.9), requiring differential diagnostic distinction from hemangiopericytomas (Fig. 3.3.10), solitary fibrous tumors (Fig. 3.3.11) and neurilemmomas (Fig. 3.3.12). Malignant orbital disease, either primary or secondary, is rare, but can affect all ages. In childhood, rhabdomyosarcoma (Fig. 3.3.4) and metastatic

Table 3.3.1. Frequency of orbital tumors in children (n = 358) (modified from Garner and Klintworth 1994, p 1525)

Table 3.3.2. Frequency of orbital tumors in adults (n = 1,599) (modified from Garner and Klintworth 1994, p 1524)

b