Ординатура / Офтальмология / Английские материалы / Imaging of Orbital and Visual Pathway Pathology_Muller-Forell_2005

quently affect patients in the 4th to 7th decade of life (Alexiou et al. 1999), and the diagnosis is based on the presence of a mass of clonal plasma cells, immunohistochemical stains for Kappa light chains and epithelial membrane antigen, distinct from bone and bone marrow, and without evidence of occult disease elsewhere (Liebross et al.1999; Uceda-Montanes et al. 2000). Due to the fact that imaging shows a homogeneous mass in the region of the lacrimal gland (Fig. 6.140), confusion with lymphoma or idiopathic orbital inflammation may occur. The most effective therapeutic management with a high rate of complete remission consists of local radiation therapy, or combined surgery and radiation treatment (Alexiou et al. 1999; Liebross et al. 1999; Galieni et al. 2000).

6.3.4.3

Inflammatory Lesions

6.3.4.3.1

Idiopathic Inflammatory Disorder (“Pseudotumor”) of the Lacrimal Gland

As previously described, idiopathic orbital inflammation may involve any intraorbital organ, and occur either diffuse or solitary. The lacrimal gland is the preferred organ for inflammation, but there are no definite imaging criteria in the differentiation of inflammatory from other, especially systemic tumorous lesions of the gland (Au Eong and Choo 1997; Eifrig et al. 2001) or epithelioid cell granuloma e.g. in a patient with sarcoidosis (Fig. 6.141). Involvement

of the lacrimal gland leads to a presentation with acute or subacute dacryoadenitis, S-shaped upper lid deformity with tenderness and enlargement (Figs. 6.142, 6.143), palpable superotemporal mass and conjunctival injection (Mafee et al. 1999). A chronic course is not uncommon in the sclerosing type of “pseudotumor”of the lacrimal gland (Fig. 6.144). Imaging shows diffuse, at times massive enlargement of the gland with moderate to marked enhancement after contrast administration, occasionally in association with posterior scleritis (Fig. 6.145). In the majority of cases, imaging is not able to unequivocally differentiate idiopathic lacrimal gland inflammation from lymphoma of the lacrimal gland (Mafee et al. 1999b).

6.3.4.3.2

Sjögren Syndrome

Sjögren syndrome is an idiopathic autoimmune disorder characterized by dryness of the eyes and mouth, caused by chronic lymphocytic infiltrates of the lacrimal and salivary glands (Fox 1996a). In the primary form (sicca complex), there is only keratoconjunctivitis sicca and xerostomia, while the secondary form comprises an association with such connective tissue diseases as rheumatoid arthritis, scleroderma, polymyositis, or polyarteritis nodosa (Weber et al. 1999). Keratoconjunctivitis is caused by impaired function of the lacrimal and the accessory lacrimal glands of the conjunctiva. Focal lymphocytic infiltration with plasma cells, genetic and environmental factors (e.g., members of the herpes

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Fig. 6.142a,b. A 12-year-old boy with painful swelling of the right eye. Diagnosis: idiopathic orbital inflammation. CT: a axial view with swelling of the conjunctiva (preseptal infiltration medially) and lateral external muscle, including the lateral lacrimal gland of the right orbit. b Coronal view demonstrates additional infiltration of the superior external muscle complex

virus or retroviral family) play a potentially important role in the initiation and perpetuation of the autoimmune process (Fox 1996a,b; Weber et al. 1999). Chronic dacryoadenitis, presenting with usually painless, slow lacrimal enlargement, is secondary to subacute infections like Sjögren or Mikulicz syndrome. Although imaging is not essential for the differential diagnosis, bilateral enlargement of the lacrimal (and parotid) glands due to infectious or neoplastic causes sometimes renders the differential diagnosis more difficult (Fig. 6.146) (Harnsberger 1990; Casper et al. 1993).

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Fig. 6.143a,b. A 72-year-old woman with slowly progressing lid swelling and extra-axial proptosis of the right globe. Diagnosis: idiopathic orbital inflammation of the lacrimal gland. MRI: a axial contrast-enhanced view demonstrating slight signal enhancement of the enlarged right lacrimal gland. Note asymmetry of the globe, caused by inferior displacement of the right. b Coronal native view in the region of the posterior lacrimal fossa; the extraconal location of the space-occupying enlargement of the right lacrimal gland is visualized

6.3.4.4

Lacrimal Pathway

Congenital disorders of the lacrimal system (gland and excretory channels) are rare but may be seen in children with facial anomalies (Older 1988).

Fig. 6.146. A 36-year-old man with proptosis and enlargement of both lacrimal glands for the past 3 months. Diagnosis: Sjögren syndrome. Axial CT, demonstrating the bilateral lacrimal gland enlargement

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Fig. 6.147a,b. A 43-year-old woman with painful swelling and redness of the left medial orbital region, and known lacrimal duct stenosis. Diagnosis: abscess-forming dacryocystitis of the left eye. Axial contrast-enhanced CT: a necrotic cyst in the region of the lacrimal point. b Preseptal swelling of the medial orbital tissue with slight dislocation of the left globe

Although a relatively common, treatable disorder, an imperforate valve of Hasner may prevent tear drainage and lead to dacryostenosis (McCormick and Linberg 1988). Lacrimal gland cysts (which may arise from any lobe or remainder of ectopic lacrimal tissue) are rare lesions, becoming evident in adult life. They may develop into dacryops or ductal cysts as a result of chronic inflammation, infection, or trauma (Brownstein et al. 1984; Eifrig et al. 2001).

Since the term dacryoadenitis is used to describe all lacrimal gland inflammations, they can be characterized as acute or chronic diseases.

Dacryocystitis may also occur in an acute or chronic form and is generally caused by superinfection with normal conjunctival flora, resulting from stagnation of lacrimal drainage in the sac due to an obstruction (Figs. 6.147, 6.148) (Linberg 1983). In the case of untreated obstruction, dacryocystitis may progress or resolve by spontaneous fistula formation, either externally into the orbit or sinus,or back into the nasolacrimal duct distal to the obstruction (Fig. 6.149) (Casper et al. 1993).

Dacryocystography represents contrast filling of the lacrimal duct after cannulation of the inferior lacrimal punctum and is the method of choice in the diagnostic management of suspected stenosis or obstruction of the lacrimal drainage system (Fig. 6.149) (Pereira et al. 1997). Dacryocystography is identified in the presence of epiphora, suggesting a mechanical obstruction of the lacrimal drainage; it may be of traumatic, tumorous, or inflammatory origin (Becker 1986). Dacryocystography defines the level of any obstruction, whether complete or incomplete. As it is able to determine the cause of the obstruction, it guides the surgeon in managing the problem (Becker 1986; Kassel and Schatz 1996). In combination with CT, the relationship between the nasolacrimal drainage system and the surrounding soft-tissue and/or bony structures is better seen (Fig. 6.149), in addition to providing the possibility of three-dimensional imaging (Kirchhof et al. 2000). MRI has limited applications but is useful to differentiate fluid from solid masses within the lacrimal sac and to define tumor extension from the sac to the duct, as well as in anatomic regions outside them (Weber et al. 1996c). Acute or chronic inflammatory residues (Figs. 6.148, 6.149) account for the majority of lacrimal sac and/or duct obstructions, followed by posttraumatic lesions and tumors. In the majority of cases, the last mentioned constitute carcinoma of nasal sinus origin, but malignant tumors of the lacrimal drainage system in the form of transitional cell carcinoma may occur (Fig. 6.150).

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Fig. 6.148a,b. A 36-year-old man with acute inflammation of the left face, chronic dacryocystitis persisting for 3 months, and putrid exudation of the left lacrimal point. Diagnosis: chronic dacryocystitis with preseptal orbital and facial phlegmon. Contrast-enhanced CT: a axial view with inflammatory, partly necrotic infiltration of the inferior, medial, extraconal space in the region of the nasolacrimal duct.Note the presence of tissue in the rostral left ethmoid, but attenuated medial muscle and tendon. b Coronal view visualizing widening of the entrance and the left nasolacrimal duct (compared with the right [arrow]) due to inflammation, extending to the adjacent ethmoid cell. Note inflammation of the subcutaneous fat of the left cheek

W. Müller-Forell and S. Pitz

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Fig. 6.149a–e. A 23-year-old woman with recurrent inflammation of the lacrimal point of the right eye and increased lacrimation. Diagnosis: blocking of the lacrimal sac by a mucosal fragment and chronic fibrosing inflammation. a Digital dacryoangiography of the right eye, demonstrating a contrast stop at the proximal lacrimal duct caused by a round X-ray-dense formation. b Corresponding view showing bone superposition, making the presence of a mucosal fragment with a dense structure more likely. c Postangiographic axial CT, demonstrating the mucosal fragment in the medial orbital angle at the level of the lacrimal point (white arrow), and a dorsal contrast level. d Axial CT at the level of the nasolacrimal duct, identifying contrast material in a poststenotic, dilated canal distal of the stenosis, and confirming the outlet function of the mucosal fragment. Compare with the normal diameter of the left lacrimal duct (dacryoangiography not shown).e 2D-recon- struction, showing poststenotic dilation of the right nasolacrimal duct (small white arrows)

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Fig. 6.150a–c. A 46-year-old man with chronic inflammation of the left lacrimal point. Diagnosis: lymphoepithelial tumor of the lacrimal duct. Axial contrast-enhanced CT: a View of the inferior orbit, where in addition to a subcutaneous, solid tumor of the medial inferior lid, widening of the left nasolacrimal canal, filled with solid tumor mass, is observed. b Corresponding bone window, demonstrating the difference in the diameter of the nasolacrimal canal and decalcification of the surrounding maxillary bone. c Axial view of the center of the orbit. The largest part of the tumor mass extends preseptally, compressing and dislocating the left globe; a definite differentiation of infiltration of the tendon of the left medial rectus muscle is not possible (not confirmed by surgery)

6.3.5

Traumatic Lesions

The variety of traumatic orbital lesions is manifold, but certain orbital fractures occur with greater frequency, i.e., fractures of the orbital floor and medial walls (lamina papyracea), than roof, lateral wall fractures or complex orbital rim fractures (Mauriello et al. 1999).

Biplanarhigh-resolutionCTistheimagingmodal- ity of choice in the evaluation of orbital traumatic lesions (see also Sect. 6.1.4.2). As the medial and lateral walls are best seen in the axial plane, the orbital roof and floor are optimally visualized on coronal images. Spiral CT enables not only rapid examination, reducing motion artifacts in uncooperative patients, and avoiding slice-by-slice misregistration, but also secondary 2Dand 3D-reconstructions (Fig. 6.151) (Lakits et al. 1998; Mauriello et al. 1999). MRI is required in evaluating vessel injuries, to determine if soft-tissue injuries mandate operative correction, or if the differentiation of edema or hematoma is needed (Fig. 6.152). Furthermore, it is a useful method in the detection of nonmetallic foreign bodies (Rothman 1997; Kleinheinz et al. 1998; Mauriello et al. 1999).

Blow-out fractures represent isolated fractures of the orbital floor without involvement of the rim (Converse and Smith 1960). As a result of a sudden increase in intraorbital pressure from a traumatic impact to the orbital soft tissues, the thin

Fig. 6.151. A 54-year-old man with facial injury after a car accident. Diagnosis: orbital wall fracture. CT 3D-reconstruc- tion: this image modality enables a lucid view of the fracture extending from the lateral right wall (white arrow) to the frontozygomatic suture and the orbital floor (arrowhead). (With permission of Müller-Forell and Lieb 1995b)

orbital floor and the medial wall (the fragile lamina papyracea) expand and displace outward (Figs. 6.153, 6.154). A fine network of fibrous septa that functionally unites the periosteum of the orbital floor, the inferior fibrofatty tissues, and the sheaths of the inferior and oblique rectus muscles may be entrapped in a number of ways between these bone fragments, leading to restricted ocular motility (Fig. 6.152). In addition, ischemia, hemorrhage, and edema of the injured muscles present with diplopia, not always demanding surgical intervention (Koornneef 1979; Lyon and Newman 1989;

Harris et al. 1998). The so-called “hanging drop” represents a small local hematoma at the fracture site (Figs. 6.152, 6.155). The inferior bony displacement causes a net increase in orbital space, resulting in enophthalmos (Fig. 6.156) (Casper et al. 1993; Mauriello et al. 1999).

Isolated medial wall fractures of the lamina papyracea are less frequently identified, but may be diagnosed indirectly as orbital emphysema, since direct communication from the nasal sinuses to the orbital soft tissues may be present. The patients typically present with a sudden increase in lid swelling after sneezing or blowing the nose (Fig. 6.157) (Casper et al. 1993).

Orbital roof fractures account for only approximately 5% of all facial fractures (Flanagan et al.1980). Although the roof itself is thin, the superior orbital rim is a strong, broad, and well-supported orbital wall that can only be fractured by severe blunt trauma with high impact (Casper et al.1993).Frequently,the frontal sinus and/or frontal bone (Fig. 6.158) may be involved, with the possibility of the development of pneumocephalus and/or associated intracranial injuries with or without CSF leakage (McLaughlin et al. 1982; Messinger et al. 1989).

The lateral orbital wall rarely fractures alone. It is anatomically unique in that it is not only partially bordered by a sinus, but is composed of tough zygomatic bones that rarely fracture alone and are associated with Le Fort type injury (Casper et al. 1993; Mauriello et al. 1999). Combined fractures involve the zygomaticofrontal suture superiorly, the zygomatic arch laterally, and the zygomaticomaxillary suture inferomedially (Mauriello et al. 1999). As a consequence of blunt trauma, a ruptured vessel with subperiosteal hematoma may be responsible for acute vision loss (Fig. 6.159), demanding emergency surgical decompression, in order to restore visual acuity.