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

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Fig. 6.159a–c. A 24-year-old man with acute vision loss of the left eye after a car accident (no seat belts!); vision loss did not resolve after emergency decompression (canthotomy). Diagnosis: extraconal retrobulbar hematoma. Axial CT: a slightly hyperdense mass (hematoma) in the left extraconal space with medial dislocation of the (hypointense compared with hematoma) lateral rectus muscle. b Corresponding diagram. 9.6 = lateral rectus muscle c Corresponding bone window (larger field of view, FOV) with superior visualization of air inclusions

6.3.6 Miscellaneous

6.3.6.1

Craniosynostosis (e.g., Crouzon Syndrome)

Craniosynostosis is divided into primary and secondary forms, with primary craniosynostosis referring to premature fusion of one or more cranial sutures due to a developmental error. Secondary synostosis refers to premature closure resulting from other causes,such as intrauterine compression, effects of teratogens, or lack of brain growth (Cohen 1987; Barkovich 2000). Another classification defines syndromic craniosynostosis as accounting for about 15% of cases and associated with other abnormalities of the body, and nonsyndromic forms in the remaining 85% (Chumas et al. 1997) of patients. Syndromic craniosynostosis includes a variety of inherited syndromes with abnormal development of the face and skull, often in conjunction with other anomalies of the brain and body. In some autosomal dominant craniosynostotic syndromes, the site of mutation of chromosome 10 in FGFR2 genes is found (Hollway et al. 1997). These include among others Apert syndrome (acrocephalosyndactyly) with syndactyly of hands and feet,Pfeiffer syndrome with a malformed enlarged thumb and big toe, soft-tissue syndactyly, and Crouzon syndrome. Craniofacial dysostosis – Crouzon syndrome – may serve as an example of these syndromes, where the early closure of variable synostosis in combination with maxillary hypoplasia and shallow orbits presents with proptosis, bifid uvula, or cleft palate (Casper et al. 1993; Barkovich 2000).

In most patients with craniosynostosis, only one suture is involved, but 20%–25% are cases of multisutural syndromes (Chumas et al. 1997). The most common fusions are coronal and sagittal, followed by the lambdoid suture, the latter leading to additional Chiari I malformation with a small posterior fossa (Barkovich 2000). In Crouzon syndrome, proptosis with prolapse of the globes in front of the eyelids is the result of flattened orbits, leading to compromised corneal coverage and damage to the optic nerve from excessive stretching (Fig. 6.160) that demands surgical management. Plain films show characteristic findings, but modern imaging should include not only MRI, which might demonstrate additional brain anomalies,but also three-dimensional CT (Fig.6.160) in order to understand the pathological morphology and to define the surgical approach (Zonneveld et al. 1998).

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6.3.6.2

Extraconal Vascular Lesions (Hemangioma)

In cases where a hemangioma occurs in the extraconal space, the capsule is not present, and the lesion extends in various ways along the orbital septum (Fig. 6.161), the lacrimal fossa (Fig. 6.162) or the lid (Fig. 6.163). Differential diagnosis for extraconal varices (Fig. 6.164) (see Sect. 6.2.2.4) or venous lymphatic

malformation (Fig. 6.165) (see Sect. 6.2.2.3) might be difficult.

6.3.6.3

Rare Lesions

Orbital involvement with bony deformation/destruction in malignant sinonasal tumors is known, but extraconal deformation of the orbital apex and

nerve compression in the optic canal by an astrocytoma, a benign intracranial tumor represents an extremely rare entity (Fig. 6.166).

Another extremely rare lesion with a clinical presentation similar to Graves’ disease, but with persisting proptosis and without clinical impairment,is the so-called benign lymphooid hyperplasia (Fig. 6.167), a disease mainly seen in dermatology (Gilliam and Wood 2000). Imaging demonstrates

homogeneous tumors with a close relationship to the peripheral branches of the trigeminal nerve, resembling neurinoma.

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Fig. 6.165a–e. A 34-year-old man with progressing pressure and swelling of the right orbit, state after surgery for venous lymphatic malformation 15 years ago. Diagnosis: intraand extraconal venous lymphatic malformation. MRI: a Axial T2weighted view with hyperintense lesions medial and lateral of the superior rectus muscle as well as in the temporal fossa. b Corresponding, enlarged, T1-weighted, contrast-enhanced (FS) image. Note the intramedullary veins converging in the medial basal ganglia, corresponding to an additional DVA (arrow). c Coronal T1-weighted native image showing the lesions isointense to the muscles primarily in the extraconal space. This is observed not only in the superior but also in the medial orbit. d Coronal, T1-weighted, contrast-enhanced (FS), enlarged view with distinct signal enhancement of the vascular lesions also in the thickened muscles of the temporal fossa e Corresponding diagram. 10.1 = interior rectus muscle, 10.2 = medial rectus muscle, 10.3 = superior rectus muscle, 10.4 = lateral rectus muscle, 10.11 = optic nerve

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