Orbital infarction syndrome, less commonly known as global orbital infarction syndrome, is a rare entity defined as ischaemia, usually acutely, to all intraorbital and intraocular structures.

Clinical presentation

The clinical presentation is usually acute but can be progressive and subacute or chronic in tempo depending on the cause ^1-9. Clinical features include ocular pain, monocular visual loss, complete ophthalmoplegia, proptosis, ptosis, chemosis, ophthalmoplegia, rapid afferent pupillary defect, and retinal pallor ^1-9. Intraocular pressure may also be raised ⁵.

Pathology

Orbital infarction syndrome is caused by loss of arterial supply to the orbital structures ^1-9. Under normal circumstances, the orbit is supplied by both the ophthalmic artery and branches of the middle meningeal artery, which usually have extensive collateralisation and anastomoses between them, often including communicating branches ³. Due to this extensive collateralisation and anastomotic network, infarction of the orbital structures rarely occurs ³.

Aetiology

• internal or common carotid artery pathology, e.g. dissection, acute occlusion ^2,3

• post-endovascular clot retrieval (1-2%) ^3-5

• post-intracranial aneurysm surgery (rare) ^3,9

• vasculitis, e.g. giant cell arteritis ^2,3,8

• infection, e.g. mucormycosis, orbital cellulitis ^2,3

• prolonged orbital pressure, e.g. Saturday night retinopathy ¹⁰

Radiographic features

All patients with suspected orbital infarction syndrome should have angiographic and orbital imaging performed. The below radiographic findings are of orbital infarction syndrome generally; additional findings may be present depending on the aetiology.

CT

Non-contrast enhanced CT brain is often normal or may have subtle findings, such as proptosis and enlargement of the extraocular muscles ^5,9,10. CT angiography may reveal occlusion of the ophthalmic artery and/or occlusion of more proximal vasculature (e.g. internal carotid artery) ³.

MRI

Similar to CT, there may be proptosis and the extraocular muscles may be enlarged ^3,9,10. Additionally, MRI may reveal high T2 signal affecting the optic nerve, optic nerve sheath, retina, extraocular muscles, and intraorbital fat ^3,4,6,7,9,10. There may also be diffusion restriction of the optic nerve and retina ^4,6,7,8. Angiographic findings are identical to those aforementioned on CT angiography ⁷.

Angiography (DSA)

Digital subtraction angiographic findings are those of non-invasive angiography, including non-opacification of the ophthalmic artery and/or other more proximal vasculature, depending on the cause ^3-5. Post-endovascular clot retrieval, loss of normal choroidal blush, normally indicative of orbital perfusion, has been described as a highly sensitive sign for orbital infarction syndrome ³.

Treatment and prognosis

Management depends on the underlying aetiology, but symptomatic management may include reduction of intraocular pressure and analgesia. In most instances, visual recovery is poor.

See also

• orbital compartment syndrome