Unilateral proptosis — enumerate causes.

Common causes

• Inflammatory: orbital pseudotumor, thyroid eye disease, orbital inflammatory syndrome.

• Infective: orbital cellulitis, cavernous sinus thrombosis, orbital abscess.

• Vascular: carotid-cavernous fistula, cavernous hemangioma/venous malformation, retrobulbar hemorrhage.

• Neoplastic: orbital lymphoma, optic nerve glioma ,schwannoma, meningioma, metastatic disease.

• Traumatic / iatrogenic: post-traumatic or post-surgical hematoma, orbital compartment syndrome.

• Developmental / bony: fibrous dysplasia, paranasal sinus enlargement, orbital wall lesions.

Exam-style grouping

1. Acute unilateral proptosis: infection, hemorrhage, vascular lesion.

2. Chronic unilateral proptosis: tumor is more likely.

3. Pulsatile proptosis: carotid-cavernous fistula or other vascular malformation

Common causes of pulsatile exophthalmos are:

• Carotid-cavernous fistula.

• Orbital or intracranial arteriovenous malformation.

• Saccular aneurysm of opthalmic artery or other vascular malformations

• Trauma, especially orbital roof fracture or skull base injury.Encephalocele ,meningoencephalocele due to CSF pulsations.

• Neurofibromatosis type 1 with sphenoid wing dysplasia.