MCQ MAHE 2000 Surgery Answer 16

The Correct Answer is D


Exophthalmos, or proptosis, occurs when there is a discordant relationship between the soft tissue and bone of the anterior orbit and the globe. The adult orbit has a fixed volume of approximately 30 ml. When the soft tissue contents of the orbit exceed this amount, exophthalmos occurs. As an example, an increase in soft tissue volume of 5 ml (16%) will result in 4-5 mm of proptosis.

Graves disease represents the most common cause of bilateral exophthalmos. This condition is generally referred to as Graves orbitopathy (ophthalmopathy).

Pseudotumor cerebri represents the second most common cause of bilateral exophthalmos. CT or MRI shows generalized edema of the orbital soft tissues and occasionally the brain. However, there is no specific enlargement of the external ocular muscles. The use of high dose corticosteroids will generally improve the proptosis within 24 to 48 hours.

Meningioma en plaque results in severe exophthalmos with eyelid edema. Usually, the lower lid is affected without lid retraction.

Axial myopia is a common cause of unilateral exophthalmos. This is diagnosed by retinoscopy and A-scan ultrasound.

Inflammatory pseudotumor mimics a neoplasm with the sudden onset of proptosis, lid edema, pain, ophthalmoplegia, and visual loss. This typically responds to steroids.

Lymphoma of the orbit typically causes eccentric proptosis. CT or MRI typically demonstrates a mass, or masses, located near the orbital apex. Other orbital masses, generally associated with unilateral proptosis, include metastasis, vascular anomalies, neurofibromas, and retinoblastoma.

In addition, congenital shallowness of the orbits, such as in Apert or Crouzon Syndromes, may be the cause of proptosis. In such cases, surgery is generally cosmetic.

Category: MAHE 2000 MCQs