In adult Pulsatile proptosis seen in
**Core Concept**
Pulsatile proptosis refers to the protrusion of the eyeball due to a space-occupying lesion that is pulsatile in nature, often resulting from a vascular anomaly or tumor. This condition is characterized by the presence of a palpable pulsation synchronous with the patient's heartbeat.
**Why the Correct Answer is Right**
The most common cause of pulsatile proptosis in adults is a carotid-cavernous fistula (CCF), which is an abnormal communication between the carotid artery and the cavernous sinus. This fistula leads to an increase in venous pressure within the orbit, causing the eyeball to protrude. The pulsatile nature of the proptosis is due to the direct transmission of arterial pressure from the carotid artery to the orbital veins.
**Why Each Wrong Option is Incorrect**
* **Option A:** Orbital varices are a possible cause of non-pulsatile proptosis, not pulsatile proptosis.
* **Option B:** Thyroid ophthalmopathy is a common cause of non-pulsatile proptosis in adults, especially in patients with Graves' disease.
* **Option C:** Orbital lymphangioma is a benign tumor that can cause non-pulsatile proptosis, but it is not typically pulsatile.
**Clinical Pearl / High-Yield Fact**
When evaluating a patient with pulsatile proptosis, it is essential to investigate for a possible carotid-cavernous fistula, particularly in patients with a history of head trauma or surgery in the neck.
**Correct Answer: C. Carotid-cavernous fistula.**