Oculocardiac reflex is seen in which surgery: March 2007
**Core Concept**
The oculocardiac reflex is a physiological reflex that involves a decrease in heart rate (bradycardia) in response to traction or pressure on the extraocular muscles or the eyeball. This reflex is mediated by the trigeminal nerve (cranial nerve V) and the vagus nerve (cranial nerve X).
**Why the Correct Answer is Right**
When the extraocular muscles are stretched or manipulated during eye surgery, it activates the afferent fibers of the trigeminal nerve, which then stimulates the efferent fibers of the vagus nerve to release acetylcholine. Acetylcholine acts on the sinoatrial node, leading to a decrease in heart rate. This reflex is a protective mechanism to prevent cardiac complications during eye surgery.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the oculocardiac reflex is not typically associated with thyroid surgery, which involves different anatomical structures and nerve pathways.
**Option B:** This option is incorrect because the oculocardiac reflex is not directly related to the vasovagal response, although both involve a decrease in heart rate.
**Option C:** This option is incorrect because the oculocardiac reflex is not commonly seen in orthopedic surgery, which involves different anatomical structures and nerve pathways.
**Clinical Pearl / High-Yield Fact**
The oculocardiac reflex can be triggered by any manipulation of the extraocular muscles, not just surgery. It's essential to be aware of this reflex during any procedure involving the eye to prevent bradycardia and cardiac complications.
**Correct Answer: C. Otosclerosis.**