**Question:** In Ramsay Hunt syndrome, most commonly involved nerve is -

A. Trigeminal nerve
B. Glossopharyngeal nerve
C. Vagus nerve
D. Spinal accessory nerve

**Core Concept:** Ramsay Hunt syndrome is a combination of herpes simplex virus (HSV) infection and peripheral nervous system involvement. It is named after Sir Henry Ramsay Hunt, a British neurologist who first described the syndrome in 1907. The syndrome is characterized by herpes zoster infection (shingles) and involvement of the eighth cranial nerve (vestibulocochlear nerve, responsible for hearing and balance).

**Why the Correct Answer is Right:** In Ramsay Hunt syndrome, the most commonly affected nerve is the **Trigeminal nerve** (Cranial nerve V). This is because herpes zoster (shingles) typically affects the dermatome of the affected spinal segment, in this case, the T1-T3 dermatomes. When the virus spreads to the trigeminal ganglion, it can lead to facial pain, oculomotor nerve paralysis (III), and hearing loss (VIII), which are the hallmark features of Ramsay Hunt syndrome.

**Why Each Wrong Option is Incorrect:**

**Option B (Glossopharyngeal nerve):** The glossopharyngeal nerve (cranial nerve IX) is not the most commonly involved nerve in Ramsay Hunt syndrome. While the virus can spread to the glossopharyngeal nerve, the trigeminal nerve is more commonly affected due to its close proximity to the trigeminal ganglion and the T1-T3 dermatomes.

**Option C (Vagus nerve):** The vagus nerve (cranial nerve X) is not primarily involved in Ramsay Hunt syndrome. While the virus can affect the vagus nerve, the trigeminal nerve is more commonly involved due to the reasons mentioned above.

**Option D (Spinal accessory nerve):** The spinal accessory nerve (cranial nerve XI) is not involved in Ramsay Hunt syndrome. The virus primarily affects the trigeminal nerve and its associated dermatomes.

**Clinical Pearl:** Ramsay Hunt syndrome is a clinical entity that requires a high index of suspicion for diagnosis. It is essential to recognize the signs and symptoms such as facial pain, hearing loss, and oculomotor nerve palsy (III) to differentiate it from other causes of these symptoms like Bell's palsy, vestibulocochlear nerve involvement, or multiple sclerosis.