**Core Concept**
Ramsay Hunt syndrome is a rare neurological disorder caused by the reactivation of varicella-zoster virus (VZV) in the geniculate ganglion, leading to facial nerve palsy, ear pain, and vesicular eruptions in the external auditory meatus.

**Why the Correct Answer is Right**
The correct answer is related to the pathophysiology of Ramsay Hunt syndrome. Varicella-zoster virus reactivation in the geniculate ganglion causes inflammation and damage to the facial nerve, resulting in facial weakness or paralysis, ear pain, and vesicular eruptions. The virus also affects the vestibulocochlear nerve, leading to vestibular symptoms such as vertigo and tinnitus.

**Why Each Wrong Option is Incorrect**
**Option A:** Ramsay Hunt syndrome is not caused by herpes simplex virus (HSV), which is a different viral pathogen. HSV typically causes herpes labialis or genital herpes.
**Option B:** While Ramsay Hunt syndrome can cause hearing loss, it is not typically characterized by sensorineural hearing loss, but rather by conductive hearing loss due to Eustachian tube dysfunction or middle ear effusion.
**Option C:** Ramsay Hunt syndrome is not an autoimmune disorder, but rather a viral infection caused by reactivation of VZV.

**Clinical Pearl / High-Yield Fact**
Ramsay Hunt syndrome is a classic example of a cranial neuropathy caused by viral reactivation, and it highlights the importance of considering viral infections in the differential diagnosis of facial nerve palsy.

**Correct Answer: D. Ramsay Hunt syndrome is not an autoimmune disorder, but rather a viral infection caused by reactivation of VZV.**