Following cranical nerve is most commonly involved in patients with sarcoidosis –
**Core Concept**
Sarcoidosis is a systemic granulomatous disease that can affect multiple organ systems, including the nervous system. Cranial nerve involvement in sarcoidosis is a well-documented phenomenon, often presenting with a variety of neurological symptoms.
**Why the Correct Answer is Right**
The most commonly affected cranial nerve in sarcoidosis is the seventh cranial nerve, also known as the facial nerve. This is due to the fact that the facial nerve is responsible for controlling the muscles of facial expression, and sarcoid granulomas can infiltrate the nerve, leading to facial weakness or paralysis. Additionally, the facial nerve is also responsible for carrying taste fibers from the anterior two-thirds of the tongue, and sarcoidosis can cause dysgeusia (altered taste).
**Why Each Wrong Option is Incorrect**
**Option A:** The third cranial nerve (oculomotor nerve) is less commonly involved in sarcoidosis, and when it is, it typically presents with diplopia (double vision) due to paralysis of the extraocular muscles.
**Option B:** The fifth cranial nerve (trigeminal nerve) can be involved in sarcoidosis, but it typically presents with facial pain or numbness, rather than the characteristic facial weakness or paralysis seen with the seventh cranial nerve.
**Option C:** The ninth cranial nerve (glossopharyngeal nerve) is not typically involved in sarcoidosis, and when it is, it typically presents with symptoms such as dysphagia (difficulty swallowing) or hoarseness.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that cranial nerve involvement in sarcoidosis can be a presenting feature of the disease, and a thorough neurological examination is crucial in diagnosing and managing patients with sarcoidosis.
**Correct Answer: C.**