**Question:** Infection of CNS spreads in inner ear through

A. Viral
B. Bacterial
C. Mycotic
D. Protozoal

**Core Concept:**
The central nervous system (CNS) can be infected by various pathogens, including viruses, bacteria, mycetes, and protozoa. Infections can spread to the inner ear, leading to various neurological and audiological symptoms.

**Why the Correct Answer is Right:**
The correct answer, **D. Protozoal**, refers to infections caused by protozoa, which are single-celled organisms. Infections involving the CNS that originate from protozoa are relatively rare but can lead to spread to the inner ear, causing significant complications.

**Why Each Wrong Option is Incorrect:**

A. Viral infections typically affect the CNS directly or indirectly through the bloodstream or lymphatic system. Viruses do not typically spread to the inner ear via the CNS.
B. Bacterial infections usually involve meningitis or encephalitis, rather than direct spread to the inner ear. While bacterial infections can cause complications in the inner ear, they are not the primary route for spread to the inner ear.
C. Mycotic infections, caused by fungi, rarely involve the CNS. The direct spread to the inner ear from a mycotic CNS infection is exceedingly rare.

**Why the Correct Answer is Right:**
In contrast, protozoal infections, which are caused by protozoa, can directly infect the CNS and subsequently spread to the inner ear, leading to severe complications.

**Clinical Pearl:**
It is crucial for healthcare professionals to consider protozoal infections as a potential cause of CNS and inner ear infections, especially in endemic areas. Early diagnosis and appropriate treatment can help minimize complications and improve patient outcomes.

**Correct Answer:** D. Protozoal