**Core Concept**
Tubercular meningitis is a severe infection of the meninges, the protective membranes surrounding the brain and spinal cord, caused by Mycobacterium tuberculosis. This condition can lead to a range of complications due to inflammation, scarring, and damage to the central nervous system.

**Why the Correct Answer is Right**
Cortical venous thrombosis is not a typical complication of tubercular meningitis. The primary complications of tubercular meningitis include hydrocephalus, cerebral artery thrombosis, cranial nerve palsy, and others. Cortical venous thrombosis is more commonly associated with other conditions such as sinus thrombosis or dural venous sinus thrombosis, which are not directly related to tubercular meningitis.

**Why Each Wrong Option is Incorrect**
**Option A:** Hydrocephalus is a common complication of tubercular meningitis, often resulting from the blockage of cerebrospinal fluid pathways due to inflammation and scarring.

**Option C:** Cerebral artery thrombosis can occur in tubercular meningitis due to inflammation and damage to the blood vessels supplying the brain.

**Option D:** Cranial nerve palsy is a possible complication of tubercular meningitis, resulting from the direct involvement of cranial nerves by the infection or secondary effects such as hydrocephalus.

**Clinical Pearl / High-Yield Fact**
Tubercular meningitis often presents with a triad of symptoms: headache, fever, and altered mental status. It is essential to consider this diagnosis in patients with a history of tuberculosis exposure or symptoms suggestive of central nervous system involvement.

**✓ Correct Answer: B. Cortical venous thrombosis**