In a severe untreated case of tuberculous meningitis CSF shows
**Core Concept**
Tuberculous meningitis is a form of central nervous system (CNS) tuberculosis, characterized by inflammation of the meninges due to Mycobacterium tuberculosis infection. The cerebrospinal fluid (CSF) analysis is a crucial diagnostic tool in this condition.
**Why the Correct Answer is Right**
In tuberculous meningitis, the CSF typically shows an elevated lymphocyte count, often with a lymphocyte predominance. This occurs due to the activation of lymphocytes in response to the tubercular antigens. The lymphocytes are predominantly T-lymphocytes, which play a key role in the cellular immune response against M. tuberculosis. The elevated lymphocyte count is often accompanied by a decrease in CSF glucose levels and an increase in protein levels.
**Why Each Wrong Option is Incorrect**
**Option A:** Increased sugar is not characteristic of tuberculous meningitis, as the CSF glucose levels are typically decreased due to the inflammatory process and bacterial metabolism.
**Option C:** Increased polymorphs (neutrophils) are not typically seen in tuberculous meningitis, which is a chronic infection. Polymorphs are more commonly associated with acute bacterial infections.
**Option D:** Increased RBCs (red blood cells) are not characteristic of tuberculous meningitis, as this condition primarily involves inflammation of the meninges rather than direct vascular damage.
**Clinical Pearl / High-Yield Fact**
In tuberculous meningitis, the CSF protein level is often elevated, and the glucose level is decreased. The albumin-cytological dissociation, characterized by an elevated protein level with a normal or decreased albumin level, is a helpful diagnostic clue in this condition.
**✓ Correct Answer: B. Increased lymphocytes**