A 25-year-old lady presented with fever of one month duration, ataxia and headache. Brain imaging showed dilated ventricles with basal exudates. Which among the following is the most likely CSF finding?
**Core Concept**
The patient's presentation of fever, ataxia, and headache, along with brain imaging showing dilated ventricles and basal exudates, is suggestive of tuberculous meningitis (TBM), a form of central nervous system (CNS) tuberculosis. TBM is characterized by inflammation of the meninges, the protective membranes surrounding the brain and spinal cord, often caused by the bacterium *Mycobacterium tuberculosis*.
**Why the Correct Answer is Right**
In TBM, the cerebrospinal fluid (CSF) analysis typically shows elevated protein levels, decreased glucose levels, and a high lymphocytic cell count. The decreased glucose levels in the CSF are due to the impaired glucose transport across the blood-brain barrier and the consumption of glucose by the inflammatory cells. The high lymphocytic cell count is indicative of the body's immune response to the infection.
**Why Each Wrong Option is Incorrect**
* **Option A:** In viral meningitis, the CSF typically shows elevated lymphocyte count, but the glucose levels are usually normal or slightly decreased. The protein levels may be elevated, but not to the same extent as in TBM.
* **Option B:** In bacterial meningitis, the CSF typically shows elevated neutrophil count, low glucose levels, and high protein levels. However, the lymphocyte count is usually not as high as in TBM.
* **Option D:** In fungal meningitis, the CSF typically shows elevated protein levels, low glucose levels, and a high lymphocytic or monocytic cell count. However, the clinical presentation and imaging findings are often different from those in TBM.
**Clinical Pearl / High-Yield Fact**
In patients with suspected TBM, a high index of suspicion is necessary, as the clinical presentation can be nonspecific. A lumbar puncture should be performed promptly, and the CSF analysis should be interpreted in the context of the patient's clinical presentation and imaging findings.
**Correct Answer:** C. Elevated protein, decreased glucose, and high lymphocytic cell count.