CSF analysis in a 25-year-old with two weeks of headache and low-grade fever shows 60 cells per microlitre, predominantly lymphocytes, glucose 28 mg/dL with simultaneous blood glucose 110 mg/dL, and protein 180 mg/dL. On standing overnight, a fine web-like pellicle forms on the specimen. The finding responsible for the very high protein level is:

• A Active secretion of immunoglobulin by choroid plexus plasma cells
• B Neutrophil lysis releasing intracellular proteins into CSF
• C Increased permeability of inflamed meningeal vessels with blockage of arachnoid villi ✓
• D Haemorrhagic contamination during lumbar puncture

Explanation

In tuberculous meningitis, thick basal exudates raise meningeal vascular permeability and obstruct CSF resorption through the arachnoid villi, so protein rises sharply, often exceeding 150 to 200 mg/dL. The cobweb clot forms from fibrinogen leaking across damaged meninges and traps acid-fast bacilli, aiding ZN smear yield. Neutrophil counts are low here, and xanthochromia would indicate haemorrhage rather than this picture.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.