| Condition | Pressure | WBCs (cells/μL) | Predominant Cell | Protein | Glucose | Pathognomonic Finding / Key Differentiator |
|---|
| Normal | Normal (6-20) | < 5 | Lymphs | <40 | 40-70 | - |
| Bacterial Meningitis | ↑↑↑ | >1,000 | PMNs | >250 | <40 | Neutrophils dominate with very low glucose. |
| Viral Meningitis | N / ↑ | < 1,000 | Lymphs | <150 | Normal | Normal glucose with a lymphocytic pleocytosis. |
| Fungal / TB c | N / ↑ | < 500 | Lymphs | 100-500 | <45 | Low glucose with a lymphocytic pleocytosis. |
| SAH | ↑ | High RBCs | RBCs | ↑ | Normal | Xanthochromia (yellow supernatant); differentiates bleed from traumatic tap. |
| Guillain-Barré | N | Normal | Lymphs | ↑↑↑ | Normal | Albuminocytologic dissociation (high protein, normal WBC). |
| Multiple Sclerosis | N | N / <50 | Lymphs | N / ↑ | Normal | Oligoclonal bands of IgG unique to CSF. |