A 38-year-old woman undergoing emergency cesarean section under spinal anesthesia (1.8 mL of 0.5% hyperbaric bupivacaine at L3–L4) develops sudden onset of severe headache, neck stiffness, photophobia, and altered mental status 6 hours postoperatively. CSF analysis shows elevated protein (180 mg/dL), normal glucose, and pleocytosis with lymphocytic predominance. Which of the following is the MOST likely diagnosis, and what is the key distinguishing feature that differentiates it from other post-dural puncture complications?

Question

Accepted Answer

B. Aseptic meningitis; distinguished by lymphocytic pleocytosis, elevated protein, and normal glucose with symptom onset within 24–48 hours. ## Aseptic Meningitis Following Spinal Anesthesia

**Clinical Presentation:**
The patient presents with classic meningeal signs (headache, neck stiffness, photophobia) and altered mental status within 6 hours of spinal puncture—a timeline consistent with aseptic (chemical) meningitis rather than PDPH, which typically develops 24–48 hours post-procedure and is positional.

**CSF Profile (Gold Standard):**
- **Lymphocytic pleocytosis** (100–1000 cells/μL, predominantly lymphocytes)
- **Elevated protein** (100–500 mg/dL)
- **Normal glucose** (>40 mg/dL, CSF:serum ratio >0.4)
- **Negative bacterial cultures** and Gram stain

**Pathophysiology:**
Aseptic meningitis post-spinal anesthesia is caused by chemical irritation of meninges from:
- Detergents in local anesthetic solutions (historically methylparaben, propylparaben)
- Needle trauma
- Intrathecal medications (NSAIDs, antibiotics, corticosteroids if injected intrathecally)

**Key Distinguishing Features:**
1. **Timing:** Onset within 6–48 hours (vs. PDPH: 24–48 hours, positional)
2. **CSF findings:** Lymphocytic pleocytosis + normal glucose (vs. bacterial meningitis: neutrophilic + low glucose)
3. **Cultures:** Always negative
4. **Self-limited course:** Resolves in 24–72 hours with supportive care

**High-Yield:** The normal CSF glucose with lymphocytic pleocytosis is pathognomonic for aseptic meningitis; bacterial meningitis presents with low CSF glucose (<40 mg/dL) and neutrophilic predominance.

**Clinical Pearl:** Modern preservative-free local anesthetic solutions have dramatically reduced the incidence of aseptic meningitis post-spinal anesthesia.

Answer

A. Post-dural puncture headache (PDPH) with meningeal irritation; distinguished by CSF pleocytosis and normal glucose

Answer

C. Bacterial meningitis; distinguished by CSF culture positivity and neutrophilic predominance

Answer

D. Spinal cord ischemia; distinguished by lower limb weakness and elevated CSF lactate with normal cell count

Explanation

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