A 52-year-old man with chronic lower back pain due to lumbar spondylosis is scheduled for epidural steroid injection under epidural anesthesia. During the procedure, the anesthesiologist notes sudden onset of severe headache, neck stiffness, and photophobia 2 hours post-injection. The patient's temperature is 38.2°C, BP 140/90 mmHg, HR 110/min. CSF analysis shows pleocytosis with predominantly lymphocytes, elevated protein (120 mg/dL), and normal glucose. Blood cultures are pending. What is the most likely diagnosis?

Explanation

## Clinical Diagnosis: Aseptic Meningitis Post-Epidural Steroid Injection ### Key Features of This Case **Key Point:** Aseptic meningitis is a recognized complication of epidural steroid injection, occurring within hours to days post-procedure, characterized by meningeal irritation WITHOUT bacterial infection. ### Diagnostic Criteria Met | Feature | Finding | Significance | |---------|---------|---------------| | **Onset** | 2 hours post-injection | Consistent with aseptic meningitis (sterile chemical irritation) | | **CSF pleocytosis** | Predominantly lymphocytes | Viral/aseptic pattern, not bacterial (which shows neutrophil predominance) | | **CSF protein** | 120 mg/dL (elevated) | Typical in aseptic meningitis (50–500 mg/dL) | | **CSF glucose** | Normal | Rules out bacterial meningitis (low glucose) | | **Blood cultures** | Pending, but expected negative | Aseptic process—no bacteremia | | **Temperature** | 38.2°C (low-grade fever) | Consistent with aseptic inflammation | ### Pathophysiology **High-Yield:** Epidural steroid injection can trigger aseptic meningitis via: 1. Direct chemical irritation of meninges by steroid particles or preservatives (e.g., methylparaben) 2. Inflammatory response to steroid crystals in CSF 3. Occurs in absence of bacterial contamination ### Management 1. **Supportive care:** NSAIDs, hydration, bed rest 2. **Avoid antibiotics** unless bacterial infection confirmed (blood culture negative expected) 3. **Symptom resolution:** typically within 3–7 days 4. **Monitor:** repeat LP if deterioration or no improvement in 48 hours **Clinical Pearl:** The key discriminator is the **normal CSF glucose** and **lymphocytic predominance** with **negative blood cultures**—these rule out bacterial meningitis and point to sterile chemical inflammation. ### Differential Exclusions - ~~Bacterial meningitis~~ → Would show **neutrophilic pleocytosis, low glucose, positive cultures** - ~~Epidural abscess~~ → Would present with **progressive neurological deficit, cord compression signs, imaging findings** - ~~Post-dural puncture headache~~ → Typically **positional, no fever/meningismus, normal CSF**