What is the best course of action for a post-operative adult, 1 day after L5 to S1 microdiscectomy, presenting to the emergency room (ER) with severe back pain radiating superiorly to the neck?

Immediate Evaluation for Severe Post-Operative Pain After L5-S1 Microdiscectomy

This patient requires urgent MRI lumbar spine without IV contrast to rule out life-threatening complications including epidural hematoma, recurrent/new disc herniation, or infection, as severe pain radiating superiorly one day post-operatively represents a potential surgical emergency. 1

Critical Red Flags Requiring Immediate Imaging

This clinical presentation demands urgent evaluation because:

• Severe pain within 24 hours post-operatively is abnormal and may indicate acute complications including epidural hematoma, recurrent disc herniation, or infection 1
• Pain radiating superiorly to the neck is atypical for routine post-operative pain from L5-S1 surgery and suggests either meningeal irritation, cerebrospinal fluid leak with intracranial hypotension, or severe muscle spasm 1
• Sudden profound pain can indicate acute intraoperative or immediate post-operative disc herniation, which has been documented to occur and cause neurologic compromise 2

Immediate Diagnostic Workup

First-Line Imaging

• MRI lumbar spine without IV contrast is the most sensitive modality for detecting soft-tissue complications including epidural hematoma, recurrent disc herniation, nerve root compression, and assessing the spinal canal 1
• Obtain stat laboratory studies including complete blood count, erythrocyte sedimentation rate, and C-reactive protein to evaluate for infection, particularly given the timing within 24 hours of surgery 1

Physical Examination Priorities

• Assess for cauda equina syndrome including urinary retention, saddle anesthesia, bilateral leg weakness, and decreased rectal tone—these findings mandate emergent surgical decompression 1
• Evaluate for progressive neurologic deficits including new or worsening motor weakness, sensory changes, or reflex abnormalities compared to immediate post-operative examination 1
• Check for signs of infection including fever, wound drainage, erythema, or warmth at the surgical site 1

Differential Diagnosis by Priority

Life-Threatening Complications (Rule Out First)

1. Epidural hematoma causing acute spinal cord or cauda equina compression 1
2. Acute recurrent or new disc herniation at the operative level or adjacent level, which can occur intraoperatively or immediately post-operatively 2, 3
3. Epidural abscess or discitis though less likely within 24 hours unless there was intraoperative contamination 1

Serious but Non-Emergent Complications

1. Cerebrospinal fluid leak causing intracranial hypotension and severe headache/neck pain, particularly if pain worsens when upright 1
2. Severe muscle spasm from surgical manipulation, though this would be unusual to radiate to the neck 1

Pain Management While Awaiting Imaging

• Multimodal analgesia should be implemented immediately, combining opioids with NSAIDs (if no contraindications) and adjuvant medications such as gabapentin or pregabalin for neuropathic pain 1
• Avoid delaying imaging for pain control—the diagnostic workup takes priority given the concerning presentation 1
• Do not assume this is routine post-operative pain—the severity and radiation pattern are atypical and warrant investigation 1

Common Pitfalls to Avoid

• Do not discharge this patient without imaging and definitive diagnosis—severe pain one day post-operatively with atypical radiation is not normal post-operative course 1
• Do not attribute symptoms to anxiety or pain tolerance—objective evaluation is mandatory given the timing and severity 1
• Do not delay imaging for a trial of conservative management—the 24-hour post-operative timeframe and severity mandate urgent evaluation 1
• Recognize that intraoperative disc herniation can occur and may not be immediately apparent until the patient awakens or mobilizes 2

Disposition Based on Imaging Results

If MRI Shows Acute Complication

• Epidural hematoma with compression: Emergent surgical evacuation 1
• Recurrent/new disc herniation with neurologic deficit: Urgent neurosurgical consultation for possible revision surgery 1, 2
• Infection/abscess: Urgent surgical consultation, blood cultures, and broad-spectrum antibiotics 1

If MRI is Negative

• Consider CT myelography if MRI is limited by hardware artifact and clinical suspicion remains high 1
• Aggressive multimodal pain management with close outpatient follow-up within 24-48 hours 1
• Re-evaluate for CSF leak if positional component to pain, consider blood patch if confirmed 1