Can a lumbar spine injection (epidural steroid injection, facet‑joint injection, or nerve‑root block) cause new difficulty lifting the leg a few days later?

Can Lumbar Spine Injection Cause Difficulty Lifting Leg Several Days Later?

Yes, lumbar spine injections can cause new difficulty lifting the leg several days after the procedure, though this is not a commonly reported complication in the literature and warrants immediate evaluation to rule out serious complications such as epidural hematoma, abscess, or direct nerve injury.

Mechanism of Post-Injection Leg Weakness

The provided evidence focuses primarily on efficacy and indications for lumbar injections rather than complications, but several mechanisms could explain delayed leg weakness:

Direct Nerve Injury or Irritation

• Transforaminal epidural injections deliver medication directly onto nerve roots, which could theoretically cause nerve irritation or injury 1
• The targeted nature of these injections, while advantageous for pain relief, increases proximity to neural structures 1

Steroid-Related Myopathy

• Epidural steroid injections use corticosteroids in combination with local anesthetics 2
• High-dose steroids can rarely cause acute steroid myopathy, though this typically occurs with systemic administration

Epidural Hematoma or Abscess

• These are rare but serious complications that can present with progressive neurological deficits days after injection
• New motor weakness developing days after injection requires urgent imaging evaluation

Clinical Evaluation Required

Red Flags Requiring Immediate Imaging

• Progressive motor weakness (inability to lift leg against gravity)
• Bowel or bladder dysfunction (cauda equina syndrome)
• Saddle anesthesia or bilateral leg symptoms
• Severe or worsening back pain at injection site

Expected vs. Concerning Symptoms

• Common side effects include injection-site pain, transient pain increases, and vasovagal reactions 3
• New motor deficits are NOT expected and require investigation
• Transient numbness from local anesthetic should resolve within hours, not persist for days

Diagnostic Approach

Immediate Steps

• Urgent MRI of lumbar spine to evaluate for:
  • Epidural hematoma
  • Epidural abscess
  • Nerve root injury or compression
• Detailed neurological examination documenting:
  • Specific muscle groups affected (hip flexors, knee extensors, ankle dorsiflexors)
  • Sensory deficits in corresponding dermatomes
  • Reflexes and straight leg raise testing

Timing Considerations

• Epidural hematomas typically present within 24-72 hours post-procedure
• Epidural abscesses may present 3-7 days post-injection with fever and progressive symptoms
• Direct nerve injury symptoms usually appear immediately or within 24 hours

Management Algorithm

If motor weakness is present:

1. Stop any planned repeat injections until etiology is determined
2. Obtain urgent MRI within 24 hours
3. Neurosurgical consultation if imaging shows compressive lesion
4. Document baseline neurological status for medicolegal purposes

If imaging is negative:

• Consider EMG/NCS at 3-4 weeks to evaluate for nerve injury
• Physical therapy for supportive care
• Close neurological monitoring with serial examinations

Important Caveats

• The evidence provided focuses on therapeutic efficacy rather than complications, limiting specific guidance on this adverse event 2, 1
• Fluoroscopic or CT guidance is mandatory for all lumbar injections to minimize complications 4
• The literature shows epidural injections are generally safe with low complication rates, but serious neurological complications, though rare, do occur 3
• For radicular symptoms from disc herniation, transforaminal epidural injections have good evidence for efficacy, but this does not negate the need to evaluate complications 1

The development of new motor weakness days after lumbar injection is a potential medical emergency requiring urgent evaluation, as it may represent a serious complication rather than an expected side effect of the procedure.