Cauda Equina Syndrome After Sacral Injections: Emergency Management
Cauda equina syndrome (CES) following sacral injections requires immediate emergency surgical decompression, with outcomes critically dependent on whether the patient still has voluntary bladder control at the time of intervention. 1, 2, 3
Immediate Recognition and Classification
The first priority is determining the stage of CES, as this dictates both urgency and prognosis:
Clinical Staging System
CESS (CES Suspected): Bilateral radiculopathy with subjective sphincter symptoms but no objective findings—these patients should undergo emergency MRI and surgical discussion, with surgery typically performed the next day unless progression occurs 1, 3
CESI (CES Incomplete): Objective signs of CES (impaired perineal sensation, reduced anal tone) but retained voluntary bladder control—this is the true surgical emergency requiring decompression by day or night 1, 3
CESR (CES with Retention): Complete urinary retention with paralyzed, insensate bladder—operate emergently within 12 hours if presentation is recent or if any perineal sensation remains 1, 3
Emergency Management Protocol
Within First 3 Hours
The critical window is narrow. Case reports document CES developing 3 hours post-injection with perineal numbness, lower extremity weakness, saddle anesthesia, and urinary retention 4. Immediate actions include:
Neurological examination: Test perineal sensation bilaterally, perform digital rectal exam for anal tone, assess bilateral lower extremity motor function and reflexes 1, 5
Bladder assessment: Determine if patient can voluntarily void—do not catheterize before this assessment as it obscures whether the patient is CESI versus CESR 1
Emergency MRI lumbar spine without contrast: This is mandatory and should not be delayed 6, 7
Surgical Decision-Making
For CESI patients (retained voluntary control): Emergency surgical decompression by day or night is indicated, as these patients typically achieve normal or socially normal bladder and bowel control long-term if treated before progression to retention 1, 3
For CESR patients (complete retention): Operate emergently if within 12 hours of retention onset or if any perineal sensation persists, as recovery of function is more likely with preserved sensation 1, 3
For prolonged CESR with no residual sacral function: Surgery can be performed on the next day's list, though outcomes are significantly worse with many patients requiring intermittent self-catheterization and manual bowel evacuation 1, 3
Injection-Specific Considerations
Sacral injections carry unique risks in the setting of severe spinal stenosis:
Severe stenosis is a major risk factor: Case reports document persistent CES lasting 3 months to over 1 year after caudal epidural injection in patients with severe L4-L5 stenosis, with complete motor loss (MRC grade 0) and neurogenic bladder 8, 9
Volume and pressure effects: The injectate (typically bupivacaine, triamcinolone, hyaluronidase, and saline) can cause direct mechanical compression and venous congestion in an already compromised canal 8, 9
Transient versus persistent: While most injection-related nerve blocks resolve within 8 hours, severe stenosis predisposes to persistent injury requiring aggressive rehabilitation 4, 9
Critical Pitfalls to Avoid
Do not wait for "white flag" symptoms (complete incontinence, perineal anesthesia, absent reflexes)—by this stage, permanent damage is likely despite surgery 1, 5
Do not dismiss bilateral leg symptoms as routine post-injection effects—bilateral radiculopathy is the earliest red flag distinguishing CES from simple transient sciatic block 1, 5
Do not catheterize before determining retention status—this prevents accurate staging and may lead to inappropriate surgical timing 1
Do not delay MRI for "observation"—even subtle clinical findings warrant immediate imaging in the post-injection setting 6, 7
Prognosis Based on Treatment Timing
The stage at intervention determines outcome:
- CESI stage: 90%+ achieve normal or socially normal function 1
- CESR within 12-72 hours: 48-93% show improvement, but many have severe residual deficits 1
- Delayed CESR: Majority require permanent catheterization, only minority return to work 1
Post-Operative Rehabilitation
For persistent deficits after injection (particularly with severe stenosis), interdisciplinary rehabilitation including bladder training, bowel management protocols, and physical therapy can lead to recovery over 3 months, though some cases show permanent polyradiculopathy 8, 9