What are the potential complications of sacral injections?

Complications of Sacral Injections

Sacral injections are generally safe procedures with minimal risk of serious complications, though common minor side effects occur in approximately 40% of patients, including injection-site soreness, pain exacerbations, vasovagal reactions, and transient sciatic nerve block. 1

Common Minor Complications

Immediate Side Effects

• Injection-site soreness occurs in 12.9-17.1% of patients and represents the most frequent delayed adverse event 1
• Pain exacerbations affect 5.3-8.8% of patients immediately following injection 1, 2
• Vasovagal reactions occur in 2.5% of patients, manifesting as lightheadedness, nausea, or syncope 1, 2
• Facial flushing and/or sweating affects approximately 2.3% of patients and is specific to corticosteroid use 1

Transient Neurological Effects

• Transient sciatic nerve block can occur from anterior capsular disruption when local anesthetic is included in the injectate, with rates ranging from 6.3% (8 of 127 patients) in some technique-dependent studies to lower rates in others 1
• This complication carries fall risk and patients should be counseled accordingly 1
• Increased radicular pain occurs in 8.8-18.2% of patients immediately post-procedure 2

Serious but Rare Complications

Infectious Complications

• Joint infection of the sacroiliac joint following intra-articular injection has been reported in case reports 1
• Spinal epidural abscess, meningitis, and endocarditis have been documented in immunosuppressed patients 1
• These serious infections remain exceedingly rare in clinical practice 3

Catastrophic Neurological Complications

• Cauda equina syndrome has been reported after caudal epidural sacral injection, particularly in patients with severe lumbar spinal stenosis, presenting with motor weakness, buttocks numbness, and voiding difficulties 4
• While particulate corticosteroids have been linked to catastrophic complications including blindness, paralysis, and death in cervical spine injections, serious neurologic injuries have also been reported at thoracic, lumbar, and sacral levels 5
• Patients with severe stenosis visible on MRI scans represent higher-risk candidates and clinicians should exercise particular caution 4

Corticosteroid-Related Systemic Effects

Metabolic and Endocrine Complications

• Hyperglycemia is a well-described effect of systemic steroid absorption 1
• Hypothalamic-pituitary axis suppression can occur with repeated injections 1
• Cushing Syndrome has been reported with chronic steroid exposure 1

Musculoskeletal Effects

• Decreased bone mineral density with possible increased fracture risk occurs with repeated corticosteroid injections 1
• Immunosuppression with increased risk of infection is a recognized systemic effect 1

Medication-Specific Considerations

Particulate vs. Nonparticulate Corticosteroids

• Particulate corticosteroid preparations (methylprednisolone acetate, triamcinolone acetonide) carry higher risk of embolic complications but provide longer-lasting anti-inflammatory effects 5
• Nonparticulate preparations (dexamethasone) are safer regarding embolic risk but have shorter-lived therapeutic effects 5
• The choice of corticosteroid should balance safety and efficacy, with particular attention to anatomical considerations 5

Local Anesthetic Toxicity

• Neural and cardiac toxicities from local anesthetics are possible, though everyday risks are minimal with proper injection technique 5
• Local anesthetic-related side effects include lightheadedness (6.5-13.6%) and nausea (3.4-3.7%) 2

Risk Mitigation Strategies

Imaging Guidance

• Fluoroscopic guidance is preferred as it allows confirmation of intra-articular needle placement and rules out intravascular needle tip position through contrast injection observation 1, 3
• Image-guided injection is recommended to ensure optimal needle positioning, particularly below S3 for sacral hiatus approaches 6
• Radiation exposure from fluoroscopy is low, though long-term effects on operators have not been fully studied 1

Anticoagulation Management

• Bleeding risks are low and most guidelines recommend continuing anticoagulation during sacroiliac joint injections 1

Critical Clinical Pitfalls

• Avoid sacral injections in patients with severe spinal stenosis without careful risk-benefit assessment, as they face higher risk of cauda equina syndrome 4
• Counsel patients about fall risk when local anesthetic is used due to potential transient sciatic nerve block 1
• Screen for immunosuppression as these patients face elevated risk of serious infectious complications 1
• Monitor diabetic patients closely for hyperglycemia following corticosteroid injection 1
• Consider nonparticulate corticosteroids when embolic risk is a concern, accepting the trade-off of shorter therapeutic duration 5