Potential S1 Nerve Root Blocks Associated with Sacroiliac Joint Injections

Area of Science:

• Pain Management
• Radiology
• Anatomy

Background:

• Sacroiliac (SI) joint dysfunction is a frequent cause of lower back pain.
• Diagnosing SI joint pain is challenging, with SI joint injections serving as a gold standard for diagnosis and therapy.
• A known complication of SI joint injection is temporary leg numbness and weakness.

Purpose of the Study:

• To evaluate SI joint anatomy and contrast flow during injections.
• To understand how local anesthetics may impact nerve roots, leading to temporary leg symptoms.
• To correlate imaging findings with potential neurological complications.

Main Methods:

• Retrospective case series design at an academic medical center.
• Review of patients undergoing SI joint injection with 3D cone beam CT (CBCT) fluoroscopy.
• Analysis of CBCT images to assess contrast spread within the SI joint and surrounding structures.

Main Results:

• 27 patients (mean age 56) were analyzed.
• 14.8% of patients showed contrast spread into the S1 posterior neuroforamen.
• 85.2% of patients had contrast confined to the SI joint.

Conclusions:

• Lower concentrations and volumes of local anesthetic may reduce the risk of S1 nerve root and epidural blocks.
• Consideration of S1 nerve pathology is important for accurate diagnosis of SI joint pain.
• Optimizing SI joint injection techniques can enhance diagnostic specificity and minimize complications.