BACKGROUND: Chronic low back pain is notoriously challenging to diagnose and manage, especially when imaging fails to reveal a cause. Superior cluneal nerve entrapment is an increasingly recognized, but often overlooked, source of pain that can mimic lumbosacral radiculopathy.

CASE REPORT: We describe a 43-year-old woman with longstanding chronic low back pain unresponsive to physical therapy, extracorporeal shockwave therapy, and targeted sacroiliac joint injections. A physical examination revealed focal tenderness along the posterior iliac crest, a positive Tinel sign, and pain over the iliac crest. Lumbar magnetic resonance imaging was unremarkable. She underwent fluoroscopic and ultrasound-guided superior cluneal nerve blocks in separate sessions; each block produced immediate and complete pain resolution.

CONCLUSION: Superior cluneal nerve entrapment should be considered when a patient has axial low back pain with negative imaging. Ultrasound-guided superior cluneal nerve blocks are a safe and effective alternative to fluoroscopic guidance, offering real-time visualization without radiation exposure.

KEYWORDS: Low back pain, nerve entrapment, superior cluneal nerve block, ultrasound guidance