Ultrasound Localization and Guided Injection for Superior Cluneal Nerve Entrapment

Low back pain (LBP) is a common complaint in the clinical setting. Among all the differential diagnosis for LBP, superior cluneal nerve (SCN) entrapment is the commonly omitted one. The superior cluneal nerve is the terminal branch of the lateral branches of the posterior rami of the L1-L3 spinal nerves, which passes through the osseous tunnel interposed between the thoracolumbar fascia and iliac crest. This nerve can be entrapped due to poor posture, trauma or stretching of the surrounding thoracolumbar fascia and osseous membrane. The cardinal symptom of the superior cluneal nerve entrapment is buttock pain. Sometimes the pain may radiate to the lower limb, which mimics sciatica, and makes the diagnosis difficult. Early diagnosis and treatment of SCN entrapment is crucial, which can facilitate the improvement of health related quality of life and decrement the socioeconomic loss due to disability. The study aims is (1) to scan the SCN and thoracolumbar fascia by ultrasound in patients with LBP and normal subjects. The transcutaneous electrical stimulation will be used to confirm the location of SCN by asking the subject to depict the sensory distribution after stimulation; (2) to analyze the related factors of LBP with SCN entrapment, which may help in setting up the diagnostic criteria of SCN entrapment; (3) to analyze the therapeutic effect of perineural injection to SCN in SCN entrapment, and to find the factors that related responsiveness.