The frequency of superior cluneal nerve entrapment diagnosed with ultrasound-guided nerve block in patients with low back pain: A prospective, cross-sectional study.

Introduction: To determine the frequency of superior cluneal nerve entrapment (SCN-E) in patients who applied to our outpatient clinic with low back pain.

Methods: Two hundred patients with mechanical low back pain persisting more than 3 months were included in our study. All patients were evaluated with detailed clinical history and physical examination. Ultrasound-guided diagnostic injection was performed in patients who had tenderness on the posterior iliac crest and whose main complaint emerged by pressing on this point. Patients with 70% or greater pain relief 1 h after the injection were considered as SCN-E. The frequency and clinical features of SCN-E were determined and compared with other mechanical low back pain.

Results: The mean age of the patients included in our study was 48.56 ± 14.11 years, with 138 female and 62 male patients. The diagnostic injection was performed on 31 patients and considered positive in 24 of them. The frequency of SCN-E was determined as 12%. The Hip-Knee Flexion Test was determined to be more specific for SCN-E than other causes of low back pain, the sensitivity and specificity of the test were 41.67% and 88.64% (p = 0.001; p < 0.01). In addition, all demographic and clinical features in patients diagnosed with SCN-E were found to be similar to other mechanical low back pain cases.

Conclusions: In patients with chronic low back pain, SCN-E is not a rare cause and is often overlooked. Increasing the awareness and experience of physicians on SCN-E will prevent patients from being exposed to unnecessary surgical or non-surgical treatments.