Superior and Middle Cluneal Nerve Entrapment as a Cause of Low Back Pain.

Low back pain (LBP) is encountered frequently in clinical practice. The superior and the middle cluneal nerves (SCN and MCN) are cutaneous nerves that are purely sensory. They dominate sensation in the lumbar area and the buttocks, and their entrapment around the iliac crest can elicit LBP. The reported incidence of SCN entrapment (SCN-E) in patients with LBP is 1.6%-14%. SCN-E and MCN entrapment (MCN-E) produce leg symptoms in 47%-84% and 82% of LBP patients, respectively. In such patients, pain is exacerbated by lumbar movements, and the symptoms mimic radiculopathy due to lumbar disorder. As patients with failed back surgery or Parkinson disease also report LBP, the differential diagnosis must include those possibilities. The identification of the trigger point at the entrapment site and the disappearance of symptoms after nerve block are diagnostically important. LBP due to SCN-E or MCN-E can be treated less invasively by nerve block and neurolysis. Spinal surgeons treating patients with LBP should consider SCN-E or MCN-E.