INTRODUCTION: Maigne reported that entrapment of the superior cluneal nerve (SCN) in osteofibrous tunnels between the iliac crest and the thoracolumbar fascia could cause low back pain (LBP) (Surg Radiol Anat. 1989). LBP was successfully treated by surgically opening the osteofibrous tunnel (Spine. 1997). The purpose of this study is to ascertain the frequency and the features of entrapment neuropathy of the SCN.
METHODS: Two hundred and eighty‐five patients (132 male and 153 female; average age 62.4 years) suffering from LBP, radiating posterior leg pain or numbness were investigated. Suspected SCN entrapment was defined as cases where LBP, pain or numbness radiating from the buttock to the posterior leg reproduced by palpation of the trigger point above the posterior iliac crest approximately 7cm from the midline. Patients with the diagnostic features of SCN syndrome underwent injection with 5ml of 1% lidocaine. They evaluated their pain, on the visual analogue scale (VAS) before, 15 minutes after and 1 week after injection.
RESULTS: Ten of the 285 patients (3.5%; 2 male and 8 female; average age 68.6 years) underwent injection. The mean VAS score was 69 (25‐100) before injection. At 15 minutes, 9 of the 10 experienced a reduction in pain, with a mean VAS score of 36.5 (0‐90). At one week, all patients experienced pain reduction, with a mean VAS score of 33.5 (0‐85). Although 4 patients needed additional injections because of recurrence of pain, the other 6 patients needed no more injections. No complications were seen.
DISCUSSION: Talu (Reg Anesth Pain Med. 2000) and Aly (Tohoku J Exp Med. 2002) treated medial SCN entrapment neuropathy by local anesthetic block. When other causes of LBP are ruled out and the pain is relieved by local injection, possibile SCN entrapment should be considered, and diagnostic local anesthetic blocks should be tried.