Anatomical etiology of “pseudo-sciatica” from superior cluneal nerve entrapment: a laboratory investigation
Authors Konno T, Aota Y, Kuniya H, Saito T, Qu N, Hayashi S, Kawata S, Itoh M
Received 22 May 2017
Accepted for publication 20 September 2017
Published 1 November 2017 Volume 2017:10 Pages 2539—2545
Checked for plagiarism Yes
Review by Single-blind
Peer reviewers approved by Dr Colin Mak
Peer reviewer comments 2
Editor who approved publication: Dr E Alfonso Romero-Sandoval
Tomoyuki Konno,1 Yoichi Aota,2 Hiroshi Kuniya,1 Tomoyuki Saito,1 Ning Qu,3 Shogo Hayashi,3 Shinichi Kawata,3 Masahiro Itoh3
1Department of Orthopaedic Surgery, Yokohama City University Graduate School of Medicine, 2Department of Spine & Spinal Cord Surgery, Yokohama Brain and Spine Center, Yokohama, 3Department of Anatomy, Tokyo Medical University, Tokyo, Japan
Objective: The superior cluneal nerve (SCN) may become entrapped where it pierces the thoracolumbar fascia over the iliac crest; this can cause low back pain (LBP) and referred pain radiating into the posterior thigh, calf, and occasionally the foot, producing the condition known as “pseudo-sciatica.” Because the SCN was thought to be a cutaneous branch of the lumbar dorsal rami, originating from the dorsal roots of L1–L3, previous anatomical studies failed to explain why SCN causes “pseudo-sciatica”. The purpose of the present anatomical study was to better elucidate the anatomy and improve the understanding of “pseudo-sciatica” from SCN entrapment.
Materials and methods: SCN branches were dissected from their origin to termination in subcutaneous tissue in 16 cadavers (5 male and 11 female) with a mean death age of 88 years (range 81–101 years). Special attention was paid to identify SCNs from their emergence from nerve roots and passage through the fascial attachment to the iliac crest.
Results: Eighty-one SCN branches were identified originating from T12 to L5 nerve roots with 13 branches passing through the osteofibrous tunnel. These 13 branches originated from L3 (two sides), L4 (six sides), and L5 (five sides). Ten of the 13 branches showed macroscopic entrapment in the tunnel.
Conclusion: The majority of SCNs at risk of nerve entrapment originated from the lower lumbar nerve. These anatomical results may explain why patients with SCN entrapment often evince leg pain or tingling that mimics sciatica.
Keywords: superior cluneal nerve, entrapment neuropathy, dorsal rami, pseudo-sciatica, osteofibrous tunnel, LBP
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