Abstract
BackgroundEntrapment of the superior cluneal nerve (SCN) in an osteofibrous tunnel has been reported as a cause of low back pain (LBP). However, there are few reports on the prevalence of SCN disorder and there are several reports only on favorable outcomes of treatment of SCN disorder on LBP. The purposes of this prospective study were to investigate the prevalence of SCN disorder and to characterize clinical manifestations of this clinical entity.MethodsA total of 834 patients suffering from LBP and/or leg symptoms were enrolled in this study. Diagnostic criteria for suspected SCN disorder were that the maximally tender point was on the posterior iliac crest 70 mm from the midline and that palpation of the tender point reproduced the chief complaint. When patients met both criteria, a nerve block injection was performed. At the initial evaluation, LBP and leg symptoms were assessed by visual analog scale (VAS) score. At 15 min and 1 week after the injection, VAS pain levels were recorded. If insufficient pain decrease or recurrence of pain was observed, injections were repeated weekly up to three times. Surgery was done under microscopy. Operative findings of the SCN and outcomes were recorded.ResultsOf the 834 patients, 113 (14%) met the criteria and were given nerve block injections. Of these, 54 (49%) had leg symptoms. Before injection, the mean VAS score was 68.6 ± 19.2 mm. At 1 week after injection, the mean VAS score significantly decreased to 45.2 ± 28.8 mm (p < 0.05). Ninety-six of the 113 patients (85%) experienced more than a 20 mm decrease of the VAS score following three injections and 77 patients (68%) experienced more than a 50% decrease in the VAS score. Surgery was performed in 19 patients who had intractable symptoms. Complete and almost complete relief of leg symptoms were obtained in five of these surgical patients.ConclusionsSCN disorder is not a rare clinical entity and should be considered as a cause of chronic LBP or leg pain. Approximately 50% of SCN disorder patients had leg symptoms.Electronic supplementary materialThe online version of this article (doi:10.1186/s13018-014-0139-7) contains supplementary material, which is available to authorized users.
Highlights
Entrapment of the superior cluneal nerve (SCN) in an osteofibrous tunnel has been reported as a cause of low back pain (LBP)
The diagnostic criteria for suspected SCN disorder were the following: 1) the maximal tender point was on the posterior iliac crest approximately 70 mm from the midline and 45 mm from the posterior superior iliac spine where the medial branch of the SCN runs through an osteofibrous tunnel consisting of the thoraco-lumbar fascia and the iliac crest and 2) palpation of the maximally tender point reproduced the chief complaint of LBP and/or leg symptoms
Because a recent anatomical study by Kuniya et al [10] indicated that one to three SCN branches may pass through the osteofibrous tunnel and that 2% of the specimens had severe constriction of the SCN within a bony groove on the iliac crest, we routinely explored all branches passing around the tender point by tracing each anastomosing branch until the rim of the iliac crest was explored (Figure 1B)
Summary
Entrapment of the superior cluneal nerve (SCN) in an osteofibrous tunnel has been reported as a cause of low back pain (LBP). The superior cluneal nerve (SCN) is derived from the cutaneous branches of the dorsal rami of T11-L4 [1,2,3]. Maigne [3,5] drew attention to the so-called “Maigne’s syndrome”, which involves facet syndromes at the thoraco-lumbar junction causing unilateral LBP. In this syndrome, the pain is not experienced at the junction but is referred lower to the dermatomes of corresponding cutaneous dorsal rami.
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