They presented a CASE REPORT of a longstanding chronic low back pain related to entrapment neuropathy of the L1-L2 dorsal ramus (also named cluneal nerves) over the iliac crest. They performed 3 anesthetic blocks at the trigger point (7 cm form midline and 1.5 cm above the iliac crest). The blockage was successful for 3 weeks each. A surgical procedure was performed. They found the entrapment in a kind of osteofibrous orifice between the upper rim of the iliac crest and the thoracolumbar fascia. Pain decreased dramatically the same day, and disappeared completely within less than a week.
They also argue that some patients have the wrong diagnosis of iliolumbar syndrome and explain that anatomically, just by palpation, the iliolumbar ligaments are not accessible.
They point out that entrapment neuropathies appear to be underrecognized and undertreated. They warn that a greater awareness of this possible etiology could avoid expense as well as persistent discomfort and discouragement for certain number of patients incorrectly classified as suffering from nonspecific chronic low back pain.
Article’s keywords: entrapment neuropathy, low back pain, surgery, iliac crest, cluneal nerves, dorsal ramus.
Personal notes of the article:
A Potentially Underrecognized and Treatable Cause of Chronic Back Pain: Entrapment Neuropathy of the Cluneal Nerves
By Berthelot J.M., Delecrin J., Maugars Y., Caillon F., Prost A.
From the Department of Rheumatology in Nantes, France
J Rheumatol. 1996 Dec; 23(12): 2179-81. PubMed PMID: 8970063.
Berthelot et al. introduction
Chronic low back pain is a common syndrome that can give serious consequences for daily life and work.
As a definite organic lesion is seldom detected, which leads often to unsuccessful treatment causing frustration for patients and doctors.
Berthelot et al CASE REPORT
A 48-year-old active woman. She had 20 years past history of chronic low back pain attributed to zygapophyseal osetoarthretis (OA). She sought medical help in November 1992 because of a progressive worsening of the pain, which reached an intolerable level (8/10 on a visual analog scale) and no longer responded to analgesic or anti-inflammatory drugs.
On admission, she presented a slight obesity (68 kg 1.63 m). She complained of dull but intense pain starting from L4-L5 level and lateralizing to the left, with radiation to the left gluteus but no paresthesia. The pain persisted all day long for several months and was increased by standing more than 10 min, walking and bending over. Her sleep was disturbed especially when turning over. She was unable to perform housework.
Examination revealed slight hyperlordosis and fibrositis of the left maximus gluteus. But no neurological signs of sciatica. Stretched leg raising was negative. Forward bending was painless, but right bending, rotation and hyperextension worsened the pain. The only tender points on palpation were in the left paravertebral areas L4-L5 and L5-S1.
Computed tomography detected no discal bulging or any sacroiliac abnormalities.
Steroid infiltrations under fluoroscopy in the L4-S1 zygapophyseal joints in 1993 were unsuccessful. Thermocoagulation at the same level failed to alleviate the pain. A rigid cast in 1994 failed to relieve the pain.
Later, a careful analysis of the painful area revealed a trigger point 7 cm left to the L5 spine process and just above the iliac crest. Pressure at this point exquisitely reproduced the pain that reached level 9/10. Then an anesthetic blockage with xylocaine and bethametasone gave her pain relief for 3 weeks lowering the VAS 4/10. Two more blocks were effective. Then they made the diagnosis of possible LOCAL CLUNEAL NERVE ENTRAPMENT NEUROPATHY.
MRI failed to detect any abnormalities in the iliolumbar area.
The surgery showed that the nerve was entrapped within a rigid osteofibrous orifice between the upper rim of the iliac crest and the thoracolumbar fascia (as previously described by Maigne in 1991). No relapse of pain occurred after 15 months of follow-up. She has resumed doing all her housework.
Discussion
The case emphasizes the importance of the nerve entrapment of the dorsal ramus also named cluneal nerves (T12-L3) over the iliac crest as a source of severe and apparently inexplicable chronic low back pain.
The pain is usually ascribed to fibromyalgia, “iliolumbar syndrome” or spinal OA problems.
They think the prevalence of this neuropathy could be around 5-20% of the patients they see for low back pain.
Many patients also present regional pain syndrome over the greater trochanter.
Many patients with cluneal neuropathy are diagnosed as iliolumbar syndrome
Berthelot et al. showed criticism with the diagnosis of the affection of the iliolumbar ligament. Since the iliolumbar ligament lies in a position that can NOT BE ACCESSIBLE by palpation.
Diagnostic method to suspect cluneal nerve or dorsal rami entrapment
The diagnosis relies solely on reproduction of the pain by applying pressure over the iliac crest (no image diagnosis is possible, even in the woman of the case report, the MRI images were normal)
There are difficulties to do the diagnosis so there can be other side of tenderness, as pointed out by the Valleix-points.
Published in September 2018 By Marta Cañis Parera 
Some references
-Berthelot J. M., Delecrin J., Maugars Y, Caillon F., Prost A. A potentially Underrecognized and Treatable Cause of Chronic Back Pain: Entrapment Neuropathy of the Cluneal Nerves. J Rheumatol. 1996 Dec; 23(12): 2179-81. PubMed PMID:8970063.
-Maigne 1991
