If you have years of “low back and buttock pain” with negative SI joint injections, negative facet medial branch blocks, and a lumbar MRI that shows age-typical degeneration but no radicular cause for your pain — and you can press a specific point on the back of your iliac crest to reproduce the pain — you are probably reading the right post. The condition may be cluneal nerve entrapment. It is still a niche diagnosis, the literature is small but growing, and a short ultrasound-guided block at the iliac crest tests for it.
Why this gets missed
The lumbosacral pain differential is a well-worn workup tree. The three branches that get explored are facet joints (treated with medial branch blocks and RFA), SI joint (treated with intra-articular injection and lateral branch RFA), and lumbar disc (treated with epidural steroid injection and physical therapy). Patients run the tree once, twice, sometimes three times across different practices. When all three come back negative or inadequate, the next labels are often “chronic pain syndrome” or, for some, a referral for lumbar fusion for “axial low back pain”.
Neither of those is cluneal nerve entrapment. The cluneal nerves are not on the standard lumbar-spine workup tree. Patients can end up cycling through medication trials and sometimes spine surgery that does not help. In the Kuniya series, 11 of the 19 patients who eventually needed cluneal nerve surgery had already had lumbar spine surgery, and 8 of them had no improvement from it (Kuniya 2014).
The Maigne and Doursounian 1997 Spine paper documented 19 surgical cases (Maigne 1997). The Kuniya and Aota group in Japan mapped the superior cluneal tunnel in cadavers (Kuniya 2013) and then followed 834 patients with low back pain or leg symptoms. 14% met the bedside criteria for superior cluneal trouble, and about half of those had leg symptoms that could be mistaken for a lumbar radiculopathy (Kuniya 2014). Aota has also described entrapment of the middle cluneal nerves (Aota 2016). The body of work is small but consistent, and it suggests cluneal entrapment is under-diagnosed because it is under-considered.
The fix is the lateral iliac-crest palpation. Palpate 7–8 cm lateral to the midline along the iliac crest with the patient prone or in a sidelying position. If a discrete tender point reproduces the patient’s typical band of buttock-and-lumbosacral pain, cluneal entrapment becomes the leading hypothesis until a block says otherwise.
The anatomy that matters
Three nerve groups make up the cluneal cluster:
Superior cluneal nerves — cutaneous branches of the lower thoracic and lumbar dorsal rami, classically described as L1–L3, though cadaver work traces some branches as low as L4–L5 (Kuniya 2014). They cross the iliac crest through a small osteofibrous tunnel formed by the thoracolumbar fascia and the bone itself, approximately 7–8 cm lateral to the midline. They then become subcutaneous and supply the skin over the upper-outer buttock. The osteofibrous tunnel is the entrapment site. In a cadaver study of 109 sides, 56% had at least one superior cluneal branch running through such a tunnel, though obvious entrapment was seen in only 2 medial branches (Kuniya 2013). At surgery, the same group more often found the nerves caught under tight fascia at the crest than squeezed in a bony groove (Kuniya 2014). Prior iliac crest bone graft harvest is another known cause of injury to these nerves.
A tender point higher up, about 3–5 cm from the midline between the tip of the shoulder blade and the lowest rib, points to a different nerve: a skin branch of a thoracic dorsal ramus. That pattern is posterior cutaneous nerve entrapment syndrome (POCNES), covered in our ACNES guide. We treat it the way we treat ACNES: a lidocaine-only test injection, no pulsed radiofrequency, and a surgical referral when the relief keeps fading.
Middle cluneal nerves — lateral cutaneous branches of the dorsal rami of S1–S3. They pass under (or sometimes through) the long posterior sacroiliac ligament and supply the central buttock skin. Entrapment where they pass under the ligament was described by Aota as a distinct cause of low back and leg symptoms, separate from superior cluneal entrapment at the iliac crest (Aota 2016).
Inferior cluneal nerves — branches of the posterior femoral cutaneous nerve (S2–S3). They supply the lower buttock skin. Entrapment is less commonly diagnosed but can occur around the ischial tuberosity or under the gluteus maximus, particularly post-trauma.
All three groups are sensory nerves. No motor weakness, no reflex changes. The diagnostic clue is the cutaneous band reproduced by Tinel testing at the suspected entrapment point.
How we diagnose
The diagnostic procedure is an ultrasound-guided cluneal nerve block at the Tinel-positive point. Performed in our procedure suite. Total visit time: about 30 minutes.
Technique for superior cluneal entrapment: with the patient in a sidelying or prone position, the posterior iliac anatomy is identified by ultrasound — the iliac crest as a bright hyperechoic line, the thoracolumbar fascia as a thin hyperechoic stripe immediately above the crest, the underlying multifidus muscle. A thin needle is advanced under direct ultrasound visualization to the fascial plane at the Tinel-positive point, typically 7–8 cm lateral to the midline. After negative aspiration, a small volume of local anesthetic is injected, and the spread is watched in real time.
For middle cluneal entrapment: ultrasound or fluoroscopic guidance at the long posterior sacroiliac ligament, with the medication deposited in the fascial plane superficial to the ligament.
The diagnostic effect arrives within 5–10 minutes. A clear drop in the typical cluneal-territory pain while the anesthetic works makes the cluneal nerve the likely source, not a certainty. There is no universal cut-off: how much relief counts, and whether a second block is needed, depends on the clinical question and your insurance plan’s policy. In the largest prospective series, 68% of patients had their pain score cut by more than half after up to three weekly injections, though on average the pain crept partway back within a week of each one (Kuniya 2014). The block is low risk but not risk-free. In that series, 2 of 113 patients developed erectile dysfunction after the block, temporary in one and permanent in the other (Kuniya 2014).
Treatment ladder and when surgery is the right call
Step 1 — neuropathic-pain medication trial. Gabapentin or pregabalin at standard titration. Topical 5% lidocaine patch over the affected cutaneous band.
Step 2 — ultrasound-guided diagnostic cluneal nerve block. The workhorse. A small volume of local anesthetic, diagnostic in 5–10 minutes. When it clearly relieves the usual pain and the pain keeps coming back, the next step is surgical referral.
Step 3 — surgical decompression. Decompression of the cluneal nerve(s) at the entrapment site, done by a surgeon who focuses exclusively on peripheral nerve entrapment. Maigne and Doursounian reported excellent results in 13 of 19 patients, with 6 unsatisfactory, including 4 in whom no compression was found at surgery (Maigne 1997). In the Kuniya series, 19 of 113 patients went on to surgery (Kuniya 2014). The procedure releases the osteofibrous tunnel (superior cluneal) or the long posterior sacroiliac ligament’s compressive fibers (middle cluneal). Modal Pain coordinates the referral when indicated and provides the documented diagnostic-block response surgical programs require.
Step 4 — peripheral nerve stimulation referral. For severe refractory pain, percutaneous PNS at the cluneal nerve is an option that requires referral to an implanting specialist. A 2022 review found the evidence for every cluneal intervention, PNS included, limited to small uncontrolled studies (Gill 2022).
The literature on cluneal entrapment is smaller than for inguinal-region neurectomies. Surgical referral follows a clearly positive test injection when the pain keeps coming back. It is not a first-line move.
For referring physicians (especially spine and pain medicine)
When you have a chronic-low-back-pain patient with negative medial branch blocks, negative SI joint injection, and a lumbar MRI that doesn't explain the symptoms — and the cutaneous distribution stays in the buttock and lower lumbosacral region without crossing into the leg below the gluteal crease — send: the prior interventional workup summary, the lumbar MRI report, the medication trial history, and a note on whether you've palpated the iliac crest. We document a Tinel sign at the iliac crest, run an ultrasound-guided cluneal block when indicated, and send notes back to your practice as requested or as needed. When the block is clearly positive and the pain keeps coming back, we coordinate the surgical referral.
Ready to evaluate your back and buttock pain
If chronic lumbosacral pain has persisted through facet, SI, and lumbar disc workups without a clear answer, and a specific point along your iliac crest reproduces the pain, the next step is a nerve-focused evaluation, which often leads to an ultrasound-guided cluneal block. Same-week new-patient consultations are available.
Verify your insurance covers a cluneal entrapment workup Book a same-week consultation
Or call (646) 290-6660.
For the broader framework on peripheral nerve entrapments, see the peripheral nerve entrapment page.
References
This article is reviewed against the peer-reviewed literature. Citations retrieved from PubMed.
- Maigne JY, Doursounian L. Entrapment neuropathy of the medial superior cluneal nerve. Nineteen cases surgically treated, with a minimum of 2 years' follow-up. Spine (Phila Pa 1976). 1997. doi:10.1097/00007632-199705150-00017 · PubMed
- Kuniya H, Aota Y, Saito T, et al.. Anatomical study of superior cluneal nerve entrapment. J Neurosurg Spine. 2013. doi:10.3171/2013.4.SPINE12683 · PubMed
- Aota Y. Entrapment of middle cluneal nerves as an unknown cause of low back pain. World J Orthop. 2016. doi:10.5312/wjo.v7.i3.167 · PubMed
- Kuniya H, Aota Y, Kawai T, Kaneko K, Konno T, Saito T. Prospective study of superior cluneal nerve disorder as a potential cause of low back pain and leg symptoms. J Orthop Surg Res. 2014. doi:10.1186/s13018-014-0139-7 · PubMed
- Gill B, Cheng DS, Buchanan P, Lee DW. Review of Interventional Treatments for Cluneal Neuropathy. Pain Physician. 2022. · PubMed
Frequently Asked Questions
Three small sensory nerve groups supplying the skin over the buttock and lumbosacral region. The superior cluneal nerves are skin branches of the lower thoracic and lumbar dorsal rami (classically L1–L3, though cadaver work traces some branches to L4–L5) and supply the upper outer buttock. The middle cluneal nerves are the lateral cutaneous branches of S1–S3 dorsal rami and supply the central buttock. The inferior cluneal nerves are branches of the posterior femoral cutaneous nerve (S2–S3) and supply the lower buttock. All three groups are sensory, so there is no muscle weakness, and all three can be entrapped where they cross bone or ligament.
Two main entrapment sites. Superior cluneal: at the iliac crest, where the nerves cross through a small osteofibrous tunnel between the thoracolumbar fascia and the bone, approximately 7–8 cm lateral to the midline. Middle cluneal: at the long posterior sacroiliac ligament, where the nerves pass under (or sometimes through) the ligament. Inferior cluneal entrapment is less common but documented around the ischial tuberosity or under the gluteus maximus. Tinel sign at the entrapment point — most reliably the superior cluneal at the iliac crest — reproduces the typical band of buttock-and-lumbosacral pain.
Because the usual workup for chronic low back pain checks the facet joints, the SI joint and the lumbar discs, and the cluneal nerves are not on that list. A patient can have negative medial branch blocks, a negative SI joint injection and a clean MRI and still have cluneal nerve pain, because none of those tests examine these nerves. In a prospective study of 834 patients with low back pain or leg symptoms, 14% met simple bedside criteria for superior cluneal nerve trouble, and about half of them also had leg symptoms that could pass for sciatica (Kuniya 2014). Aota described the middle cluneal version as a possibly underdiagnosed cause of low back pain (Aota 2016).
An ultrasound-guided injection of a small volume of local anesthetic at the Tinel-positive point along the iliac crest, about 7 cm from the midline. The effect arrives within 5–10 minutes. A clear drop in the usual pain makes the cluneal nerve the likely source, not a certainty. In a prospective study of 113 patients, 77 (68%) had their pain score cut by more than half after up to three weekly injections, though on average the pain crept partway back within a week of each one (Kuniya 2014). Middle cluneal entrapment is blocked at the long posterior sacroiliac ligament.
Often not. In the largest prospective series, 19 of 113 patients treated with injections went on to surgery (Kuniya 2014). Before surgery come medication and the ultrasound-guided test injection. When that injection clearly relieves the usual pain and the pain keeps coming back, the next step is surgical referral. The procedure is release (decompression) of the cluneal nerve(s) at the entrapment point through a small incision, done by a surgeon who focuses exclusively on peripheral nerve entrapment. In Maigne's original series of 19 patients, results were excellent in 13 and unsatisfactory in 6, including 4 in whom no compression was found at surgery (Maigne 1997). The literature is small. Modal Pain coordinates the referral when indicated.
SI joint dysfunction produces deep, dull, mechanical pain centered over the sacroiliac joint itself, reproduced by SI provocation tests (FABER, Gaenslen, thigh thrust, compression). The pain is mechanical and constant rather than burning or electric. Cluneal entrapment produces burning, electric, or lancinating pain in a defined cutaneous band, with a positive Tinel sign at the iliac crest or long posterior SI ligament. The two can coexist and both can produce buttock pain, and the diagnostic blocks help separate them. An SI joint injection should ease SI joint pain without changing cluneal pain, and a cluneal block should do the opposite. Neither block is a perfect test, so the result is read together with the exam.
Most commercial PPO plans cover ultrasound-guided cluneal nerve blocks for suspected cluneal nerve entrapment, typically with prior authorization. We check your benefits and go over what your plan covers and any expected cost by phone before your visit, so there are no surprise bills. We accept most commercial PPO plans, including Aetna, Anthem Blue Cross Blue Shield, Cigna, Empire Blue Cross Blue Shield, the Empire Plan, Oscar, Oxford, UMR and UnitedHealthcare, and do not accept Medicare, Medicaid, HMO plans, or workers' compensation. Check your plan or call (646) 290-6660.
