Cluneal Neuropathy Treatment in St. Louis

The cluneal nerves are small feeling nerves. They serve the skin and deeper tissue over the upper buttock. The superior cluneal nerves cross the top rim of the pelvis, the iliac crest, through a tight tunnel of tough tissue. The middle cluneal nerves pass near the sacrum and the sacroiliac ligaments. Both cross bone in tight spaces, and both can get squeezed there.

Cluneal entrapment causes pain across the lower back and buttock. It can spread into the thigh. That pattern matches almost exactly with sacroiliac joint dysfunction, with lumbar radiculopathy, and with piriformis syndrome, which gives a very similar buttock and leg pattern. Both sit on the same list of suspects: when sciatica is not a disc. Patients often get treated for a disc or an SI joint for months with no relief. MRI does not show it. We make the diagnosis by exam. We find one exact tender spot over the iliac crest that sets off the pain. Then a diagnostic block proves it.

The exam finds the tender spot where the nerve crosses bone. A cluneal nerve block then goes at that exact spot, guided by imaging. We use a small amount of local anesthetic (numbing medicine) so the result points to that one nerve. We use both ultrasound and fluoroscopy (live X-ray). We prefer fluoroscopy when we have it, because the nerve is trapped against an edge of bone, and fluoroscopy shows that bone directly. Contrast dye proves the medicine stayed at that spot and did not spread to nearby branches. If the pain goes away while the numbing lasts, the diagnosis is all but proven. Electrodiagnostic testing helps when we also need to rule out a lumbar nerve root problem, since the two can happen together.

Many patients get better with a series of blocks plus changes in activity and posture that stop irritating the tunnel. When the trap is mechanical and does not let go, hydrodissection can free the nerve from the tough band squeezing it. Radiofrequency treatment of the problem branch is an option when blocks help but wear off fast. Surgery to release the nerve is saved for the few who fail all of the above.

The superior cluneal nerves are the outer skin branches of the L1 to L3 dorsal rami. Their weak spot is a feature of the anatomy. As they cross the iliac crest, they pass through a tunnel. One wall is the thoracolumbar fascia (a sheet of tough tissue). The other wall is the bone itself. Bone on one side and tough tissue on the other means the tunnel cannot stretch when its contents swell.

Anatomy work, most of all by Maigne, showed these nerves are pinned at that point and can be squeezed there. That work also described the syndrome that results. The middle cluneal nerves, from the S1 to S3 dorsal rami, face the same kind of problem. They pass under the long posterior sacroiliac ligament. In both spots the nerve is squeezed between a band that will not give and bone. That is why the tender spot is so small and sets off the pain every time.

Here is the strange part. These are pure skin nerves that only carry feeling. Yet patients describe a deep ache, not a surface burn. Trapping the nerve makes the nerve trunk itself sensitive. The nervi nervorum (tiny nerves that supply the nerve’s own sheath) create exactly this deep, hard-to-pin-down ache. Constant signals then make dorsal horn neurons in the spinal cord sensitive. Those same neurons also get signals from deeper parts. So the brain reads the pain as coming from the joint, not the skin.

This is why it gets misdiagnosed. The patient reports deep buttock pain. The doctor, reasonably, looks at deep parts. Imaging, sure enough, finds wear and tear somewhere. Nothing points to a small skin nerve at the rim of the pelvis unless someone presses on that exact spot. That is why this condition is thought to cause a real share of the low back pain that has failed standard treatment.