I saw a couple of links that I copy and pasted the info regarding superior cluneal nerve entrapment, where they mentioning releasing the nerve from within the osteofibrous tunnel or providing a SCN block to treat the patient's pain. I would think that if there is documentation of this nerve being block I would use 64450.
A case of acute unilateral low back pain treated by superior cluneal nerve block has been reported.
The patient was a 55-year-old woman presenting to the outpatient clinic with unilateral low back pain localised on the right iliac crest and radiating to the right buttock.
Pain due to superior cluneal nerve entrapment is a rare cause of unilateral low back pain. Entrapment is liable where it passes through the fascia near the posterior iliac crest and the clinical findings, the symptoms she presented with, are the typical clinical symptoms.
The case was written up by researchers at the Department of Algology, Medical Faculty of Istanbul, Istanbul University, Turkey, led by Dr. Talu.
Said Dr. Talu, "After transient pain relief with a diagnostic trigger-point injection, entrapment of superior cluneal nerve was diagnosed and therapeutic nerve block with local anaesthetic and steroid combination was performed."
http://en.wikipedia.org/wiki/Superior_cluneal_nerves
Anatomic considerations of superior cluneal nerve at posterior iliac crest region.
Lu J, Ebraheim NA, Huntoon M, Heck BE, Yeasting RA.
SourceDepartment of Orthopaedic Surgery, Medical College of Ohio, Toledo 43614, USA.
Abstract
No previous studies describe the anatomic relationship of the superior cluneal nerve to the posterior iliac crest and thoracolumbar fascia. In the current study, 15 cadavers were dissected to determine the relationship of the superior cluneal nerve to the posterior iliac crest and thoracolumbar fascia. The distances from the medial branch of the superior cluneal nerve to the posterior superior iliac crest and the midline were 64.7 +/- 5.3 mm and 81.0 +/- 9.2 mm, respectively. The distances between the level of the iliac crest and perforating points of the superior cluneal nerve on the thoracolumbar fascia were 5.8 +/- 1.8 mm inferiorly for the medial branch, 2.2 +/- 1.8 mm superiorly for the intermediate branch, and 12.0 +/- 4.4 mm superiorly for the lateral branch, respectively. The proximal dissection above the perforating point of the nerve showed that the medial branch of the superior cluneal nerve is confined within a tunnel consisting of the thoracolumbar fascia and the superior rim of the iliac crest as it passes over the iliac crest. The intermediate and lateral branches of the superior cluneal nerve either pierce the thoracolumbar fascia or pass through an orifice or fissure in the thoracolumbar fascia. In two specimens, the medial branches of the superior cluneal nerve were constricted within the osteofibrous tunnel. The nerve was entrapped between the rigid fibers of the thoracolumbar fascia and the iliac crest.