Goal of the Study?
In this clinical anatomical study and literature review article from the European Spine Journal 1 the authors’ goals were twofold: (a) identify the anatomical mechanism of the Sinuvertebral Nerve in its relationship to lumbar discogenic pain and (b) clarify the different morphological aspects of the Sinuvertebral Nerve they found to those in similar clinical anatomical literature.
Why are they doing this study?
The Sinuvertebral Nerve (SVN) is a recurrent nerve that originates from the ventral ramus and enters the intervertebral canal supplying the bone, disc, ligament, dura mater and veins. Its complex anatomy and relationship to discogenic pain have warranted great interest among clinical anatomists owing to its sympathetic contribution to the lumbar spine. In healthy individuals, the intervertebral disc is only weakly supplied by primary and sympathetic postganglionic fibres via the SVN. In degenerative disc disease, the increased load leads to an inflammatory reaction and the release of growth factors resulting in increased sprouting of the nerve fibres in the deeper layers of the disc. Previous experimental studies have established a correlation between hyperinnervation of the annulus fibrosus by additional sprouting of the SVN and increased discogenic pain, but the anatomical mechanism is not clearly understood and was inconsistent when reviewing existing literature.
What was done?
Six spine blocks were dissected and thoroughly examined from six embalmed human body donors, three males and three females aged between 59 and 94. Forty-eight levels were dissected and 43 SVN’s in 39 levels were observed (89.6%). Major factors limiting the dissection of all SVN’s were caused by the disruption of the surrounding structures. The author’s dissection and anatomical results were compared to similar literature that used a combination of human body donors, fetuses, embryos, rats and other animals.
What did they find?
The origin of the Sinuvertebral Nerve was always formed by two roots; a somatic root arising from the spinal nerve and sympathetic branch from the rami communicantes. In all the 43 SVN’s segments studied the nerve was close to the interior notch of the vertebral pedicle. The authors conclude that this location could be an effective anatomical landmark for SVN blocking.
Why do these findings matter?
According to some studies, the lumbar intervertebral disk accounts for 39% of chronic low back pain. One possible cause of lumbar discogenic diffuse pain is the lumbar SVP. Reports of significant improvements in low back pain with low complication rates involve blocking the SVN. This treatment is most effective when combined with a clear indication using imaging techniques to identify the best anatomical landmark. A thorough understanding of the anatomy of the SVN might lead to significant benefits in therapy of discogenic low back pain. This study confirms blocking the SVN at the level of the inferior vertebral notch of two adjacent segments may be the most effective landmark.
At Dynamic Disc Designs, we craft realistic models to help clinicians of spine educate patients about the sources (and solutions) of lower back pain.