Perspectives of Treatment of Low Back Pain
Authors: Takahashi Kazuhisa , Ohtori Seiji 
Published: May 2014

Recent advances in basic research on intervertebral disc have revealed the unique innervation pattern and the pathological changes related to generation of low back pain. In this presentation, we will review the results obtained mainly at author's institution and to discuss the future treatment of discogenic low back pain.

The intervertebral disc has been confirmed as a pain source in early 20th century by stimulation of the annulus fibrosus during posterior spine surgery under local anesthesia.1,2 In 1970, Shinohara3 reported the presence of nerve fibers in the deep layers of the annulus fibrosus of the degenerated disc, which was obtained during anterior decompression and interbody fusion surgery in patients with painful lumbar disc. Groen et al4 studied the anatomy of nerves and nerve plexuses in the human fetus with acetylcholinesterase whole-mount method. Groen reported that the vertebral column is surrounded by ventral and dorsal nerve plexuses which are interconnected. In 1993, Takahashi et al5 demonstrated that the rat L5-L6 disc was innervated by the upper L2 dorsal root ganglion (DRG) neurons. In 1997, Freemont et al6 reported nerve ingrowth into diseased intervertebral disc in patients with chronic back pain. Thereafter, Ohtori et al7 showed that the sensory fibers from T13, L1, and L2 DRGs innervated the dorsal portion of the L5-L6 disc through the paravertebral sympathetic trunks, whereas those from L3-L5 DRGs may innervate the disc through the sinuvertebral nerves in rats. In 2004, Aoki et al8 reported that nerve growth factor (NGF)-sensitive neurons are predominant in the rat intervertebral disc. On the contrary, there are very few glial cell line-derived neurotrophic factor-sensitive neurons in the rat disc, indicating that discogenic pain can be related to inflammatory pain rather than neuropathic pain. In 2009, Yamauchi et al9 cocultured DRG cells from newborn Wistar rats with conditioned medium of nucleus pulposus or annulus fibrosus cells obtained from patients with discogenic low back pain, and the average length of the axons from the DRG neurons was measured. She reported NGF of cultured medium from human degenerative nucleus pulposus promoted sensory nerve growth in vitro. In 2012, Miyagi et al10 reported that disc dynamic compression in rats produces long-lasting increases in inflammatory mediators (NGF, TNF-α, interleukin-1β, interleukin-6) in discs and induces long-lasting nerve injury and regeneration of the afferent fibers innervating discs using rats. Tumor necrosis factor α (TNF-α) has been reported as a pain-related proinflammatory mediator in the degenerative intervertebral disc. Sainoh et al11 reported a prospective randomized study in which bupivacaine 2 mL with etanercept 10 mg was administered intradiscally in 30 patients with discogenic low back pain (etanercept group) and bupivacaine 2 mL was administered into the disc in other 30 patients (control group). Visual analog scale and Oswestry Disability Index were used for evaluation. He reported that intradiscal administration of 10-mg etanercept significantly improved the clinical outcomes of the patients with discogenic low back pain after 4 weeks without any adverse events.

At present, majority of low back pain were classified into nonspecific low back pain. However, to improve our treatment of patients with low back pain, we have to know the exact pathophysiology. We believe the basic and the clinical researches will surely open a new horizon in the treatment of patients with low back pain.

Disclosure of Interest

None declared

References

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