The dorsal root ganglion in chronic pain and as a target for neuromodulation: a review.

BACKGROUND: In the not-too-distant past, the dorsal root ganglion (DRG) was portrayed as a passive neural structure without involvement in the development or maintenance of chronic neuropathic pain (NP). The DRG was thought of as a structure that merely "supported" physiologic communication between the peripheral nervous system (PNS) and the central nervous system (CNS). Newer scientific information regarding the anatomic and physiologic changes that occur within the DRG as a result of environmental pressures has dispelled this concept and suggests that the DRG is an active participant in the development of NP. This new information, along with new clinical data showing that stimulation of the DRG reduces intensity of pain, suggests that the DRG can be a robust target for neuromodulation therapies.

METHODS: A review of the anatomical and physiological literature regarding the role of the DRG in the development of NP was performed utilizing SciBase, PubMed, and Google Scholar. The information gathered was used to lay an anatomic and physiologic foundation for establishing the DRG as a relevant target for neuromodulation therapies and to formulate a hypothesis as to how electrical stimulation of the DRG might reverse the process and perception of NP.

CONCLUSIONS: The DRG is an active participant in the development of NP. DRG stimulation has multiple effects on the abnormal changes that occur within the DRG as a result of peripheral afferent fiber injury. The sum total of these stimulation effects is to stabilize and decrease hyperexcitability of DRG neurons and thereby decrease NP.