Scarpa's Ganglion Compared to Dorsal Root Ganglion?
In the peripheral vestibular system, Scarpa's Ganglion have a baseline firing rate of 100 spikes/second making the objective findings from a lesion possible. Both Scarpa's Ganglion oppose one another (there is one on the right and left). They play tug of war. When one becomes irritated, it pulls harder than the other and when one becomes inhibited, it "let's go" of the rope. This is the mechanism behind the fast and slow phases of nystagmus.
The question I have is do the ganglion in pain fibers have a baseline firing rate that would allow us to somehow find an objective signal that would allow us to "see" pain?
After a quick PubMed search, I found a quote by Krame's that has spiked my curiosity into this matter: "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."1
Perhaps a decrease in pain following stimulation to the dorsal root ganglion is as objective as we can get?
Krames ES. The dorsal root ganglion in chronic pain and as a target for neuromodulation: a review. Neuromodulation. 2015;18(1):24‐32. doi:10.1111/ner.12247