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Dorsal Root Ganglion

What Is It, Where Are They Located, Function, and More

Author: Lily Guo

Editors: Alyssa Haag, Ian Mannarino, MD, Kelsey LaFayette, DNP, ARNP, FNP-C

Illustrator: Jessica Reynolds, MS

Copyeditor: Stacy M. Johnson, LMSW

What is a dorsal root ganglion?

A dorsal root ganglion, also known as a spinal ganglion, refers to the collection of sensory neuron cell bodies that are part of the peripheral nervous system. Sensory neurons are a type of pseudounipolar neuron, defined as a cell body with one short axon that bifurcates into two dendritic processes, with a distal and a proximal end. Sensory neurons transmit sensory information (e.g., fine touch, vibration, pressure, temperature, and pain) from the environment to the central nervous system. Dorsal root ganglia are formed from neural crest cells that arise from the margins of the neural tube during embryonic development.  

Where are dorsal root ganglia located?

Dorsal root ganglia are located near the spinal cord. Each spinal nerve has a pair of dorsal root ganglia lateral to the spinal cord. The posterior, or dorsal, root emerges from the intervertebral neural foramen or the bony opening between two adjacent spinal vertebrae. These nerve roots then converge to form individual dorsal root ganglia. Notably, dorsal root ganglia have fenestrated capillaries and thus are not protected by a tight blood-nerve barrier, which makes them vulnerable to attack. 

What is the function of dorsal root ganglia?

The function of the dorsal root ganglia is to transmit sensory information from the peripheral nervous system to the central nervous system. Specifically, they transmit sensory messages from thermoreceptors (i.e., receptors that convey temperature), nociceptors (i.e., receptors that convey pain), proprioceptors (i.e., receptors that convey position sense), and chemoreceptors (i.e., receptors that convey the pH, CO2, O2 composition in the blood).  

What is the role of the dorsal root ganglia in chronic pain?

The dorsal root ganglia are active in potentiating pain, including chronic pain. The dorsal root ganglia contain many small, unmyelinated, nociceptive C-fiber cells involved in pain reception. The C-fiber cells contain substance P and calcitonin gene-related peptide (CGRP), two substances implicated in inflammation and neuropathic pain. Additionally, pain impulses have been shown to originate in the dorsal root ganglia themselves, making them a good target for the treatment of chronic pain. 

The spinal nerves and the dorsal root ganglia can be affected by traumatic injury, degenerative disc disease, herniated or bulging discs, and other spinal abnormalities resulting in pain. Current methods to reduce neuropathic pain directed at the dorsal root ganglia include radiofrequency ablation (RFA), electrical neurostimulation, and dorsal root ganglionectomy. Radiofrequency ablation is the most common of these three due to its minimally invasive nature. RFA also treats chronic pain in areas that are not easily accessible, such as the lower back and foot. Conversely, ganglionectomy, an irreversible neurosurgical technique, is less effective long-term and can produce pain in other unwanted areas.

What are the most important facts to know about dorsal root ganglia?

The dorsal root ganglia are collections of the cell bodies of sensory neurons located lateral to the spinal cord emerging at each spinal level. They are responsible for conveying various sensory stimuli, including pain, touch, vibration, proprioception, and temperature, from the peripheral nervous system to the central nervous system. The dorsal root ganglia generate chronic pain due to their role in creating and transmitting pain signals. This is particularly common in the event of a herniated disc or injury to the spine. As a result, therapies have been developed that specifically target the dorsal root ganglia, including radiofrequency ablation, neurostimulation, and surgical removal via ganglionectomy. 

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