Neuroplasticity and chronic pain
Neuroplasticity is a term that often pops up in discussions about rehabilitation and usually in the context of being a positive "thing" associated with the potential for recovery of function. However, neuroplasticity can "go wrong" and at least that seems to be the case with chronic pain.
Chronic pain is thought to represent an undesirable adaptation of the nervous system to repeated stimulation. In other words, over time, the stimulation produces changes in the nervous system itself. Unfortunately, If we want to understand how chronic pain develops and what to do about it, we really need to understand the interactions between three aspects of the nervous system.
- The central nervous system
- The peripheral nervous system
- The autonomic nervous system
Often chronic pain develops from repeated stimulation and inflamation at a peripheral body site. As this stimulation persists, a neuroplastic response is generated at the cortical level leading to changes in somatotopic organisation (the link between the body part and the area of the brain responsible for its motor function) including central sensitisation.
In his book "The Brain that Changes Itself", Norman Doidge speculated that when a body part is lost, the brain seeks stimulation and releases sprouts to grow and develop looking for nerves or sites in the brain that are similar in type to those lost. Sometimes this results in a mixing of nerve impulses. Doidge also suggested that these neuroplastic factors might be involved in the development of chronic pain.
Research has shown that individuals experiencing Complex Regional Pain Syndrome in a hand demonstrate a diminished cortical somatotopic representation of the hand contralaterally as well as a descreased spacing between the representation of the hand and the mouth in the somatosensory cortex. Similar results have been noted in phantom limb pain, low back pain and carpal tunnel syndrome.
The peripheral nervous system also appears to be involved with neuroplasticity. The peripheral nerves respond to repeated stimulation with dendrites that grow in diameter and length whilst their axons spread the field of innervation. Some research suggests that peripheral nerve injury induces a cascade of events at the systemic, cellular and molecular levels - progressing throughout the spinal cord to the brainstem relay nuclei, thalamus and cortex.
Often, health care providers are trained to consider only one aspect othe nervous system and tend to produce short-term results. Biofeedback techniques offer this type of scenario a unique, multi-modal approach, which can impact upon the functioning of all three parts of the nervous system. No other approach offers this ability.