The idea that sympathetic pain exists is based on clinical findings seen in a small subset of patients suffering from neuropathic pain. Sympathetic pains occurs when the pain is clearly dependent on activity in the sympathetic nervous system. This is often referred to the ‘sympathetically maintained pains.’
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Silas Weir Mitchell, who lived from 1830 to 1914, was the first to describe sympathetically maintained pains. During the Civil War, he studied nerve injuries. He described these pathological states and causalgia.
Sympathetic pains are classified into three groups:
- Various Autonomic Dysfunctions
- NPP with sympathetic activation
- Complex Regional Pain Syndrome
Autonomic dysfunctions develop when certain Autonomic Nervous System (ANS) nerves are damaged. There are multiple types of the dysfunctions. Once common type is Raynaud’s Disease.
Raynaud’s Disease is characterized by constriction of the blood vessels. It can be caused or provoked by exposure to cold or extreme emotional stress.
Related Reading: Does Emotional Approach Coping Ease Chronic Pain?
Complex Neuropathic Pain
Complex Neuropathic Pain (NPP with sympathetic activation) occurs when the pain is clearly aggravated by the sympathetic nervous system. For example, stress makes the pain more severe, and there is an enhanced vasoconstriction reaction associated with the
pain. Complex NPP is sometimes described as sympathetic maintained pain and is distinguished from CRPS in that SMP is not as severe and does not meet all of the criteria for CRPS-I or CRPS-II.
Related Reading: RGS4 Protein May Help Play a Role in Chronic Pain Maintenance
Complex Regional Pain Syndrome
There are two types of Complex Regional Pain Syndrome. The first is called Reflex Sympathetic Dystrophy (CRPS – I), commonly caused by an innocuous injury. The symptoms vary in duration and can develop over weeks or months. Sometimes, no symptoms can be identified. In CRPS – I, genetic predisposition is likely.
The second type is Causalgia (CRPS – II). This is caused by a clearcut nerve trunk injury. The onset of symptoms is immediate and obvious after the injury. The symptoms in CRPS – II are more severe than the symptoms of CRPS – I. Genetic predisposition is likely.
Related Reading: Understanding Complex Regional Pain Syndrome (CRPS)
Clinical Features of Sympathetic Pains
- Allodynia (vibrational or thermal)
- Disproportionate pain to injury
- Periphery pain that spreads centrally
- Contralateral side involvement
- Color changes in affected limbs
- Sweating in affected limbs
- Cold periphery with vasoconstriction in affected limbs
Related Reading: Does Self-Compassion Help with Chronic Pain Management?
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