Role of the sympathetic nervous system in pain

The involvement of the sympathetic nervous system in chronic pain conditions has been well described and recognized for over a century. However, the exact mechanism of the relationship has not been fully explained. In certain chronic pain conditions (e.g. complex regional pain syndrome (CRPS)), the presence of sympathetic signs forms part of the diagnostic criteria.Typical management will involve a multidisciplinary approach, including physical, pharmacological, and psychological therapies. Interventional techniques such as sympathetic blocks can also be used; however evidence of efficacy for many treatments remains poor.