European journal of anaesthesiology
-
Review
Systemic and specific autonomic reactions in pain: efferent, afferent and endocrine components.
The sympathetic nervous system is hierarchically organized. At the bottom of this organization are the sympathetic pre-post-ganglionic channels which supply the autonomic target organs, at the top the hypothalamus and cortical structures. Each level of this hierarchy contains neuronal programmes which govern the sympathetic activity in a patterned fashion. ⋯ No conclusive experimental evidence exists to show that peripheral nociceptors are controlled by activity in sympathetic post-ganglionic neurones. In certain pathophysiological situations, however, it may happen that activity in sympathetic post-ganglionic neurones, which supply an extremity, leads to excitation of afferent axons, thus establishing a vicious circle between primary afferent neurones, spinal cord and sympathetic outflow. This situation may occur after partial lesions of peripheral nerves in a syndrome which is called 'reflex sympathetic dystrophy'.