Sympathetic microneurography.

The sympathetic nervous system plays important roles in the beat-to-beat control of blood pressure, the control of blood flow through various organs and the maintenance of core temperature through thermoregulatory processes. The development of microneurography, in which nerve activity can be recorded directly from intraneural microelectrodes inserted percutaneously into a peripheral nerve in awake human subjects, has provided a wealth of information on the control of sympathetic outflow to muscle and skin. Although not intended to be diagnostic, recordings of muscle sympathetic nerve activity (MSNA) and skin sympathetic nerve activity (SSNA) in different disease states have increased our understanding of the operation of the sympathetic nervous system. And while quantification of sympathetic nerve activity is still largely limited to measures of burst frequency (bursts/minute) and burst incidence (bursts/100 heart beats), the development of single-unit recordings of MSNA and SSNA have provided more detailed information on how the sympathetic nervous system grades its output. This chapter reviews the development of sympathetic microneurography and its application in health and disease.