The autonomic medical history

Abstract

The most important autonomic function test-the autonomic medical history-is the patient's account, interpreted by a clinician skilled in asking the right questions, of symptoms during daily activities that relate to the autonomic nervous system. The chronology and pattern of these symptoms combine to create a portrait of autonomic function or dysfunction. We summarize the steps in obtaining a comprehensive autonomic medical history.

Keywords: Autonomic; Cholinergic; Noradrenergic; Parasympathetic; Sympathetic.

Figure 1:. Key elements of the autonomic medical history.

These include the Chief Complaint, the History of the Present Illness, and questions related to components of the autonomic nervous system.

Figure 2:. Components of the autonomic nervous system (ANS).

Langley’s ANS consists of the enteric nervous system (ENS), parasympathetic nervous system (PNS), and sympathetic nervous system. The sympathetic nervous system can be sub-classified based on the main chemical messenger, into the sympathetic noradrenergic system (SNS), the sympathetic adrenergic system (SAS), and the sympathetic cholinergic system (SCS). The SNS chemical messenger is norepinephrine (NE), the SAS messenger epinephrine (EPI), and the SCS messenger acetylcholine (ACh).

Figure 3:. Overview of the organization of the ANS.

At all ganglia and adrenomedullary chromaffin cells ACh mediates signaling via neuronal nicotinic receptors (+N). Post-ganglionic ACh receptors are muscarinic (+M). Parasympathetic nerves include the vagus nerve (the tenth cranial nerve) and pelvic nerves (although this has been disputed recently). Sympathetic nerves mainly consist of post-ganglionic, non-myelinated fibers, whereas parasympathetic nerves mainly consist of pre-ganglionic, myelinated fibers.