4.3 Conditions and Disease of the ANS

As you have just learned, the autonomic nervous system regulates vital functions of our internal organs, such as heart rate, blood pressure, digestion, water balance, urinary excretion, and body temperature. Individuals with an autonomic disorder have trouble regulating one or more of these systems, which can result in fainting, lightheadedness, fluctuating blood pressure, and other symptoms.^[1]

Autonomic nervous system disorders can occur alone or as the result of another disease, such as Parkinson’s disease, cancer, autoimmune diseases, alcohol abuse, or diabetes.

A common autonomic nervous system condition you may see in practice is orthostatic hypotension.

Orthostatic Hypotension

Orthostatic hypotension refers to a drop in blood pressure upon standing (after a prolonged period of sitting or lying).  This can occur when autonomic reflexes are impaired or intravascular volume is markedly depleted. Failure of autonomic reflexes leading to hypotension is specifically knowns as baroreflex dysfunction.  In baroreflex dysfunction, an individual’s neurons do not release appropriate levels of the hormone norepinephrine, causing poor vasoconstriction.  In these clients, blood pressure drops after standing because the pooling of blood in the legs cannot be compensated by vasoconstriction. ^[2]

Orthostatic hypotension can be asymptomatic or symptomatic.

Symptoms can include: dizziness, lightheadedness, syncope, muscle ache in the neck and shoulders, and even angina.^[3]

Other ANS Conditions and Disorders

Due to the limited scope of this textbook, we will not be discussing other ANS disorders as they are extremely rare.  If you are interested in ANS dysfunction, consider reviewing resources on the following disorders:

• postprandial hypotension
• multiple system atrophy
• pure autonomic failure
• familial dysautonomia

ANS regulation is also closely linked to other concepts, such as Perfusion, Cognition and Central Nervous System Regulation. These concepts and their related medications are discussed in later chapters.