Dr. Louis H. Weimer responds:

Autonomic neuropathy involves damage to certain nerves that run through the peripheral nervous system. Peripheral nerves transmit electrical signals from the brain and spinal cord to and from the rest of the body. Each nerve fiber serves a dedicated function: motor nerves control movement; sensory nerves control physical sensation; and autonomic nerves transmit signals for the "automatic" functions, such as heart rate and blood pressure, which require no conscious control.

Because autonomic nerves help control virtually every organ in the body, the symptoms of autonomic neuropathy can be highly varied and widespread. Common complaints include dry eyes and mouth, reduced or excessive sweating, bloating, nausea, or episodes of diarrhea. Autonomic functions decline to some degree with normal aging.

Autonomic neuropathy can worsen, improve, or continue unchanged depending on the severity and progression of the underlying cause. The most common cause is diabetes. Severe cases of autonomic neuropathy can result from autoimmune or bone marrow disorders, certain toxins and medications, and rare genetic conditions. In some cases, no cause can be identified.

Some degree of autonomic neuropathy occurs in the majority of neuropathy cases. Patients with neuropathy affecting their sensory nerves typically have more severe foot and lower leg involvement; the condition is often aggravated by additional autonomic impairment in affected areas—for example, coldness, loss of sweating and hair, and susceptibility to foot ulcers.