WHAT CAUSES AUTONOMIC NEUROPATHY?

LOTS of things can cause autonomic neuropathy: genetic diseases, infections, vitamin deficiencies, toxic exposures, autoimmune diseases and more.

In my case, an autoimmune disease called Sjogren's Syndrome has caused my autonomic neuropathy, which has caused POTS.  I had many, many tests looking for the cause of my neuropathy before my doctors figured out that I had Sjogren's.

If you suspect you have autonomic neuropathy, you should seek the advice of a neurologist, preferably one with experience in autonomic disorders.  It may take a long time and you may have to go through lots of testing, but in my opinion it is worth it if you can find the underlying cause, especially because many of the things that cause neuropathy are treatable.  If you can treat the underlying cause of your neuropathy, you may be able to get rid of your POTS symptoms entirely.  Wouldn't that be great?

When you are reading about autonomic neuropathy and the causes of it, keep an eye out for information on peripheral neuropathy and small fiber neuropathy too.  These are broader classes of neuropathy, but both include autonomic neuropathy.  As a rule of thumb, most things that can cause peripheral or small fiber neuropathy can cause autonomic neuropathy too.

Here are some good resources that discuss the causes of peripheral, small fiber and/or autonomic neuropathy:

-Therapath, a neurology lab, explains some of the causes of small fiber neuropathy and the tests that can be performed to confirm or rule out these causes;

-Cleveland Clinic journal article;

-American Family Physician journal, which contains a VERY long list of things that cause small fiber neuropathy;

 -Quest Diagnostics has a list of tests that they offer to evaluate patients for small fiber neuropathy.

WHAT IS AUTONOMIC NEUROPATHY?

Neuropathy is any damage or destruction of nerve cells.  Autonomic neuropathy is damage or destruction of nerve cells that are part of the Autonomic Nervous System (ANS).

To understand autonomic neuropathy and how it impacts the body, we need a basic understanding of the ANS.  The ANS is responsible for monitoring conditions inside the body and then regulating various parts of the body to maintain appropriate conditions.  For example, the ANS regulates body temperature.  If the ANS detects that the body is too cold, it sends out messages to other parts of the body that help increase body temperate.

The ANS regulates the involuntary functions of the body - those that occur without us having to think about it: heart rate, digestion, blood pressure regulation, pupil dilation/constriction, urination, salivation and sweating to name a few.  The ANS also plays a large role in regulating respiration, but we can exert some voluntary control over our breathing.

The ANS contains two parts, the Sympathetic Nervous System (SNS) and the Parasympathetic Nervous System (PNS).  A good way to remember the difference between the two parts of the ANS is to think of the Sympathetic Nervous System as the "fight or flight" or excitable part of the ANS and the Parasympathetic Nervous System as the "rest and digest" or calming part of the ANS.  

When autonomic neuropathy occurs, the bodies ability to properly regulate the functions of the ANS is impaired.  The level of impairment depends on the severity of the autonomic neuropathy, and also which autonomic nerves are damaged.

For example, autonomic nerves that run along the small veins in your legs help control your blood pressure by constricting your veins when you change positions from laying to sitting to standing - to help counter the effects of gravity on your blood.  If those autonomic nerves are damaged, your veins won't be able to constrict very well.  Gravity will naturally pull your blood downwards to your lower legs and feet, and thus your body would have trouble regulating your blood pressure when you stand up.  This is called orthostatic intolerance, and it is common in people with autonomic neuropathy in their lower legs. This is common in POTS.  

Autonomic nerves are also regulate the movement of food along your gastrointestinal tract from your mouth to your intestines and out your rear end.  When the autonomic nerves that control your digestion (sometimes called your enteric nervous system) are damaged, that can cause gastroparesis or bowel dysmotolity.  This can result in pain, cramping, bloating, diarrhea, constipation and difficulty absorbing vitamins and nutrients.  This is also fairly common in POTS.

Autonomic nerves are also in your bladder and help control your ability to hold urine and excrete it in a controlled manner.  If your autonomic nerves controlling your bladder are damaged, you can have problems retaining too much urine in your bladder, which can lead to painful infections and even kidney damage.  Some people with "urogenic bladder" as doctors call it, can also loose their ability to hold in their urine, thus they become incontinent.  This is not common in POTS and could be a sign of a more serious problem.

Just because you have autonomic neuropathy in one area of the body, does not mean you will have it everywhere.  Some people have a limited or restricted autonomic neuropathy - often confied to the lower extremities and/or the GI tract.  This is fairly common in POTS.  Other people have more widespread autonomic neuropathy.

Now that we have the basics down on what autonomic neuropathy can to the body, let's talk about WHAT CAUSES AUTONOMIC NEUROPATHY?