Autonomic neuropathy is damage to the nerves that control automatic body functions, and the reason it goes unrecognized for years is that its symptoms arrive dressed as organ problems. Lightheadedness on standing, feeling full after a few bites, sweating that has changed, bladder trouble, and pupils that are slow to adjust between light and dark are all documented autonomic symptoms [1]. Each one usually gets referred to a different specialist before anyone asks whether one set of nerves connects them.
The nerves involved regulate heart rate and blood pressure, digestion, bladder and sexual function, sweating and temperature control, and pupil response [1]. When those signals fail, the body looks like it is having several unrelated problems at once.
Why the pattern gets filed under other organs
Autonomic symptoms are scattered by design. The autonomic nervous system reaches nearly every organ, so damage to it produces complaints in nearly every clinic, and each complaint is plausible on its own terms.
That is the mechanism behind the long delay to diagnosis. The symptoms are not vague, they are distributed — and distributed symptoms get split up rather than added together.
Lightheadedness or fainting when you stand
Nerve damage may cause you to feel light-headed or faint when you stand up or during physical activity, and it can also cause a rapid heart rate or sudden changes in heart rate [1]. In some people it prevents the chest pain that would normally signal a heart problem [1].
Why it is usually blamed on dehydration
Orthostatic symptoms look like low blood volume or a blood pressure medication effect, and sometimes they are. When the pattern keeps returning after fluids and medication adjustments, that is the point to ask whether the reflex itself is intact.
Digestion that changes without a structural cause
Autonomic damage can cause bloating, fullness and nausea, constipation, vomiting, and diarrhea that is often worse at night [1]. It may also cause gastroparesis, which slows or stops the movement of food from the stomach into the small intestine [1].
Why the workup usually starts elsewhere
Reflux care, irritable bowel pathways and gallbladder imaging are reasonable first moves, and they are what most people get. They are also why the nerve driver often waits years for its turn, particularly in someone whose feet were the only thing anyone connected to neuropathy.
Losing the low-blood-sugar warning
Hypoglycemia unawareness means you do not feel the symptoms of low blood glucose, which can allow an episode to become severe before it is recognized [1]. This is a safety problem, not just a comfort problem.
The shakiness and sweating that normally announce a low are themselves autonomic signals. When that circuitry is damaged, the alarm is quiet even though the emergency is real.
Sweating and temperature control
Autonomic damage may cause excessive sweating at night or while eating, or sweat glands may not work at all, which prevents the body from controlling its temperature properly [1].
Patients commonly describe this as hot flashes, a medication side effect or skin sensitivity. The timing of the sweating, and whether it appears alongside the other symptoms on this page, is what separates the explanations.
Pupils that adjust slowly, and trouble driving at night
Nerve damage may make the pupils slow to respond to changes in light and darkness, which causes difficulty adjusting in dark rooms and difficulty with oncoming headlights while driving at night [1].
This is nearly always taken to an eye clinic first, and the vision complaint is genuine. The driver behind it, in this case, is neurologic.
Bladder and sexual function
Nerve damage may make it hard to know when the bladder needs emptying and when it is empty, which can lead to holding urine too long and to infections, or to incontinence [1]. In men it can prevent erection and cause ejaculation problems; in women it can reduce lubrication, sensation and the ability to reach orgasm [1].
When screening is recommended
The American Diabetes Association position statement on diabetic neuropathy advises that all patients be assessed for distal symmetric polyneuropathy starting at diagnosis of type 2 diabetes and five years after the diagnosis of type 1 diabetes, and at least annually thereafter [2]. It further advises that symptoms and signs of autonomic neuropathy be assessed in patients who have microvascular and neuropathic complications [2].
If you already have neuropathy in your feet and any of the symptoms above, that guidance places you squarely in the group that should be asked about autonomic function rather than waiting for it to be volunteered.
What we do with the pattern
Neuropathy is a category, not a diagnosis. We work to identify the specific driver — metabolic, nutritional, autoimmune, toxic or structural — because the driver decides what the plan should be. Our approach to the drivers that most often get missed is described in the hidden drivers of peripheral neuropathy.
What testing adds, and what it does not
We perform electrodiagnostic testing (EMG and nerve conduction studies) on site. Those studies evaluate peripheral nerve function; they do not measure autonomic function, so they narrow the question rather than answer it.
Where dizziness needs sorting out, we use VNG (videonystagmography), a diagnostic test of inner-ear balance function. VNG is a test only — it tells us whether the inner ear is contributing to your dizziness, and it does not treat anything.
What comes before treatment
The first work is history and pattern mapping: when the symptoms occur, what triggers them, and what your diabetes, alcohol, medication and nutritional history looks like. Bring that timeline to the visit. It is the most useful thing you can bring, and it is the part no test can supply.
Frequently asked questions
How is autonomic neuropathy different from the neuropathy in my feet?
The neuropathy most people know about affects sensation in the feet and hands — burning, numbness, pins and needles. Autonomic neuropathy affects the nerves that run the body automatically: blood pressure on standing, stomach emptying, bladder emptying, sweating and pupil response [1]. The two often travel together in the same person. See peripheral neuropathy of the feet, symptoms and patterns.
Why do these symptoms get blamed on something else for so long?
Because each one lands in a different specialty. Lightheadedness on standing looks cardiac, early fullness and nausea look gastrointestinal, and slow pupil adjustment looks ophthalmic, so the shared nerve driver is rarely the first thing anyone tests for. Small nerve fibers carry much of this traffic — see small fiber neuropathy symptoms and testing.
When should someone with diabetes be screened?
The American Diabetes Association position statement advises assessing all patients for distal symmetric polyneuropathy starting at diagnosis of type 2 diabetes and five years after diagnosis of type 1 diabetes, and at least annually thereafter, and assessing symptoms and signs of autonomic neuropathy in patients who have microvascular and neuropathic complications [2]. Our evaluation when diabetes is the driver is described on our diabetic peripheral neuropathy treatment page.
What if I do not have diabetes and no one can find a cause?
Autonomic symptoms still need a driver, and idiopathic usually means the driver has not been identified yet. Nutritional deficiency is one of the categories worth ruling in or out before the label sticks — see functional B12 deficiency and neuropathy.
What testing does Regenerve perform on site?
We perform electrodiagnostic testing (EMG and nerve conduction studies) on site, and we use VNG (videonystagmography) as a diagnostic test of inner-ear balance function when dizziness needs to be sorted out. VNG is a test, not a treatment. The full list is on our neuropathy services page.
Start with the Nerve Damage Score
The Nerve Damage Score is a free five-question assessment that helps identify which driver is most likely behind your symptoms, so your evaluation starts with a direction instead of a guess.
Regenerve, 4477 Woodson Rd #104, St. Louis, MO 63134. Serving the St. Louis region, Missouri and Illinois, minutes from St. Louis Lambert International Airport.
Sources
- National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), National Institutes of Health. “Autonomic Neuropathy.” Last reviewed February 2018. https://www.niddk.nih.gov/health-information/diabetes/overview/preventing-problems/nerve-damage-diabetic-neuropathies/autonomic-neuropathy — cited for the cardiovascular symptoms (lightheadedness or faintness on standing, rapid or sudden changes in heart rate, absent chest pain), the digestive symptoms and gastroparesis, hypoglycemia unawareness, sweating and temperature-control changes, bladder and sexual dysfunction, and the slow pupil response and night-driving difficulty.
- Pop-Busui R, Boulton AJM, Feldman EL, Bril V, Freeman R, Malik RA, Sosenko JM, Ziegler D. “Diabetic Neuropathy: A Position Statement by the American Diabetes Association.” Diabetes Care, 2017;40(1):136–154. DOI: 10.2337/dc16-2042. https://pmc.ncbi.nlm.nih.gov/articles/PMC6977405/ — cited for the recommendation to assess all patients for distal symmetric polyneuropathy starting at diagnosis of type 2 diabetes and five years after diagnosis of type 1 diabetes and at least annually thereafter, and to assess symptoms and signs of autonomic neuropathy in patients with microvascular and neuropathic complications.