The autonomic nervous system (ANS) controls several basic functions, including:
- heart rate
- body temperature
- breathing rate
You don’t have to think consciously about these systems for them to work. The ANS provides the connection between your brain and certain body parts, including internal organs. For instance, it connects to the heart, liver, sweat glands, and even the interior muscles of your eye.
The ANS includes the sympathetic autonomic nervous system (SANS) and the parasympathetic autonomic nervous system (PANS). Most organs have nerves from both the sympathetic and parasympathetic systems.
The SANS usually stimulates organs. For example, it increases heart rate and blood pressure when necessary. The PANS usually slows down bodily processes. For example, it reduces heart rate and blood pressure. However, the PANS stimulates digestion and the urinary system and the SANS slows them down.
The main responsibility of the SANS is to trigger emergency responses when necessary. These fight-or-flight responses get you ready to respond to stressful situations. The PANS conserves your energy and restores tissues for ordinary functions.
What is autonomic dysfunction?
Autonomic dysfunction develops when the nerves of the ANS are damaged. This condition is also called autonomic neuropathy or dysautonomia. Autonomic dysfunction can range from mild to life-threatening. It can affect part of the ANS or the entire ANS. Sometimes, the conditions that cause damage are temporary and reversible. Others are chronic and may continue to worsen over time.
Diabetes and Parkinson’s disease are two examples of chronic conditions that can lead to autonomic dysfunction.
Autonomic dysfunction can affect a small part of the ANS or the entire ANS. Some symptoms that may indicate the presence of an autonomic nerve disorder include:
- dizziness and fainting upon standing up, or orthostatic hypotension
- an inability to alter heart rate with exercise, or exercise intolerance
- sweating abnormalities, which could alternate between sweating too much and not sweating enough
- digestive difficulties, such as a loss of appetite, bloating, diarrhea, constipation, or difficulty swallowing
- urinary problems, such as difficulty starting urination, incontinence, and incomplete emptying of the bladder
- sexual problems in men, such as difficulty with ejaculation or maintaining an erection
- sexual problems in women, such as vaginal dryness or difficulty having an orgasm
- vision problems, such as blurry vision or an inability of the pupils to react to light quickly
You can experience any or all of these symptoms, and the effects may be mild to severe.
Orthostatic hypotension and a milder form of it called “orthostatic intolerance” are two of the most common conditions that occur due to autonomic dysfunction. Orthostatic intolerance occurs when your blood pressure drops as you stand up. This can cause lightheadedness, fainting, and heart palpitations.
Symptoms such as tremor and muscle weakness may occur due to certain types of autonomic dysfunction.
Different types of autonomic dysfunction can vary in symptoms and severity, and they can stem from different underlying causes. Certain types of autonomic dysfunction can be very sudden and severe, yet also reversible.
Different types of autonomic dysfunction include:
Multiple system atrophy (MSA)
MSA is a fatal form of autonomic dysfunction. It has symptoms similar to Parkinson’s disease, but has quicker progression. People with this condition usually have a life expectancy of about five to 10 years from their diagnosis. It’s a rare disorder that usually occurs in adults over the age of 40. The cause of MSA is unknown, and no cure or treatment slows the disease.
Postural orthostatic tachycardia syndrome (POTS)
POTS is the most common type of autonomic dysfunction. It can affect both teenagers and adults, and it is often associated with other clinical conditions such as Ehlers-Danlos syndrome. The symptoms can range from mild to severe. People with mild symptoms can typically continue with their daily lives, including going to school or work, and participating in social and recreational activities. Those with more severe symptoms may experience restrictions.
Possible causes for POTS include:
- multiple sclerosis
- mitochondrial diseases
- Lyme Disease
Neurocardiogenic syncope (NCS)
NCS is the most common type of autonomic dysfunction. Some cases of NCS are fairly mild, with people rarely experiencing symptoms. Some symptoms can indicate serious underlying health concerns. A sudden decline in blood flow to the brain triggers fainting. Causes can vary, and injury from NCS can often be as much of a concern as the cause behind it.
Hereditary sensory and autonomic neuropathies (HSAN)
HSAN is a group of related genetic disorders that cause widespread nerve dysfunction in children and young adults. Familial dysautonomia is in this group of diseases. HSAN often begins in infancy. A symptom can be an inability to feel pain, and it can cause a loss of feeling. A genetic mutation causes it.
Holmes-Adie syndrome (HAS)
HAS mostly affects the nerves controlling the muscles of the eye, causing vision problems. One pupil will likely be larger than the other, and it will constrict slowly in bright light. Deep tendon reflexes, like those in the Achilles tendon, may also be absent. HAS may occur due to a viral infection that causes inflammation and damages neurons. The loss of deep tendon reflexes is permanent, but HAN isn’t life-threatening or severely disabling.
Other types of autonomic dysfunction can result from disease or damage to the body. Autonomic neuropathy refers to damage to nerves from certain medications, injury, or disease. Diseases causing this neuropathy include:
- bacterial infection
- long-term heavy drinking
- autoimmune disorders
Parkinson’s disease causes orthostatic hypotension and other symptoms of ANS damage.
Your doctor will treat autonomic dysfunction by addressing the symptoms. They can treat orthostatic hypotension by suggesting lifestyle changes and prescribing medication. The symptoms of orthostatic hypotension can respond to:
- elevating the head of your bed
- drinking enough fluids
- wearing compression stockings to prevent blood pooling in your legs
- taking medications like midodrine
Your doctor will also treat the underlying cause such as alcohol use disorder, diabetes, or Parkinson’s This may help slow the progression of autonomic dysfunction. Nerve damage is difficult to cure. Physical therapy, walking aides, feeding tubes, and other methods may be necessary to help treat more severe symptoms.
Finding support to help you cope with autonomic dysfunction can be just as important for improving quality of life as managing physical symptoms.
Methods for coping and improving quality of life include the following:
- Depression can occur with autonomic dysfunction. Therapy with a qualified counselor, therapist, or psychologist can help you cope.
- Ask your doctor or therapist about support groups in your area. They’re available for different conditions.
- You may find that you have more limitations than before your diagnosis. Set priorities to help you make sure you’re doing the things that are important to you.
- Accept help and support from family and friends if you need it.
- Ask for help if you need it.
Damage to the nerves of the autonomic system is often irreversible. However, people with some conditions such as Guillain-Barré syndrome may have significant recovery. Talk to your doctor if you have any symptoms of autonomic dysfunction. Early diagnosis and treatment of the underlying condition can help slow the progression of the disease and lessen symptoms. This can improve your quality of life regardless of the severity of the condition.