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 your heart, liver, sweat glands, skin, 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 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 problems are temporary and reversible. Others are chronic, or long term, and may continue to worsen over time.
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 depending on the cause, and the effects may be mild to severe. Symptoms such as tremor and muscle weakness may occur due to certain types of autonomic dysfunction.
Orthostatic intolerance is a condition whereby your body is affected by changes in position. An upright position triggers symptoms of dizziness, lightheadedness, nausea, sweating, and fainting. Lying down improves the symptoms. Often this is related to an improper regulation of the ANS.
Orthostatic hypotension is a type of orthostatic intolerance. Orthostatic hypotension occurs when your blood pressure drops significantly as you stand up. This can cause lightheadedness, fainting, and heart palpitations. Injury to nerves from conditions like diabetes and Parkinson’s disease can cause episodes of orthostatic hypotension due to autonomic dysfunction.
Other types of orthostatic intolerance due to autonomic dysfunction include:
- postural orthostatic tachycardia syndrome
- neurocardiogenic syncope or vasovagal syncope
Autonomic dysfunction can vary in symptoms and severity, and they often 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:
Postural orthostatic tachycardia syndrome (POTS)
POTS affects anywhere from 1 to 3 million people in the United States. Nearly five times as many women have this condition compared to men. It can affect children, teenagers and adults. It can be also associated with other clinical conditions such as Ehlers-Danlos syndrome, an inherited condition of abnormal connective tissue.
POTS symptoms can range from mild to severe. Up to one out of four people with POTS have significant limitations in activity and are unable to work due to their condition.
Neurocardiogenic syncope (NCS)
NCS is also known as vasovagal syncope. It’s a common cause of syncope, or fainting. The fainting is a result of a sudden slowing of blood flow to the brain and can be triggered by dehydration, sitting or standing for a long time, warm surroundings and stressful emotions. Individuals often have nausea, sweating, excessive tiredness, and ill feelings before and after an episode.
Multiple system atrophy (MSA)
MSA is a fatal form of autonomic dysfunction. Early on, it has symptoms similar to Parkinson’s disease. But people with this condition usually have a life expectancy of only about 5 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.
Hereditary sensory and autonomic neuropathies (HSAN)
HSAN is a group of related genetic disorders that cause widespread nerve dysfunction in children and adults. The condition can cause an inability to feel pain, temperature changes, and touch. It can also affect a wide variety of body functions. The disorder is classified into four different groups depending on age, inherited patterns, and symptoms.
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. Often it involves both eyes. 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 considered life-threatening. Eye drops and glasses can help correct vision difficulties.
Other types of autonomic dysfunction can result from disease or damage to your body. Autonomic neuropathy refers to damage to nerves from certain medications, injury, or disease. Some diseases causing this neuropathy include:
- uncontrolled high blood pressure
- long-term heavy drinking
- autoimmune disorders
Parkinson’s disease can cause orthostatic hypotension and other symptoms of ANS damage. This often causes significant disability in individuals with this disease.
Your doctor will treat autonomic dysfunction by addressing the symptoms. If an underlying disease is causing the problem, it’s important to get it under control as soon as possible.
Often, orthostatic hypotension can be helped by lifestyle changes and prescription medication. The symptoms of orthostatic hypotension may respond to:
- elevating the head of your bed
- drinking enough fluids
- adding salt to your diet
- wearing compression stockings to prevent blood pooling in your legs
- changing positions slowly
- taking medications like midodrine
Nerve damage is difficult to cure. Physical therapy, walking aids, feeding tubes, and other methods may be necessary to help treat more severe nerve involvement.
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 ANS is often irreversible. 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.