Dysautonomia: A Faulty Nervous System

Dysautonomia
Dysautonomia

Chances are, you don’t have to tell your body at what rate to digest the food you consume, what your optimal heart rate should be, or when to breathe in oxygen. These simple functions occur automatically without thinking because of the autonomic nervous system. Occasionally, however, the autonomic nervous system is faulty—resulting in a condition known as Dysautonomia.

Dysautonomia: The Autonomic Nervous System

The autonomic nervous system is the involuntary part of the nervous system. It receives signals from the hypothalamus—the area of the brain that links the nervous system to the endocrine system.

A variety of neurons and autonomic nerves comprise the three branches of the autonomic nervous system: the sympathetic, parasympathetic, and enteric nervous systems. Each facilitates the following bodily functions an organism has little conscious awareness of.

  • Respiration
  • Heart rate
  • Blood pressure
  • Digestion
  • Reflex actions (i.e. coughing, sneezing, vomiting, swallowing)
  • Sexual arousal
  • Pupillary response
  • Urination

Dysautonomia:Sympathetic Nervous System

The sympathetic division of the autonomic nervous system is designed to initiate physiological changes in response to stress—also known as the “fight or flight” mechanism. Experts describe its role as priming the body for action with its influence over every organ system. It is always functioning, as the sympathetic nervous system is the primary component to maintain homeostasis.

Dysautonomia
Dysautonomia

As the sympathetic nervous system is activated, heart rate accelerates, blood pressure increases, bronchial passages widen, blood vessels constrict, pupils dilate, and bowel motility is decreased. This prepares the body for stressful behaviors or situations.

Dysautonomia: Parasympathetic Nervous System

The parasympathetic nervous system controls organ and gland activities that occur when the body is at rest. Its nicknames are “rest and digest” and “feed and breed” because the parasympathetic nervous system is imperative to speed up the gastrointestinal tract, spur sexual arousal, and dominates the functions of urination, defecation, and lacrimation (tear production).

The parasympathetic nervous system tempers the heightened activities the body undergoes while in a state of stress. When not on alert, there is time to resume normal function. Digestion increases, bladder and bronchial muscles contract, and pupils constrict. It has a calming effect, so the heart rate decreases.

Dysautonomia:The Enteric Nervous System

The enteric nervous system is a complex division of the autonomic nervous system that controls the digestive tract. It is located in the lining of the gastrointestinal tract from the esophagus, stomach, small intestine, large intestine, rectum, and anus, and is comprised of millions of neurons which allow it to function independently of the brain and spinal cord.

Two networks of neurons—the myenteric plexus and submucous plexus— regulate peristalsis (intestinal contractions) to move food and secretions along the gastrointestinal tract, as well as to regulate blood flow. Neurons also control the secretion of digestive enzymes. A large portion of neurotransmitters lie in the enteric nervous system, including over 90% of the body’s serotonin.

What is Dysautonomia?

Dysautonomia or autonomic dysfunction is a disorder characterized by the malfunctioning of the autonomic nervous system. An estimated 70 million people worldwide suffer from the condition. In general, Dysautonomia is the failure of the sympathetic and parasympathetic branches. However, it is possible for an overactive system to occur. Since the autonomic nervous system controls all of the “automatic” functions of the body, the effects of dysautonomia are widespread.

Symptoms of Dysautonomia

Imagine someone constantly flipping the on/off switch in your body. That analogy is equivalent to the effects of dysautonomia. The symptoms tend to range from one extreme to the other. Symptoms do differ by type and severity, but most patients with dysautonomia present with a standard set of maladies in a variety of organ systems. 

Cardiac

  • Tachycardia—heart rate above 100 beats per minute
  • Bradycardia—heart rate below the normal 60 beats per minute
  • Hypotension—low blood pressure 90/60
  • Hypertensionhigh blood pressure
  • Orthostatic intolerance—a sudden drop of blood pressure caused by a change in posture (i.e. from laying to sitting, sitting to standing)
  • Syncope—temporary loss of consciousness or fainting caused when the heart does not pump sufficient oxygen to the brain
  • Presyncope—“blacking out” and a feeling of lightheadedness without losing consciousness
  • Dizziness—rhythm abnormalities and alterations in blood pressure  are characterized by dizziness, feeling woozy, faint, or imbalanced
  • Blood pooling—poor circulation in which blood accumulates in the extremities rather than being pumped back upwards towards the brain
  • Cold or heat intolerance—cardiovascular symptoms are made worse by the dilation or constriction of blood vessels from temperature changes

Gastrointestinal

  • Diarrhea—watery, loose stools three or more times daily
  • Constipation—fewer bowel movements than usual
  • Abdominal pain
  • Gastroparesis—delayed emptying of the stomach after consuming a meal, typically leading to nausea, vomiting, bloating, and early satiety
  • Dysphagia—difficulty swallowing with signs that include the sensation of food being stuck in chest, choking during eating or drinking, and chest pain
  • Nausea
  • Vomiting
  • Reflux—the regurgitation of food, heartburn, and indigestion

Neurological

  • Insomniaa sleep disorder causing trouble falling asleep, difficulty staying asleep, and frequent waking throughout the night
  • Headaches
  • Seizures—An uncontrolled electrical disturbance in the brain that can produce abnormal movements and behaviors
  • Sensitivity to stimuli—including light, sound, smell, and touch
  • Unevenly dilated eyes
  • Blurry vision
  • “Brain fog”—cognitive dysfunction resulting in memory problems, confusion, and mental cloudiness
  • Tremors—involuntary movement of the muscles
  • Aphasiadifficulty understanding and forming speech

Endocrine

  • Hypoglycemia—the autonomic nervous system controls insulin release from the pancreas. If too much insulin is released, blood glucose, which is the body’s energy source, is too low.
  • Hyperglycemia—blood sugar is higher than normal because insulin is produced.  
  • Salt craving—craving salt is a hallmark sign of rising stress levels, especially in the case of secondary adrenal insufficiency    
  • Weight fluctuations—Weight gain and weight loss regardless of caloric intake and exercise are both prevalent in people with dysautonomia.

Other

  • Fatigue—an overwhelming sense of exhaustion without overexertion
  • Increased or decreased sweating—The autonomic nervous system induces sweating to cool the body or as a response to fear or stress. Excessive or reduced sweating can emerge independent of environmental temperature.
  • Hyperventilation—breathing very quickly, exhaling more than inhaling
  • Involuntary breath holding—holding breath without realizing it
  • AnxietyWith the fight or flight response on the fritz, anxiety and psychological disturbances are common because the body is in a stressed state indefinitely.
  • Bladder dysfunction—Bladder symptoms are retaining urine, burning, urgency, and incontinence.
  • Inability to regulate body temperature
  • Impotence—Men with dysautonomia can struggle with erectile dysfunction.

Types of Dysautonomia 

Dysautonomia is an umbrella term relevant to any dysfunction of the autonomic nervous system. However, the diagnosis is not always vague. There are numerous forms of dysautonomia. While all forms of dysautonomia share some symptoms, no two patients are alike. The type of dysautonomia determines the exact combination of symptoms.

Dysautonomia
Blood Pressure Monitoring for Dysautonomia

Postural Orthostatic Tachycardia Syndrome

Postural orthostatic tachycardia syndrome (POTS) is the development of symptoms upon postural changes. Upon standing, the autonomic nervous system is supposed to coordinate circulation to pump blood to the brain, while also regulating heart rate and blood pressure. With this form of dysautonomia called postural orthostatic tachycardia syndrome (POTS), the blood does not circulate throughout the body as it should. Blood pools in the lower extremities and does not reach the brain. The main feature is a pulse of ≥ 120 beats/minute or an increase of ≥ 30 beats/minute from a supine to a standing position after ten minutes. The increase in pulse is frequently accompanied by symptoms of orthostatic hypotension. Blood pressure drops when standing and the heart increases its pulse rate to compensate. This provokes symptoms like tachycardia, fainting, migraines, dizziness, nausea, and exercise intolerance. Laying improves symptoms.

Neurocardiogenic Syncope (NCS)

Neurocardiogenic syncope is a form of dysautonomia similar to POTS. The symptoms are still triggered by an upright posture, but the heart rate drops rather than increasing. A decrease in blood pressure also responds to the postural change. Patients with NCS experience symptoms of orthostatic intolerance—dizziness, bradycardia, low blood pressure, dizziness, blackouts, blurred vision, pale skin—and syncope (fainting) typically follows.

Pure Autonomic Failure

Pure autonomic failure is the dysfunction of many processes controlled by the autonomic nervous system. The extensive effects are the result of an abnormal accumulation of synuclein, which is a protein in the brain necessary for cells to communicate. The brain and spinal cord remain unaffected, but cells of the autonomic ganglia are unable to receive appropriate signals.

Severe orthostatic hypotension is the hallmark symptom of pure autonomic failure. REM sleep behavior disorder, urinary retention, constipation, fecal incontinence, and pupils that do not dilate or constrict as they should are other symptoms.

Familial Dysautonomia

Unlike the other types, familial dysautonomia is a genetic disorder occurring amongst families of Jewish descent. Symptoms are present at birth due to mutations in the ELP1 gene responsible for providing instructions for building protein in cells. Improper development of nerve cells causes the manifestations of poor muscle tone, lung infections, fluctuating temperature and blood pressure, breath-holding behavior, and impaired kidney function. Familial dysautonomia is progressive and worsens with age.

Multiple System Atrophy (MSA)

Multiple system atrophy is a degenerative neurological condition that resembles Parkinson’s disease, but with an earlier onset. White males in their 50s are the majority of the patient population. It is characterized by alpha-synuclein deposits that affect several parts of the brain. Early signs of MSA are neurogenic orthostatic hypotension, headaches, loss of bladder control, dilated pupils, and dry eyes, mouth, and skin. As the condition progresses, heart arrhythmias, cognitive impairment, dementia, muscle rigidity, tremors, reduced motor skills, and gastrointestinal complaints can develop.

Autonomic Neuropathy

Autonomic neuropathy is a group of symptoms derived from damage of autonomic nerves. An estimated 20% of the population has a diagnosis of autonomic neuropathy, making it the most prevalent form of dysautonomia. With the nerves damaged, they cannot deliver information to the heart, blood vessels, sweat glands, bladder, intestines, and eyes. According to physicians, this form is associated with cardiovascular mortality.

Inappropriate Sinus Tachycardia

Inappropriate sinus tachycardia comes with fewer symptoms than other types of dysautonomia. The condition manifests as a heart rate of over 100 beats/min. at rest. The stress on the body from sustained tachycardia precipitates dizziness, fainting, fatigue, chest pain, palpitations, and episodes of pre-syncope.

Autoimmune Autonomic Ganglionopathy

Autoimmune Autonomic Ganglionopathy is a relatively rare disorder in which the immune system attacks the autonomic nervous system. The autonomic ganglia, which is a cluster of cells in the autonomic nervous system, do not receive messages because the immune system fails to produce ganglionic AChR antibodies. Classic symptoms consist of constipation, syncope, orthostatic hypotension, neurogenic bladder, inability to swear, and small fiber neuropathy. Suppression of the immune system shows promising outcomes for symptom management.  

Autonomic Dysreflexia

Autonomic dysreflexia is connected to spinal cord injury of the thoracic spinal nerves. Something below the area of injury prompts the occurrence of an autonomic reaction. For example, the urge to urinate or clothing that is too tight. The stress on the body causes dangerously high blood pressure, low heart rate, facial flushing, nasal stuffiness, clamminess, goosebumps, and headache that becomes an emergency if the autonomic nervous system cannot counteract the cardiac response because of the injury.

Baroreflex Failure

Baroreflexes aid in arterial pressure by preventing drastic blood pressure fluctuations. Baroreflex failure interferes with blood pressure regulation. Patients experience low resting blood pressure, as well as high blood pressure in times of stress.

Cerebral Salt Wasting Syndrome

Cerebral salt wasting syndrome is a rare form of dysautonomia effecting the endocrine system. The kidneys excrete excessive amounts of sodium. It is distinguished by dehydration and low sodium concentration in the blood as a response to injury, trauma, or a brain tumor.

Panayiotopoulos Syndrome

Panayiotopoulos Syndrome is a seizure disorder in children. The average age of onset is between 3 and 10 years. The seizures seen in Panayiotopoulos Syndrome do not involve convulsions or periods of unconsciousness. They are partial seizures with symptoms that are autonomic in nature like nausea, eye deviation, tachycardia, and paleness. An EEG (electroencephalogram) measures brain activity. Children with Panayiotopoulos Syndrome have spikes in the occipital lobes.

Causes of Dysautonomia

Dysautonomia is almost always secondary to a primary condition. It rarely occurs alone. The most common causes of dysautonomia genetic and autoimmune conditions. These illnesses include diabetes, lupus, Sjögren Syndrome, Ehlers Danlos Syndrome, Eaton-Lambert Syndrome, HIV and AIDS, spinal cord injury, Lyme’s disease, Parkinson’s disease, Multiple Sclerosis, Mitochondrial disease, and post viral.

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Diagnosing Dysautonomia

A range of tests diagnose dysautonomia. For a thorough diagnosis, a physician must assess the overall autonomic function. An autonomic reflex screen evaluates cardiovagal, adrenergic, and sudomotor function:

  • Tilt Table Test (TT)—The TTT records blood pressure, heart rate, and oxygen saturation during postural changes. The patient is strapped to a table and then tilted upright at an angle of 60 to 80 degrees to measure fluctuations in vitals. The test ends when the patient has a syncopal episode or when they develop symptoms.
  • Thermoregulatory sweat test— This measures the ability to sweat in a lab with controlled temperature factors.
  • Quantitative sudomotor axon reflex test (QSART)—The QSART measures autonomic nerves that control sweating by placing four electrodes filled with acetylcholine on the legs and wrist.
  • EKG monitoring—An electrocardiogram is a records electrical signals of the heart to detect abnormalities in rhythm.
  • Nerve biopsy—To diagnose small fiber neuropathy secondary to dysautonomia, a piece of nerve is removed from the lower leg area and examined under a microscope for damage.  
  • Cold pressor test—Patients submerge hands in ice water while cardiovascular vitals are measured.
  • Deep breathing test—Deep breathing provokes a cardiovascular response that is abnormal in patients with dysautonomia. The deep breathing test records vital changes at baseline, a 5-second inhalation, and a 5-second exhalation period.
  • Valsalva maneuver—The Valsalva maneuver is the exhalation against a closed airway. The nose is pinched closed. Physicians observe the cardiac response.

Dysautonomia Treatment

Treating dysautonomia is tricky, as it requires identifying and addressing the underlying cause. Although dysautonomia has no cure, interventions do exist to better manage symptoms.  

Medication

Physicians prescribe medications to decrease the severity of symptoms.

  • Beta blockers—Beta blockers treat abnormal heart rhythms by blocking epinephrine.
  • Fludrocortisone—a salt retaining steroid that causes the kidneys to retain sodium in exchange for potassium. As the body retains fluid, blood pressure increases regardless of posture.It requires a high salt diet in order to work.
  • Midodrine—Midodrine tightens the blood vessels, acting as artificial norepinephrine to support blood pressure. This drug is effective for patients with damage to the sympathetic noradrenergic nerves, as norepinephrine is not released, and the vessels become sensitive to postural changes.
  • Tricyclic antidepressants—Tricyclic antidepressants are thought to rebalance the autonomic nervous system and regulate mood.
  • Selective serotonin reuptake inhibitors (SSRIs)—Through the increase of the neurotransmitter serotonin, SSRIs reduce anxiety caused by the body remaining in a continuously stressed-state. They also increase nerve communication to improve orthostatic intolerance. Studies theorize that disturbances in serotonin levels play a role in cardiac response (Agarwal, 2007).    
  • Non-steroidal anti-inflammatory drugs (NSAIDs)—Chronic pain is frequently reported by dysautonomia patients. NSAIDs reduce the generalized achiness of the muscles and joints without harmful side effects of traditional pain medications.

Exercise

Exercise is imperative for dysautonomia patients. Deconditioning only contributes to the symptoms of orthostatic intolerance. Gaining muscle tone reduces syncope, tachycardia, and dizziness because the muscle squeezes the vessels upon standing to help circulate blood to the brain. Physical therapists can advise which exercise activities are safe for stabilizing the autonomic nervous system without exacerbating symptoms. Modified exercises that do not involve standing are optimal for patients with orthostatic intolerance.

Diet

It is recommended that those with dysautonomia increase their fluid and salt intake. Fluid consumption should be between 1 to 4 liters of water, along with 4 to 5 grams of salt. The combination of sodium and hydration combats low blood pressure and tachycardia. In patient’s whose digestive tracts are severely compromised, or who are in a hypotensive crisis, IV therapy might be warranted.

Compression Garmets

Blood often pools in the extremities causing fluid in the veins to leak into surrounding tissue. Compression garments (i.e. socks, leggings, arm sleeves) support the vessels in contracting to improve the circulation of blood throughout the body.

References

Agarwal, A. K., Garg, R., Ritch, A., & Sarkar, P. (2007). Postural orthostatic tachycardia syndrome. Postgraduate medical journal, 83(981), 478–480. doi:10.1136/pgmj.2006.055046

Nwazue, V. C., & Raj, S. R. (2013). Confounders of vasovagal syncope: postural tachycardia syndrome. Cardiology clinics, 31(1), 101–109. doi:10.1016/j.ccl.2012.09.004