Dysautonomia

Dysautonomia describes several different medical disorders of the autonomic nervous system that cause disturbances in all or some autonomic functions. Dysautonomia can be caused by other disease (e.g., diabetes), or by injury or poisoning/toxins, by genetics, or may not have a known cause. People with dysautonomia can have problems regulating autonomic functions, including heart rate, blood pressure, body temperature, and digestion. Thus, dysautonomia can present with various symptoms, such as lightheadedness, fainting, unstable blood pressure, and orthostatic intolerance.

Types of dysautonomia
More than 70 million people have dysautonomia. There are various types of dysautonomia, each presenting with different underlying mechanisms as well as some overlapping mechanisms. Forms of dysautonomia include: Dysautonomia can occur independently or secondary to other medical conditions, such as diabetes, MS, rheumatoid arthritis, and lupus.
 * Postural orthostatic tachycardia syndrome (POTS), a form of orthostatic intolerance that can cause lightheadedness, fainting, tachycardia, chest pains, exercise intolerance, temperature sensitivity, and more.
 * Neurocardiogenic syncope is the most common form of dysautonomia, with many individuals having a mild case (fainting once or twice in their lifetime). Severe cases can result in fainting several times per day.
 * Multiple system atrophy (MSA), a fatal and rare form of dysautonomia, affects 350,000 people worldwide. It is a neurodegenerative disorder occurring in adults over the age of 40. MSA progresses rapidly; patients usually become bedridden within 2 years of diagnosis.
 * Familial dysautonomia (FD) is a rare genetic disorder in persons of Ashkenazi Jewish descent. It is a very serious condition, consisting of abnormal development, progressive degeneration of the sensory and autonomic nervous systems, and is inevitably fatal. FD is caused by a point mutation in the IKBAP gene, resulting in the severe reduction of the IKAP protein, which is involved in many intracellular processes.
 * Autonomic dysreflexia (AD) is a form of dysautonomia associated with spinal cord injuries, affecting the communication of the autonomic nervous system.
 * Baroreflex failure; the baroreflex is the body’s homeostatic mechanism for maintaining blood pressure. If the baroreceptor or its system fails, patients experience inappropriate blood pressure.
 * Cerebral salt wasting syndrome is a condition in response to physical injury or the presence of tumors in the brain, presenting as hyponatremia (excessive sodium secretion from the kidney) and dehydration.
 * Diabetic autonomic neuropathy is a very common form of dysautonomia, affecting 69 million people worldwide (20% of diabetics). It is a serious complication of diabetes, associated with an increased risk of cardiovascular mortality.
 * Panayiotopoulos syndrome, also known as autonomic epilepsy is a childhood-specific seizure disorder consisting of seizures with predominantly autonomic symptoms (without convulsing).
 * Reflex sympathetic dystrophy is a an extremely painful neurological condition that is sometimes considered a form of dysautonomia.

Comorbidities/causes of dysautonomia
Comorbidities and causes of dysautonomia include:
 * Amyloidosis
 * A group of rare disorders caused by the accumulation of amyloid protein in various tissues throughout the body. If the amyloid accumulation occurs in the heart or on peripheral nerves, it can cause dysautonomia.
 * Celiac disease
 * Charcot-Marie-Tooth disease
 * Chiari malformation
 * Chronic inflammatory demyelinating polyneuropathy
 * Inflammatory bowel disease (such as Crohn’s and ulcerative colitis)
 * Deconditioning
 * The physical change in the way the body functions due to a decrease in activity. The most common cause of deconditioning is bed rest. Due to debilitating symptoms, patients with various chronic illnesses may experience deconditioning, which can exacerbate symptoms. It is important to take steps to prevent and/or reverse deconditioning.
 * Diabetes
 * Ehlers-Danlos syndrome
 * Mast cell disorders
 * Mitochondrial diseases
 * Paraneoplastic syndrome
 * Parkinson’s disease
 * Sarcoidosis
 * Sjögren's syndrome
 * Physical trauma or surgery
 * Vitamin deficiencies
 * Patients have also reported dysautonomia caused by viral infections

Treatment
There are currently no cures for dysautonomia, as it is an umbrella term that covers many conditions related to the dysfunction of the autonomic system. Therefore, there are treatments  that are used to improve quality of life by treating specific symptoms, or treating the underlying disease that is causing the dysautonomia. Further treatments are used to improve quality of life.

Myalgic Encephalomyelitis
Many people with myalgic encephalomyelitis (ME) experience autonomic dysfunction. Symptoms of autonomic dysfunction in ME include altered blood pressure, heart rate, digestion, body temperature, exercise intolerance, and neurological correlates with autonomic nervous system (ANS) dysfunction (for a complete list, see our Autonomic Nervous System page).

Some researchers suggest that dysautonomia is central to the pathophysiology of ME. Various studies have investigated the efficacy of treating ME patients by targeting autonomic symptoms without significant success.

Studies on Dysautonomia and ME
One study (Orjatsalo et al. 2018) has looked at autonomic cardiac function in different sleep stages of people with chronic fatigue syndrome (CFS). They found that people with CFS had higher nocturnal systolic and mean BP and lower heart rate than controls, suggesting a nocturnal dysfunction of the cardiac ANS in CFS. This means that patients have a lower parasympathetic tone and higher sympathetic tone during sleep. Another study (Miwa 2016) investigated POTS in patients with both ME and orthostatic intolerance. They hypothesized that the characteristics of sympathetic activation may differ between these patients’ “good days” and “bad days”. Patients were characterized with an active standing test and an echocardiography. Their results indicated that ME patients may experience exaggerated activation of the sympathetic nervous system. They suggest that sympathetic activation in ME is impaired and is associated with preload failure.

Newton et al. aimed to determine the prevalence of autonomic dysfunction in CFS using the Composite Autonomic Symptom Scale (COMPASS) and the Fatigue Impact Scale (FIS). The study included a healthy control group and a control group of patients with primary biliary cirrhosis (PBC; where 60% of patients experience significant fatigue and some experience autonomic dysfunction). Their results indicated that symptoms of autonomic dysfunction were strongly associated with the presence of CFS or PBC (in some but not all patients), and that symptoms correlated with severity of fatigue. COMPASS scores were significantly higher for the CFS group than for the PBC group and healthy control group.

Ehlers-Danlos Syndrome
A study of 39 female Hypermobile EDS patients showed increased sympathetic activity at rest and reduced sympathetic reactivity to stimuli. It also showed an increased rate of orthostatic intolerance (74% in hEDS v. 34% in controls). A study of hEDS patients found that 74.4% had Orthostatic Intolerance. A study of 48 patients meeting the 1998 Brighton criteria found that 78% had orthostatic intolerance versus 10% of controls.

Fibromyalgia
A symptom survey study comparing patients with EDS and fibromyalgia found that fibromyalgia patients had a much higher autonomic symptom burdens than controls, but similar to patients with EDS.