Orthostatic intolerance (OI) is the development of symptoms when standing upright that are relieved when reclining. There are many types of orthostatic intolerance. OI can be a subcategory of

dysautonomia Dysautonomia or autonomic dysfunction is a condition in which the autonomic nervous system (ANS) does not work properly. This may affect the functioning of the heart, bladder, intestines, sweat glands, pupils, and blood vessels. Dysautonomia ha ...

, a disorder of the autonomic nervous system occurring when an individual stands up. Some animal species with orthostatic hypotension have evolved to cope with orthostatic disturbances. A substantial overlap is seen between syndromes of orthostatic intolerance on the one hand, and either chronic fatigue syndrome or fibromyalgia on the other. It affects more women than men (female-to-male ratio is at least 4:1), usually under the age of 35. Orthostatic intolerance occurs in humans because standing upright is a fundamental

stressor A stressor is a chemical or biological agent, environmental condition, external stimulus or an event seen as causing stress to an organism. Psychologically speaking, a stressor can be events or environments that individuals might consider demandin ...

, so requires rapid and effective circulatory and neurologic compensations to maintain blood pressure,

cerebral blood flow Cerebral circulation is the movement of blood through a network of cerebral arteries and veins supplying the brain. The rate of cerebral blood flow in an adult human is typically 750 milliliters per minute, or about 15% of cardiac output. Art ...

, and

consciousness Consciousness, at its simplest, is sentience and awareness of internal and external existence. However, the lack of definitions has led to millennia of analyses, explanations and debates by philosophers, theologians, linguisticians, and scien ...

. When a human stands, about 750 ml of

thoracic The thorax or chest is a part of the anatomy of humans, mammals, and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main divisions of the crea ...

blood are abruptly translocated downward. People who have OI lack the basic mechanisms to compensate for this deficit. Changes in

heart rate Heart rate (or pulse rate) is the frequency of the heartbeat measured by the number of contractions (beats) of the heart per minute (bpm). The heart rate can vary according to the body's physical needs, including the need to absorb oxygen and excr ...

, blood pressure, and cerebral blood flow that produce OI may be caused by abnormalities in the interactions between blood volume control, the cardiovascular system, the

nervous system In biology, the nervous system is the highly complex part of an animal that coordinates its actions and sensory information by transmitting signals to and from different parts of its body. The nervous system detects environmental changes ...

, and circulation control system.

Signs and symptoms

Orthostatic intolerance is divided, roughly based on patient history, in two variants: acute and chronic.

Acute OI

Patients who have acute OI usually manifest the disorder by a temporary

loss of consciousness Loss may refer to: Arts, entertainment, and media Music * ''Loss'' (Bass Communion album) (2006) * ''Loss'' (Mull Historical Society album) (2001) *"Loss", a song by God Is an Astronaut from their self-titled album (2008) * Losses "(Lil Tjay son ...

and

posture Posture or posturing may refer to: Medicine * Human position ** Abnormal posturing, in neurotrauma ** Spinal posture ** List of human positions * Posturography Posturography is the technique used to quantify postural control in upright stance in ...

, with rapid recovery (simple faints, or syncope), as well as remaining conscious during their loss of posture. This is different from a syncope caused by cardiac problems because the triggers for the fainting spell (standing, heat,

emotion Emotions are mental states brought on by neurophysiology, neurophysiological changes, variously associated with thoughts, feelings, behavioral responses, and a degree of pleasure or suffering, displeasure. There is currently no scientific ...

) and identifiable

prodromal In medicine, a prodrome is an early sign or symptom (or set of signs and symptoms) that often indicates the onset of a disease before more diagnostically specific signs and symptoms develop. It is derived from the Greek word ''prodromos'', meaning ...

symptoms (nausea, blurred vision, headache) are known. As Dr. Julian M. Stewart, an expert in OI from

New York Medical College New York Medical College (NYMC or New York Med) is a private medical school in Valhalla, New York. Founded in 1860, it is a member of the Touro College and University System. NYMC offers advanced degrees through its three schools: the Scho ...

states, "Many syncopal patients have no intercurrent illness; between faints, they are well." Symptoms: * Altered vision ( blurred vision, "white outs"/ gray outs, black outs,

double vision Diplopia is the simultaneous perception of two images of a single object that may be displaced horizontally or vertically in relation to each other. Also called double vision, it is a loss of visual focus under regular conditions, and is often v ...

) *

Anxiety Anxiety is an emotion which is characterized by an unpleasant state of inner turmoil and includes feelings of dread over anticipated events. Anxiety is different than fear in that the former is defined as the anticipation of a future threat wh ...

Exercise intolerance Exercise intolerance is a condition of inability or decreased ability to perform physical exercise at the normally expected level or duration for people of that age, size, sex, and muscle mass. It also includes experiences of unusually severe pos ...

* Fatigue * Headache * Heart palpitations, as the heart races to compensate for the falling blood pressure *

Hyperpnea Hyperpnea, or hyperpnoea (forced respiration) is increased volume of air taken during breathing. It can occur with or without an increase in respiration rate. It is characterized by deep breathing. It may be physiologic—as when required by oxyge ...

or sensation of difficulty breathing or swallowing (see also hyperventilation syndrome) *

Lightheadedness Lightheadedness is a common and typically unpleasant sensation of dizziness or a feeling that one may faint. The sensation of lightheadedness can be short-lived, prolonged, or, rarely, recurring. In addition to dizziness, the individual may feel ...

* Sweating * Tremulousness *

Weakness Weakness is a symptom of a number of different conditions. The causes are many and can be divided into conditions that have true or perceived muscle weakness. True muscle weakness is a primary symptom of a variety of skeletal muscle diseases, i ...

A classic manifestation of acute OI is a soldier who faints after standing rigidly at attention for an extended period of time.

Chronic OI

Patients with chronic orthostatic intolerance have symptoms on most or all days. Their symptoms may include most of the symptoms of acute OI, plus: *

Nausea Nausea is a diffuse sensation of unease and discomfort, sometimes perceived as an urge to vomit. While not painful, it can be a debilitating symptom if prolonged and has been described as placing discomfort on the chest, abdomen, or back of the ...

Neurocognitive Neurocognitive functions are cognitive functions closely linked to the function of particular areas, neural pathways, or cortical networks in the brain, ultimately served by the substrate of the brain's neurological matrix (i.e. at the cellular ...

deficits, such as attention problems * Pallor * Sensitivity to heat *

Sleep problems A sleep disorder, or somnipathy, is a medical disorder of an individual's sleep patterns. Some sleep disorders are severe enough to interfere with normal physical, mental, social and emotional functioning. Polysomnography and actigraphy are tests ...

* Other

vasomotor Vasomotor refers to actions upon a blood vessel which alter its diameter. More specifically, it can refer to vasodilator action and vasoconstrictor action. Control Sympathetic innervation Sympathetic nerve fibers travel around the tunica media of ...

symptoms.

Causes

Symptoms of OI are triggered by: * An upright posture for long periods (e.g. standing in line, standing in a shower, or even sitting at a desk) * A warm environment (e.g. hot summer weather, a hot crowded room, a hot shower or bath, after exercise) * Emotionally stressful events (seeing blood or gory scenes, being scared or anxious) * Return from an extended stay in space, when the body is not yet readapted to gravity * Extended bedrest * Inadequate fluid and salt intake.

Diagnosis

OI is "notoriously difficult to

diagnose Diagnosis is the identification of the nature and cause of a certain phenomenon. Diagnosis is used in many different disciplines, with variations in the use of logic, analytics, and experience, to determine " cause and effect". In systems engin ...

." As a result, many patients have gone undiagnosed or misdiagnosed and either untreated or treated for other disorders. Current tests for OI (

tilt table test A tilt table test (TTT), occasionally called upright tilt testing (UTT), is a medical procedure often used to diagnose dysautonomia or syncope. Patients with symptoms of dizziness or lightheadedness, with or without a loss of consciousness ...

, autonomic assessment, and

vascular The blood vessels are the components of the circulatory system that transport blood throughout the human body. These vessels transport blood cells, nutrients, and oxygen to the tissues of the body. They also take waste and carbon dioxide away f ...

integrity) can also specify and simplify treatment. Patients with dysautonomia symptoms can be referred to a cardiologist, neurologist, or even a gastroenterologist for treatment and management.

Management

Most patients experience an improvement of their symptoms, but for some, OI can be gravely disabling and can be progressive in nature, particularly if it is caused by an underlying condition that is deteriorating. The ways in which symptoms present themselves vary greatly from patient to patient; as a result, individualized treatment plans are necessary. OI is treated pharmacologically and nonpharmacologically. Treatment does not cure OI; rather, it controls symptoms. Physicians who specialize in treating OI agree that the single most important treatment is drinking more than 2 l (8 cups) of fluids each day. A steady, large supply of water or other fluids reduces most, and for some patients all, of the major symptoms of this condition. Typically, patients fare best when they drink a glass of water no less frequently than every two hours during the day, instead of drinking a large quantity of water at a single point in the day. For most severe cases and some milder cases, a combination of medications is used. Individual responses to different medications vary widely, and a drug that dramatically improves one patient's symptoms may make another patient's symptoms much worse. Medications focus on three main issues: Medications that increase blood volume: *

Fludrocortisone Fludrocortisone, sold under the brand name Florinef, among others, is a corticosteroid used to treat adrenogenital syndrome, postural hypotension, and adrenal insufficiency. In adrenal insufficiency, it is generally taken together with hydroc ...

(Florinef) * Erythropoietin * Hormonal contraception Medications that inhibit acetylcholinesterase: *

Pyridostigmine Pyridostigmine is a medication used to treat myasthenia gravis and underactive bladder. It is also used together with atropine to end the effects of neuromuscular blocking medication of the non-depolarizing type. It is typically given by mouth ...

Medications that improve vasoconstriction: * Stimulants: (e.g., Ritalin or

Dexedrine Dextroamphetamine is a central nervous system (CNS) stimulant and an amphetamine enantiomer that is prescribed for the treatment of attention deficit hyperactivity disorder (ADHD) and narcolepsy. It is also used as an athletic performance and c ...

) *

Midodrine Midodrine is a vasopressor/ antihypotensive agent (it raises the blood pressure). Midodrine was approved in the United States by the Food and Drug Administration (FDA) in 1996 for the treatment of dysautonomia and orthostatic hypotension. In A ...

(ProAmatine) *

Ephedrine Ephedrine is a central nervous system (CNS) stimulant that is often used to prevent low blood pressure during anesthesia. It has also been used for asthma, narcolepsy, and obesity but is not the preferred treatment. It is of unclear benefit in ...

and pseudoephedrine ( Sudafed) *

Theophylline Theophylline, also known as 1,3-dimethylxanthine, is a phosphodiesterase inhibiting drug used in therapy for respiratory diseases such as chronic obstructive pulmonary disease (COPD) and asthma under a variety of brand names. As a member of the ...

(low-dose) *

Selective serotonin reuptake inhibitors Selective serotonin reuptake inhibitors (SSRIs) are a class of drugs that are typically used as antidepressants in the treatment of major depressive disorder, anxiety disorders, and other psychological conditions. SSRIs increase the extracellul ...

(SSRIs -

Prozac Fluoxetine, sold under the brand names Prozac and Sarafem, among others, is an antidepressant of the selective serotonin reuptake inhibitor (SSRI) class. It is used for the treatment of major depressive disorder, obsessive–compulsive disorde ...

, Zoloft, and

Paxil Paroxetine, sold under the brand names Paxil and Seroxat among others, is an antidepressant of the selective serotonin reuptake inhibitor (SSRI) class. It is used to treat major depressive disorder, obsessive-compulsive disorder, panic disorder, ...

) Behavioral changes that patients with OI can make are: * Avoiding triggers such as prolonged sitting, quiet standing, warm environments, or vasodilating medications * Using postural maneuvers and pressure garments * Treating co-existing

medical conditions A disease is a particular abnormal condition that negatively affects the structure or function of all or part of an organism, and that is not immediately due to any external injury. Diseases are often known to be medical conditions that a ...

* Increasing fluid and salt intake * Physical therapy and exercise

Notable case

A notable person with OI is Greg Page, founding member and original

lead singer The lead vocalist in popular music is typically the member of a group or band whose voice is the most prominent melody in a performance where multiple voices may be heard. The lead singer sets their voice against the accompaniment parts of the ...

of the Australian children's music group

The Wiggles The Wiggles are an Australian children's music group formed in Sydney in 1991. The group are currently composed of Anthony Field, Lachlan Gillespie, Simon Pryce and Tsehay Hawkins, as well as supporting members Evie Ferris, John Pearce, ...

. Due to being diagnosed with this illness, Page left the group in late 2006, and was replaced by his understudy, Sam Moran. Two years later in late 2008, he went on to create his own fund for OI to help fund research into this then-little known disorder. Page recovered enough to temporarily return to The Wiggles in early 2012 to help with the transition to the next generation of Wiggles, after which he again left the group end of the year and was replaced by Emma Watkins and again by

Tsehay Hawkins Tsehay Hawkins (, ; born 15 November 2005) is an Australian dancer and singer. In August 2021, she became an auxiliary member of The Wiggles, wearing a red shirt. Later in the year, she replaced Emma Watkins as the Yellow Wiggle. She is the s ...

References

External links

{{Autonomic diseases Vascular diseases Peripheral nervous system disorders Sensitivities