Editing Orthostatic intolerance

{{Short description|Human disease}}
'''Orthostatic intolerance''' ('''OI''') is the development of symptoms when [[orthostasis|standing upright]] that are relieved when [[supine position|reclining]].<ref name="overview">{{cite web | title = Orthostatic Intolerance: An overview | author = Julian M. Stewart | publisher = [[WebMD]] | url = http://www.emedicine.com/ped/topic2860.htm | access-date = 2007-08-20}}</ref> There are many types of [[orthostatic]] intolerance.  OI can be a subcategory of [[dysautonomia]], a disorder of the [[autonomic nervous system]]<ref name="defintion">{{cite web | title = What is dysautonomia? | publisher = National Dysautonomia Research Foundation (NDRF) | url = http://www.ndrf.org/ | access-date = 2007-08-20}}</ref> occurring when an individual stands up.<ref>[https://web.archive.org/web/20080202064651/http://www.mercksource.com/pp/us/cns/cns_hl_dorlands.jspzQzpgzEzzSzppdocszSzuszSzcommonzSzdorlandszSzdorlandzSzdmd_i_11zPzhtm Definition at Dorland's Illustrated Medical Dictionary] Retrieved through web archive on 2008-10-09.</ref> Some animal species with orthostatic hypotension have evolved to cope with orthostatic disturbances.<ref>{{cite journal |last1=Lillywhite |first1=Harvey B. |title=Orthostatic Intolerance of Viperid Snakes |journal=Physiological Zoology |date=November 1993 |volume=66 |issue=6 |pages=1000–1014 |doi=10.1086/physzool.66.6.30163751 |jstor=30163751 |s2cid=88375293 }}</ref><ref>{{cite journal |last1=Nasoori |first1=Alireza |last2=Taghipour |first2=Ali |last3=Shahbazzadeh |first3=Delavar |last4=Aminirissehei |first4=Abdolhossein |last5=Moghaddam |first5=Sharif |title=Heart place and tail length evaluation in Naja oxiana, Macrovipera lebetina, and Montivipera latifii |journal=Asian Pacific Journal of Tropical Medicine |date=September 2014 |volume=7 |pages=S137–S142 |doi=10.1016/S1995-7645(14)60220-0 |pmid=25312108 |doi-access=free }}</ref>

A substantial overlap is seen between [[syndromes]] of orthostatic intolerance on the one hand, and either [[chronic fatigue syndrome]]  or [[fibromyalgia]]  on the other.<ref name="generalinfo">{{cite web|author=Peter C. Rowe|author-link=Peter Rowe (doctor)|title=General information brochure on Orthostatic Intolerance and its treatment|url=http://www.pediatricnetwork.org/medical/OI/johnshopkins.htm|url-status=live|archive-url=https://web.archive.org/web/20070728190350/http://www.pediatricnetwork.org/medical/OI/johnshopkins.htm <!-- Bot retrieved archive -->|archive-date=2007-07-28|access-date=2007-08-21|publisher=The Pediatric Network}}</ref>  It affects more women than men (female-to-male ratio is at least 4:1), usually under the age of 35.<ref name="vanderbilt">{{cite web | title = Vanderbilt autonomic dysfunction center | publisher = Vanderbilt Medical Center | url = http://www.mc.vanderbilt.edu/root/vumc.php?site=adc&doc=4788 | access-date = 2007-08-20 | archive-url = https://web.archive.org/web/20070808101106/http://www.mc.vanderbilt.edu/root/vumc.php?site=adc&doc=4788 | archive-date = 2007-08-08 | url-status = dead }}</ref> OI can also be a symptom of [[mitochondrial cytopathy]].<ref>{{Cite journal |last=Kanjwal |first=Khalil |last2=Karabin |first2=Beverly |last3=Kanjwal |first3=Yousuf |last4=Saeed |first4=Bilal |last5=Grubb |first5=Blair P. |date=October 2010 |title=Autonomic dysfunction presenting as orthostatic intolerance in patients suffering from mitochondrial cytopathy |url=https://pubmed.ncbi.nlm.nih.gov/20960537/ |journal=Clinical Cardiology |volume=33 |issue=10 |pages=626–629 |doi=10.1002/clc.20805 |issn=1932-8737 |pmc=6653231 |pmid=20960537}}</ref>

Orthostatic intolerance occurs in humans because standing upright is a fundamental [[stressor]], so requires rapid and effective [[circulatory]] and [[neurologic]] compensations to maintain [[blood pressure]], [[cerebral blood flow]], and [[consciousness]].  When a human stands, about 750 ml of [[thoracic]] blood are abruptly translocated downward.  People who have OI lack the basic mechanisms to compensate for this deficit.<ref name=overview/>  Changes in [[heart rate]], 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]], and [[circulation control system]].<ref name=nymc/>

==Signs and symptoms==
Orthostatic intolerance can be classified as [[acute (medicine)|acute]] OI and [[chronic (medicine)|chronic]] OI.{{citation needed|date=June 2021}}

===Acute orthostatic intolerance===

Patients who have acute OI usually manifest the disorder by a temporary [[loss of consciousness]] and [[List of human positions|posture]], with rapid recovery (simple [[fainting|faints]], or [[Syncope (medicine)|syncope]]), as well as remaining conscious during their loss of posture.  This is different from a syncope caused by [[Cardiovascular disease|cardiac problems]] because the triggers for the fainting spell (standing, heat, [[emotion]]) and identifiable [[prodromal]] symptoms (nausea, blurred vision, headache) are known.  As  Dr. Julian M. Stewart, an expert in OI from [[New York Medical College]] states, "Many syncopal patients have no intercurrent illness; between faints, they are well."<ref name=overview/>

'''Symptoms:'''<ref name="nymc">{{cite web | title = Orthostatic Intolerance | author = Julian M. Stewart | publisher = New York Medical College | url = http://www.nymc.edu/fhp/centers/syncope/orthostatic_intolerance.htm | access-date = 2007-08-20 | archive-url = https://web.archive.org/web/20070806053841/http://nymc.edu/fhp/centers/syncope/orthostatic_intolerance.htm | archive-date = 2007-08-06 | url-status = dead }}</ref>
* [[Visual impairment|Altered vision]] ([[blurred vision]], "white outs"/[[Greyout|gray outs]], [[Syncope (medicine)|black outs]], [[diplopia|double vision]])
* [[Anxiety]]
* [[Exercise intolerance]]
* [[Fatigue (medical)|Fatigue]]
* [[Headache]]
* [[Heart palpitations]], as the [[Tachycardia|heart races]] to compensate for the [[Hypotension|falling blood pressure]]
* [[Hyperpnea]] or sensation of [[Shortness of breath|difficulty breathing]] or [[Dysphagia|swallowing]] (see also [[hyperventilation syndrome]])
* [[Lightheadedness]]
* [[Sweating]]
* [[Tremulousness]]
* [[Weakness]]

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

===Chronic orthostatic intolerance===

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]]
* [[Neurocognitive]] deficits, such as [[Attention span|attention]] problems
* [[Pallor]]
* [[Heat intolerance|Sensitivity to heat]]
* [[Sleep problems]]
* Other [[vasomotor]] symptoms<ref name=overview/><ref>{{Cite journal |date=2023-06-30 |title=Orthostatic Intolerance: Background, Pathophysiology, Etiology |url=https://emedicine.medscape.com/article/902155-overview}}</ref>

==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<ref name=Joyner>{{cite journal |last1=Joyner |first1=Michael J. |last2=Masuki |first2=Shizue |title=POTS versus deconditioning: the same or different? |journal=Clinical Autonomic Research |date=December 2008 |volume=18 |issue=6 |pages=300–307 |doi=10.1007/s10286-008-0487-7 |pmid=18704621 |pmc=3770293 }}</ref>
* Extended [[bedrest]]<ref name=Joyner />
* Inadequate [[fluid intake|fluid]] and [[Health effects of salt|salt intake]]<ref name="generalinfo"/>
* Concussion<ref>{{Cite journal |last=Pertab |first=Jon L. |last2=Merkley |first2=Tricia L. |last3=Cramond |first3=Alex J. |last4=Cramond |first4=Kelly |last5=Paxton |first5=Holly |last6=Wu |first6=Trevor |date=2018 |title=Concussion and the autonomic nervous system: An introduction to the field and the results of a systematic review |url=https://pubmed.ncbi.nlm.nih.gov/29660949/ |journal=NeuroRehabilitation |volume=42 |issue=4 |pages=397–427 |doi=10.3233/NRE-172298 |issn=1878-6448 |pmc=6027940 |pmid=29660949}}</ref>

== Diagnosis ==
Many patients go undiagnosed or [[Medical error|misdiagnosed]] and either untreated or treated for other disorders. Current tests for OI ([[tilt table test]], NASA Lean Test,<ref>{{Cite journal |last1=Lee |first1=Jihyun |last2=Vernon |first2=Suzanne D. |last3=Jeys |first3=Patricia |last4=Ali |first4=Weam |last5=Campos |first5=Andrea |last6=Unutmaz |first6=Derya |last7=Yellman |first7=Brayden |last8=Bateman |first8=Lucinda |date=2020-08-15 |title=Hemodynamics during the 10-minute NASA Lean Test: evidence of circulatory decompensation in a subset of ME/CFS patients |journal=Journal of Translational Medicine |volume=18 |issue=1 |pages=314 |doi=10.1186/s12967-020-02481-y |issn=1479-5876 |pmc=7429890 |pmid=32799889 |doi-access=free }}</ref> adapted Autonomic Profile (aAP),<ref>{{Cite journal |last1=M |first1=Sivan |last2=J |first2=Corrado |last3=C |first3=Mathias |date=2022-08-08 |title=The adapted Autonomic Profile (aAP) home-based test for the evaluation of neuro-cardiovascular autonomic dysfunction |url=https://acnr.co.uk/articles/the-adapted-autonomic-profile-aap-home-based-test-for-the-evaluation-of-neuro-cardiovascular-autonomic-dysfunction/ |journal=Advances in Clinical Neuroscience and Rehabilitation |language=en-GB |doi=10.47795/qkbu6715|doi-access=free }}</ref> [[Autonomic nervous system|autonomic]] assessment, and [[Blood vessel|vascular]] integrity) can also specify and simplify treatment.<ref name=nymc/> Patients with dysautonomia symptoms can be referred to a cardiologist, neurologist, or even a gastroenterologist for treatment and management.<ref>{{Cite web | url=http://www.dynainc.org/living/finding-right-doctor | title=Finding the Right Doctor for You | date=9 August 2011 }}</ref><ref>{{cite web |url=https://www.medicalnewstoday.com/articles/76785 |title = Dysautonomia: Symptoms, types, and treatment| date=16 December 2021 }}</ref>

==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.<ref name="ndrf">{{cite web | title = National Dysautonomia Research Foundation  | publisher = National Dysautonomia Research Foundation (NDRF) | url = http://www.ndrf.org/orthostat.htm | access-date = 2007-08-21}}</ref>

OI is treated [[pharmacologically]] and non-pharmacologically. Treatment does not cure OI; rather, it controls symptoms.{{citation needed|date=June 2021}}

Physicians who specialize in treating OI agree that the single most important treatment is drinking more than 2 liters (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.<ref name = generalinfo/>

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:<ref name = generalinfo/>

''Medications that increase blood volume:''
* [[Fludrocortisone]] (Florinef)
* [[Erythropoietin]]
* [[Hormonal contraception]]

''Medications that inhibit acetylcholinesterase:''
* [[Pyridostigmine]]

''Medications that improve vasoconstriction:''
* [[Stimulants]]: (e.g., [[Ritalin]] or [[Dexedrine]])
* [[Midodrine]] (ProAmatine)
* [[Ephedrine]] and [[pseudoephedrine]] ([[Sudafed]])
* [[Theophylline]] (low-dose)
* [[Selective serotonin reuptake inhibitors]] (SSRIs - [[Prozac]], [[Zoloft]], and [[Paxil]])

''[[Behavior change method|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 [[Compression stockings|pressure garments]]
* Treating co-existing [[medical conditions]]
* Increasing [[fluid intake|fluid]] and [[Health effects of salt|salt intake]]
* [[Physical therapy]] and [[exercise]]<ref name = generalinfo/>

==Notable case==
A notable person with OI is [[Greg Page (musician)|Greg Page]], founding member and original [[lead vocalist|lead singer]] of the Australian [[children's music]] group [[The Wiggles]]. Due to being diagnosed with this illness, Page left the group in late 2006, and was replaced by his understudy, [[Sam Moran]].<ref name="gregpage">{{cite web |title=Greg Page leaves the Wiggles |url=http://www.thewiggles.com.au/au/mediacentre/news/31 |url-status=dead |archive-url=https://web.archive.org/web/20070928023000/http://www.thewiggles.com.au/au/mediacentre/news/31 |archive-date=2007-09-28 |access-date=2007-08-21 |publisher=The Wiggles Home Page}}</ref><ref>{{cite news | last = Maddox | first = Greg | title = Life without a skivvie | publisher = The Sydney Morning Herald Online | url = http://www.smh.com.au/news/entertainment/people/yellow-wiggle-keen-to-perform-again/2008/11/28/1227491826882.html | access-date = 2008-11-29}}</ref> 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.<ref>{{Cite web | url=http://www.bakeridi.edu.au/support/greg_page_fund/ |title = Orthostatic Intolerance}}</ref> 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 at the end of 2012 and was replaced by [[Emma Watkins]] and again by [[Tsehay Hawkins]].<ref>{{cite news| url=http://www.news.com.au/entertainment/original-yellow-wiggle-greg-page-gets-his-skivvy-back/story-e6frfmq9-1226247238549/ | work=The Daily Telegraph | title=Original Yellow Wiggle Greg Page gets his skivvy back | date=2012-01-18}}</ref>

==See also==
* [[Orthostatic hypertension]]
* [[Orthostatic hypotension]]
* [[Postural orthostatic tachycardia syndrome]] (POTS)
* [[Vasovagal response]]

==References==
{{Reflist}}

== External links ==
{{Medical resources
|  DiseasesDB     =
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|  OMIM           = 604715
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|  eMedicineSubj  =
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|  MeshID         = D054971
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{{Autonomic diseases}}

[[Category:Vascular diseases]]
[[Category:Peripheral nervous system disorders]]
[[Category:Sensitivities]]