Orthostatic intolerance

Orthostatic intolerance (OI) is the development of symptoms when standing upright that are relieved when reclining.[1] There are many types of orthostatic intolerance. OI can be a subcategory of dysautonomia, a disorder of the autonomic nervous system[2] occurring when an individual stands up.[3] Some animal species with orthostatic hypotension have evolved to cope with orthostatic disturbances.[4][5]

A substantial overlap is seen between syndromes of orthostatic intolerance on the one hand, and either chronic fatigue syndrome or fibromyalgia on the other.[6] It affects more women than men (female-to-male ratio is at least 4:1), usually under the age of 35.[7] OI can also be a symptom of mitochondrial cytopathy.[8]

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.[1] 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.[9]

  1. ^ a b Julian M. Stewart. "Orthostatic Intolerance: An overview". WebMD. Retrieved 2007-08-20.
  2. ^ "What is dysautonomia?". National Dysautonomia Research Foundation (NDRF). Retrieved 2007-08-20.
  3. ^ Definition at Dorland's Illustrated Medical Dictionary Retrieved through web archive on 2008-10-09.
  4. ^ Lillywhite, Harvey B. (November 1993). "Orthostatic Intolerance of Viperid Snakes". Physiological Zoology. 66 (6): 1000–1014. doi:10.1086/physzool.66.6.30163751. JSTOR 30163751. S2CID 88375293.
  5. ^ Nasoori, Alireza; Taghipour, Ali; Shahbazzadeh, Delavar; Aminirissehei, Abdolhossein; Moghaddam, Sharif (September 2014). "Heart place and tail length evaluation in Naja oxiana, Macrovipera lebetina, and Montivipera latifii". Asian Pacific Journal of Tropical Medicine. 7: S137–S142. doi:10.1016/S1995-7645(14)60220-0. PMID 25312108.
  6. ^ Peter C. Rowe. "General information brochure on Orthostatic Intolerance and its treatment". The Pediatric Network. Archived from the original on 2007-07-28. Retrieved 2007-08-21.
  7. ^ "Vanderbilt autonomic dysfunction center". Vanderbilt Medical Center. Archived from the original on 2007-08-08. Retrieved 2007-08-20.
  8. ^ Kanjwal, Khalil; Karabin, Beverly; Kanjwal, Yousuf; Saeed, Bilal; Grubb, Blair P. (October 2010). "Autonomic dysfunction presenting as orthostatic intolerance in patients suffering from mitochondrial cytopathy". Clinical Cardiology. 33 (10): 626–629. doi:10.1002/clc.20805. ISSN 1932-8737. PMC 6653231. PMID 20960537.
  9. ^ Cite error: The named reference nymc was invoked but never defined (see the help page).