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The Headache of High Altitude and Microgravity?Similarities with Clinical Syndromes of Cerebral Venous Hypertension.
MedLine Citation:
PMID:  22087727     Owner:  NLM     Status:  Publisher    
Abstract Wilson, Mark H., C.H.E. Imray, A.R. Hargens. The headache of high altitude and microgravity?similarities with clinical syndromes of cerebral venous hypertension. High Alt. Med. Biol. 12:xxx?xxx.?Syndromes thought to have cerebral venous hypertension as their core, such as idiopathic intracranial hypertension and jugular foramen outlet obstruction, classically result in headaches. Do they provide an insight into the cause of the headache that commonly occurs at altitude? The classic theory of the pathogenesis of high altitude headache has been that it results from increased intracranial pressure (ICP) secondary to hypoxemia in people who have less compliant intracranial volumes (Roach and Hackett, 2001 ). However, there does not appear to be a correlation between the headache of acute mountain sickness (AMS) and the presence of cerebral edema (Bailey et al, 2006 ; Wilson et al, 2009 ). Research has concentrated on arterial perfusion to the brain in hypoxia, but there has been little study of venous drainage. Hypoxia results in markedly increased cerebral blood flow; however, if it has been considered at all, venous outflow has to date been assumed to be of little consequence. Retinal venous distension and the increased venous blood demonstrated by near infra-red spectroscopy and more recently by MRI imply that, in hypoxia, a relative venous insufficiency may exist. Similarly, there is increasing evidence that manifestations of the fluid shift during microgravity is of similar nature to idiopathic intracranial hypertension, which is thought to be primarily a venous insufficiency condition. The unique anthropomorphic adaptations of large brained biped humans with cerebral venous systems that have to cope with large changes in hydrostatic pressure may predispose us to conditions of inflow/outflow mismatch. In addition, slight increases in central venous pressures (e.g., from hypoxia-induced pulmonary vasoconstriction) may further compromise venous outflow at altitude. A better understanding of cerebral venous physiology may enlighten us with regards the pathogenesis of headaches currently considered idiopathic. It may also enable us to trigger headaches for study and hence enable us to develop new treatment strategies.
Mark H Wilson; Christopher H E Imray; Alan R Hargens
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-11-16
Journal Detail:
Title:  High altitude medicine & biology     Volume:  -     ISSN:  1557-8682     ISO Abbreviation:  -     Publication Date:  2011 Nov 
Date Detail:
Created Date:  2011-11-17     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  100901183     Medline TA:  High Alt Med Biol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
1 National Hospital for Neurology and Neurosurgery and University College London , London, United Kingdom .
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