Chronic mountain sickness (CMS) is a disease that can develop during extended time living at altitude. It is also known as 'Monge’s disease' , after its first description in 1925 by Carlos Monge Medrano. The acute form of mountain or altitude sickness is acute mountain sickness, and is experienced shortly after ascent to high altutude by those unacclimatised to such altitudes.

CMS is characterised by polycythaemia (increased haematocrit) and hypoxaemia which both decrease on descent from altitude. In medicine, high altitude is defined as over 2500 metres, but most cases of CMS occur at over 3000 m.

The most frequent symptoms and signs of CMS are headache, dizziness, tinnitus, breathlessness, palpitations, sleep disturbance, fatigue, anorexia, mental confusion, cyanosis, and dilation of veins.

Clinical diagnosis by laboratory indicators have ranges of: Hb > 200 g/L, Hct >65%, and arterial oxygen saturation (SaO2) <85% in both genders.

Treatment involves descent from altitude, where the symptoms will diminish and the haematocrit return to normal slowly. Acute treatment at altitude involves bleeding, removal of circulating blood, to reduce the haematocrit; however this is not ideal of extended periods.

References

1. Monge CC, Whittembury J. Chronic mountain sickness. Johns Hopkins Med J. 1976 Dec;139 SUPPL:87-9. PMID 1011412
2. Wu TY. Chronic mountain sickness on the Qinghai-Tibetan plateau. Chin Med J (Engl). 2005 Jan 20;118(2):161-8. PMID 15667803
3. Chinese Medical Association for High Altitude Medicine. Recommendation for the classification and diagnostic criteria of high altitude disease in China. Chin High Alt Med J (Chin) 1996;6:2-5.

Diseases | Mountaineering