Chronic mountain sickness
| Chronic mountain sickness | |
|---|---|
| Classification and external resources | |
| Specialty | emergency medicine |
| ICD-10 | T70.2 |
| ICD-9-CM | E902.0 |
| DiseasesDB | 29615 |
Chronic mountain sickness (CMS or Monge's disease) is a disease in which the proportion of blood volume that is occupied by red blood cells increases (polycythaemia) and there is an abnormally low level of oxygen in the blood (hypoxaemia). CMS typically develops after extended time living at high altitude (over 2,500 metres (8,200 ft)) so is most common amongst native populations of high altitude nations. The most frequent symptoms of CMS are headache, dizziness, tinnitus, breathlessness, palpitations, sleep disturbance, fatigue, loss of appetite, confusion, cyanosis, and dilation of veins.
CMS was first described in 1925 by Carlos Monge Medrano, a Peruvian doctor who specialised in diseases of high altitude. While acute mountain sickness is experienced shortly after ascent to high altitude, chronic mountain sickness may develop only after many years of living at high altitude. In medicine, high altitude is defined as over 2,500 metres (8,200 ft), but most cases of CMS occur at over 3,000 metres (9,800 ft).
It has recently been correlated with increased expression of the genes ANP32D and SENP1.
Although CMS generally affects people native to altitudes higher than 3,000 metres (9,800 ft), it does not affect populations around the world equally. A recent study by Sahota and Panwar (2013) reviewed CMS prevalence rates around the world and found the highest rates were found in Andean countries of South America and the lowest rates in people native to the East African Mountains of Ethiopia. CMS prevalence rates reported from the study are summarised below:
CMS is characterised by polycythaemia (with subsequent increased ) and hypoxaemia; raised blood pressure in the lungs (pulmonary hypertension) can develop over time and in some cases progress to heart failure (cor pulmonale). CMS is believed to arise because of an excessive production of red blood cells (erythrocytes) due to the low oxygen levels at altitude, which increases the oxygen carrying capacity of the blood. The increased levels of erythrocytes causes increased blood viscosity and uneven blood flow through the lungs (V/Q mismatch). However, CMS is also considered an adaptation of pulmonary and heart disease to life under chronic hypoxia at altitude.
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