Headache caused by hypoxia and/or hypercapnia and occurring in conditions of exposure to either or both.
- Any headache fulfilling criterion C
- Exposure to conditions of hypoxia and/or hypercapnia
- Evidence of causation demonstrated by either or both of the following:
- headache has developed in temporal relation to the exposure
- either or both of the following:
- a) headache has significantly worsened in parallel with increasing exposure to hypoxia and/or hypercapnia
- b) headache has significantly improved in parallel with improvement in hypoxia and/or hypercapnia
- Not better accounted for by another ICHD-3 diagnosis.