Abstract
The authors are to be complimented on a most interesting article (1). ‘Airplane headache’ may well turn out to be more common than is generally thought. I must take issue with them, however, on the explanation that they offer on a possible mechanism for the pain that occurs on landing (87% of attacks).
They theorise that with the increase of barometric pressure during descent, if the ostial patency is marginal, pressure cannot be equilibrated within the sinus, and a relative negative pressure develops in the sinus. This causes a vacuum effect in the sinus, which may cause oedema, transudation and haemorrhage to develop in the mucosal lining of the sinus, causing pain. While it seems self-evident that the change in barometric pressure is the trigger for headache in this group of patients, the mechanism that the authors propose does not seem plausible.
During pressurised flight, the cabin pressure is maintained at a level lower than that on the ground, usually at a pressure equivalent to that at 8000 feet, so that the difference between the cabin pressure and the outside pressure at high altitudes is reduced. The smaller the difference between cabin and outside pressure, the fewer stresses are placed on the fuselage. This allows the fuselage to be constructed of lighter material.
So it is quite true that on descent there will be a negative pressure in the sinus relative to the ambient pressure. The pressure in the sinus will, however, have been low for most of the flight, without the development of mucosal oedema, transudation, haematomata or headache. If the ostia are not patent, an increase in ambient pressure on descent will have no effect on the existing low pressure in the sinus – it will remain at the same low pressure that it was at for most of the flight.
If the pain were in some way related to reduced sinus pressure, it would seem more logical that the difference between haemostatic pressure and sinus pressure would be a more likely cause of mucosal changes. This difference is indeed greatest during most of the flight, when cabin and intra-sinus pressures are at their lowest, and when the blood pressure remains unchanged. If the proposed theory were correct, this is when one would expect the pain to occur, but it doesn’t.