In the 1940s, sinus barotrauma from aviation exposure was well described by Campbell1,2. Although sinus barotrauma is the second most common disease in diving medicine, there has been very little detailed documentation, apart from individual case reports. The injury results from the changes in volume of the gas spaces within the paranasal sinuses during ascent or descent – when those changes could not be compensated for by the passage of air between the sinus and the nasopharynx. It is the clinical manifestation of Boyle’s Law as it affects the para-nasal sinuses.
The pathological changes found within the sinuses included: Mucosal detachment; submucosal haematoma; blood clots in membranous sacs; small haemorrhages within the mucosa; and swelling of the mucous membrane.
Weissman and associates3 described a series of 15 cases of frontal sinus barotrauma in aviators. Most of these cases were grade III. These investigators used the following grading system:
- Grade I – a transient discomfort that cleared promptly and had only slight mucosal oedema, but no x-ray changes.
- Grade II – characterized by pain over the affected sinus for up to 24 hours. There was thickening of the mucosa seen on x-ray studies. If such a sinus was opened, small amounts of blood-tinged fluid were found. Serosanguineous fluid sometimes drained from the sinus, with or without the use of decongestants.
- Grade III – a severe pain or a ‘bee sting’ or ‘being shot’ sensation. If the pain was not quickly relieved by the Valsalva manoeuvre, the pilot had to descend rapidly to relieve symptoms.
Usually, aviators with grade I and II barotrauma did not seek medical aid, and symptoms usually cleared spontaneously. Grade III cases resulted in oedema and congestion of the sinus mucosa with submucosal haemorrhages. As the sinus mucous membrane was pulled away from the periosteum by the negative intrasinus pressure, a haematoma formed. Sinus x-ray studies showed an air-fluid level or a polypoidal mass. Incising this mass brought forth a spurt of old blood, with clots.