If a sinus ostium is blocked during descent, mucosal congestion and haemorrhage compensate for the contraction of the air within the sinus cavity. During ascent, expansion of the enclosed air expels blood and mucus from the sinus ostium. Ostia blockage may be the result of sinusitis with mucosal hypertrophy and congestion, rhinitis, redundant mucosal folds in the nose, nasal polyps and so forth.
As described with ear barotraumas, sinus barotraumas are more frequently noted in female divers and in the young; however, chronic sinus problems are an increasing problem with age and excessive diving frequency (more in dive instructors than in dive masters15).
Symptoms include pain over the sinus during descent. It may be preceded by a sensation of tightness or pressure. The pain usually subsides with ascent but may continue as a persistent dull ache for several hours. On ascent, blood or mucus may be extruded into the nose or pharynx, on the same side as the sinus disease.
Headache developing during the dive, with the diver neither ascending nor descending, should not exclude the diagnosis of sinus barotrauma. When this develops at considerable depth, the sedative effects of narcosis may distort the clinical features. Also, small changes of depth may not be particularly noticeable but produce a misleading history.
The pain is usually over the frontal sinus; less frequently it is retro-orbital and probably sphenoidal. Maxillary pain is not common but may be referred to the upper teeth on the same side. Although the teeth may feel hypersensitive, abnormal or loose, they are not painful on movement. Coughing, sneezing or holding the head down may aggravate the pain and make it throb. Numbness over the maxillary division of the fifth nerve is possible (see later).
The superficial ethmoidal sinuses near the root of the nose occasionally rupture and cause a small haematoma or discolouration of the skin between the eyes (see Figure 8.2).
Discomfort persisting after the dive may result from fluid within the sinus (continuous from the dive), infection (usually starts a few hours after the dive) or the development of chronic sinusitis or mucocoeles.
Sinus x-ray examination, CT or MRI scan may disclose thickened mucosa, opacity or fluid levels. The opacities produced by the barotrauma may be haemorrhagic, serous or mucous cysts. The maxillary and frontal sinuses are commonly involved. The ethmoid and sphenoidal sinuses may also be affected. The newer imaging techniques can clearly demonstrate these features.
CASE REPORT 8.1: DN, a 22-year-old sports diver, occasionally noticed a trace of blood from his face mask following ascent. He had often complained of nasal blockage and had various treatments for this, including cautery. His first dive to 12 metres for 10 minutes was uneventful. After a brief surface interval he again descended, but he was unable to proceed beyond 6 metres because of a severe tearing headache in the frontal region. He equalized his face mask, and this provided some relief. He then continued the descent feet first but still had some slight pain. On reaching the bottom, the severe sharp pain recurred. During ascent it lessened in severity, but on reaching the surface he noted mucus and blood in his face mask. A dull frontal headache persisted for 3 hours after the dive. Examination revealed a deviated nasal septum to both right and left, with hyperaemic nasal mucosa. X-ray studies showed gross mucosal thickening in both maxillary sinuses, the right being completely opaque. There was also some slight shadowing on the right frontal sinus. The radiological signs cleared over the next 2 weeks. Because the airways were patent on both sides of the nasal septum, operative intervention was not indicated. The patient’s nasal mucosa returned to normal after he abstained from cigarette smoking.
Diagnosis: sinus barotrauma of descent.