Comprehensive reviews of diving-related sinus barotraumas were not easy to find. Flottes4, in 1965, described sinus barotrauma in divers.
Sinus barotrauma has been described in various texts on diving medicine5, but initially without specific clinical series being documented. A reasonably large clinical series of divers with sinus barotrauma was first described in Australia by Fagan, McKenzie and Edmonds in 19766 and was quoted widely thereafter. This series described minor and acute cases and was complemented by another series of 50 more serious cases in patients who were referred for definitive treatment7.
The first Australian series
The cases in this series were equivalent to Campbell’s aviation sinus barotrauma grades 1 and 2. This series included 50 consecutive cases of sinus barotrauma as they were observed in a Navy environment, where all such cases were referred for medical opinion irrespective of severity6. It included many cases that might otherwise have not attended for treatment.
In this series, 68 per cent of the presenting symptoms developed during or on descent, and they developed in 32 per cent during or after ascent.
In the majority, the divers were undergoing their first open water diver training course. Pain was the predominant symptom in all the cases on descent and in 75 per cent of those on ascent. Pain was referred to the frontal area in 68 per cent, the ethmoid in 16 per cent and the maxillary in 6 per cent. In one case it was referred to the upper dental area.
Epistaxis was the second most common symptom, occurring in 58 per cent of cases. It was rarely more than an incidental observation, perhaps of concern to the diver but not usually of great severity. It was the sole symptom in 25 per cent of the cases of ascent barotrauma.
Even though these were inexperienced divers, 32 per cent had a history of previous sinus barotrauma, produced by scuba diving, aviation exposure or free diving. Half had a history of recent upper respiratory tract inflammation, and others gave a history of intermittent or long-term symptoms referable to the upper respiratory tract, e.g. nasal and sinus disorders, recurrent infections or hay fever.
In 48 per cent of cases, otoscopy showed evidence of middle ear barotrauma on the tympanic membrane.
Radiologically, the affected sinuses did not replicate the clinical sites and manifestations. Either mucosal thickening or a fluid level was observed in the maxillary sinus in 74 per cent of the cases, in the frontal sinus in 24 per cent and in the ethmoid in 15 per cent. These findings contrast with the clinical manifestations. A fluid level was present in 12 per cent of the maxillary sinus cases.
Most of these divers required no treatment or responded to short-term use of nasal decongestants. Antibiotics were prescribed if there was pre-existing or subsequent sinusitis. Neither sinus exploration nor surgery was required in any case. This series has inappropriately been used to imply that such intervention is never applicable in the treatment of sinus barotrauma.
This prospective Australian series, by its design, included relatively minor cases of sinus barotrauma. It has, by default, been used as being typical of all sinus barotrauma cases, even those that manifest in patients with recurrent or delayed symptoms, or complications, in emergency wards or ear, nose and throat consulting rooms. That extrapolation is not necessarily valid. Also, this study was done more than 4 decades ago, before computer imaging techniques became commonplace and when sphenoidal disease was not easily detected.
Sinus barotrauma and its complications remain common medical problems of div-ing. The importance has been stressed by many workers including Edmonds, Freeman, Thomas and colleagues8, Becker and Parell9, Neblett10 and Roydhouse11.
The second Australian series
The cases in this series were equivalent to Campbell’s aviation sinus barotrauma grade 3. A series of 50 more severe cases, i.e. in patients referred for medical treatment of sinus barotrauma, was reported in 19947. These patients were seen within 1 month of the latest incident.
The cases were self-selecting because the divers with repetitive or more significant problems were more likely to present for treatment. The investigations frequently involved computed tomography (CT) scans of the sinuses, sinus endoscopy and occasionally magnetic resonance imaging (MRI).
These cases were in more experienced divers – 88 per cent had in excess of 50 dives. The distribution was skewed strongly to the extremely experienced, with 70 per cent of the divers having more than 5 years of experience, and many being dive masters, dive instructors or professional divers. Because of the extreme amount of diving exposure in this group, it is presumed that the sinus ostia or ducts may have become scarred and narrowed from the repeated insults they sustained.
In 12 per cent of the patients, the presenting headache developed and progressed while at depth. It could usually be made worse with subsequent ascents or descents, but the initial development of the headache during a time in which there was no substantial change in depth did cause some confusion in the initial physician’s assessment.
From the aviation literature, it is believed that a small degree of negative pressure is sustainable within the sinuses, without symptoms12. Exceeding this pressure may be sufficient to cause a gradual effusion to develop, and the full or heavy sensation within the sinus may take some time to develop. Extrapolation would suggest that diving-related barotrauma could occur with a reduction in sinus air volume of 5 to 10 per cent, i.e. at a depth of 0.5 to 1 metre below the surface.
In 8 per cent of the patients there was a very clear-cut and dramatic sensation of a bursting or popping during depth changes. Of these, half were on descent and half on ascent. It has been described in aviation medicine as the ‘popping of a champagne cork’, a ‘gunshot’, ‘like a bee sting over the eye’ and ‘like being struck on the head with a club or bat’. It is presumed, from the observations of Campbell1,2 and of Mann and Beck12, as well as from this series, that the sensation results from a haemorrhage stripping up the mucosa of the sinus, produced by the negative intrasinus pressure with descent.
A similar sudden sensation can also occur from the rupture of an air sac or release of pressure from a distended sinus during ascent. This may be followed by a ‘hissing’ sensation of air movement, which may then relieve discomfort and pain. One of the cases involved the ethmoidal area, and the patient had a subsequent small, oval haematoma noted over the ethmoid region within hours (Figure 8.2).
In 10 per cent, repetitive incidents of sinus barotrauma appeared to be provoked by inappropriate diving and equalization techniques. In these cases there would frequently be a head first descent, and/or swallowing as a method of middle ear equalization. The substitution of the feet first descent (preferably down a shot line), together with frequent positive-pressure middle ear equalization manoeuvres, appeared to rectify the situation. These are now described in medical texts used by divers13.
A similar problem developed if descents were slow, because of discomfort noted in the sinus. The blood or effusion gradually accumulating in the sinus equalizes the pressure and reduces the degree of pain and discomfort. This may be appropriate for an emergency dive, but it is not prudent if disease is to be avoided. On the contrary, divers inappropriately used this development of the disorder (e.g. blood or effusion, mucosal congestion) as a measure to replace a contracting air space in the sinus during descent, to allow the dive to continue.
Divers in these categories were advised of the correct methods of descent and to use positive pressure middle ear equalization (e.g. the Valsalva manoeuvre; see Chapter 7). This may have an effect of aerating the sinuses before major disease and haemorrhage develop.
Previous radiological descriptions included haematomas, mucous cysts, mucocoeles, polyps or polypoid masses, opacification and, most commonly, a thickening of the mucosa. The series reported by the authors was no different in the various radiological descriptions; however, the CT scans showed more identifiable and definitive pathological features (Figure 8.3). MRI using T1- and T2-weighted imaging was more diagnostic in differentiating blood from mucosal thickening14. Sphenoidal involvement was common.
The current use of MRI and CT scans of the sinuses made diagnosis and treatment more definitive in most of these cases. Sinus endoscopy, sinus surgery or nasal surgery was needed in 12 per cent, often with excellent results.