The exact incidence and prevalence of barosinusitis is not known but is believed to fluctuate with underlying etiology. The prevalence ranges from 34% in divers to 19.5% to 25% in pilots. Concomitant sinus inflammation (e.g., allergic rhinitis) increases the prevalence of barosinusitis in pilots, with rates of up to 34% in high-performance fighter pilots and 55% in commercial pilots. Hyperbaric oxygen treatment causes up to 3% of annual cases of barosinusitis. Sinus barotrauma is most common in divers, in whom the incidence of descent barotrauma approximately doubles that of ascent. Pain after a change of pressure is the most marked symptom and is seen in up to 92% of cases. Sinus barotrauma is second in frequency only to middle ear barotrauma. The frontal sinus is most commonly involved. These injuries occur after a rapid change in pressure, such as with flying or scuba diving. Epistaxis is a serious sign. Brain and orbital complications are rare but can occur.
Underwater, diving injuries are most commonly the cause of barotrauma. Diving and aviation studies show that decompression associated with descent and increased gravity cause sinus barotrauma twice as often as in cases related to ascent, compression, and reverse squeeze. Clinical examination will reveal upper respiratory tract pathology in many patients. A cascade of events occurs in the sinuses during changes in atmospheric pressure. Barosinusitis is often caused when sudden changes in ambient pressure are not compensated for by force equalization mechanisms within the paranasal sinuses. Risk factors for sinus barotrauma when underwater diving or flying include (1) nasal polyps or other anatomical obstructions; (2) sinus obstruction due to edema or mucous, as occurs in allergic rhinitis; or (3) sinusitis. Barosinusitis also is associated with automobile travel, the use of gaseous general anesthetic agents, Chinook wind exposure, prolonged high altitude exposure, submarine decompression, nasal blowing, vigorous Valsalva maneuver, and hyperbaric oxygen therapy.
Upper respiratory tract pathology is the most common predisposing factor for barosinusitis, second to a history of recent or past barosinusitis. In divers who underwent a pre-dive exam, paranasal barosinusitis was not related to alcohol consumption, gender, tobacco, decongestant use, mild nasal septal deviation, or inability to perform the Toynbee or Valsalva maneuvers. Divers with a history of middle-ear barotrauma or sinusitis may be more likely to suffer paranasal sinus barotrauma.
The paranasal sinuses are maze-like, air-filled spaces flanked by fixed, thick, bony outer walls and pliable, thin, internal walls. Normally, air pressure within the sinus cavities equilibrates with that of the surrounding nasal passages via openings into the sinuses, termed the ostia. Small changes in the volume of gas within the sinuses are compensated for by the passageway between the central nasal cavity and laterally located sinuses which allows for pressure changes. Boyle's Law states that, at a given temperature, the volume of a gas varies inversely with pressure. In people who develop sinus barotrauma, the ostia may be anatomically smaller because of small changes in the wall positions around the ostia; or blocked or narrowed due to edema, local inflammation, or trauma. This then impairs the ability of the ostia to equilibrate and help aid air exchange. These uncompensated changes in intrasinus pressure can then result in the mucosal injuries observed in sinus barotrauma.
The nasal mucosa is usually edematous with inflammation and bloody discharge. Mucosal thickening was the more commonly noted pathology, but in 12% of cases, there was a fluid level.
The majority of patients complain of a frontal distribution of pain, with ethmoidal and maxillary being much less significant. Epistaxis is the second most common symptom and may be the sole symptom in some ascent cases. The pain usually starts in the frontal region, spreads up towards the vertex, and then radiates between and behind the eyes and sometimes into the maxillae. Frequently, there is excessive lacrimation from the eye on the side most involved. There may also be swollen turbinates.
Examination of the nose during an episode of sinus barotrauma may show no evidence of any changes in the mucosa. Later there may be a discharge of black blood or serous fluid coming from the superior or middle meatus. One case which came under observation had a discharge of black blood into the middle meatus eight days after the initial episode of sinus barotrauma. There was an associated haziness of the left frontal sinus on transillumination and x-ray. This took more than one month to clear.
If recurrent symptoms or suspected complications of barosinusitis occur, then CT scanning is indicated for further evaluation and treatment planning. Nasal endoscopy also is diagnostic. In one study, the radiological signs of abnormality were present in over three-quarters of the cases examined. In most of these cases, the maxillary sinus was affected. Of the other cases, the frontal represented one quarter and the ethmoidal in less than a fifth. Of note, although symptoms were predominantly frontal, x-ray changes were most often present in the maxillary sinuses. An x-ray may occasionally show findings such as fluid levels, but the gold standard test is CT.
Pain control, oral/topical decongestants, nasal lavage, and antibiotics are indicated for treatment. The antibiotics are preventative as the traumatized mucosa is prone to infection. Fluoroquinolones are the first-line treatment for antibiotics. Treatment is directed at relief of pain and nasal shrinkage. The cause of the obstruction should be ascertained, and if possible, corrected surgically. This may necessitate a submucous resection, nasal polypectomy, or opening some of the ethmoid cells. Careful investigation by an otolaryngologist is paramount. Preventive measures include avoidance of flying or diving during head colds and episodes of allergic rhinitis or sinusitis.
For isolated acute barosinusitis, surgery is required only for complications such as pneumocephalus, orbital complications, or septal abscess. For recurrent acute barosinusitis, a workup with imaging studies and endoscopy is indicated for predisposing and correctable anatomic anomalies. Possible surgical procedures are septoplasty, concha bullosa reduction, uncinectomy, and targeted sinus surgery. These should be tailored to the individual. The most involved surgery would be complete bilateral endonasal surgery to correct anatomic causes of barosinusitis.
In patients with chronic barosinusitis who have failed proper medical therapy, treatment with endoscopic surgery offers a long-term success rate of 92% to 95%. A maximal sinus ostial opening should be created to prevent restenosis and return or the worsening of symptoms, especially if there is a possibility the patient will be re-exposed to sudden, ambient pressure changes. Recommendations include sphenoethmoidectomy, surgery to all paranasal sinuses, maxillary antrostomy, and wide frontal recess clearance (Draf IIA minimum), +/- turbinate and septal surgery. The modified Lothrop procedure (Draf III) should be reserved as a rescue procedure for recurrent restenosis with associated frontal recess barotrauma. In patients who have mainly stenosis and/or sinus ostial narrowing, balloon catheter dilatation provides the best prognosis for preventing further occurrences.
Classification: (1) acute barosinusitis, (2) recurrent acute barosinusitis, and (3) chronic barosinusitis. Differentiation between these terms is related to the symptoms one is having between acute episodes and the frequency of episodes.
Prognosis is good after treatment.
Preventative measures to avoid barosinusitis includes counseling patients to avoid significant altitude changes during episodes of an acute URI or allergic rhinitis. If this is not an option, then counsel patients to take oral decongestants such as pseudoephedrine as well as topical decongestants such as oxymetazoline before the anticipated event.