Barosinusitis is a disease of sinonasal injury and inflammation due to rapid, uncompensated changes of pressure within the sinonasal anatomy. This leads to mucosal damage, most commonly resulting in facial pain or pressure over the affected sinuses (92%), headache, odontalgia, cloudy mucus, and more severely, epistaxis. Out of the paranasal sinuses, the paired frontal sinuses are most commonly affected followed by the maxillary sinuses, and more rarely the sphenoid sinuses. There are no reported cases of ethmoid barosinusitis likely due to there location and surrounding anatomical configuration.
The first reported case of barosinusitis was noted in 1942, in an aviation pilot during World War Two and the first case of diving-related barosinusitis was noted in 1965. Since those initial case reports, multiple other causes of barosinusitis have been reported in the literature which includes hyperbaric oxygen chambers, chinook winds, general anesthesia, nose-blowing, vigorous Valsalva maneuvers, and long exposure to high altitudes.  
Although society is spending increasing amounts of time traveling at high altitudes and diving to the depths of the ocean, the literature surrounding barosinusitis is lacking. The authors of this study hope to provide information to physicians and the public alike for proper identification of this disease. Improvement in barosinusitis identification will lead to increased reporting in the literature, thus allowing for treatment teams to improve treatment outcomes and primary prevention
The symptoms of barosinusitis - facial pain, headache, lacrimation, and even epistaxis - originate from local sinus inflammation and destruction of sinonasal mucosa after corresponding barotrauma. Barotrauma is defined as bodily injuries caused by rapid changes in surrounding pressure. Barosinusitis is often caused when sudden changes in ambient pressure are not compensated for by force equalization mechanisms within the paranasal sinuses. 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. Risk factors for sinus barotrauma when underwater diving or flying include any etiology that would narrow or obstruct the natural sinus ostia. These etiologies include but are not limited to (1) nasal polyposis; (2) stenosis of sinus ostia; (3) obstruction with mucous or fungus ball; or (4) sinusitis. 
Barosinusitis is most commonly reported in deep-sea divers during the process of ascent and twice more commonly, descent. The second most common reported cause is aviation travel. Other reported causes include automobile travel, gaseous general anesthetic agents, Chinook wind exposure, prolonged high-altitude exposure, submarine decompression, nasal blowing, vigorous Valsalva maneuver, and hyperbaric oxygen therapy. According to a few separate studies, the prevalence of barosinusitis ranges from 34% in divers to 19.5% to 25% in pilots. 
Concomitant sinus inflammation increases the prevalence of barosinusitis in pilots, with rates of 34% in fighter pilots and 55% in commercial pilots. Hyperbaric oxygen treatment causes up to 3% of annual cases of barosinusitis. Upper respiratory tract pathology is the most common predisposing factor for barosinusitis, second to a history of recent or past barosinusitis. Divers with a history of middle-ear barotrauma or sinusitis may be more likely to suffer paranasal sinus barotrauma. 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.
The paranasal sinuses are air-filled cavities within the skull that decrease the weight of the skull while allowing for areas of compression in the event of facial trauma. The sinuses are covered with the same mucosa as the nasal cavity - pseudostratified columnar epithelium. Normally, air pressure within the sinus cavities equilibrates with that of the surrounding nasal passages via openings into the sinuses (ostia). Small changes in the volume of gas within the sinuses are compensated for by the passageways between the central nasal cavity and the sinuses, which allow for pressure equalization. The sinuses follow Boyle's Law, which states at a given temperature, the volume of a gas varies inversely with pressure. In people who develop sinus barotrauma, the ostial diameter is narrowed due to either anatomic stenosis or reversible obstruction like edema, local inflammation, or polyps. This impairs the ability of the ostia to equilibrate and provide adequate pressure exchange, leading to mucosal injuries seen in barosinusitis.
This section will cover the pathophysiology of the two most common causes of barosinusitis: diving and aviation. During ascent on a flight or after diving, surrounding pressure decreases allowing for gas expansion within the nasal sinuses and therefore increased sinus pressure. Normally, the sinuses will equilibrate with the nasal cavity quickly as the patient ascends; in cases of ostial obstruction, this process is slowed keeping high pressure within the sinus and causing pain, headache, and mucosal damage. During descent in both flying and diving increasing surrounding pressure will compress the gas within the sinuses causing negative pressure thus creating a pulling effect on the mucosa causing edema, tearing, or hematoma formation.
The majority of patients complain of facial pain and pressure, which usually starts over the frontal sinuses then spreads cranially; this is followed by radiation between and behind the eyes and occasionally into the maxillary sinuses. Frequently, there is excessive lacrimation from the eye on the side most involved. Epistaxis is the second most common symptom and may be the sole symptom in some ascent cases. Other described symptoms include headache, cloudy nasal discharge, or barodontalgia.  If there is involvement of the sphenoid sinuses, due to the anatomical configuration of the optic nerve and internal carotid artery, there is an increased likelihood of orbital complications and headache. 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 non-contrast computed tomography (CT) scanning of the sinuses 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, steroid nasal spray, nasal lavage, and antibiotics are all possible indications for treatment depending on the suspected etiology of the obstruction. Antibiotics can be used either preventatively in the case of suspected acute bacterial sinusitis or to treat traumatized mucosa, which would be prone to infection. Fluoroquinolones are the first-line treatment in these cases. In patients with a history of positive allergy testing or suspected environmental allergies, azelastine can be a great treatment choice to reduce edema of the turbinates and mucosa. Prophylactic pain control can help reduce symptoms of headache and facial pain in some cases. Topical nasal decongestants like oxymetazoline can also serve to vasoconstrict mucosal vessels and allow for the reduction of edema and mucosal obstruction. Nasal saline lavage can also remove obstructive particulate or allergic material from the nasal cavity. Topical nasal steroids can also be used to reduce mucosal edema as well as decrease polyp burden in patients with a history of nasal polyposis.
If patients fail medical management, surgical treatment may be indicated. Treatment with functional endoscopic sinus surgery (FESS) can offer a long-term success rate of 92% to 95%. Recommendations include sphenoethmoidectomy, polypectomy, mucosal resection, 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. Septoplasty or removal of concha bullosa may be indicated in some patients. Balloon Sinuplasty (BSP) is a relatively new technique that consists of using a high-pressure balloon system to dilate sinus ostia and outflow tracts via local microfracturing - without destroying the overlying mucosa and maintaining physiologic function. The goal of BSP is to allow for improved mucociliary clearance by minimizing obstruction of the outflow tracts thus causing symptomatic improvement in patients suffering from sinusitis. 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.
When a patient presents with any combination of the following symptoms: headache, facial pressure, rhinorrhea, epistaxis, or congestion, an otolaryngologist must consider multiple differential diagnoses that share some overlapping features with barosinusitis. Some possible symptomatic mimics of barosinusitis include acute bacterial sinusitis, chronic sinusitis with or without polyposis, allergic rhinosinusitis, non-allergic rhinitis with eosinophilia syndrome (NARES), septal irritation, vasomotor rhinitis, or fungal sinusitis. A clinician must look hard at the patient's history and physical exam to help differentiate barosinusits from the other possible causes. With that in mind, patients who suffer from barosinusitis likely have a history of one or more of the above diagnoses, which predispose them to barosinusitis anyway.
The only reported classification system was created by Vaezeafshar et al. in 2017. They described three specific categories: (1) acute barosinusitis, (2) recurrent acute barosinusitis, and (3) chronic barosinusitis. Acute barosinusitis is defined as having one single episode lasting hours to days after exposure. Both recurrent acute and chronic barosinusitis are defined as having multiple episodes, with chronic barosinusitis having persistence of symptoms between acute episodes and recurrent acute barosinusitis having separate episodes without the persistence of symptoms between them.
Since the disease is based on pressure equalization, the symptoms tend to be transient in nature. The overall prognosis is good, especially if prophylactic measures are taken by the patient. Treatment is based on the underlying etiology of nasal obstruction. Mucosal edema and irritation can be managed with topical steroid nasal sprays as well as topical decongestants. Prophylactic antibiotics can reduce mucosal edema and purulent obstructive nasal drainage. Surgical interventions like balloon sinuplasty or functional endoscopic sinus surgery can open or dilate sinus ostia as well as remove abundant mucosal tissue overlying an outflow tract.
Preventative measures to avoid barosinusitis include counseling patients to avoid significant altitude changes during episodes of an acute upper respiratory tract infection or allergic rhinitis. If this is not an option, then counsel patients to start prophylactic medical treatment for their individual risk factors. Of note, flying safety can be endangered by barosinusitis and appear to be a cause for medical grounding of flights in the aircrew population. Preventative measures to avoid barosinusitis include counseling patients to avoid significant altitude changes during episodes of an acute URI, uncontrolled polyposis, or allergic rhinitis. If this is not an option, then counsel patients to try topical decongestants, topical corticosteroids, or oral antihistamines before the anticipated event.
The management of barosinusitis is with an interprofessional team that includes the primary care physician, nurse practitioner, otolaryngologist, internist, dentist, and an infectious disease consultant. Hyperbaric and otolaryngology nurses are often involved in the care, providing patient education and coordination of care between the team members. The mainstay of treatment is pain control, oral/topical decongestants, nasal lavage, and antibiotics. The pharmacist should evaluate for drug-drug interactions and should assist with patient education and compliance, reporting any concerns to the clinical team. 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. The outcomes for treated patients are good.
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