On ascent, the air in the paranasal sinuses will expand according to Boyles law, contracting during descent. Normally, the sinuses drain into the nasal cavity through small ostia, which permit mucociliary clearance and ventilation that equilibrates pressure. However, when the opening is obstructed due to inflammation, polyps, mucosal thickening, anatomical abnormalities, or other lesions, pressure equilibration is impossible. Squeeze is produced on descent when trapped air in the sinuses contracts and produces negative pressure. The pressure differentials are directed to the center of the sinuses producing mucosal edema, transudation, and mucosal-or submucosal-hematoma, leading to further occlusion of the sinus ostium. The sinus will fill with fluid or blood unless the pressure differential is neutralized.If the outlet is blocked during ascent, the situation is reversed and "reverse squeeze" appears. Pressure inside the sinus increases, affecting the walls of the sinus and producing pain or epistaxis. Location
The majority of episodes of sinus barotrauma occur in the frontal sinuses with pain localized over the frontal area. Possible explanations for this might be the relatively long and delicate nasofrontal duct that connects the narrow frontal recess with the frontal sinuses. Barotrauma located in the maxillary, ethmoidal, or sphenoid sinuses is observed less frequently and appears when the ostia are blocked; the majority of cases are probably caused by an acute upper respiratory tract infection. The magnitude of the pressure difference needed to produce a barotrauma probably shows great individual variation and is related to the size of the sinus ostium and the rate of ambient pressure change.
Presentation of nephrotic syndrome in the context of mesangial proliferative glomerulonephritis have been treated with immunosuppressants, such as steroids and cyclophosphamide. Presentation with nephrotic syndrome can resolve with treatment, but can also progress. Patients can become resistant to steroids or specific immunosuppressive agents, in which case it may be necessary to use different immunosuppressive agents. References


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