Sinusitis is an inflammation of the mucosa lining the paranasal sinuses (maxillary, ethmoid, frontal, and sphenoid sinuses). It almost always originates from an inflammatory focus in the nose, which is why it is commonly referred to as rhinosinusitis. Sinusitis can be acute, when the onset is less than three weeks; subacute, when symptoms persist between three weeks and three months; and...
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