Sinusitis is a condition resulting from inflammation of the paranasal sinuses. This may be a result of infection from one of the following issues:
Impaired immune system
The newest classification of sinusitis refers to it as rhinosinusitis (rhinology is the medical specialty that deals with the nose and its diseases). The logic behind this choice is that inflammation of the sinuses cannot occur without some inflammation of the nose as well.
Differences Between Chronic and Acute Sinusitis
If you suffer from a quickly occurring and short but acute sinus infection lasting anywhere up to eight weeks, then that is probably an acute attack. Chronic sinusitis on the other hand usually recurs and is a long lasting condition. So any attack over eight weeks duration or repeat attacks would be classified as chronic sinusitis. That said, the symptoms of the chronic condition are usually less severe than those of acute sinusitis, but it may lead to complications requiring prolonged treatment and sometimes surgery. An attack which lasts up to 12 weeks but just a one off will more likely than not be classified as subacute.