Our sinuses are located within  cavities beneath the formation of our cheekbones, called maxillary, behind the forehead and eyebrows, called frontal, on both sides of the bridge of the nose, called ethmoid, and behind the nose, in front of the brain, called sphenoid. 

Each sinus cavity is joined to an opening into a continuous membrane, called the nasal passage, that allows to breathe in and exhale air  and to eliminate mucous   However, when the nasal passage becomes swollen, either due to swelling caused by a cold, narrow nasal openings, a deviated septum, nasal polyps or allergic rhinitis, the sinus openings become blocked, and sinus drainage, blood flow and ventilation impaired.  This occurrence enables bacteria in the sinuses to multiply, causing an infection. 

Sinusitis, "itis" meaning inflammation, can or cannot be caused by an infection.  Often caused by bacteria, acute sinusitis usually  develops as a result of a viral respiratory infection, or common cold. Most of the time, the common cold subsides on its own without medical treatment.  However, a small percentage of cases, the common cold progresses into acute sinusitis.  

When sinusitis lasts more than three months, the sinusitis is considered to be chronic.  Unfortunately, chronic sinusitis is more complicated and difficult to treat than acute sinusitis. Also, chronic sinusitis is commonly seen in patients with a medical history of allergic rhinitis, asthma or nasal structural problems.

Typical symptoms of acute sinusitis include cough, sinus pressure, facial pain, toothache, a stuffed nose, postnasal drip, yellow-green nasal discharge or even fever. For patients with chronic sinusitis, symptoms may be less sudden, but may still include facial pain and pressure, cough, nasal congestion with colored discharge, in addition to reduced sense of smell, loss of taste, foul breath, hoarseness and recurrent sore throat.

If you have sinusitis, and in addition to a detailed history and physical examination, your allergist may perform allergy skin testing, and order a sinus x-ray, CT scan and even endoscopic examination to rule out other possible underlying causes of chronic sinusitis.