Why do we have sinuses?

Why do we have sinuses? 

The sinuses are air pockets located inside the bones in the skull. They are located to either side of the nose (maxillary), behind and in between the eyes (ethmoid), in the forehead (frontal), and there is one much further back in the head (sphenoid). (For a better understanding of this, please look at the CT scan page when you finish reading this page.) They are probably present to reduce the weight of the skull as well as to create resonance to the voice. The sinuses are lined with very fine hair-like projections called cilia. The function of the cilia is to move mucus ( which is normally produced by the sinus) towards the tiny hole ( the ostium) about the size of a pin hole which provides drainage for the sinus. Unfortunately, that hole is located at the top of the largest sinus, and consequently drainage may be poor.

What causes sinusitis? 

Sinusitis starts as a result of blockage of the hole (actually a short hairpin shaped tube) into the sinuses, called an ostium. This blockage can occur as a result of an anatomical obstruction, swelling due to a cold or allergy, drying of the mucus, or a foreign body. When this occurs, mucus that normally is expelled from the sinus builds up in the sinus. This can cause pressure or pain. In addition the mucus is an excellent culture medium for bacteria. If the mucus is not cleared immediately, an abscess can develop in the sinus. An abscess is a pus-pocket inside a closed space. Ideally, treatment of an abscess involves opening the abscess up with a knife and allowing the abscess to drain to the outside. Unfortunately, this is obviously not feasible in the case of a sinus infection without doing extensive surgery.

How common is sinusitis? 

Sinusitis is one of the most common medical problems affecting approximately 30% of the population at some point. Acute sinusitis commonly follows a cold and typically lasts for up to three weeks. After three weeks it becomes defined as a chronic sinusitis and may become much more difficult to treat.
Why is sinusitis increasing? 
Since the Spring of 1990, we have noticed a significant increase in the number of people who have sinus infections. The reason for this is not clear at the present, but it is most likely due to increasing amounts of pollution and ozone. There have been similar increases in other major cities in the United States.

How is sinusitis diagnosed?

It may be extremely difficult to diagnose a sinus infection early in the course of the disease. After taking a careful history, which is extremely valuable in helping diagnose sinusitis, and doing a physical exam, the diagnosis is typically made by looking inside the nose with a flexible rubber or rigid steel tube called an endoscope.

Depending on what is found at the time of the endoscopy, an x-ray (CT scan) of your sinuses may need to be done. Previously, x-rays of the sinuses were done. Now CT scans are ordinarily done because a much greater amount of information can be gleaned from the CT scan, and at a very slight increase in the cost. If you need to have surgery, a CT scan will ordinarily be done prior to surgery. The CT scan is often performed in a special way ( called coronal views) so that certain portions of the sinuses are better seen. Endoscopy and CT scans are now done very commonly for sinus infections. Many doctors and all sinusitis specialists can look inside your nose with the endoscope. It's not painful but might be a little uncomfortable. Don't worry - your nose is sprayed first with a local anesthetic. Believe it or not, I've done it to myself!
There is a section later in this website with CT scans, and an explanation for the layman. Don't be afraid to look at them. By the time you finish, you are likely to know more than your doctor!

What causes mucus to be moved out of the sinuses?

There are tiny hairs in the sinuses called cilia. They beat like waves and move mucus out of the sinuses through a tiny hole (actually a short tube). The tube forms a hairpin turn and is only about 1/6 of an inch in diameter. Obviously it is very easy for this to get blocked.

Why can't the cilia move the mucus out?
Typically, early in the development of a sinus infection, the cilia (tiny hairs lining the sinuses) are lost and mucus becomes increasing thick. Consequently, the mucus is retained in the sinus. If the sinus infection lasts for a long enough period of time, the lining of the sinus may actually physically change, causing an even thicker mucus to develop. The bacteria become trapped in all of the nooks and crannies and proliferate. Once this happens, it is common that patients need to have surgery. Given the above problems, it is obviously important to treat a sinus infection as soon as it starts to occur.

Why do I often have symptoms when I wake up in the morning?
As a result of sleeping, patients will often breathe through their mouth, not be able to clear the mucus from the nose and also not swallow. As a result, mucus is often pooled in the back of the nose and throat causing irritation.

How do I find a doctor to treat my sinus problems?
That is a very difficult question to answer. Assuming that you are not from New York, I would suggest that you go over the information in the website carefully and discuss it with your doctor. You might want to ask him to look at the information in the physicians section, or print it out for him or her. Hopefully you can get them to be receptive to the ideas which I have compiled here. If you feel that you are not getting better, and your doctor is not receptive to trying some of the treatments in here, I would suggest that you find an allergist or otolaryngologist who may be better able to treat you.
If you are located near a medical school, call the department of allergy or otolaryngology and ask to see someone with extensive experience in treatment of sinusitis.