What are paranasal sinuses?
Sinuses are air-filled cavities that are located within the bones of the skull and face. They possess various functions - including lightening the weight of the head, humidifying and heating inhaled air, increasing the resonance of speech, and insulating sensitive structures like dental roots and eyes from rapid temperature fluctuations in the nasal cavity. There are four main groups of sinuses: maxillary sinuses – located under the cheek, frontal – in the forehead area, ethmoid sinuses – situated between the eyes; and the sphenoid – the hidden paranasal cavity, located approximately in the middle of the head.
Sinuses are connected to the nasal cavities by narrow channels (called the osteomeatal complex). These channels permit air to flow from the nose into the sinuses and allow drainage of mucous from sinuses into the nose. We are normally not aware of this process because the mucous is thin and watery and these channels are completely permeable.
The osteomeatal complex can in different people substantially vary in its length or width. Sometimes, this difference can impact greatly on the ability of these channels to function properly. They may be very narrow or tortuous and therefore easily become blocked by swollen tissue such as occurs with inflammation or formation of polyps.
Sinuses and diving
As stated by Boyle’s law, there is an inverse relationship between pressure and the volume of gas in gas-filled spaces. In diving, increasing pressure on descent reduces the gas volume and decreasing pressure on ascent increases the gas volume proportionately. Unless the diver equalizes pressure in sinuses on descent or allow the expanding gas on ascent to escape from the sinuses, problems related to barotrauma can occur. The same may happen for the ear, as well as other gas-filled spaces.
Sinus squeeze, facial pain and nose bleeds
Sinus squeeze - also known as sinus barotrauma - commonly occurs when a diver cannot equalize sinus pressure due to nasal congestion. In the case of blocked nose, there is almost always associated blockage of the sinus openings, and there is no gas flow between the nose and sinuses. The bony structure will not collapse under the pressure changes, but the lower pressure in the blocked sinus will draw blood into it. Blood vessels in sinuses will swell and leak. In more severe cases the squeeze results in a blood-filled sinus, which will drain during ascent when the air in the sinus expands. Sinus squeeze can be recognized as pressure or pain in the forehead or around the teeth, cheeks, or eyes. Sometimes, the nosebleed may occur. Pressure and pain regularly increase with depth.
The most common reasons for nasal congestion and sinus squeeze are colds and allergies, and they should be treated by proper medications. Until the congestion and sinus problems heal, divers should not be diving.
What if these problems persist?
If diver is constantly experiencing these symptoms or they get worse over time it is advised to visit a doctor who specialize in chronic nose and sinus problems – the ENT doctor. In some people, the channels that connect sinuses to the nose may become blocked by swollen tissue. The causes of swelling may relate to allergy or different infections. In addition, certain structural conditions (such as a deviated nasal septum) or nasal polyps – may be further responsible for persistent sinus openings blockage and complaints. All of the above factors may eventually cause thickening (hypertrophy) of the nasal and sinus lining tissue, which can be only detected by nasal endoscopy and CT scans – modern diagnostic techniques performed by the ENT specialist.
Dr. Sasa Janjanin is double European Board-certified in ENT and Facial Plastic Surgery. Besides being experienced surgeon and proficient in curing problems related to thyroid gland; facial cosmetic procedures; nose, sinus and snoring complaints; and kids’ ENT problems, Dr. Janjanin’s particular expertise is in sport and diving-related ENT problems – acting many years as an ENT consultant for several professional and national sport teams and athletes, some of them Olympic medal and European championship winners.
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