Empty Nose Syndrome - Aetiology

Aetiology

The turbinates are known as the main humidifying, heat exchanging, air-filtering, airflow controlling and airflow sensing structures of the nose. They control, heat, humidify and filter the airflow by streamlining it around them as it progresses through the nose, thus significantly increasing the mucosal surface that comes into contact with the airflow. Their integrity and function is crucial for maintaining nasal and sinus health and physiology. Built aerodynamically from anterior to posterior they are designed to not over obstruct breathing while processing the airflow.

The turbinates play a vital role in protecting the inner nasal mucosa and allowing it to recuperate and regenerate. A normal nose of an adult processes on average 10,000 liters of air in 24 hours, it therefore needs some form of resting period to recuperate and maintain good health and integrity of the delicate respiratory epithelium layer that lines the entire nasal airway and sinuses. The recuperation of the nose is achieved by a phenomenon known as the 'nasal cycle'. Every 3–6 hours one side of the nose congests with blood while the other remains decongested - thus the majority of the workload of breathing is done through the decongested side while the congested side rests and recuperates. When the inferior turbinates are resected the nasal cycle can no longer fully congest the side of the nose where they were resected and therefore much of the natural recuperation capability on that side is lost.

There are typically three pairs of turbinates in the human nose - the inferior concha, the middle concha and the superior concha. Each pair is very different in size and in shape, and each protect a different region of the nasal cavity: The inferior turbinates are the largest and extend all across the lower part of the nasal cavity, from the very front of the nose almost up to the nasopharynx. As the inferior turbinates are the largest and the first to mitigate the inspired air, their loss has the most profound effect on the physiology of the remaining mucosa. The middle turbinates hover above the inferior turbintaes and begin from approximately the midsection of the nasal cavity. They are much smaller and unlike the inferior turbinates harbour some olfactory nerve axons and protect the upper regions of the cavity, in particularly the olfactory bundle of nerves at the roof of the nose and the openings of the ethmoid and frontal sinuses. Their loss will play a lesser role in the over all reduction of the retained heat and humidity in the nose, but it might impact the quality of the sense of smell and the health of the ethmoid and frontal sinuses. The superior turbinates are tiny in comparison to the inferior and middle ones and have the sole role of being the last line of protection around the olfactory bulb.

The loss of too much turbinate tissue may cause the remaining mucosa at the vicinity of the site of resection, and directly behind and above that area, to gradually become more and more inflamed, dry, go through metaplasia, endertitis and eventually atrophy. As a result all four major functions of the nose become impaired: breathing, defense, olfaction, and phonology. This can take many years to fully develop, which may complicate the proper diagnosis.