Dysgeusia and Diminished Olfactation
by Katrina M. Jensen, Fort Worth, Texas, USA
Many laryngectomees feel the sense of taste is lost, changed or greatly diminished following surgery . In fact, the taste buds are just as they were before surgery. There is nothing altered regarding the taste buds on the tongue or the nerves used to taste. These are intact following a laryngectomy surgery. Then why is the sense of taste so different following surgery?
It is important to understand the ability to taste primarily comes from our ability to smell. Tasting with the nose plugged (prior to a laryngectomy), drastically limits how a food tastes. This is because ~70% of the sense of taste comes from our ability to smell. The tongue has taste buds that are able to detect the taste of sweet, sour, salt, bitter and umami (savory).  But it is the sense of smell that tells our brain we are eating a slice of pizza and not a cheeseburger! 
Like the taste buds, the nerves that allow us to smell are also intact.
So if the taste buds are normal, and the sense of smell has not been changed, why do foods taste different? Following a laryngectomy, it is true the sense of smell, or olfaction, remains intact. In a standard laryngectomy surgery, there is no impact from the surgery to the nerves of olfaction that allow for smelling scents, aromas and odors. What has changed, however, is the pathway of airflow during respiration. Prior to the laryngectomy, air would flow into the body through the nose and mouth. This movement of air through the nose allowed for scents and aromas to be detected as the small particles came in contact with the tiny nerve endings in the nose that are responsible for the sense of smell.
Following a laryngectomy, the nose and mouth have been separated from the lungs. During respiration, there is no longer air moving through the nose and mouth . In fact, the ability to draw air into the nose and mouth has been greatly changed. Without air flowing through the nose, allowing tiny paricles to contact the nerve endings that allow us to smell, it seems as if the ability to smell has been lost .
And with a loss a smell, goes ~70% of the sense of taste. The ability to smell and taste is there . The capacity to taste and smell as it was before the laryngectomy is what has been altered.
Restoring Taste and Smell
As in many other ways, the body will adapt to the altered means of tasting and smelling. More subtle taste differences begin to be noticed. Techniques can be employed that help with moving air through the nasal passages.
Polite Yawn Technique
One study found ~50% of laryngectomy patients could improve their sense of taste and smell using the Polite Yawn Technique. This was developed at the Netherlands Cancer Institute and is widely used as a technique to improve the sense of taste and smell in laryngectomees. 
In this technique, a repeated extended yawning movement is performed, lowering the jaw, floor of niouth, tongue, base of tongue, and soft palate while keeping the lips securely closed. This is easily taught to patients by describing it as yawning with the mouth closed, ie, "polite yawning."  This creates a vacuum effect in the mouth and throat which causes air to be drawn through the nose. This means odorous substances will once again come in contact with the olfactory epithelium, where the cells that sense smell are located. Your Speech Pathologist may help you master this technique although many have been able to master it independently.
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