Smell Loss

People tend to take the sense of smell for granted until they lose it.

The smell of fresh-baked cookies, the scent of pine trees, and the aroma of flowers are all pleasant sensations enjoyed by many. Smell loss can have distressing effects. Many people are also unaware that the sense of smell is an important warning system for potential dangers, such as gas leaks or smoke. When the sense of smell is lost, it can lead to a false sense of safety and could put you at risk. The sense of smell is closely linked with the sense of taste, and without one, it can be difficult to enjoy the other. Read on to learn more about smell loss treatment from rhinology expert, Dr. Thomas Higgins, MD, MSPH.

How does the sense of smell work?

We use the sense of smell to remember things, gauge the weather, and help us enjoy food in the kitchen. But how does the sense of smell work? The sense of smell is a chemical sensory sense. Olfactory nerves or smell nerves detect chemicals that are dissolved in the air or released from certain objects. The sense of smell actually is broken into two types. This first type is called orthonasal smelling, which is the smelling of chemicals that are in the air that we take in through our nose. The second type is called retronasal smelling, or the detection of the smells from our mouth. Retronasal smelling often occurs when food is in our mouth and is mixed with the saliva in our mouth, and the olfactory receptors in the nasal cavity are stimulated by the aromatic chemicals. Retronasal smelling is harder to study than orthonasal smelling, because our brains have to play tricks to make us perceive retronasal smelling as the same smell as the orthonasal one. That is, our brains need to match the smell from our orthonasal smell with the smell from our retronasal smell.

Our olfactory sensory lining is located in the upper parts of the nasal cavities and contains olfactory receptor cells that take in odorants. The olfactory nerve then processes the chemical and sends a signal to the olfactory bulb. All of these parts of the brain process odor and make the neurological response of the sense of smell.



How is smell loss diagnosed?

Diagnosing smell loss can be difficult, as it is not a sense that can be tested like sight or hearing, but there are a few things you can do to try and determine whether you have lost your sense of smell. A common way to test for smell loss is to hold a strong-smelling object, such as a piece of paper with coffee beans, under your nose and see if you can smell it. Another test is to put a few drops of peppermint oil on a cotton ball and hold it under your nose. If you can't smell the peppermint, your sense of smell may be impaired.

Performing a nasal endoscopy in the office is important to identify any structural issues, damage, or inflammation that may be blocking the nasal cavity, and thus preventing odors from reaching the smell nerves.

Dr. Thomas Higgins often will perform a validated smell test in the office to check the level of smell loss, which can range from microsmia (small amount of smell) to anosmia (no smell at all). Occasionally, an imaging study, such as a CT scan or MRI, may be necessary to evaluate the cause of the smell loss.

How is smell loss treated?

Smell loss is treated based on the cause of the condition. If nasal polyps are seen obstructing the nasal cavities, sinus surgery, nasal polypectomy, or medications may be helpful in regaining the smell. A deviated septum may benefit from a septoplasty, the correction of the septum. One of the most common treatments for allergic rhinitis is to use a form of nasal spray that contains a medicine that is released into the nose to reduce inflammation, such as an intranasal corticosteroid therapy. If anosmia has occurred from viruses, such as the Common Cold or COVID-19, then the approach is different and may include intensive smell training therapy to help the brain relearn to smell.



What is smell training therapy?

Smell training therapy is a form of therapy that trains the brain to reassociate smells from our memories. This is done through a process of introducing the smell to the nose on a regular basis. The idea of smell training therapy is to improve a patient's sense of smell. The patient will be given a series of odors to sniff at least twice a day and imagine the smells from before. These odorants include: 

• Lemon (or citrus)
• Rose (or flowers)
• Eucalyptus
• Clove

There are many aspects of smell loss that unpleasant. Maybe the worst thing about losing your sense of smell is that it makes life less enjoyable. You can't enjoy food, flowers or anything else because you can't smell it. If you can't enjoy the smell of cookies baking, the smell of rain, or the smell of your favorite flowers, it's not a good feeling. Come see Dr. Thomas Higgins, MD, MSPH, a smell loss expert in Louisville, KY, and Jeffersonville, IN to see if you can get on the road to improvement.