Loss of smell (Anosmia) or decreased sense of smell (Hyposmia) can be a mild or devastating disease process that can be temporary or permanent. It is estimated to impact 3% of the population under 40 and 20% of the population over 60. During the COVID-19 pandemic these numbers have increased due to anosmia / hyposmia being one of the most common symptoms noted by infected patients. Phantosmia is a condition where patients smell something that is not actually there (burnt cigarette, foul odors, metallic smell). Phantosmia has been noted by patients as they recover from loss of smell caused by COVID-19. It can also be associated with neurological conditions like epilepsy, migraines or dementia. Hyperosmia is hypersensitive smell and can cause severe discomfort when patients are exposed to fragrances or other airborne chemicals. For some, Hyperosmia is a benefit as they work with perfumes or in the food & beverage industry.
Symptoms vary from total loss of smell (anosmia) to decreased sense of smell (hyposmia). Symptoms can be short-term lasting for a few days to permanent depending on the individual causes. Often patients will notice decreased or altered sense of taste as well since these two senses are intimately related and synergistic with each other. Very often patients will not know they have a problem until others around them say “can you smell that?” and when they say no to the surprise and astonishment of others. Sense of smell is also important to interacting with our environment. Whether smelling something burning in the kitchen or enjoying the fresh smell of spring in Central Park it is an important part of our interactions with the World around us. Associated symptoms can include nasal congestion (stuffy nose), sinus infection or pressure, nasal blockage, history of nasal trauma, symptoms from prior COVID-19 infection and various neurological symptoms (memory loss, headaches, visual changes).
The causes of loss or decreased sense of smell are wide ranging and can be very obvious to subtle and difficult to identify:
- Acute or chronic infections of the nose and sinuses
- COVID-19 infection
- Nasal blockage due to deviated septum or enlarged turbinates
- Structural changes to the nose from trauma or surgery
- Benign or cancerous growths in the nose and surrounding structures of the skull base and brain
- Inflammation of the nose and sinuses from allergies or acid reflux
- Nasal polyps
- Medication side effects
- Neurological diseases and conditions such as Multiple Sclerosis, Alzheimer’s, and Parkinson’s disease
- Congenital diseases such as Kallman Syndrome and Choanal Atresia
- Afrin or Zinc nasal spray
- Radiation treatment for Head & Neck Cancers
Other multiple causes exist and with the advent of molecular science and gene level medicine and technology we will be advancing our understanding of this disease process at a rapid rate.
A thorough evaluation, history and exam by an ENT specialist is the first step in identifying the potential causes of anosmia and hyposmia. Treatment plans can be customized based on each individual patient’s disease process. Nasal Endoscopy is easily done in the office and allows for direct visualization of the inner nose and adjacent structures to help determine the causation of symptoms. CT Scan of the nose and sinuses along with MRI of the brain and cranial nerves found at the skull base are also often needed diagnostic steps. Various smell tests can be used to determine the degree and type of anosmia. Concomitant allergy testing and studies for reflux are also considered in the process.
Depending on the cause or causes of the decreased smell, various treatment plans can be recommended and implemented. This can vary from observation and supportive vitamins for the common cold to complex skull base surgery to remove tumors from the olfactory cleft / skull base. Customized care is the keystone to helping patients recover this especially important sense whenever possible. It is also important to treat the associated medical conditions when they are found – often loss of smell is telling us that there are other medical conditions that require treatment.