Introduction

Post-traumatic anosmia and ageusia refer to the loss or impairment of the sense of smell and taste, respectively, as a result of a traumatic event or injury. These “chemosensory” impairments can have a significant impact on a person’s quality of life.

Chemosensory impairment after trauma is often associated with traumatic brain injury (even concussions), cranial/head/facial trauma as well as whiplash injuries. Smell loss is much more common than taste loss and can occur for multiple reasons including due to shearing forces at the cribriform plate where the olfactory nerve enters the skull, damage to the parts of the brain involved in processing olfactory signals as well as interruption of air flow in the nasal passage due to inflammation, swelling and/or fractures. Often times the loss of smell is perceived as a loss of taste when in fact taste function is totally preserved. It is very uncommon to loss all taste function as taste perception if mediated from both sides of the brain by 3 different cranial nerves (7, 9 and 10).

Chemosensory Terms and Definitions

• Anosmia: Anosmia refers to the loss of the sense of smell. Individuals with posttraumatic anosmia may find it challenging to detect or identify odors, and they may lose the ability to appreciate flavors in food due to the close connection between smell and taste.
• Dysosmia: defines a distorted sense of smell and can include parosmias and/or phantosmias as follows:
  • Parosmia: Parosmia refers to a distorted sense of smell in which smells that were previously enjoyable may be perceived as foul/malodorous.
  • Phantosmia: when an odor is perceived that is not actually present such as a rotten odor, cigarette smoke or chemicals like ammonia.
• Ageusia: Ageusia is the loss of the sense of taste. This can result in the inability to detect or distinguish various tastes (e.g., sweet, salty, sour, bitter, umami), which can lead to a diminished or altered experience of food.
• Dysgeusia: defines a distorted sense of taste.
• Parageusia: typically refers to an altered sense of taste with perception of a bad taste such as metallic.
• Phantogeusia, which refers to tasting something that is not actually there or hallucinating a particular taste.

Diagnosis:

Diagnosing post-traumatic anosmia and ageusia typically involves a comprehensive evaluation by a healthcare provider, often a brain injury medicine specialists who is aware of risk factors, knows the pertinent history to elicit and is aware of screening tests that can be done in a clinic setting. Diagnostic tests may include:

• Clinical Assessment: A detailed medical history and physical examination, including a neurological assessment, can help determine the extent of sensory loss.
• Smell and Taste Testing: Specialized tests, such as olfactory and gustatory testing, can assess the degree of sensory impairment as well as its legitimacy (the latter in the case of need for objectification in a legal matter).
• Imaging: Imaging studies, such as CT scans or MRIs of the head, may be performed to identify any structural abnormalities or injuries to the brain or nasal passages that may correlate with the chemosensory impairment.
• Laboratory testing: certain labs may be checked as clinically significant such as zinc levels to assure that there are not other contributors to chemosensory dysfunction.
• Medication assessment: medications can be a cause or contributor to chemosensory dysfunction, in particular taste dysfunction.

Treatment:

The treatment of post-traumatic anosmia and ageusia can be challenging, and recovery outcomes can vary. Treatment options may include:

• Education: Understanding the nature of changes in smell and/or taste following any type of brain injury is important as such losses can be quite catastrophizing to the individual.
• Rehabilitation:
• Provision of chemosensory compensatory strategies can be helpful for individuals with significant impairment in terms of quality of life including safety (both at home and at work), hygiene, diet, cooking, intimacy and socialization, among other areas.
• Some individuals may benefit from olfactory or gustatory rehabilitation:
  • Sensory rehabilitation programs designed to retrain and improve the sense of smell and taste may be recommended. These programs typically involve exercises and activities to stimulate the sensory receptors. Olfactory retraining, for example, may involve daily exposure to a set of strong and recognizable odors to help reawaken the olfactory system. “Smell retraining” may help about a third of individuals improve their sense of smell.
• Medication Prescription: In some cases, medications or nasal corticosteroid sprays may be prescribed to reduce inflammation and promote recovery of olfactory function.
• Medication Discontinuation: as appropriate medication that may be causing or worsening chemosensory impairment would be discontinued as clinically feasible.
• Surgery: Surgical intervention may be considered in cases where there are structural issues, such as nasal obstructions or fractures, that can be repaired to improve sensory function.
• Supportive Care: Individuals with posttraumatic anosmia and ageusia may need to make lifestyle adjustments, such as using visual cues to determine food freshness and safety.
• Alternative Therapies: Some individuals explore complementary and alternative therapies, such as acupuncture or aromatherapy, to enhance sensory recovery. While these approaches may not have definitive scientific support, some people find them helpful.
• Psychological Support: Coping with the loss of smell and taste can be emotionally challenging. Psychological support and counseling can help individuals adapt to these changes.

Prognosis and Follow Along:

The prognosis for post-traumatic anosmia and ageusia can vary depending on the severity of the injury and individual factors. Some people may experience partial or gradual recovery of their sensory functions over time, while others may have long-term or permanent impairments. It’s important to note that the success of treatment for post-traumatic smell and taste loss can vary widely among individuals. Some people may experience partial or full recovery, while others may have long-term or permanent impairments. The treatment plan should be tailored to your specific circumstances and guided by a healthcare professional with expertise in the field. Additionally, ongoing follow-up and monitoring may be necessary to assess progress and adjust the treatment approach as needed.

Conclusions:

In conclusion, post-traumatic anosmia and ageusia are sensory impairments that can result from traumatic injuries and can significantly impact a person’s life. Seeking timely medical evaluation and appropriate treatment is essential to manage these conditions and optimize the chances of chemosensory recovery and overall well-being. Recovery from post-traumatic anosmia and ageusia can be gradual and may take weeks, months, or even longer. Patience is essential as you work towards sensory improvement.

ABOUT THE AUTHOR

NATHAN D. ZASLER, MD, DAAPM&R, FAAPM&R, FACRM, BIM, CBIST is Founder, CEO & Medical Director of Concussion Care Centre of Virginia, Ltd., as well as Tree of Life Services, Inc. Dr. Zasler is board certified in PM&R, fellowship trained in brain injury and subspecialty certified in Brain Injury Medicine. You can read more about Dr. Zasler HERE.