Olfactory Loss and Beyond: A Practical Review of Chemosensory Dysfunction

Background: Our ability to smell and taste is dictated by 3 chemosensory systems with distinct physiologic mechanisms - olfaction, gustation, and chemesthesis. Although often overlooked, dysfunction of these special senses may have broad implications on multiple facets of patients' lives -including safety, nutritional status, quality of life, mental health, and even cognitive function. As "loss of smell or taste" emerged as a common symptom of coronavirus disease 2019 (COVID-19), the importance of intact chemosensory function has been thrust into the spotlight. Despite the growing recognition of chemosensory dysfunction, this already highly prevalent condition will increasingly impact a larger and more diverse population, highlighting the need for improved awareness and care of these patients. Methods: Comtemporary review of chemosensory function and assessments. Conclusions: Although patient-reported chemosensory function measures highlight the ease of screening of chemosensory dysfunction, self-reported measures underestimate both the prevalence and degree of chemosensory dysfunction and do not adequately distinguish between olfaction, gustation, and chemesthesis. Meanwhile, psychophysical assessment tools provide opportunities for more accurate, thorough assessment of the chemosenses when appropriate. Primary care providers are uniquely situated to identify patients burdened by chemosensory dysfunction and raise patient and provider awareness about the importance of chemosensory dysfunction. Identification of chemosensory dysfunction, particularly olfactory dysfunction, may raise suspicion for many underlying medical conditions, including early detection of neurodegenerative conditions. Furthermore, identification and awareness of patients with chemosensory dysfunction may help primary care providers to identify those who may benefit from additional therapeutic and safety interventions, or consultations with specialists for more detailed evaluations and management.