Chronic Anosmia

Introduction

Chronic anosmia is a condition characterized by the loss of smell, with various causes and risk factors, including post-viral infections, chronic rhinosinusitis, head trauma, neurodegenerative diseases, and idiopathic anosmia 1, 2

Post-viral infections, including COVID-19, are a common cause of chronic anosmia, with 35-85% of COVID-19 patients experiencing olfactory dysfunction 1
Chronic rhinosinusitis (CRS) with or without nasal polyps is a major cause of chronic anosmia, according to the American Academy of Allergy, Asthma, and Immunology 3, 2, 4
Nasal polyps are associated with persistent nasal obstruction and anosmia, with 29% of patients reporting anosmia, as reported by the American Academy of Allergy, Asthma, and Immunology 4
Granulomatous inflammation and atrophic rhinitis can also cause chronic anosmia, as noted by the European Rhinologic Society and the American Academy of Otolaryngology 2, 4

Diagnosis of chronic anosmia involves evaluating duration and onset pattern, associated symptoms, and history of viral infections or head trauma, as recommended by the American Academy of Otolaryngology 1
Validated olfactory function tests are essential for quantifying degree of dysfunction, with nasal endoscopy and imaging (CT/MRI) indicated for suspected sinonasal disease or intracranial pathology, as suggested by the European Rhinologic Society 2

Olfactory training is recommended for all patients with persistent anosmia, involving systematic exposure to 4 different strong odors, practice twice daily for at least 12 weeks, with potential benefit from longer training periods, as supported by the Clinical Microbiology and Infection guidelines 5, 1
Intranasal corticosteroids may be considered in combination with olfactory training, with studies showing 62% recovery with combined therapy vs. 52% with olfactory training alone, although evidence for their use alone is insufficient 5
Surgical intervention (functional endoscopic sinus surgery) may be necessary for cases refractory to medical management, as recommended by the American Academy of Allergy, Asthma, and Immunology 3
Patient counseling regarding safety concerns and quality of life impact is essential, with considerations for referral to specialized smell and taste clinics for patients with severe or persistent symptoms beyond 6 months 5, 1

Prognosis depends on severity of disease and persistence of mucosal inflammation, as reported by the European Rhinologic Society 2
Quality of life impact of chronic anosmia is significant and should not be dismissed, with patients experiencing decreased quality of life and mental health effects 5
Referral to specialized smell and taste clinics may be necessary for persistent anosmia, as suggested by the American Academy of Otolaryngology 1
Post-viral olfactory loss, such as that resulting from COVID-19, can persist for over 2 years, with olfactory training recommended as the first-line treatment due to its safety profile and evidence of effectiveness 5, 1

Patients should be advised about safety issues related to anosmia, including the installation of gas and smoke alarms, checking food expiration dates carefully, and being cautious with gas appliances, to mitigate risks associated with impaired olfaction 5, 1
Persistent anosmia significantly decreases quality of life and should be addressed proactively, with considerations for referral to specialized smell and taste clinics for patients with severe or persistent symptoms beyond 6 months 5, 1

Assuming spontaneous recovery will occur is not advisable, as while common in the first few months, recovery becomes less likely after 6-12 months, highlighting the need for proactive management strategies 5
Overreliance on unproven therapies should be avoided, as many proposed treatments lack sufficient evidence, underscoring the importance of evidence-based practice in managing anosmia 5
Dismissing the psychological impact of anosmia is inappropriate, as it significantly affects quality of life and mental health, necessitating a holistic approach to patient care 5
Inadequate duration of olfactory training should be avoided, as training must be continued for at least 12 weeks to show benefit, emphasizing the importance of adherence to recommended treatment protocols 5