What is the treatment for anosmia?

Treatment for Anosmia

Olfactory training is the primary recommended treatment for anosmia, particularly for post-viral and post-COVID anosmia cases, as it has shown effectiveness in improving smell function with minimal risk.

Causes and Evaluation

Anosmia (complete loss of smell) can result from various causes:

• Post-viral infections (including COVID-19)
• Sinonasal diseases (chronic rhinosinusitis, nasal polyps)
• Head trauma
• Neurodegenerative diseases
• Aging

Before initiating treatment, it's essential to identify the underlying cause through:

• Detailed history of onset and associated symptoms
• Nasal endoscopy to evaluate for obstruction or inflammation
• Olfactory function testing (e.g., University of Pennsylvania Smell Identification Test)

Treatment Approaches Based on Etiology

1. Post-viral/COVID-19 Anosmia

• Primary treatment: Olfactory training
  • Involves exposure to four distinct odors (typically rose, eucalyptus, lemon, and clove) twice daily for at least 12 weeks
  • Patients should be directed to resources like Fifth Sense (www.fifthsense.org.uk) for guidance 1
• Recovery patterns: Many patients show spontaneous improvement within 1-2 weeks, but some may have prolonged symptoms

2. Sinonasal Disease-Related Anosmia

• First-line treatment: Topical corticosteroid nasal spray in head-down-forward position
  • Significantly improves olfactory scores and reduces signs of nasal/sinus disease 2
  • Administer twice daily (2 sprays each nostril)
  • Continue for at least 8 weeks
• Additional measures:
  • Concurrent antibiotic treatment if bacterial infection is present
  • Consider oral steroids for severe cases with nasal polyps

3. Traumatic Anosmia

• Treatment options:
  • Zinc gluconate supplementation has shown promising results
  • In one study, 25.7% of patients treated with zinc gluconate alone showed recovery of olfactory function 3
  • Combined zinc gluconate and prednisolone showed 28.2% recovery rate
  • Both significantly outperformed no treatment (2.7% recovery) 3

4. Neurodegenerative or Age-Related Anosmia

• Limited evidence-based treatments
• Olfactory training may provide some benefit
• Focus on safety counseling and quality of life management

Patient Education and Safety Counseling

All patients with anosmia should receive:

• Information about potential hazards (inability to detect gas leaks, smoke, spoiled food)
• Recommendations for smoke detectors and gas detectors in the home
• Guidance on food safety and checking expiration dates
• Counseling on potential impact on quality of life and social interactions

Treatment Efficacy and Prognosis

Recovery rates vary significantly based on etiology:

• Post-viral: Generally good prognosis with 60-80% showing improvement within weeks to months
• Sinonasal disease: 66% report subjective improvement with topical corticosteroids 2
• Traumatic: Lower recovery rates (25-28% with zinc/steroid treatment) 3
• Neurodegenerative: Poor prognosis for recovery

Common Pitfalls and Caveats

1. Unnecessary imaging: For isolated anosmia with normal nasal endoscopy, imaging studies (MRI, CT) typically do not provide additional diagnostic information 4

2. Inadequate treatment duration: Olfactory training requires consistent practice over months, not weeks

3. Improper nasal spray technique: For sinonasal disease, the head-down-forward position is crucial for medication delivery to the olfactory cleft

4. Overlooking quality of life impact: Anosmia significantly affects enjoyment of food, social interactions, and can lead to depression

5. Failure to provide safety counseling: Patients with anosmia are at increased risk from hazards they cannot smell

By following this treatment algorithm based on the underlying cause of anosmia, clinicians can optimize outcomes while managing patient expectations regarding recovery potential.