How should I assess and manage a patient presenting with anosmia, distinguishing acute (<4 weeks) from chronic (>4 weeks) loss of smell?

Assessment and Management of Anosmia

Immediately initiate olfactory training for a minimum of 3-6 months, as this is the only intervention with consistent guideline support for post-viral olfactory dysfunction, and direct patients to validated resources like www.fifthsense.org.uk for proper technique. 1

Initial Assessment

History and Clinical Evaluation

• Obtain detailed history focusing on:

  • Onset and duration of symptoms to distinguish acute (<4 weeks) from chronic (>4 weeks) loss 2
  • Temporal relationship with viral infections, particularly COVID-19 2
  • Associated symptoms including flu-like symptoms, fever, or cough 3
  • Presence or absence of traditional nasal symptoms (congestion, rhinorrhea) - notably, COVID-19-related anosmia often lacks these symptoms 4

• Perform rigid nasal endoscopy to differentiate between conductive (obstructive) and sensorineural causes 1

Diagnostic Testing

• COVID-19 testing is mandatory in patients with sudden onset smell loss, especially during pandemic periods or when anosmia presents as an isolated symptom 2, 3

  • Loss of smell occurs in 59-86% of COVID-19 patients and can be the sole presenting feature in 11.9-22% of cases 4
  • Healthcare workers with isolated anosmia pose significant transmission risk since viral load is comparable between symptomatic and minimally symptomatic individuals 4, 3

• Objective psychophysical testing is mandatory rather than relying on patient self-report, as patients commonly underestimate their impairment severity 1

  • Use validated tests: UPSIT (University of Pennsylvania Smell Identification Test) or Sniffin'Sticks 1, 3
  • Objective testing reveals dysfunction in 98.3% of patients even when only 35% report symptoms 1, 4
  • These tests take 4-25 minutes to administer and have high test-retest reliability 1

Primary Treatment Protocol

Olfactory Training (First-Line Treatment)

• Start olfactory training immediately upon diagnosis and continue for minimum 3-6 months 1, 2
• This is a self-administered home-based protocol requiring no specialized equipment or clinical supervision once initial instruction is provided 1
• Direct patients to www.fifthsense.org.uk for validated technique instruction 3, 1
• Patients can use either commercially available olfactory training kits or common household scents 1

Additional Treatment Considerations

• Topical corticosteroids combined with olfactory training showed no significant benefit over olfactory training alone in the highest quality RCT, so routine use is not recommended 1
• Intranasal insulin showed significantly higher olfactory detection scores in one small RCT but requires further validation before routine recommendation 1

Nutritional Support

• Refer to registered dietitian for counseling on flavor enhancement, additional seasoning, avoiding unpleasant foods, and expanding dietary options to maintain nutrition 2, 1

Expected Recovery Timeline

• Most patients recover within 1-2 months, with 73% improving within 7-14 days of onset 1, 4
• 44-73% of patients recover within the first month 3, 1
• However, 20% have symptoms persisting beyond 14 days, and some develop permanent dysfunction 4

Follow-Up Protocol

• Re-evaluate at 1 month, 3 months, and 6 months after initiating treatment with repeat objective psychophysical testing to document changes 2, 1
• Refer to otolaryngologist or specialized smell/taste clinic if no improvement occurs after 3-6 months of olfactory training 2, 1

When to Order Advanced Imaging

• CT and MRI of skull base and brain should only be ordered when psychophysical testing severity does not correlate with endoscopic findings, raising suspicion for occult sinonasal or skull base tumor 1
• Do not order unnecessary neuroimaging when there is clear temporal relationship to viral infection 2, 1

Critical Safety Counseling

• Address safety concerns immediately regarding inability to detect spoiled food, gas leaks, or smoke, as these pose real-world risks to patients with persistent chemosensory dysfunction 1

Common Pitfalls to Avoid

• Do not rely on patient self-assessment of severity - objective testing is mandatory 1
• Do not assume true gustatory dysfunction - most "taste loss" is actually retronasal olfactory loss (loss of flavor perception) 3, 4
• Do not overlook COVID-19 as a potential cause, especially when smell loss is the primary or isolated symptom 2, 3
• Do not delay olfactory training - it should be initiated immediately, not after waiting for spontaneous recovery 1