What is the evaluation and management approach for chronic loss of taste and smell?

Evaluation and Management of Chronic Loss of Taste and Smell

Begin with objective psychophysical testing using validated instruments (UPSIT or Sniffin'Sticks) combined with rigid nasal endoscopy to differentiate between conductive and sensorineural causes, as patients typically cannot accurately assess their own degree of impairment. 1

Initial Diagnostic Approach

History and Physical Examination

• Obtain detailed history focusing on onset timing, duration, and temporal relationship to viral infections (particularly COVID-19), as post-viral olfactory loss accounts for 20-25% of specialist clinic presentations 1
• Document associated symptoms including nasal obstruction, rhinorrhea, or flu-like illness 2
• Review all medications, as pharmacologic agents frequently interfere with chemosensory function 3
• Note predisposing factors: nasal polyps, asthma, aspirin-exacerbated respiratory disease (N-ERD), previous sinus surgery, and advancing age all increase risk of greater smell loss 1

Physical Examination

• Perform rigid nasal endoscopy on all patients to identify polyps, masses, inflammation, or anatomic obstruction that may explain the deficit 1
• Examine oral cavity for infections, dental pathology, or appliances that may cause taste dysfunction 3
• Complete otorhinolaryngologic examination to assess for sinonasal disease 4

Objective Testing

Psychophysical Testing (Essential)

• Use validated smell tests: UPSIT (or short versions B-SIT, SIT) or Sniffin'Sticks extended version - these have high test-retest reliability and take 4-25 minutes to administer 1
• Patients are commonly unaware of their impairment severity, making objective testing mandatory rather than optional 1
• Testing helps monitor treatment outcomes and provides baseline for follow-up 1

COVID-19 Specific Considerations

• Perform COVID-19 testing in all patients with sudden-onset taste/smell loss, especially during pandemic periods, as olfactory dysfunction may be the sole presenting symptom 1, 2
• Recovery occurs in 44-73% of COVID-19 patients within the first month, though some develop persistent dysfunction 1, 2

Advanced Imaging (Selective Use)

Order CT and MRI of skull base and brain only when:

• Psychophysical testing severity does not correlate with endoscopic findings, raising suspicion for occult sinonasal or skull base tumor 1
• Imaging can detect reduced olfactory bulb volume, decreased olfactory sulcus depth in congenital loss, and exclude olfactory/pituitary tumors or aneurysms 1
• Avoid unnecessary neuroimaging when clear temporal relationship to viral infection exists 2

Common Etiologies by Frequency

Based on large clinic series evaluation:

1. Nasal/sinus disease (30%) - most amenable to treatment 4
2. Idiopathic causes (16-26%) 4, 5
3. Post-viral (19-27%) - including COVID-19 4, 5
4. Post-head trauma (14%) 5
5. Allergic rhinitis (15%) 5

Treatment Strategy

Address Underlying Causes

• Treat sinonasal inflammatory disease with appropriate medical or surgical management 2
• Excise obstructing polyps or masses 3
• Use corticosteroids for inflammatory conditions 6, 3

Olfactory Training (Primary Treatment for Persistent Loss)

• Start olfactory training immediately and continue for minimum 3-6 months - this is the primary evidence-based treatment for persistent dysfunction 2
• Consider phosphodiesterase inhibitors, insulin, or corticosteroids for COVID-19-related loss based on emerging evidence 6

Dietary Management

• Refer to registered dietitian for counseling on flavor enhancement, additional seasoning, and expanding dietary options 2
• Use flavor enhancers to promote adequate food intake 2

Follow-Up Protocol

• Re-evaluate at 1 month, 3 months, and 6 months after initiating treatment 2
• Refer to otolaryngologist or specialized smell/taste clinic if no improvement after 3-6 months 2
• Repeat psychophysical testing at follow-up visits to objectively document changes 1

Critical Safety Considerations

• Address inability to detect spoiled food or gas leaks - counsel patients on safety measures 2
• Document impact on quality of life, as chemosensory dysfunction significantly affects daily functioning 3

Key Pitfalls to Avoid

• Do not overlook COVID-19 as causative agent, especially when smell/taste loss is the primary or sole symptom 2
• Do not rely on patient self-assessment - 60-80% of chronic rhinosinusitis patients have smell loss but cannot accurately gauge severity 1
• Recognize that most "taste" complaints actually represent olfactory dysfunction (loss of retronasal olfaction/flavor perception) rather than true gustatory loss of basic tastes (sweet, salty, sour, bitter, umami) 1, 7
• Total circulating eosinophil count may serve as useful screening test for underlying nasal/sinus disease 4