What investigations are recommended for an elderly patient with anosmia (loss of smell) since COVID-19 infection a few years ago?

Investigations for Persistent Post-COVID Anosmia in Elderly Patients

For an elderly patient with anosmia persisting years after COVID-19 infection, perform nasal endoscopy and standardized olfactory testing (UPSIT or Sniffin'Sticks), and consider MRI brain with olfactory protocol if symptoms persist beyond 6 months or if neurological signs are present. 1, 2

Essential Initial Investigations

Nasal Endoscopy (Mandatory)

• Rigid nasal endoscopy is essential to differentiate between obstructive causes (polyps, masses, tumors) and non-obstructive inflammatory causes 2
• This examination identifies treatable sinonasal pathology that may be contributing to or causing the olfactory dysfunction 1
• Look specifically for polyps, masses, inflammatory changes, or obstructing lesions that could explain persistent symptoms 2

Standardized Olfactory Testing (Strongly Recommended)

• Perform objective psychophysical testing using UPSIT (University of Pennsylvania Smell Identification Test) or Sniffin'Sticks extended version 1, 2
• Objective testing is critical because patients commonly underestimate their impairment - one study showed 98.3% had objective olfactory dysfunction even when only 35% self-reported complaints 2
• This quantifies the severity of dysfunction and provides baseline data for monitoring recovery 1

Advanced Imaging (Conditional)

CT Sinuses

• Indicated if chronic rhinosinusitis is suspected on endoscopy 2
• Chronic rhinosinusitis accounts for a significant proportion of chronic olfactory dysfunction cases 2

MRI Brain with Olfactory Protocol

• Consider MRI if neurologic signs are present or symptoms persist beyond 6 months despite treatment 2
• Early COVID-19 studies showed normal olfactory bulb volume and signal intensity on MRI, but olfactory cleft obstructive inflammation 3
• This helps rule out central nervous system pathology and evaluates olfactory bulb integrity 3

What NOT to Do (Common Pitfalls)

• Do not rely on patient self-report alone - objective testing reveals much higher rates of dysfunction than subjective complaints 2
• Do not skip nasal endoscopy - visual inspection is essential to identify treatable sinonasal pathology 2
• Do not order extensive blood work or metabolic panels unless other systemic symptoms suggest metabolic causes (insidious onset over weeks-to-months suggests metabolic causes, but sudden post-viral onset does not) 2

Clinical Context

The evidence shows that COVID-19-related anosmia typically occurs without traditional nasal symptoms (congestion, rhinorrhea), unlike other viral upper respiratory infections 2. In elderly patients with persistent symptoms years after infection, the mechanism likely involves sustained damage to the olfactory epithelium or sustentacular cells rather than active inflammation 4, 5. Most patients recover fully or partially, but recovery duration varies significantly 4, 6.

Immediate Management Recommendation

While completing investigations, initiate olfactory training immediately using four strong-smelling substances for 20 seconds each, twice daily, continued for at least 3-6 months 2. This should be started regardless of investigation results, as it provides benefit across all etiologies 2.

Follow-Up Schedule

• Re-evaluate at 1,3, and 6 months after initiating treatment 2
• Refer to otolaryngology or specialized smell/taste clinic if no improvement after 3-6 months of olfactory training 2