Postinfectious olfactory loss: A retrospective study on 791 patients

Abstract

Objectives/Hypothesis: Postinfectious olfactory loss is among the most common causes of olfactory impairment and has substantial negative impact on patients' quality of life. Recovery rates have been shown to spontaneously improve in most of patients, usually within 2 to 3 years. However, existing studies are limited by small sample sizes and short follow-up. We aimed to assess the prognostic factors for recovery in a large sample of 791 patients with postinfectious olfactory disorders.Study Design: Retrospective cohort.Methods: We performed a retrospective analysis of 791 patients with postinfectious olfactory loss. Olfactory functions were assessed using the Sniffin' Sticks test at the first and final visits (mean follow-up 5 1.94 years).Results: Smell test scores improved over time. In particular, patient's age and the odor threshold (T), odor discrimination (D), and odor identification (I) (TDI) score at first visit were significant predictors of the extent of change. The percentage of anosmic and hyposmic patients exhibiting clinically significant improvement was 46% and 35%, respectively.Conclusions: This study provides new evidence within the postinfectious olfactory loss literature, shedding light on the prognostic factors and showing that recovery of olfactory function is very frequent, even many years after the infection.

The use of platelet‐rich plasma in treatment of olfactory dysfunction: A pilot study

“…However, all patients subjectively continued to report smell loss. In light of recent findings suggesting spontaneous recovery is possible even after a year, we should consider our results in that context. However, the direct temporal relationship of the improvement in our patients after injection causes us to consider this a finding worth investigating further.…”

“…The etiology of olfactory dysfunction is quite varied, including postviral, post‐traumatic, and idiopathic loss of smell. Unfortunately, with these etiologies, the likelihood of spontaneous recovery is generally poor, with only approximately one‐third of people regaining function and the duration of loss negatively correlating with recovery rate . Treatment for olfactory dysfunction is also limited.…”

Examination of olfactory training effectiveness in relation to its complexity and the cause of olfactory loss

“…Former studies suggest that spontaneous recovery can be observed in approximately one-third of postinfectious patients. [24][25][26] Although we are unable to exclude the possible effects of spontaneous recovery, the improvement in our training cohort occurred approximately within 6 months, as opposed to at least the 12-month period typical of untreated patients. 24,26 Further studies with placebo control should be performed.…”

Symptom Criteria for COVID‐19 Testing of Heath Care Workers

“…Respiratory tract infections can cause direct damage to neurons in the olfactory epithelium. Postinfectious olfactory dysfunction is seen frequently after a respiratory tract infection and accounts for 18% to 45% of all cases of anosmia 8 . Recent reports have suggested that anosmia and ageusia could be potential symptoms of COVID‐19 5,9,10 .…”