The effectiveness of cerebrolysin, a multi-modal neurotrophic factor, for treatment of post-covid-19 persistent olfactory, gustatory and trigeminal chemosensory dysfunctions: a randomized clinical trial

Background: This trial aimed to monitor the outcomes of persistent post-covid-19 smell and taste disorders after cerebrolysin therapy, a NTF, and olfactory and gustatory trainings.Research design and methods: This was a prospective randomized trial. It included 250 patients (male = 93, female = 157; age: 31.3 +/- 8.9 years). Patients were randomized into group 1 (n = 150): received cerebrolysin [5 ml/d (IM), 5d/week] and practiced olfactory and gustatory trainings, and group 2 (n = 100): practiced olfactory and gustatory trainings only, for >= 8-24 weeks. Measures of outcomes were: a clinical questionnaire; sniffin' odor, taste and flavor identification tests; and global rating scales for smell and taste.Results: The duration of disorders was 11.7 +/- 3.7mo (range: 6-24mo). The majority (n = 167; 66.8%) developed parosmia within months (3.6 +/- 2.7mo) after anosmia. Objective testing showed anosmia in all and taste, flavor, and trigeminal sensory losses in 18% (n = 45). Analyses for secondary outcome were done on 202 patients (group 1 = 130; group 2 = 72). Recovery was complete in 61.5% (n = 80) with cerebrolysin therapy and partial in 17% (n = 22). There was no recovery with trainings only. There were no predictors for recovery.Conclusions: Cerebrolysin had fast, promising, and constant effect, with cure rate of > 60%. This might be due to its ability to initiate and enhance neuronal regeneration and reorganization of sensory epithelia.