Article Text

Download PDFPDF
Impact of tDCS on persistent COVID-19 olfactory dysfunction: a double-blind sham-controlled study
  1. Lucilla Vestito1,
  2. Laura Mori1,2,
  3. Carlo Trompetto1,2,
  4. Diego Bagnasco1,3,
  5. Rikki F Canevari1,4,
  6. Marta Ponzano5,
  7. Davide Subbrero2,
  8. Ester Cecchella2,
  9. Cristina Barbara6,
  10. Piero Clavario6,
  11. Fabio Bandini7
  1. 1IRCCS Ospedale Policlinico San Martino, Genoa, Italy
  2. 2Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Genoa, Italy
  3. 3Department of Internal Medicine, University of Genoa, Genoa, Italy
  4. 4Department of Surgical Sciences, University of Genoa, Genoa, Italy
  5. 5Department of Health Sciences, Section of Biostatistics, University of Genoa, Genoa, Italy
  6. 6Cardiac Rehabilitation Center of Genoa, ASL 3 Genovese, Genoa, Italy
  7. 7Department of Neurology, ASL 3 Genovese, Ospedale Villa Scassi, Genoa, Italy
  1. Correspondence to Dr Fabio Bandini, Department of Neurology, ASL 3 Genovese, Ospedale Villa Scassi, Genoa 16149, Italy; fabio.bandini{at}asl3.liguria.it

Statistics from Altmetric.com

Request Permissions

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.

Introduction

Loss of smell is a characteristic finding of COVID-19. It may outpersist the resolution of the disease, though recovery varies significantly, ranging from 15 to 180 days.1 Studies have purported central nervous system involvement in COVID-19 anosmia, mostly in the orbitofrontal cortex (OFC), the neural substrate for conscious olfactory perception.2 Given the high prevalence of COVID-19, an enormous number of patients worldwide are at risk of long-term loss of smell. Olfaction is essential for detecting environmental hazards and for enjoying food. Smell loss can cause mood disorders, even suicidal ideation.3 Treating olfactory dysfunction is therefore of paramount importance. Different interventions have been tried in order to alleviate COVID-19 hyposmia, but with limited efficacy.4

Non-invasive brain stimulation techniques can be deemed as a promising alternative to traditional neurorehabilitative approaches for several diseases, including smell disturbances.5 In this double-blind, sham-controlled study, we implemented a 2-week session of combined olfactory training (OT) and anodal transcranial direct current stimulation (A-tDCS) in seven patients with persistent COVID-19 hypo/anosmia, with the aim of investigating the effect of tDCS on olfactory function.

Materials and methods

Seven consecutive patients were enrolled in the study, according to the following inclusion criteria: (1) persistent (at least 6 months) hypo/anosmia due to COVID-19; (2) a score below 12 on the ‘Sniffin’ Sticks’ identification subtest. The exclusion criteria were: (1) severe mood disorder; (2) rhinological diseases; (3) epilepsy; (4) sensitive scalp. No medications for alleviating olfactory symptoms were allowed. Patients’ smell performances were first assessed immediately preceding stimulation (t0). A visual analogue scale smell …

View Full Text

Footnotes

  • Contributors LV and FB conceived the study and wrote the manuscript. LM and CT contributed to the design of the study. DB, RFC, CB and PC contributed to the acquisition of the data. DS and EC participated in the experiments. MP analysed the data.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.