A Randomized Controlled Trial of Smell Training and Trigeminal Nerve Stimulation in the Treatment of COVID-related Persistent Smell Loss
Medical University of South Carolina
Summary
Persistent smell loss that can include diminished or distorted smell function is a common symptom of long COVID syndrome. There are limited treatment options for long COVID-related smell loss. This study aims to determine the efficacy of two at-home treatments, smell training and non-invasive trigeminal nerve stimulation. This study requires participants to conduct daily at-home treatment sessions, attend three in-person study visits at the MUSC Department of Psychiatry and Behavioral Sciences, and complete electronic questionnaires over the 12-week trial, and again at the six-month timepoint. Participants in this trial may benefit directly with an improvement in sense of smell. However, participation may also help society more generally, as this study will provide new information about long COVID-related smell loss and its treatment.
Description
Sudden smell loss (SL), a hallmark feature of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-coV-2/COVID), frequently persists well past the initial recovery; rates of unresolved anosmia (total loss) are 21%, with unresolved hyposmia (reduced smell) or parosmia (distorted smell) higher at nearly 50%. SL is now recognized as a core symptom of "long COVID" (LC), which also includes other impairments in mood, cognition, and sleep. Given that SL itself can negatively impact many of the same problems being recognized in the symptomatology of LC, it is likely that SL is both a symptom of LC a…
Eligibility
- Age range
- 18–65 years
- Sex
- All
- Healthy volunteers
- No
Inclusion Criteria: * treatment-seeking for COVID-related persistent SL (anosmia, hyposmia, phantosmia or parosmia) * at least 1-month from SARS-coV-2 PCR-positive and/or rapid home-positive tests * normal sense of smell prior to COVID * naïve to both smell training (ST) and trigeminal nerve stimulation (TNS) * able to comprehend English and provide informed consent Exclusion Criteria: * history of head injury (e.g. sport, accident, combat blast) * sinonasal condition (e.g. upper respiratory infection, rhinosinusitis, polyps) * neurological disorder (e.g. epilepsy, neurodegenerative disorde…
Interventions
- DeviceTrigeminal Nerve Stimulation (TNS)
Non-invasive, pain-free, low-level electrical stimulation to the forehead to modulate the trigeminal nerve and enhance smell function through activation of the highly connected olfactory-intranasal trigeminal brain circuits.
- OtherActive Smell Training (ST)
Sniffing various higher intensity odorant chemicals while performing odor-related cognitive tasks. 16 odorant chemicals will be used for training including: 2 phenyl ethanol, eugenol, lemon, eucalyptus, cinnamon, peppermint, coffee, mandarin, lavender, vanilla, lilac, ginger, chocolate, thyme, banana, and bacon.
- OtherPlacebo Smell Training (PBO)
Sniffing the same lower intensity odorant chemicals (i.e. N-butanol and 2-phenyl ethanol) over the course of the trial and performing no odor-related cognitive tasks.
Location
- Medical University of South CarolinaCharleston, South Carolina