Post-COVID-19 syndrome often includes symptoms that persist after the acute phase of infection, including loss of taste and smell (anosmia and aginguia, respectively). Photobiomodulation therapy (PBMT) has shown promise in treating neurological sequelae associated with COVID-19. In this case study, we present the results of PBMT using a class 4 therapeutic laser to restore taste and smell in two patients, aged 75 and 42, who experienced anosmia and aginguia after COVID-19.
Patient #1
A 75-year-old woman with a history of COVID-19 infection 1 year prior presented with persistent loss of taste and smell.
The patient underwent one transcranial PBMT using a Bell’s palsy protocol and a class 4 therapeutic laser. The treatment consisted of two parts, the first part was administered in the posterior superior cervical region targeting cranial nerve nuclei in the brainstem, and the second part was administered via neural pathways in the face and head.
The first section delivered 800 Joules at an average power of 8 Watts, a treatment time of 100 seconds, and a power density of 1.6 W/cm .2 Energy density (dose) is 8 J/cm2The second section delivered 720 Joules at an average power of 4 Watts, a treatment time of 180 seconds, and a power density of 0.8 W/cm .2 The energy density is about 7 J/cm2Both parts used wavelengths of 650, 810, 915, and 980 nm and were delivered at a combination of continuous wave and pulsed frequencies.
Within 24 hours of treatment, the patient reported a significant improvement in his sense of taste and smell, the first time he had experienced these sensations in over a year. Follow-up assessments one week and one month later revealed continued improvement in taste and smell perception, and the patient reported continued restoration of sensory function and improved quality of life.
Patient 2
A 42-year-old woman presented with symptoms similar to post-COVID-19 anosmia and dysgeusia after recovery from a moderate COVID-19 infection. The patient underwent one session of transcranial PBMT using the same parameters and protocol as patient 1.
Following the PBMT session, the patient reported immediate improvement in her sense of taste and smell. Subsequent follow-up assessments showed continued improvement in sensory perception, with the patient reporting gradual recovery of taste and smell sensitivity over several weeks. One month after treatment, the patient reported near complete resolution of her anosmia and taste loss, and a significantly improved quality of life.
Discussion
These case studies highlight the potential of transcranial PBMT using a class 4 therapeutic laser as a promising intervention to restore taste and smell in people experiencing long-term anosmia and taste loss following COVID-19 infection. The rapid and sustained improvement in sensory function observed after a single PBMT session suggests that PBMT may offer a viable therapeutic approach to address the neurological symptoms of COVID-19.
These findings are supported by a published pilot clinical study of PBM for COVID-19-associated anosmia and taste disorders, which concluded that “our findings demonstrated significant improvement in both olfactory and gustatory function.”1 Further studies are needed to validate these findings and optimize treatment protocols for people with long-term sensory disorders associated with COVID-19.
reference
- Panhoca VH, Ferreira LT, de Souza VB, et al. “Can photobiomodulation restore smell and taste disorders caused by COVID-19? A pilot clinical study” J Biophotonics2023 Jun;16(6):e202300003.
