Effect of High-Tone External Muscle Stimulation (High-Tone Therapy) in Neuro-Musculoskeletal Disorders: A Narrative Review

High-tone external muscle stimulation (HTEMS) or high-tone therapy is a new type of electrotherapy. Unlike the conventional electrotherapy that uses a fixed frequency, in HTEMS, the frequency and amplitude are simultaneously modulated, delivering much higher energy into the tissues. Recently, considerable attention has been paid to applying high-tone therapy in managing different disorders. This systematic study, therefore, was set out to assess the effect of high-tone therapy in various neuro-musculoskeletal disorders. After an exclusive search in databases of PubMed, Scopus, and Google Scholar, seven relevant studies were selected, including 3 studies for low back pain, 2 studies for peripheral neuropathy, 1 study in multiple sclerosis patients, and 1 preprint study on the subjects with anterior cruciate ligament reconstruction. PEDro (the physiotherapy evidence database) scale was used to assess the quality of the included articles. Although the studies reported that high-tone therapy significantly improved signs and symptoms, the low number and poor methodological quality of included studies do not allow determining certain effectiveness of HTEMS, and it could be an important reason for performing more research in the future.