Masseter Muscle in Somatosensory Tinnitus and Potential Therapeutic Role for Botulinum Toxin Type A: A Scoping Review

Background: Increasing evidence supports the existence of a somatosensory subtype of tinnitus, in which craniocervical-craniomandibular structures can modulate tinnitus perception also through central auditory pathways. Despite growing mechanistic evidence, no targeted pharmacological intervention has been validated for this subtype. Objectives: This study aimed to synthesize the anatomical and neurophysiological rationale linking masseter hyperactivity to somatosensory tinnitus and to discuss BoNT/A as a hypothesis-generating therapeutic option requiring clinical validation. Methods: A PRISMA-ScR-guided scoping review was conducted in MEDLINE and EMBASE, using three complementary search lines (last search: 31 May 2026). Results: Of 284 records screened, four studies met eligibility criteria: three from the search strategy on BoNT/A and tinnitus and one from the search strategy on tinnitus and masticatory dysfunction. One additional record (Ranoux and Levine, 2024) was identified through manual search, describing tinnitus improvement following periauricular and splenius capitis BoNT/A injections, with masseter/temporalis injection proposed as an alternative site in the same protocol. Conclusions: Current anatomical and neurophysiological evidence supports a plausible link between masseter hyperactivity and somatosensory tinnitus in selected patients. BoNT/A is established for reducing masseter hyperactivity and may theoretically reduce abnormal somatosensory input; however, direct clinical evidence for tinnitus improvement remains insufficient. Its use should be considered experimental or hypothesis-based, within a multidisciplinary framework and with standardized outcome assessment. Prospective controlled trials are needed.