Botulinum Toxin for Somatosensory Tinnitus Relief

A scoping review has mapped the emerging rationale for using Botulinum Toxin Type A (BoNT/A) in the masseter muscle as a potential treatment for a specific subtype of tinnitus. Published in Toxins, the work by Jacopo Gardellin and colleagues synthesizes the anatomical and neurophysiological evidence connecting jaw muscle tension to altered sound perception. The central finding is a plausible biological link, but with a clear caveat: clinical validation through controlled trials is still missing.

Method: Tracking a Specific Hypothesis

To capture the state of evidence, the researchers followed the PRISMA-ScR guidelines for a scoping review. They searched MEDLINE and EMBASE with three specific strategies focused on BoNT/A and tinnitus, and on masticatory (jaw) dysfunction and tinnitus. The search period ended on 31 May 2026. Of 284 records initially screened, only four met the pre-defined eligibility criteria. Three emerged from the BoNT/A-tinnitus search line, and one from the masticatory dysfunction-tinnitus line. The authors also noted one additional relevant report by Ranoux and Levine (2024) through manual search, which described tinnitus improvement after BoNT/A injections in neck and periauricular muscles, and suggested masseter or temporalis injections as an alternative approach.

Anatomical Basis: How the Jaw Talks to the Ear

The review builds a logical case for why masseter tension might influence tinnitus in some individuals. The masseter, a primary chewing muscle, is innervated by the trigeminal nerve. Sensory fibers from this nerve converge with auditory pathways in brainstem nuclei like the cochlear nucleus and inferior colliculus. This convergence is the foundation of “somatosensory tinnitus,” where sensations from the head and neck can modulate auditory perception. The researchers propose that hyperactivity or dysfunction in the masseter muscle could send abnormal or increased somatosensory signals into these shared central pathways, potentially increasing neural gain or “turning up the volume” on tinnitus perception.

Findings: Limited but Focused Evidence

The retrieved studies collectively support a testable hypothesis. BoNT/A is a well-established treatment for conditions involving masseter hyperactivity, such as bruxism and temporomandibular disorders (TMD), by causing temporary muscle relaxation. Theoretically, injecting BoNT/A into the masseter could reduce this abnormal somatosensory input to the auditory system, thereby reducing tinnitus loudness or annoyance in patients where the two are linked. The case report by Ranoux and Levine adds a practical dimension, demonstrating that targeting related muscles can have an effect and proposing masseter injections as a logical next step. As the authors note, this idea shares conceptual ground with other neuromodulatory approaches for related conditions, such as the use of vagus nerve stimulation for misophonia.

A Strong Rationale, But a Clinical Evidence Gap

Gardellin and colleagues conclude that while the anatomical and neurophysiological rationale is strong, the direct clinical evidence is insufficient. The lack of prospective, controlled trials means it is not yet possible to confirm BoNT/A’s efficacy or identify which patients with tinnitus might benefit. The connection between craniocervical health and auditory symptoms is a recognized area of interest, also observed in studies linking migraine to hearing disorders and tinnitus.

Practical Implications for Patients and Clinicians

The authors are explicit about the current status of this approach: it should be considered experimental or hypothesis-based. For clinicians, this means any use of BoNT/A for tinnitus should be embedded within a multidisciplinary framework that includes audiological, dental, and neurological assessment. Standardized outcome measures for tinnitus severity and impact are essential. Patients interested in this avenue should understand it is not a validated treatment but a rational experimental option based on their specific symptoms, particularly if they have co-occurring jaw tension, bruxism, or TMD. This precision aligns with a broader trend in tinnitus management, moving towards stratified subtypes rather than a one-size-fits-all approach, similar to the targeted dietary research for conditions like Ménière’s disease and tinnitus.

What Comes Next: The Need for Targeted Trials

The primary call from this review is for prospective controlled trials. Future research must clearly define the “somatosensory tinnitus” subtype, likely through provocation maneuvers or confirmed comorbid TMD, and test BoNT/A against a placebo injection. The authors suggest these trials should use standardized injection protocols and validated tinnitus questionnaires. This careful, evidence-building path is necessary before BoNT/A can transition from a plausible idea to a recommended therapy.

Source: Gardellin, J.; D’Angelo, M.; Spadotto, L. Masseter Botulinum Toxin Injections for Somatosensory Tinnitus: A Scoping Review on Rationale and Current Evidence. Toxins 2026, 18, 310. https://doi.org/10.3390/toxins18070310