# Safety, efficacy, and mechanism of action of the temporo-masseteric nerve block

## TL;DR

This study shows that the temporo-masseteric nerve block is effective and safe for reducing masticatory pain, with minimal side effects.

## Contribution

The study provides new evidence on the efficacy and safety of the temporo-masseteric nerve block for masticatory myalgia.

## Key findings

- The TMNB injection reduced pain scores by 70% in 52 patients with masticatory myalgia.
- Motor nerve conduction studies showed impaired compound-motor-action-potential after TMNB injection.
- Only four out of 90 cases showed no pain relief, with mild adverse events reported.

## Abstract

The objective of the study was to assess the utility and safety of
Temporo-masseteric Nerve Block (TMNB), and to explore the mechanism for its
apparent sustained pain relief. This manuscript describes, (1) a retrospective
study evaluating pain reduction in patients who received the TMNB injection for
the management of masticatory myogeneous pain (myalgia, per Diagnostic Criteria
for Temporomandibular Disorders (DC/TMD criteria)), and (2) a motor nerve
conduction study (NCS) of the temporalis and masseter, performed in the absence
of signs or symptoms of TMD, before and after the TMNB injection. The results
were as follows. (1) Retrospective study: (n = 186). 52 instances had available
baseline and post-TMNB Numerical Pain Rating Scores (NRS) scores, the TMNB
injection reduced baseline NRS scores by 70%; pain difference was qualitatively
documented in 90 instances (pain relief or improvement in 86/90 instances). 4
instances yielded no pain relief. Mild adverse events recorded included a
vasovagal episode (n = 1), transient weakening of blink (n = 2) or burning
sensation (n = 1). (2) The Motor NCS demonstrated impairment of the
compound-motor-action-potential (CMAP) as recorded from temporalis and masseter
muscles following the TMNB injection. In conclusion, the TMNB injection is
efficacious and safe. Further studies are warranted to warrant its effectiveness.