Aim:

To evaluate the efficacy of botulinum toxin A injection (BTA) in the lateral pterygoid muscles assisted by electromyography (EMG) for the treatment of masticatory myofascial pain (MMP).

Material and methods:

We conducted a retrospective study of 31 patients diagnosed of MMP who were treated by infiltration of botulinum toxin A in 1, 2 or 3 times, in the lateral and medial pterygoid muscles by electromyographic control of the puncture site. We assessed the treatment effectiveness in pain intensity decrease by numerical scales (NS) and categorical scales (CS). The impact of pathology on its quality of life, the decrease of demand for analgesic drugs, and the duration of BTA effect and its side effects were also valued.

Results:

The mean decrease in pain after treatment was 4.9 ± 2.9 points in NS. A statistical decrease of the pain (p = 0.01) can be shown after treatment. There is no statistical relationship between greater improvement after the administration of a greater number of injections. However, there is a significant improvement in the decrease of the pain in CS (p = 0.028) after the administration of several injections. There is also a significant decrease (p = 0.012) of the use of analgesic medication post-treatment.

Conclusions:

EMG assisted pterygoid muscles infiltration of BTA is effective in the treatment of MMP; it improves quality of life and decreases the consumption of health resources.

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