Masseter trigger points and manual therapy

A recent study from Spain evaluate the immediate effects, on pressure pain sensitivity and active mouth opening, following the application of neuromuscular or strain/counter-strain technique in latent myofascial trigger points (MTrPs) in the masseter muscle. The study was published in Journal of Bodywork and Movement Therapies in January 2009.

The study involved seventy-one subjects aged between 20–65 years old with MTrPs in the masseter muscle. Myofascial trigger points (MTrPs) was assesed as follows: subject supine and the examiner standing at the head of the table, the examiner used his thumb and index fingers to palpate (using pincer palpation) the masseter muscle to establish if MTrPs were present. MTrPs were located in the middle of the most superficial fibers of the masseter muscle. The referred pain produced by these MTrPs spread to the maxilla or to the mandible teeth. (A & B figure below)

Subjects were divided randomly into three groups: group A which was treated with a neuromuscular intervention, group B treated with the strain/counter-strain technique, and group C as control group. Each treatment group received a weekly treatment session during 3 consecutive weeks.

Strain/counter-strain technique, the subject lay supine with the cervical spine in a neutral position. The therapist located the latent MTrPs in the masseter muscle using flat palpation. Once located, the therapist applied gradually increasing pressure to the MTrP until the sensation of pressure became one of pressure and pain. At that moment, the subject was then passively placed in a position that reduced the tension under the palpating fingers and caused a subjective reduction of pain by around 75%. In the present study, the position that reduced pain was usually ipsi-lateral side-flexion of the cervical spine in addition to a slightly mouth opening, i.e. 5–8 mm. That position was maintained for 90 s. Finally, the subject was slowly passively placed in a neutral position.

Pictures from Ibáñez-García et al. JBMT: January 2009.

Neuromuscular technique: the subject lay supine with the cervical spine in a neutral and relaxed position. A classic lubricant was placed over the skin of the subjects to prevent skin irritation and to facilitate smooth movement. Then, the therapist placed his thumb over the masseter fibers. Once applied pressure, the thumb slides over the muscle six to eight times, without pain. Each sliding movement (5–8 cm length) lasted 4–5 seconds.

Pictures from Ibáñez-García et al. JBMT: January 2009.

Outcomes measures were pressure pain thresholds (PPTs), active mouth opening and local pain (visual analogue scale, VAS) elicited by the application of 2.5 kg/cm2 of pressure over the MTrP. They were captured at baseline and 1 week after discharge by an assessor blinded to the treatment allocation of the subject.

The results

The ANOVA found a significant group×time interaction (F=25.3; p<0.001) for changes in PPT, changes in active mouth opening (F=10.5; p<0.001), and local pain evoked by 2.5 kg/cm2 of pressure (F=10.1; p<0.001). Within-group effect sizes were large (d>1) for PPT and mouth opening, and moderate for local pain (d<0.7, 0.5) in both intervention groups; but small (d<0.2) for the control group in all outcomes. No significant differences between both intervention groups were found for any outcome (p>0.8).

Their results suggest that neuromuscular or strain/counter-strain technique might be employed in the management of latent MTrPs in the masseter muscle.

The application of a neuromuscular or strain/counter-strain technique over latent MTrPs in the masseter muscle increases PPTs, increases active mouth opening and decreases local pain induced by standard pressure. Further, the effect sizes were large for both intervention groups, suggesting a strong clinical effect, whereas the effect size of the control was small.

Jordi Ibáñez-García, Francisco Alburquerque-Sendín, Cleofás Rodríguez-Blanco, Didac Girao, Albert Atienza-Meseguer, Sergi Planella-Abella, César Fernández-de-las Peñas.   Changes in masseter muscle trigger points following strain-counterstrain or neuro-muscular technique. Journal of Bodywork and Movement Therapies Volume 13, Issue 1, Pages 2-10 (January 2009).

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