The immediate effects of atlanto-occipital joint manipulation and suboccipital muscle inhibition technique on active mouth opening and pressure pain sensitivity over latent myofascial trigger points in the masticatory muscles.
METHODS
A randomized controlled trial.


OBJECTIVE
To investigate the immediate effects on pressure pain thresholds over latent trigger points (TrPs) in the masseter and temporalis muscles and active mouth opening following atlanto-occipital joint thrust manipulation or a soft tissue manual intervention targeted to the suboccipital muscles.


BACKGROUND
Previous studies have described hypoalgesic effects of neck manipulative interventions over TrPs in the cervical musculature. There is a lack of studies analyzing these mechanisms over TrPs of muscles innervated by the trigeminal nerve.


METHODS
One hundred twenty-two volunteers, 31 men and 91 women, between the ages of 18 and 30 years, with latent TrPs in the masseter muscle, were randomly divided into 3 groups: a manipulative group who received an atlanto-occipital joint thrust, a soft tissue group who received an inhibition technique over the suboccipital muscles, and a control group who did not receive an intervention. Pressure pain thresholds over latent TrPs in the masseter and temporalis muscles, and active mouth opening were assessed pretreatment and 2 minutes posttreatment by a blinded assessor. Mixed-model analyses of variance (ANOVA) were used to examine the effects of interventions on each outcome, with group as the between-subjects variable and time as the within-subjects variable. The primary analysis was the group-by-time interaction.


RESULTS
The 2-by-3 mixed-model ANOVA revealed a significant group-by-time interaction for changes in pressure pain thresholds over masseter (P<.01) and temporalis (P = .003) muscle latent TrPs and also for active mouth opening (P<.001) in favor of the manipulative and soft tissue groups. Between-group effect sizes were small.


CONCLUSIONS
The application of an atlanto-occipital thrust manipulation or soft tissue technique targeted to the suboccipital muscles led to an immediate increase in pressure pain thresholds over latent TrPs in the masseter and temporalis muscles and an increase in maximum active mouth opening. Nevertheless, the effects of both interventions were small and future studies are required to elucidate the clinical relevance of these changes.


METHODS
Therapy, level 1b.J Orthop Sports Phys Ther 2010;40(5):310-317, Epub 12 April 2010. doi:10.2519/jospt.2010.3257.
Oliveira-Campelo
Natalia M
NM
Escuela de Osteopatía de Madrid, Escola Superior de Tecnología de Saúde, Porto, Portugal.
Rubens-Rebelatto
José
J
Martí N-Vallejo
Francisco J
FJ
Alburquerque-Sendí N
Francisco
F
Fernández-de-Las-Peñas
César
C
D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D001269:Atlanto-Occipital Joint / Q000503:physiopathology*; D005260:Female; D006801:Humans; D007592:Joint Diseases / Q000175:diagnosis / Q000534:rehabilitation / Q000628:therapy*; D008297:Male; D008349:Manipulation, Orthopedic; D008406:Masseter Muscle / Q000503:physiopathology; D008410:Masticatory Muscles / Q000503:physiopathology*; D009055:Mouth / Q000503:physiopathology*; D018482:Muscle, Skeletal / Q000503:physiopathology; D009209:Myofascial Pain Syndromes / Q000175:diagnosis / Q000534:rehabilitation / Q000628:therapy*; D011312:Pressure; D013703:Temporal Muscle / Q000503:physiopathology; D013706:Temporomandibular Joint Dysfunction Syndrome / Q000175:diagnosis / Q000534:rehabilitation / Q000628:therapy; D013997:Time Factors; D016896:Treatment Outcome; D055815:Young Adult