As part of the experiment, 30 patients with middle or lower cervical pain underwent SMT.
Results showed that SMT "produced a hypoalgesic effect as revealed by increased pressure pain thresholds on the side of treatment and decreased resting visual analogue scale scores. The treatment technique also produced a sympathoexcitatory effect with an increase in skin conductance and a decrease in skin temperature. There was a decrease in superficial neck flexor muscle activity at the lower levels of a staged cranio-cervical flexion test."
"The combination of all findings would support the proposal that SMT may, at least initially, exert part of its influence via activation of the PAG," conclude the study’s authors.
Manual Therapy – May 2001;6:72-81.