METHODS: The study involves stimulation of a trigger point locus within the supraspinatus muscle (via intramuscular dry needling). The supraspinatus TrP will be confirmed by the presence of a visible local twitch response within the muscle, evoked during needle penetration. Raw painpressure threshold values (PPT) will be recorded from a trigger point site within the ipsilateral infraspinatus muscle at selected time intervals of 1, 2, 5 and 15 minutes. A baseline (pre-needling) reading will be recorded and the absolute PPT readings at each time interval (1-15 min) represented as a ratio of this baseline value.
RESULTS: Figure 1 illustrates representative data for one of the pilot subjects in our study. PPT readings in the infraspinatus sharply increase (i.e. decreased trigger point sensitivity) for the first two minutes post-needling. At the 2 minute mark, the PPT values tend to stabilize. Interestingly, the PPT values once again demonstrate a gradual, distinct rise between the 5 to 15 minute period, suggestive of a further decline in sensitivity at the infraspinatus site.
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