Article

Current evidence suggests that spinal manipulative therapy (SMT) is
effective in the treatment of people with low back pain (LBP); however, the
corresponding mechanisms are unknown. Hypoalgesia is associated with SMT and is
suggestive of specific mechanisms. The primary purpose of this study
was to assess the immediate effects of SMT on thermal pain perception in people
with LBP. A secondary purpose was to determine whether the resulting hypoalgesia
was a local effect and whether psychological influences were associated with
changes in pain perception. DESIGN: This study was a randomized controlled trial.
SETTING: A sample of convenience was recruited from community and outpatient
clinics. PARTICIPANTS: Thirty-six people (10 men, 26 women) currently
experiencing LBP participated in the study. The average age of the participants
was 32.39 (SD=12.63) years, and the average duration of LBP was 221.79
(SD=365.37) weeks. INTERVENTION AND MEASUREMENTS: Baseline demographic and
psychological measurements were obtained, followed by quantitative sensory
testing to assess temporal summation and Adelta fiber-mediated pain perception.
Next, participants were randomly assigned to ride a stationary bicycle, perform
low back extension exercises, or receive SMT. Finally, the same quantitative
sensory testing protocol was reassessed to determine the immediate effects of
each intervention on thermal pain sensitivity. RESULTS: Hypoalgesia to Adelta
fiber-mediated pain perception was not observed. Group-dependent hypoalgesia of
temporal summation specific to the lumbar innervated region was observed.
Pair-wise comparisons indicated significant hypoalgesia in participants who
received SMT, but not in those who rode a stationary bicycle or performed low
back extension exercises. Psychological factors did not significantly correlate
with changes in temporal summation in participants who received SMT. LIMITATIONS:
Only immediate effects of SMT were measured, so the authors are unable to comment
on whether the inhibition of temporal summation is a lasting effect. Furthermore,
the authors are unable to comment on the relationship between their findings and
changes in clinical pain. CONCLUSIONS: Inhibition of Adelta fiber-mediated pain
perception was similar for all groups. However, inhibition of temporal summation
was observed only in participants receiving SMT, suggesting a modulation of
dorsal horn excitability that was observed primarily in the lumbar innervated
area.

Langue : ANGLAIS