Effect of cervical spinal adjustments on lumbar paraspinal muscle tone: evidence for facilitation of intersegmental tonic neck reflexes.

OBJECTIVES

To determine whether spinal adjustments, delivered to the upper vs. lower cervical spine, might result in tonic neck reflex-induced alterations in the activity of the lumbar paraspinal musculature.

DESIGN

Randomized, double-blind, before/after treatment comparisons.

SETTING

Cervical Ergonomics Laboratory, Palmer College of Chiropractic-West, Sunnyvale, CA.

SUBJECTS

Healthy, nonsymptomatic chiropractic college students, about evenly divided with respect to gender and ranging from 23-38 yr of age.

INTERVENTION

Modified "diversified" spinal adjustments, delivered bilaterally to either the upper (C2) or lower (C7) cervical region.

MAIN OUTCOME MEASURE

Tissue compliance measures using a tissue compliance meter, obtained from each subject at sites 2 cm on either side of the spinous processes of L1, L2, L3, L4 and L5 both prior to and within 15 min following treatments.

RESULTS

Upper cervical adjustments produced changes in lumbar tissue compliance which were only slight (p < .05) and not significantly different from that which occurred following upper cervical sham manipulation (p > .1). However, lower cervical adjustments induced increases in tissue compliance (decreases in tone) which were highly significant (p < .001) and relatively robust compared to those found following upper cervical adjustments (p < .01). Furthermore, the greatest effects were observed on either side of the L4 and L5 spinous processes, suggesting influences on the gluteal musculature in particular.

CONCLUSIONS

Results indicate that cervical spinal manipulation can have significant effects on the tone of the lumbopelvic musculature, presumably by facilitating tonic neck reflexes involving intersegmental spinal pathways.