The effects of lumbar spine high velocity low amplitude thrust (HVLAT) manipulation on upper limb cutaneous blood supply

Introduction: Spinal manipulation is commonly employed by osteopaths to correct somatic and visceral dysfunction. Much research has concentrated on the somatovisceral effects of spinal manipulation, with many studies demonstrating sympathoexcitation/inhibition following spinal manipulation. The mechanisms behind the neurophysiological effects of spinal manipulation still remains poorly understood. No published study to date has investigated the effect of spinal manipulation on the sympathetic innervation of regions of the body with no known neural connections. Previous studies that used cutaneous blood flow (CBF) as measures of sympathetic activity have not considered the contribution that breathing or postural perturbation have on study outcomes. The aim of this study was to investigate the effect a unilateral lumbosacral HVLAT on CBF to the upper limb, and to estimate the contribution that breathing or postural perturbation may have on the study outcome. Design: The study was a strictly controlled, carry-over design on a cohort of twenty-eight asymptomatic, male osteopathic students of similar age and body mass index. Methods: CBF to the distal, palmar surface of the both forearms was measured using Laser Doppler Flowmetry (LDF). After 10minute acclimatising period, each subject acted as their own control whilst an initial 5-minute baselinemeasurement of CBFwas established. This was followed directly by the first control, postural perturbation for the HVLAT in right rotation, and a further 5-minute ‘post-control 1’ recording phase. This was then followed directly by the second control, postural perturbation for the HVLAT in right rotation and breathing relaxation, and a further 5-minute ‘post-control 2’ recording phase. The experimental intervention (HVLAT to L5-S1) was then applied, and followed by a further 5-minute ‘post-experimental intervention’ recording of CBF. Results: All raw data for the different interventions were converted into percentiles relative to the baseline reading so the data could be analysed by a one way ANOVA and post-hoc Tukey’s tests. The results indicated that there was a significant change in CBF from baseline level to the experimental intervention (p 0.05). However, the results illustrate the contribution that postural perturbation and especially breathing have on the outcome of this study which was calculated to be 4.2% and 7.5%, and 48% and 65%, respectively for the contralateral and ipsilateral upper limb respectively. Conclusion: This study provides preliminary evidence that a unilaterally applied HVLAT to the right L5/S1 lumbar zygo-apophyseal joint results in side-specific peripheral changes in the upper limbs. However, there is also preliminary evidence in this study that the breathing relaxation technique used in HVLAT’s contributes to the magnitude of the outcome as assessed by changes in CBF. It is concluded that the breathing effect should be included in interpreting past studies and in the design of future studies.