Blood Pressure Influenced by Upper Cervical Adjustments
Several theories have been suggested for the effects of manipulative treatment and arterial blood pressure (BP). Subluxation and musculoskeletal dysfunction in spinal segments may result in stimulation of sympathetic tone, which may cause vasoconstriction and result in a rise of systemic BP.
Other theories include the effects of manipulation and changes in hormone levels, vestibulosympathetic and cervicosympathetic reflexes which alter BP, and the pressor reflex.
This two-part study attempted to determine whether a vectored adjustment of the atlas would cause a lowering of blood pressure. Eighty patients were evaluated by palpation, for BP (using a digital oscillometric sphygmomanometer) and for signs of pelvic rotation and a supine leg length check. Forty patients demonstrating signs of upper cervical subluxation were designated to the treatment group and 40 patients without such signs were assigned to the control group. Sideposture and upper cervical adjustments were performed on the participants in the treatment group. The control group patients were positioned in side posture but not adjusted. After two minutes BP was checked again. In the second part of this study, only patients with postural distortion were recruited. Pre-adjustment measurements with the patient in the supine and sitting positions were used as 'control' data, which was compared to the BP measurements taken after the upper cervical adjustment.
The results for both portions of this trial show significant differences between pretreatment and post treatment measurements in BP. The results also indicate that palpation and upper cervical adjustments may decrease systolic blood pressure, although it is uncertain how long this effect lasts. The authors recognize the weaknesses of this study, including the lack of blinding, repeated BP checks without adequate time for stabilization and no randomization. This article provides an interesting discussion on some of the possible theories that may explain the phenomenon of BP changes with upper cervical adjustments.
Knutson GA. Significant changes in systolic blood pressure post vectored upper cervical adjustment vs. resting control groups: a possible effect of the cervicosympathetic and/or pressor reflex. Journal of Manipulative and Physiological Therapeutics
2001:24(2), pp. 101-109.