Effects of Upper and Lower Cervical Spinal Manipulative Therapy on Blood Pressure and Heart Rate Variability in Volunteers and Patients With Neck Pain: A Randomized Controlled, Cross-Over, Preliminary Study
SOURCE: J Chiro Med 2015 (Mar); 14 (1): 1–9 ~ FULL TEXT
Ni Ni Win, MBBS, PhD, Anna Maria S. Jorgensen, PhD,
Yu Sui Chen, PhD, and Michael T. Haneline, DC, MPH
Senior Lecturer, International Medical University,
Chiropractic, School of Health Sciences,
Kuala Lumpur, Malaysia
OBJECTIVE: The aims of this study were to examine autonomic nervous system responses by using heart rate variability analysis (HRV), hemodynamic parameters and numeric pain scale (NPS) when either upper (C1 and C2) or lower (C6 and C7) cervical segments were manipulated in volunteers, and whether such response would be altered in acute mechanical neck pain patients after spinal manipulative therapy (SMT).
METHODS: A randomized controlled, cross-over, preliminary study was conducted on 10 asymptomatic normotensive volunteers and 10 normotensive patients complaining of acute neck pain. HRV, blood pressure (BP) and heart rate (HR), and NPS were recorded after upper cervical and lower cervical segments SMT in volunteer and patient groups.
RESULTS: The standard deviation of average normal to normal R-R intervals (SDNN) increased (83.54 ± 22 vs. 105.41 ± 20; P = .02) after upper cervical SMT. The normalized unit of high frequency (nuHF), which shows parasympathetic activity, was predominant (40.18 ± 9 vs. 46.08 ± 14) after upper cervical SMT (P = .03) with a significant decrease (109 ± 10 vs. 98 ± 5) in systolic BP (P = .002). Low frequency to high frequency (LF/HF) ratio, which shows predominance of sympathetic activity increased (1.05 ± 0.7 vs. 1.51 ± 0.5; P = .02) after lower cervical SMT in the healthy volunteers group. However, there was an increase in SDNN (70.48 ± 18 vs. 90.23 ± 20; P = .02 and 75.19 ± 16 vs 97.52 ± 22; P = .01), a decrease in LF/HF ratio (1.33 ± 0.3 vs. 0.81 ± 0.2; P = .001 and 1.22 ± 0.4 vs. 0.86 ± 0.3; P = .02), which was associated with decreased systolic BP (105 ± 10 vs. 95 ± 9; P = .01 and 102 ± 9 vs. 91 ± 10; P = .02) and NPS scores (3 ± 1 vs. 0; P = .01 and 3 ± 1 vs. 1 ± 1; P = .03) following both upper and lower cervical SMT in the patient’s group. The baseline HR was 67 ± 9 vs 64 ± 5 (upper cervical) and 65 ± 7 vs 69 ± 11 (lower cervical) in both the healthy volunteer’ and patient’ groups.
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CONCLUSION: Upper cervical SMT enhances dominance of parasympathetic and lower cervical SMT enhances dominance of sympathetic activity in this young volunteer group. However, dominance of parasympathetic activity was found in patients with neck pain that received both upper and lower cervical SMT.
KEYWORDS: Blood pressure; Heart rate; Manipulation; Spinal
From the FULL TEXT Article:
Hemodynamic parameters (blood pressure [BP] and heart/pulse rate) have been studied pre and post cervical [1-5] and thoracic manipulation. [2, 6-8] Hemodynamic changes have also been reported following atlas SMT, although the results are somewhat controversial with no significant changes in BP  or decrease in BP. [9-11] The results of studies concerning SMT to treat hypertension have not been clinically concluded [12-14] with the bias of hypotensive complication  and decreased diastolic BP.  The possible underlying mechanisms of spinal manipulative therapy (SMT) and hemodynamic changes, such as autonomic regulation, the effects of the pressor reflex and anatomical abnormal positions, are still poorly understood. [2, 3, 10, 11]
Heart rate variability (HRV) analysis is a noninvasive and widely used technique [15-21] which can provide important clinical information on the autonomic nervous system (ANS) and central nervous system because cyclical variation in heart rate is mediated by central neural mechanisms via baroreceptors and chemoreceptors.  HRV is used mostly to predict heart conditions, such as myocardial infarction  and to hypothesize the underlying mechanism of anesthetic drugs on hemodynamic changes. [20, 21]