Objective: This study investigates changes in the intrinsic inhibitory and facilitatory interactions within the sensorimotor cortex subsequent to a single session of cervical spine manipulation using single- and paired-pulse transcranial magnetic stimulation protocols.
Method: Twelve subjects with a history of reoccurring neck pain participated in this study. Short interval intracortical inhibition, short interval intracortical facilitation (SICF), motor evoked potentials, and cortical silent periods (CSPs) were recorded from the abductor pollicis brevis and the extensor indices proprios muscles of the dominant limb after single- and paired-pulse transcranial magnetic stimulation of the contralateral motor cortex. The experimental measures were recorded before and after spinal manipulation of dysfunctional cervical joints, and on a different day after passive head movement. To assess spinal excitability, F wave persistence and amplitudes were recorded after median nerve stimulation at the wrist.
Results: After cervical manipulations, there was an increase in SICF, a decrease in short interval intracortical inhibition, and a shortening of the CSP in abductor pollicis brevis. The opposite effect was observed in extensor indices proprios, with a decrease in SICF and a lengthening of the CSP. No motor evoked potentials or F wave response alterations were observed, and no changes were observed after the control condition.
Conclusion: Spinal manipulation of dysfunctional cervical joints may alter specific central corticomotor facilitatory and inhibitory neural processing and cortical motor control of 2 upper limb muscles in a muscle-specific manner. This suggests that spinal manipulation may alter sensorimotor integration. These findings may help elucidate mechanisms responsible for the effective relief of pain and restoration of functional ability documented after spinal manipulation.
Key Indexing Terms: Manipulation; Spinal; Neuronal Plasticity; Transcranial Magnetic Stimulation; Neural Inhibition; Central Nervous System; Chiropractic
Interexaminer reliability of a leg length analysis procedure among novice and experienced practitioners
Holt, K. R., Russell, D. G., Hoffmann, N. J., Bruce, B. I., Bushell, P. M., & Taylor, H. H. (2009)
Journal of manipulative and physiological therapeutics, 32(3), 216-222.
Objective: The purpose of this study was to evaluate the interexaminer reliability of a leg length analysis protocol between an experienced chiropractor and an inexperienced chiropractic student who has undergone an intensive training program.
Methods: Fifty participants, aged from 18 to 55 years, were recruited from the New Zealand College of Chiropractic teaching clinic. An experienced chiropractor and a final-year chiropractic student were the examiners. Participants were examined for leg length inequality in the prone straight leg and flexed knee positions by each of the examiners. The examiners were asked to record which leg appeared shorter in each position. Examiners were blinded to each other’s findings. κ statistics and percent agreement between examiners were used to assess interexaminer reliability.
Results: κ analysis revealed substantial interexaminer reliability in both leg positions and also substantial agreement when straight and flexed knee results were combined for each participant. κ scores ranged from 0.61, with 72% agreement, for the combined positions to 0.70, with 87% agreement, for the extended knee position. All of the κ statistics analyzed surpassed the minimal acceptable standard of 0.40 for a reliability trial such as this.
Conclusion: This study revealed good interexaminer reliability of all aspects of the leg length analysis protocol used in this study
Key Indexing Terms: Leg Length Inequality; Chiropractic; Observer Variation; Reproducibility of Results
Practice Characteristics of Chiropractors in New Zealand
Objective: To summarise the key findings of the 2007 New Zealand College of Chiropractic Stakeholders Advisory Committee survey of the New Zealand chiropractic profession.
Method: The survey questionnaire comprised 50 questions divided into 5 sections: the chiropractic practitioner, the chiropractic practice professional functions and referrals, accident compensation and the chiropractic patient. Hard copy surveys were mailed to all 306 chiropractors with a New Zealand postal address who were issued with an Annual Practicing Certificate during the 2005/2006 year. Chiropractors were invited to either complete the hard copy survey or complete the survey online using an electronic version.
Summary: 152 chiropractors responded to the survey. The results indicate there is a desire amongst the profession to increase the number of chiropractors in New Zealand. They also suggest that, despite the lack of mandate by the New Zealand Chiropractic Board for a set minimum number of continuing education hours, most New Zealand chiropractors appear to be engaging in a satisfactory level of continuing education.
Altered central integration of dual somatosensory input after cervical spine manipulation
Taylor, H. H., & Murphy, B. (2010)
Journal of manipulative and physiological therapeutics, 33(3), 178-188.
Objective: The aim of the current study was to investigate changes in the intrinsic inhibitory interactions within the somatosensory system subsequent to a session of spinal manipulation of dysfunctional cervical joints.
Method: Dual peripheral nerve stimulation somatosensory evoked potential (SEP) ratio technique was used in 13 subjects with a history of reoccurring neck stiffness and/or neck pain but no acute symptoms at the time of the study. Somatosensory evoked potentials were recorded after median and ulnar nerve stimulation at the wrist (1 millisecond square wave pulse, 2.47 Hz, 1 × motor threshold). The SEP ratios were calculated for the N9, N11, N13, P14-18, N20-P25, and P22-N30 peak complexes from SEP amplitudes obtained from simultaneous median and ulnar (MU) stimulation divided by the arithmetic sum of SEPs obtained from individual stimulation of the median (M) and ulnar (U) nerves.
Results: There was a significant decrease in the MU/M + U ratio for the cortical P22-N30 SEP component after chiropractic manipulation of the cervical spine. The P22-N30 cortical ratio change appears to be due to an increased ability to suppress the dual input as there was also a significant decrease in the amplitude of the MU recordings for the same cortical SEP peak (P22-N30) after the manipulations. No changes were observed after a control intervention.
Conclusion: This study suggests that cervical spine manipulation may alter cortical integration of dual somatosensory input. These findings may help to elucidate the mechanisms responsible for the effective relief of pain and restoration of functional ability documented after spinal manipulation treatment.
The elusive vertebral subluxation is the central defining clinical principle of the chiropractic profession. After almost 115 years of discussion there is still little consensus regarding the nature of the vertebral subluxation or its potential associated neurological manifestations. Some authors even deny that the subluxation exists. In this paper a model is presented that assumes that the putative vertebral subluxation represents a state of altered afferent input which is responsible for ongoing maladaptive central plastic changes that over time can lead to dysfunction, pain and other symptoms. A growing body of research that investigates the neuromodulatory effects of chiropractic care supports this model. This paper explores this research and discusses it in light of the vitalistic principles upon which chiropractic was founded. The model outlined in this paper may go some way to explain some of the beneficial effects of chiropractic care on nonmusculoskeletal conditions previously reported in the literature.
Index terms: MeSH: chiropractic; central nervous system; manipulation, spinal; proprioception; posture; evoked potentials, somatosensory; (other): sensorimotor integration; feed forward; vitalism.
Reflex effects of a spinal adjustment on blood pressure
Holt, K., Beck, R., Sexton, S., & Taylor, H. H. (2010)
Chiropractic Journal of Australia Volume 40 Issue 3 (Sep 2010)
Objective: To investigate whether an adjustment to any segment in the spine resulted in a blood pressure change and to see whether the direction of any potential blood pressure changes were dependent on the region of the spine adjusted.
Methods: Participants included 70 patients attending the New Zealand College of Chiropractic Student Health Centre. Blood pressure was recorded by a blinded examiner before and after either a single Diversified type chiropractic adjustment or an adjustment set-up with no thrust. Participants were randomly allocated to groups. Each trial was allocated to a subgroup based on the spinal region involved. Some participants were involved in more than one trial session with a total of 118 trials included in the study.
Results: Multifactorial repeated measures ANOVA assessing for any effect from the adjustment revealed a significant overall interactive effect for the factors TIME (pre / post) and GROUP (adjustment / control) [F (1,103)=4.23, p=0.042] for systolic blood pressure. Further analysis of the adjustment group revealed a significant overall effect [F (1,49)=10.89, p=0.002] with systolic blood pressure decreasing significantly (-3.9 +/- 10.3mmHg) following an adjustment. No other significant differences were found in the adjustment or control groups.
Conclusion: An adjustment to any segment in the spine resulted in a statistically significant average decrease in systolic blood pressure of 3.9 mmHg. The direction of blood pressure change that was observed was not dependent on the region of the spine adjusted. However, visual analysis suggests cervical and lumbopelvic adjustments had a greater influence on systolic blood pressure than thoracic adjustments. Diastolic blood pressure remained relatively constant. Average changes in blood pressure were unlikely to be clinically significant. However, in individual participants some blood pressure changes were considered to be clinically relevant following an adjustment.