Effect of Seated Cervical Spinal Manipulation on Autonomic Nervous System Activity as Measured by Heart Rate Variability and Plasma Norepinephrine Levels: A randomized Pre- and Poststudy.

OBJECTIVE: The objective of this study was to determine whether seated cervical manipulation produced changes in autonomic nervous system activity, as measured by heart rate variability and plasma norepinephrine levels. METHODS: Ninety-five healthy young adults (ages 20-48 years) were recruited into a single-blinded physiological study, with 47 randomized to a seated cervical manipulation and 44 randomized to a sham procedure. Heart rate variability in the frequency domain, and plasma norepinephrine levels were measured prior to, immediately following, and 5 minutes following the intervention. RESULTS: Electrocardiograms were obtained from 39 subjects in the sham group and 43 subjects in the manipulation group. No statistically significant changes were found in measures of heart rate variability in the frequency domain in either the manipulation or sham groups. Blood samples were obtained from 22 subjects in the sham group and 27 subjects in the manipulation group. Plasma norepinephrine levels, as measured by spectrophotometry, declined in both groups from pre- to immediately postintervention, and they remained at decreased levels 5 minutes after the interventions. There were no statistically significant differences between groups in pre- or postintervention norepinephrine levels. CONCLUSIONS: Measures of heart rate variability and plasma norepinephrine levels did not show that seated cervical manipulation produced short-term changes in autonomic nervous system activity compared to a sham procedure in healthy young adults.

Mitigating Bias in the Measurement of Heart Rate Variability in Physiological Studies of Spinal Manipulation: A Comparison Between Authentic and Sham Manipulation.

OBJECTIVE: The purpose of this study was to identify sources and strategies for the mitigation of bias in studies of spinal manipulation and heart rate variability. METHODS: A small-scale study compared the effects of a single session of sham and authentic cervical manipulation on heart rate variability as measured by power spectrum analysis. The participants were a sample of 31 healthy young students from the Canadian Memorial Chiropractic College, randomized into 2 study arms. The effectiveness of blinding was evaluated, and 2 alternative methods of data analysis were explored to mitigate risk of bias. Following execution of the study, the stages of implementation and data processing were scored against version 2 of the Cochrane risk-of-bias tool for randomized trials for risk of bias. RESULTS: The risk of bias arising from (1) the randomization process, (2) missing outcome data, and (3) selection of reported results was judged to be low. Risk of bias in (1) deviations from intended interventions (particularly due to the failure of masking) and (2) the measurement of the outcome, for example, through cleaning of the data, were judged to be high. CONCLUSION: The use of power spectrum analysis of heart rate variability based on 5-minute recordings of echocardiogram pre-and post-intervention contained multiple sources of bias that were challenging to mitigate. Based upon these findings, power spectrum analysis of heart rate variability using these parameters may be ill-suited to the study of physiological effects of spinal manipulative therapy.

The research enterprise at Canadian Memorial Chiropractic College.

OBJECTIVES: A bibliometric survey was conducted, using network and textual analysis tools, to assess the current state of the research enterprise at Canadian Memorial Chiropractic College and to augment planning processes. METHODS: Searches were conducted via several databases to identify publications attributable to the institution. Bibliometric data were summarized and post-processed using the programme VosViewer and analysis tools provided in the Web of Science. RESULTS: Canadian Memorial Chiropractic College is a productive source of peer-reviewed publications supported by a diverse suite of funding agencies and collaborating institutions, and published across a broad range of journals. CONCLUSIONS: As a private, single-purpose educational institution, awarding a qualification only in chiropractic, Canadian Memorial Chiropractic College probably performs well in its class of institution in terms of research productivity. However, assessment is constrained by inconsistencies on the part of authors, journals and databases in archiving data.

OBJECTIFS: On a mené une enquête bibliométrique à l'aide d'outils d'analyse de réseau et d'analyse textuelle, pour évaluer l'effort de recherche actuel du Canadian Memorial Chiropractic College et améliorer les processus de planification. MÉTHODES: On a interrogé plusieurs bases de données pour trouver des articles publiés par le College. Les données bibliométriques ont été résumées et post-traitées à l'aide du programme VosViewer et des outils d'analyse fournis dans le Web of Science. RÉSULTATS: Le Canadian Memorial Chiropractic College est une source abondante de parutions évaluées par des pairs, soutenues par un ensemble diversifié d'organismes de financement et d'établissements collaborateurs, et publiées dans un large éventail de revues. CONCLUSIONS: À titre d'établissement d'enseignement privé à vocation unique, qui ne délivre qu'une seule attestation de compétence en chiropratique, le Canadian Memorial Chiropractic College fait probablement bonne figure dans sa catégorie d'établissements pour ce qui est de la productivité en recherche. Toutefois, l'évaluation est limitée par certaines incohérences entre les données archivées par les auteurs, les revues et les bases de données.

Presumptive spondylogenic pruritus: a case study.

OBJECTIVE: To describe a case of a patient with chronic pruritus of the upper back and arms who underwent complete resolution of his complaint following a short course of chiropractic care. CASE PRESENTATION: A 36-year-old male suffering with chronic, severe pruritus affecting the upper back and both arms, presented for chiropractic treatment after pharmacological treatment and dietary restrictions failed to resolve his complaint. Physical examination revealed restrictions of thoracic and cervical intervertebral motion. However, radiological examination did not identify any substantial pathology of the spine. Following a short course of chiropractic treatment, which included spinal manipulation and home exercises, his complaint of pruritus resolved completely. SUMMARY: In this case, a severe and chronic complaint of pruritus which was refractory to other forms of care resolved quickly after the institution of chiropractic care. It is therefore hypothesized that the patient's pruritus was etiologically linked to biomechanical problems of the spine.

OBJECTIF: Décrire le cas d'un patient présentant un prurit chronique à la partie supérieure du haut du dos et aux bras qui est complètement disparu après une courte période de traitements chiropratiques. EXPOSÉ DU CAS: Un homme de 36 ans souffrant d'un prurit chronique grave à la partie supérieure du dos et aux deux bras s'est présenté à une clinique chiropratique après avoir suivi un traitement pharmacologique et un régime alimentaire qui se sont avérés infructueux. L'examen physique a révélé une limitation de la mobilité articulaire de la colonne dorsale et de la colonne cervicale. L'examen radiologique n'a révélé aucune pathologie grave de la colonne vertébrale. Après une brève période de séances chiropratiques par manipulations vertébrales et un programme d'exercices à domicile, le prurit est complètement disparu. RÉSUMÉ: Dans ce cas, un prurit grave et chronique, réfractaire à d'autres formes de traitement, est disparu rapidement après le commencement des traitements chiropratiques. On peut donc supposer que le prurit du patient était lié à des troubles biomécaniques de la colonne vertébrale.

The passive voice and comprehensibility of biomedical texts: An experimental study with 2 cohorts of chiropractic students.

OBJECTIVE:: Authors in the health sciences are encouraged to write in the active voice in the belief that this enhances comprehensibility. Hence, the purpose of this study was to compare objectively measured and subjectively perceived comprehensibility of texts in which one voice or the other was highly prevalent. METHODS:: Objectively rated comprehensibility was obtained by presenting 161 2nd-year chiropractic students with questions pertaining to 2 methods sections of biomedical articles, each presented in its original form with high prevalence of the passive voice, and in a manipulated form with all main verbs in the active voice. The difficulties and sensitivities of questions were compared for the 2 forms of each text. Comprehensibility was obtained by asking students to rate the comprehensibility of authentic sentences from biomedical manuscripts and matched manipulated form in which the voice of the main verb had been changed. Differences in comprehensibility between the 2 texts were assessed with a dependent t test. RESULTS:: There were no significant differences in the difficulties or sensitivities of questions pertaining to the 2 original texts written in the passive voice versus the active voice ( p > .35 for all comparisons). Students rated sentences written in the passive voice as marginally more comprehensible than sentences written in the active voice ( p = .003 per 2-tailed paired t test). CONCLUSION:: The texts written in the active voice were not more comprehensible than texts written in the passive voice. The results of this study do not support editorial guidelines that favor active voice over passive voice.

The influence of cervical spinal cord compression and vertebral displacement on somatosympathetic reflexes in the rat.

BACKGROUND CONTEXT: One theory within chiropractic proposes that vertebral subluxation in the upper cervical region induces spinal cord compression sufficient to alter spinal cord efferent output. We report on the feasibility of three different experimental approaches to test this theory. METHODS: A high threshold electrical-evoked somatosympathetic reflex was recorded in adrenal or renal nerves of 10 anaesthetized adult male rats before and after (1) graded pressure was applied directly to the C1/C2 spinal cord segment in eight rats by the use of either direct compression or inflation of an extradural balloon and (2) displacement, less than a dislocation applied posterior to anterior, to the C2 vertebra in two rats. The latency and amplitude of the pre- and postintervention reflex responses were compared. RESULTS: The reflex amplitude was not significantly changed by pressure (26 mmHg) from an extra-dural balloon or direct compression of the dura mater onto the dorsal spinal cord. Additional pressure, at least sufficient to occlude the dorsal vessels, induced a significant reduction in the amplitude of the reflex, and this reduction persisted for 20 minutes after removal of the pressure (Dunn's method for all pairwise multiple comparison Q stat=3.437; critical value for k=6 with α=0.05 is 2.936). Maximal vertebral (C2) displacement (4 mm), without dislocation did not induce significant changes compared with the control period. CONCLUSIONS: Although this feasibility study suggests it is unlikely that upper cervical vertebral subluxation, displacement less than a dislocation, compromises the sympathetic outflow in the adrenal or renal nerves, further vertebral displacement studies are necessary to formally test this.

A diachronic study of the language of chiropractic.

This study investigates how the language of chiropractic has changed over time. A collection of material, published up until approximately 1950 and consisting of textbooks, monographs and lecture notes from Canadian Memorial Chiropractic College, was analyzed to identify commonly occurring words and phrases. The results were compared to a corpus of recent articles from the Journal of the Canadian Chiropractic Association. This permitted the identification of words which were over-represented in the historical literature and therefore likely have become somewhat archaic or represent themes which are of less import in the modern chiropractic literature. Words which were over-represented in the historical literature often referred to anatomical, pathological and biomechanical concepts. Conversely, words which were comparatively over-represented in the modern chiropractic literature often referred to concepts of professionalism, the clinical interaction and evidence-based care. A detailed analysis is presented of trends in the use of the conceptually important terms subluxation and adjustment.

Cette étude examine l'évolution du langage de la chiropratique au fil du temps. Une collection de documents, publiés jusqu'à environ 1950 et comprenant des manuels, des monographies et des notes de cours du Canadian Memorial Chiropractic College, a été analysée pour relever les mots et expressions fréquemment rencontrés. Les résultats ont été comparés aux corpus d'articles récents du Journal de l'Association chiropratique canadienne. Cela a permis de détecter des mots qui étaient surreprésentés dans la documentation ancienne, et, donc, susceptibles de devenir quelque peu archaïques ou de représenter des thèmes qui sont moins importants dans la documentation chiropratique moderne. Les mots qui étaient surreprésentés dans la documentation ancienne se rapportaient souvent à des concepts anatomiques, pathologiques et biomécaniques. À l'inverse, les mots qui ont été relativement surreprésentés dans la documentation chiropratique moderne se rapportaient souvent aux concepts du professionnalisme, de l'interaction clinique et des soins factuels. Une analyse détaillée des tendances de l'utilisation des termes importants sur le plan conceptuel, subluxation et ajustement, est présentée.

Quantitative corpus-based analysis of the chiropractic literature - a pilot study.

In this pilot study, a collection of peer-reviewed articles from the Journal of the Canadian Chiropractic Association was analyzed by computer to identify the more commonly occurring words and phrases. The results were compared to a reference collection of general English in order to identify the vocabulary which is distinctive of chiropractic. From texts with a combined word count in excess of 280,000, it was possible to identify almost 2,500 words which were over-represented in the chiropractic literature and therefore likely to hold special importance within this domain. Additionally, readability statistics were calculated and suggest that the peer-reviewed chiropractic literature is approximately as challenging to read as that of nursing, public health and midwifery. Certain words widely considered to be of importance to the profession, for example "subluxation and adjustment," were not particularly prevalent in the literature surveyed.

Cerebrospinal fluid pressure response to upper cervical vertebral motion and displacement in the anesthetized rat.

OBJECTIVE: This study examined whether aligned or off-axis (subluxated) static and dynamic vertebral displacement within normal physiological ranges modulated cerebrospinal fluid pressure (CSF) as is considered to occur by some chiropractic theories. METHODS: Cerebrospinal fluid pressure pressure was measured via a subarachnoid catheter implanted at the lumbar level in 12 anesthetized adult male Wistar rats. A computer-driven manipulator was used to impose 3 motion patterns on the C2 vertebra: (i) dynamic oscillatory displacement (24 degrees peak-to-peak 1.0 and 2.0 Hz), (ii) static rotary (ramp 20 degrees at 10 degrees per second and hold for 4 minutes) displacement about both the normal and an offset axis of rotation, and (iii) a spinal manipulative thrust displacement (200 degrees per second; 12 degrees peak-to-peak). RESULTS: The CSF pressure at rest for all rats ranged from 4.5 to 9.1 mm Hg, with a mean (+/- SD) of 6.3 +/- 1.4 mm Hg. Of the imposed movements, only an offset ramp and hold displacement resulted in a significant (P < .05) difference between the CSF pressure before (6.1 +/- 0.7 mm Hg) and during the imposed movement (6.6 +/- 0.7 mm Hg). None of the interventions were associated with significant changes in the powers of the principal peaks of the CSF pressure power spectrum. CONCLUSIONS: The results of this study suggest that static or dynamic displacement of an upper cervical vertebra within the limits of tissue integrity do not induce physiologically important changes in absolute CSF pressure or pressure dynamics in anesthetized rats.

Cerebrospinal fluid pressure in the anesthetized rat.

OBJECTIVE: The primary aims of this study were to determine the major frequencies and powers of oscillations in cerebrospinal fluid (CSF) pressure in the anesthetized rat, and determine whether the CSF pressure oscillations correlated with the major oscillation frequencies in the cardiovascular and respiratory systems as proposed by some chiropractic theories. METHODS: The cardiac and ventilatory cycles, and CSF pressure were simultaneously recorded during spontaneous and positive-pressure mechanical ventilation in the anesthetized rat. Power spectra were generated from the raw data to identify the major oscillation frequencies in cardiorespiratory and CSF data sets. Entrainment of CSF pressure with ventilation was tested by mechanically pacing the ventilation over a range of frequencies. RESULTS: The most powerful oscillation in CSF pressure was coincident with ventilatory chest movement during both spontaneous and mechanically paced ventilation. In 22 of 26 trials, there was also a very weak oscillation in CSF pressure that was entrained to heart rate. In addition, in 21 of 26 trials, it was possible to identify a low-frequency oscillation (<0.25 Hz) in CSF pressure that was coincident with a low-frequency oscillation in the power spectrum of the cardiac cycle. CONCLUSIONS: This study suggests oscillations in CSF pressure in the anesthetized rat are entrained to and driven by ventilation. The arterial pulse pressure makes little contribution to oscillations in CSF pressure in the immobile, anesthetized rat. This study provides normative, quantitative data on which to develop studies concerning the effects of vertebral movements and spinal posture on CSF dynamics.

Spinal manipulation and spinal mobilization influence different axial sensory beds.

Manipulation and mobilization are two forms of manual therapy commonly employed in the management of musculoskeletal disorders. Spinal manipulation and mobilization are often distinguished from one another by reference to certain biomechanical parameters such as peak force, duration and magnitude of translation. However, as of yet, there is relatively little research which distinguishes between them in terms of neurological mechanisms or clinical effectiveness. Theories concerning the mechanisms underlying the therapeutic effects of manipulation and mobilization commonly make reference to mechanical events such as the release of entrapped tissue or the disruption of intra-articular adhesions. Relatively less attention is given to neural effects. In this paper, we hypothesize that, at least in part, spinal manipulation preferentially influences a sensory bed which, in terms of anatomical location and function, is different from the sensory bed influenced by spinal mobilization techniques. More specifically, we hypothesize that manipulation may particularly stimulate receptors within deep intervertebral muscles, while mobilization techniques most likely affect more superficial axial muscles. In part, our rationale for this hypothesis is based on differences in mechanical advantage of the respective manual procedures on multi-segmental versus short intervertebral muscles.