Angular Kinematics of Chiropractic Supine Cervical Spine Manipulation: Rotational Measures and Comparisons to Doctor and Recipient Perceptions.

OBJECTIVES: The primary purposes of this study were to measure axial rotation during supine cervical spinal manipulative therapy (cSMT) and to record recipients' and doctors' perceptions of rotational magnitudes. METHODS: Experienced doctors of chiropractic (DCs) provided supine cSMT and acted as recipients of cSMT. Participants who received SMT wore inertial measurement units attached to the forehead and sternum for motion capture. Afterward, recipients and DCs completed questionnaires asking about their perceptions of motion. Data were analyzed for magnitudes of axial rotation at peak thrust and correlations with patient and doctor perceptions. Secondary analyses included angular velocity, angular acceleration, and other kinematic variables. RESULTS: We recorded 23 SMT events with 14 DCs. Rotation at thrust peaks averaged 32.4° (17.4°). Doctors' and recipients' perceptions of rotation were higher than measured values 45% and 50% of the time, respectively. Maximum angular velocity and acceleration averaged 221.9°/s (124.9) and 4786.5°/s2 (2456.6), respectively. We found no correlation between perceptions and velocity or acceleration; doctors' perceptions had an inverse correlation with measurements. CONCLUSION: On average, we found rotation during supine cSMT to be 32°. Both DCs and SMT recipients overestimated rotation compared with actual measurements. These factors should be considered in discussions of rotation and SMT.

Mechanics of dystrophin deficient skeletal muscles in very young mice and effects of age.

The MDX mouse is an animal model of Duchenne muscular dystrophy, a human disease marked by an absence of the cytoskeletal protein, dystrophin. We hypothesized that 1) dystrophin serves a complex mechanical role in skeletal muscles by contributing to passive compliance, viscoelastic properties, and contractile force production and 2) age is a modulator of passive mechanics of skeletal muscles of the MDX mouse. Using an in vitro biaxial mechanical testing apparatus, we measured passive length-tension relationships in the muscle fiber direction as well as transverse to the fibers, viscoelastic stress-relaxation curves, and isometric contractile properties. To avoid confounding secondary effects of muscle necrosis, inflammation, and fibrosis, we used very young 3-wk-old mice whose muscles reflected the prefibrotic and prenecrotic state. Compared with controls, 1) muscle extensibility and compliance were greater in both along fiber direction and transverse to fiber direction in MDX mice and 2) the relaxed elastic modulus was greater in dystrophin-deficient diaphragms. Furthermore, isometric contractile muscle stress was reduced in the presence and absence of transverse fiber passive stress. We also examined the effect of age on the diaphragm length-tension relationships and found that diaphragm muscles from 9-mo-old MDX mice were significantly less compliant and less extensible than those of muscles from very young MDX mice. Our data suggest that the age of the MDX mouse is a determinant of the passive mechanics of the diaphragm; in the prefibrotic/prenecrotic stage, muscle extensibility and compliance, as well as viscoelasticity, and muscle contractility are altered by loss of dystrophin.

Regional diaphragm volume displacement is heterogeneous in dogs.

Muscle shortening and volume displacement (VD) are critical determinants of the pressure-generating capacity of the diaphragm. The present study was designed to test the hypothesis that diaphragm VD is heterogeneous and that distribution of VD is dependent on regional muscle shortening, posture, and the level of muscle activation. Radioopaque markers were sutured along muscle bundles of the peritoneal surface of the crural, dorsal costal, midcostal, and ventral costal regions of the left hemidiaphragm in four dogs. The markers were followed by biplanar video fluoroscopy during quiet spontaneous breathing, passive inflation to total lung capacity (TLC), and inspiratory efforts against an occluded airway at three lung volumes spanning the vital capacity [functional residual capacity, functional residual capacity + ½ inspiratory capacity, and TLC in both the prone and supine postures]. Our data show the ventral costal diaphragm had the largest VD and contributed nearly two times to the total diaphragm VD compared with the dorsal costal portion. In addition, the ventral costal diaphragm contributed nearly half of the total VD in the prone position, whereas it only contributed a quarter of the total VD in the supine postition. During efforts against an occluded airway and during passive inflation to TLC in the supine position, the crural diaphragm displaced volume equivalent to that of the midcostal portion. Regional muscle shortening closely matched regional VD. We conclude that the primary force generator of the diaphragm is primarily dominated by the contribution of the ventral costal region to its VD.

Obesity modulates diaphragm curvature in subjects with and without COPD.

Obesity is a common comorbidity of chronic obstructive pulmonary disease (COPD) and has been associated with worse outcomes. However, it is unknown whether the interaction between obesity and COPD modulates diaphragm shape and consequently its function. The body mass index (BMI) has been used as a correlate of obesity. We tested the hypothesis that the shape of the diaphragm muscle and size of the ring of its insertion in non-COPD and COPD subjects are modulated by BMI. We recruited 48 COPD patients with postbronchiodilator forced expiratory volume in 1 s (FEV1)-to-forced vital capacity (FVC) < 0.7 and 29 age-matched smoker/exsmoker control (non-COPD) subjects, who underwent chest computed tomography (CT) at lung volumes ranging from functional residual capacity (FRC) to total lung capacity (TLC). We then computed maximum principal diaphragm curvature in the midcostal region of the left hemidiaphragm at the end of inspiration during quiet breathing (EI) and at TLC. The radius of maximum curvature of diaphragm muscle increased with BMI in both COPD and non-COPD subjects. The size of diaphragm ring of insertion on the chest wall also increased significantly with increasing BMI. Surprisingly, COPD severity did not appear to cause significant alteration in diaphragm shape except in normal-weight subjects at TLC. Our data uncovered important factors such as BMI, the size of the diaphragm ring of insertion, and disease severity that modulate the structure of the ventilatory pump in non-COPD and COPD subjects.

Adverse events from spinal manipulations in the pregnant and postpartum periods: a systematic review and update.

BACKGROUND: The purpose of this study is to update a previous critical review of adverse events in pregnant and postpartum populations. METHODS: The following databases were searched: PubMed, CINAHL, Index to Chiropractic Literature, Cochrane Database of Systematic Reviews/Cochrane Central Register of Controlled Trials and MEDLINE. We included all study design types as it was determined a priori that there would not be enough high-quality research on spinal manipulative therapy (SMT) in these populations to make any determinations. The Scottish Intercollegiate Guidelines Network (SIGN) and CARE (CAse REport) checklists were used for quality rating. RESULTS: This update found one case study that demonstrated a serious adverse event in the cervical spine following SMT and a handful of minor and transient adverse events in the low back following SMT. CONCLUSIONS: There was limited evidence of adverse events following SMT in these populations. Although we are calling for improved reporting of such events in future studies, it may be that such injuries are rare.

CONTEXTE: La présente étude vise à mettre à jour les résultats d'un examen critique des effets défavorables des manipulations vertébrales chez la femme enceinte et la femme en postpartum. MÉTHODOLOGIE: On a interrogé les bases de données suivantes : PubMed, CINAHL, Index to Chiropractic Literature, Cochrane Database of Systematic Reviews/ Cochrane Central Register of Controlled Trials et MEDLINE. On a retenu toutes les études parce qu'il avait été établi antérieurement que le nombre de recherches de bonne qualité sur les manipulations vertébrales (MV) chez la femme enceinte et la femme en postpartum était insuffisant pour trancher toute question. On s'est servi des listes de vérification Scottish Intercollegiate Guidelines Network (SIGN) et CARE (CAse REport) pour évaluer la qualité des études. RÉSULTATS: Une étude de cas faisait état d'un grave effet indésirable à la colonne cervicale après des MV et d'une poignée d'effets indésirables mineurs et transitoires à la colonne lombaire. CONCLUSIONS: Il existe peu de preuves que les MV ont des effets indésirables chez les populations à l'étude. Il faudrait plus de données. Mais il est permis d'affirmer que ces effets indésirables sont rares.

Low-Level Laser Light Therapy Dosage Variables vs Treatment Efficacy of Neuromusculoskeletal Conditions: A Scoping Review.

OBJECTIVE: The purpose of this scoping review was to identify and synthesize literature on dosage variables on the efficacy of low-level laser therapy (LLLT) for neuromusculoskeletal conditions. METHODS: A scoping literature review was conducted by searching the following databases: the Cochrane Library, the Cumulative Index to Nursing and Allied Health Literature, Medline, the Physiotherapy Evidence Database, the Index to Chiropractic Literature, manufacturer websites, and online guidelines. The search was modeled after STARLITE criteria. The reporting used Preferred Reporting Items for Systematic Reviews and Meta-analyses Extension for Scoping Reviews (PRISMA-ScR). Articles were included if LLLT was used in any treatment group for a neuromusculoskeletal complaint with dosage and effectiveness reported. This was tabulated by source, dosage variables, conditions, outcome measures, and conclusions. Data were charted in Excel format. Frequency counts were performed on ordinal data. Descriptive statistics were computed for the continuous data. RESULTS: A total of 86 articles were included in the review. They revealed a broad range of musculoskeletal conditions and diverse dosage parameters. Seven individual parameters were found that would alter the dosage. Although duration of application is an independent clinical factor, the negative-outcome studies were inconsistent in duration. There was lack of statistical difference between the studies with improved vs unimproved outcomes. No statistical differences were noted between the dosage parameters and efficacy. CONCLUSION: Although many articles were found on LLLT for neuromusculoskeletal conditions, the studies had amorphous parameters. A heterogeneity of reported doses precluded the synthesis of sufficient evidence to correlate dosage variables with improved or unimproved outcomes. Therefore, based on the current literature, dosage variables for the efficacy of LLLT for neuromusculoskeletal conditions are uncertain at this time.

The relation between the spatial distribution of vertebral artery compromise and exposure to cervical manipulation.

BACKGROUND AND PURPOSE: The vertebral artery is made up of four segments, one of which (V3) is connected to highly mobile cervical vertebrae. This connection underlies the common assumption that persons with pre-event histories of mechanical neck movements, such as cervical spine manipulation (cSMT), should experience increased V3 dissection. METHODS: Two of the largest case series of vertebral artery dissection describing subjects with and without a specific history of cSMT were reassessed to determine which segment(s) of the vertebral artery was most commonly compromised. RESULTS: The V3 segment was the most commonly involved vertebral artery segment in both the +cSMT group (e.g., V3 vs. V1 prevalence ratio (PR) = 8.46) and the -cSMT group (V3 vs. V1 PR = 4.00). However, V3 vulnerability was augmented by the effect of cSMT. The joint effect of V3 location and exposure to cSMT was greater than if each effect were simply combined. In addition,multiple site lesions were significantly more common than single sites in both the +cSMT group (PR = 2.67, p = 0.008) and the -cSMT group (PR = 2.44, p = 0.0008). CONCLUSIONS: In prior studies which identified vertebral artery compromise, those with a history of cSMT were more likely to have involvement of the V3 segment. Although this study does not identify a mechanism which relates vertebral artery dissection and exposure to cSMT, these data are compatible with a greater than additive relation between compromise of an arterial segment thought to be mechanically vulnerable and history of a mechanical event.

Effect of cervical spine manipulation on a pre-existing vascular lesion within the canine vertebral artery.

BACKGROUND: Serious adverse events such as cervical artery dissection (CAD) have been reported to occur following cervical spine manipulation therapy (cSMT). To investigate the relation between these events, we utilized an animal model to determine if vertebral arteries with a suspected susceptibility factor (wall lesion) could be injured further by cSMT. METHODS: Lesions to the vertebral artery wall were created by angioplasty in 10 anesthetized canines. Resulting injury dimensions were quantified using intravascular ultrasound before and after cSMT. Student's t were performed to assess the significance of changes in arterial dimension. RESULTS: Statistical analysis demonstrated that the pre-cSMT and post-cSMT lesions did not differ significantly in their length, area or volume (p > 0.05). CONCLUSIONS: In this animal model, cSMT did not alter the dimensions of pre-existing vertebral artery lesions.

Survey of chiropractic clinicians on self-reported knowledge and recognition of concussion injuries.

Background: There has been little study of the recognition of mild traumatic brain injury (MTBI) by the chiropractic practitioner, or of the inquiry by the clinician to assess those patients who may be suffering from the condition, but fail to report the symptoms. Although severe cases of TBI are more often recognized and treated by attendance to hospital or emergency room, MTBI is less recognizable and would present a long-term risk to the patient. Given the clinical risk associated with failure to recognize such injuries, training of the clinician in the subtle signs of MTBI is imperative. What we currently know about training in the recognition of MTBI is from limited recent knowledge based studies. This study is intended to assess the self-reported mild traumatic brain injury (MTBI) knowledge, recognition and treatment by chiropractic practitioners. Methods: A previously published standardized set of survey items was distributed to a captive audience of chiropractic practitioners at the July 2016 Texas Chiropractic College annual symposium. The sample population was a convenience sample of chiropractic clinicians who were assessed for MTBI knowledge and common practices. Results: There was a response rate of 43% of the 125 attendees. The survey demonstrated confidence in MTBI diagnosis. Average MTBI knowledge and recognition score was only 27% ± 22%. Frequency of MTBI patients presenting to the chiropractic clinician office was an average of less than one per month. Sixty nine percent (69%) of the clinicians relied upon their history and clinical exam for diagnosis. There was no knowledge of the Balance Error Scoring system and only 20% utilized the Standardized Concussion Assessment Tool (SCAT). The primary action of the chiropractic clinician who suspected MTBI was to refer to a neurological specialist (76%). A small minority of practitioners would provide treatment. Conclusions: There is an overconfidence of the chiropractic practitioner in recognition of MTBI which is incongruent with the low knowledge scores. Further education of the chiropractic clinician is warranted. Trial registration: University Hospital Medical Information Network Clinical Trials Registry. Retrospectively registered (UMIN-CTR), trial number: UMIN#000029744 (Receipt# R000033980) data: October 27, 2017.​Date of enrollment 7/14/2016.

Defining the effect of cervical manipulation on vertebral artery integrity: establishment of an animal model.

BACKGROUND: Cervical spine manipulation is most often performed to affect relief of musculoskeletal complaints of the head and neck. Performed typically without complication, this modality is thought to be a potential cause of cerebrovascular injury, although a cause-effect relation has yet to be established. To explore this relation, an experimental platform is needed that is accessible and biologically responsive. OBJECTIVE: To establish an animal model capable of accommodating (1) direct study of its vertebral arteries and (2) creation of controlled interventions simulating arterial injury. STUDY DESIGN: Descriptive. METHODS: Under fluoroscopic guidance, an ultrasonic catheter was inserted into the left vertebral artery of 3 anesthetized dogs. The ultrasonic probe was then drawn proximally through the artery at a specific rate, and cross-sectional images of the vessel were collected. These images were then reconstructed to provide a variety of 2- and 3-dimensional representations of the vessel. This procedure was repeated after the overinflation and/or displacement of an angiographic balloon within the vertebral artery itself. RESULTS: The resulting ultrasonic images were able to delineate the structural layers that constitute the vertebral artery. Analysis of 2- and 3-dimensional reconstructions before and after angiographic intervention revealed the creation of discrete vascular injuries (aneurysm or dissection). CONCLUSIONS: For the first time, an animal model has been established that permits direct interrogation of the internal structures of the vertebral artery. This model can also be manipulated to create "preexisting" vascular injuries that are thought to be possible prerequisites for cerebrovascular injury associated with manipulation. As a result, an experimental platform has been established that is capable of providing investigators of all backgrounds with the ability to quantify biologic and mechanical outcomes of cervical manipulation.

The quality of reports on cervical arterial dissection following cervical spinal manipulation.

BACKGROUND: Cervical artery dissection (CAD) and stroke are serious harms that are sometimes associated with cervical spinal manipulation therapy (cSMT). Because of the relative rarity of these adverse events, studying them prospectively is challenging. As a result, systematic review of reports describing these events offers an important opportunity to better understand the relation between adverse events and cSMT. Of note, the quality of the case report literature in this area has not yet been assessed. PURPOSE: 1) To systematically collect and synthesize available reports of CAD that have been associated with cSMT in the literature and 2) assess the quality of these reports. METHODS: A systematic review of the literature was conducted using several databases. All clinical study designs involving CADs associated with cSMT were eligible for inclusion. Included studies were screened by two independent reviewers for the presence/absence of 11 factors considered to be important in understanding the relation between CAD and cSMT. RESULTS: Overall, 43 articles reported 901 cases of CAD and 707 incidents of stroke reported to be associated with cSMT. The most common type of stroke reported was ischemic stroke (92%). Time-to-onset of symptoms was reported most frequently (95%). No single case included all 11 factors. CONCLUSIONS: This study has demonstrated that the literature infrequently reports useful data toward understanding the association between cSMT, CADs and stroke. Improving the quality, completeness, and consistency of reporting adverse events may improve our understanding of this important relation.

Adverse events from spinal manipulation in the pregnant and postpartum periods: a critical review of the literature.

BACKGROUND: The safety of spinal manipulation during pregnancy and the postpartum periods has been a matter of debate among manual therapists. Spinal manipulative therapy during these periods is a commonly performed intervention as musculoskeletal pain is common in these patients. To date there has not been an evaluation of the literature on this topic exclusively. METHODS: A literature search was conducted on PubMed, CINAHL and the Index to Chiropractic Literature along with reference searching for articles published in English and French in the peer-reviewed literature that documented adverse effects of spinal manipulation during either pregnancy or postpartum. Case reports, case series, and any other clinical study designs were deemed acceptable for inclusion, as were systematic reviews. The appropriate Scottish Intercollegiate Guidelines Network (SIGN) tools were used to rate included articles for quality when applicable. RESULTS: Five articles identifying adverse events in seven subjects following spinal manipulation were included in this review, along with two systematic reviews. The articles were published between 1978 and 2009. Two articles describing adverse effects from spinal manipulation on two postpartum patients were included, while the remaining three articles on five patients with adverse effects following spinal manipulation were on pregnant patients. Injury severity ranged from minor injury such as increasing pain after treatment that resolved within a few days to more severe injuries including fracture, stroke, and epidural hematoma. SIGN scores of the prospective observational cohort study and systematic reviews indicated acceptable quality. CONCLUSIONS: There are only a few reported cases of adverse events following spinal manipulation during pregnancy and the postpartum period identified in the literature. While improved reporting of such events is required in the future, it may be that such injuries are relatively rare.

Learning spinal manipulation: a comparison of two teaching models.

PURPOSE: The goal of the present study was to quantify the high-velocity, low-amplitude spinal manipulation biomechanical parameters in two cohorts of students from different teaching institutions. The first cohort of students was taught chiropractic techniques in a patient-doctor positioning practice setting, while the second cohort of students was taught in a "complete practice" manipulation setting, thus performing spinal manipulation skills on fellow student colleagues. It was hypothesized that the students exposed to complete practice would perform the standardized spinal manipulation with better biomechanical parameters. METHODS: Participants (n = 88) were students enrolled in two distinct chiropractic programs. Thoracic spine manipulation skills were assessed using an instrumented manikin, which allowed the measurement of applied force. Dependent variables included peak force, time to peak force, rate of force production, peak force variability, and global coordination. RESULTS: The results revealed that students exposed to complete practice demonstrated lower time to peak force values, higher peak force, and a steeper rate of force production compared with students in the patient-doctor positioning scenario. A significant group by gender interaction was also noted for the time to peak force and rate of force production variables. CONCLUSION: The results of the present study confirm the importance of chiropractic technique curriculum and perhaps gender in spinal manipulation skill learning. It also stresses the importance of integrating spinal manipulation skills practice early in training to maximize the number and the quality of significant learner-instructor interactions.