Assessing the risk of stroke from neck manipulation: a systematic review.

BACKGROUND: Strokes, typically involving vertebral artery dissection, can follow cervical spinal manipulative therapy, and these types of stroke occur rarely. There is disagreement about whether a strong association between neck manipulation and stroke exists. An earlier systematic review found two relevant studies of association that used controls, which also discussed the limitations of the two papers. Our systematic review updates the earlier review, and aims to determine whether conclusive evidence of a strong association exists. METHODS: PRISMA guidelines for systematic reviews were followed, and the literature was searched using a strategy that included the terms 'neck manipulation' and 'stroke' from the PubMed, Embase, CINAHL Plus and AMED databases. Citations were included if they met criteria such as being case-control studies, and dealt with neck manipulation and/or neck movement/positioning. Papers were scored for their quality, using similar criteria to the earlier review. For individual criteria, each study was assigned a full positive score if the criterion was satisfied completely. RESULTS: Four case-control studies and one case-control study, which included a case- crossover design, met the selection criteria, but all of them had at least three items in the quality assessment that failed to be completely positive. Two studies were assessed to be the most robustly designed, one indicating a strong association between stroke and various intensities of neck movement, including manipulation, and the other suggesting a much reduced relative association when using primary care practitioners' visits as controls. However, potential biases and confounders render the results inconclusive. CONCLUSION: Conclusive evidence is lacking for a strong association between neck manipulation and stroke, but is also absent for no association. Future studies of association will need to minimise potential biases and confounders, and ideally have sufficient numbers of cases to allow subgroup analysis for different types of neck manipulation and neck movement.

Vertebral arteries and neck rotation: Doppler velocimeter and duplex results compared.

The purpose of this study was to test the validity of Doppler ultrasound (US) velocimeter examination of vertebral arteries during contralateral (to the opposite side) cervical rotation. Vertebral arteries from 20 subjects were insonated using a bidirectional Doppler velocimeter at the suboccipital portal (standard technique) and C2 transverse process level (new technique) during contralateral cervical rotation. The results, regarding persistence or major reduction in Doppler signals, were then compared with those from a colour-flow duplex US scanner using the same procedure. There was complete agreement between the combined suboccipital and C2 velocimeter results and those from the duplex scanner (k = 1.00 at p = 0.01): both sensitivity (n = 5) and specificity (n = 34) were 100%. This study provides evidence to support the validity of bidirectional Doppler velocimeter examination, by an experienced examiner, for the purpose of assessing the effects of contralateral rotation on vertebral artery blood flow.

A randomized prospective trial of hyperbaric oxygen in a referral burn center population.

Various studies of the effect of hyperbaric oxygen (HBO) in a wide variety of disease entities have been carried out. In the treatment of burns, animal and human studies have yielded somewhat contradictory results. Controlled studies in humans are limited. A randomized study on the effect of HBO was conducted involving 125 burn patients admitted within 24 hours of injury who were matched by age, burn size, and presence or absence of inhalation injury. Patients in the treatment arm received oxygen at two atmospheres of pressure for 90 minutes twice a day for a minimum of 10 treatments and a maximum of one treatment per total body surface per cent burn. The control group was treated in a similar fashion, except for the absence of HBO. There were no statistically significant differences between the two groups for the outcome measures of mortality, number of operations, and length of stay for the survivors. In this large clinical trial, we were unable to demonstrate any significant benefit to burn patients from the use of HBO.

Doppler studies comparing the effects of cervical rotation and lateral flexion on vertebral artery blood flow.

OBJECTIVE: To determine the effects of cervical contralateral rotation and cervical contralateral lateral flexion on vertebral artery blood flow velocity. DESIGN AND SETTING: A prospective study was performed at a private chiropractic clinic. PATIENTS: One hundred forty-eight patients had their vertebral arteries insonated as part of the premanipulative screening procedure. INTERVENTION: The vertebral arteries were insonated using a Doppler ultrasound velocimeter in the neutral position, during cervical contralateral rotation to the end range and during contralateral lateral flexion to the end range. MAIN OUTCOME MEASURES: Persistence or loss of Doppler signals from the vertebral arteries during neck movement was recorded. RESULTS: Of 280 vertebral arteries able to be insonated, 5% (0 < 5% < 9% at p = .99 confidence interval) had Doppler signals that stopped during contralateral rotation. Doppler signals from all 187 vertebral arteries tested during lateral flexion persisted, whereas 6 (3.2%) of this group of arteries had signals that ceased during contralateral rotation. CONCLUSION: Vertebral artery Doppler signals from patients can be greatly reduced or extinguished during contralateral cervical rotation. However, this is an unusual finding. The same phenomenon was not observed during contralateral cervical lateral flexion, which suggests that there may be less mechanical stress placed on the vertebral artery during lateral flexion.

Are the effects of local joint movement on blood flow limited to the vertebral and internal carotid arteries? Doppler studies of the ulnar artery.

OBJECTIVE: To determine what effect wrist extension has on ulnar artery blood flow. DESIGN AND SETTING: This is a descriptive study performed at a private chiropractic clinic. SUBJECT SELECTION: Sixty-three ulnar arteries were examined from thirty-two volunteers, 15 men and 17 women, whose ages ranged from 21-75 yr. Only wrists that were asymptomatic and freely mobile were candidates for ulnar artery examination. INTERVENTION: The arteries were insonated approximately 2 cm proximal to the pisiform bone using a continuous-wave Doppler flow meter in the neutral position and during passive wrist extension to the limit with the fingers straightened. MAIN OUTCOME MEASURES: The persistence or loss of Doppler signals. RESULTS: Doppler signals from 83% (0.99 confidence interval: 68% < p < 93%) of arteries stopped. In 4% of vessels, the signals were markedly reduced; in 13%, they remained apparently unchanged. CONCLUSION: Blood flow in ulnar arteries can be severely restricted during wrist extension. By using Doppler ultrasound, the ulnar artery may provide a good model of local joint movement effects on arterial blood flow.

Evaluation of biofeedback in the treatment of borderline essential hypertension.

Direct biofeedback of blood pressure was compared with frontal EMG biofeedback and with self-instructed relaxation for the treatment of essential hypertension in a controlled group outcome study. Patients were followed up for four months after the end of treatment. Generalization of treatment effects was assessed through pre- and posttreatment measurements of blood pressure under clinical conditions in a physician's office. There were no significant reductions in diastolic blood pressure. The systolic blood pressure (SBP) of the patients receiving blood pressure biofeedback decreased 8.1 mm mercury (p = 0.07) and the SBP of the patients in the relaxation condition decreased 9.5 mm mercury (p = 0.05). In the generalization measures, there were significant reductions in SBP for the relaxation group. The results are discussed in terms of the general lack of replicability within the area of biofeedback treatment of hypertension.

The use of feedback training and a stimulus control procedure to obtain large magnitude increases in heart rate outside of the laboratory.

A series of eight single-subject experiments were performed to test the feasibility of using a stimulus control procedure to teach subjects to control heart rate in the absence of feedback and outside of the laboratory. Four of the six subjects who completed the experiments were able to demonstrate increases in heart rate of from 15 to 35 beats per minute without the assistance of feedback and outside of the laboratory. These increases were consistently produced over six daily sesssions. Through the use of a systematic replication series of experiments, it was possible tentatively to rule out age, sex, and basal heart rate of subject, as well as type of previous feedback training and number of prior training sessions, as accounting for the differential success.

A comparison of direct blood pressure feedback and electromyographic feedback on the blood pressure of normotensives.

Groups of 20 normotensive subjects were assigned to one of three conditions to help them lower their blood pressure: (1) intermittent visual feedback of blood pressure; (2) continuous analogue auditory feedback of frontal EMG; (3) an instructed, no-feedback condition. Both groups receiving feedback showed greater within-session lowering of systolic blood pressure than the no-feedback control group. Although the group receiving intermittent visual feedback of blood pressure lowered blood pressure more than the EMG feedback group at the first session, in three subsequent sessions, the two feedback groups did not differ.