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

Test-Retest Reliability of Measuring the Vertebral Arterial Blood Flow Velocity in People With Cervicogenic Dizziness

OBJECTIVES

The purpose of this study was to determine the within-session and between-sessions reliability of measuring the vertebral artery blood flow velocities in people with cervicogenic dizziness using Doppler ultrasound at both upper and lower cervical levels.

METHODS

Outcome measures were taken on 2 occasions 3 weeks apart with no active treatment provided in between the assessments on 12 participants. Pulsed-wave Doppler ultrasound was used to quantify time-averaged mean velocities through the vertebral artery at upper cervical (C0-1) and lower cervical vertebrae (C5-6). The clinical outcome measures were also recorded in people with cervicogenic dizziness. The intraclass correlation coefficient (ICC) was used to determine the within-session and between-session repeatability. Paired t test was used to determine the differences in the time-averaged mean velocities of blood flow at the same site of the vertebral artery and the clinical outcome measures in 2 sessions 3 weeks apart.

RESULTS

In people with cervicogenic dizziness, there was no significant change in both clinical outcome measures and the time-averaged mean velocities when the patients were measured 3 weeks apart (P > .05). This study identified good within-session (ICC: 0.903-0.967) and between-session (ICC: 0.922-0.984) repeatability in measuring the vertical blood flow velocities in patients with cervicogenic dizziness when the clinical outcome measures were unchanged.

CONCLUSIONS

This study supports the use of Doppler ultrasound to identify changes in mean vertebral arterial blood flow velocities before and after intervention in people with cervicogenic dizziness in future studies.

Chronic neck pain: making the connection between capsular ligament laxity and cervical instability

The use of conventional modalities for chronic neck pain remains debatable, primarily because most treatments have had limited success. We conducted a review of the literature published up to December 2013 on the diagnostic and treatment modalities of disorders related to chronic neck pain and concluded that, despite providing temporary relief of symptoms, these treatments do not address the specific problems of healing and are not likely to offer long-term cures. The objectives of this narrative review are to provide an overview of chronic neck pain as it relates to cervical instability, to describe the anatomical features of the cervical spine and the impact of capsular ligament laxity, to discuss the disorders causing chronic neck pain and their current treatments, and lastly, to present prolotherapy as a viable treatment option that heals injured ligaments, restores stability to the spine, and resolves chronic neck pain. The capsular ligaments are the main stabilizing structures of the facet joints in the cervical spine and have been implicated as a major source of chronic neck pain. Chronic neck pain often reflects a state of instability in the cervical spine and is a symptom common to a number of conditions described herein, including disc herniation, cervical spondylosis, whiplash injury and whiplash associated disorder, postconcussion syndrome, vertebrobasilar insufficiency, and Barré-Liéou syndrome. When the capsular ligaments are injured, they become elongated and exhibit laxity, which causes excessive movement of the cervical vertebrae. In the upper cervical spine (C0-C2), this can cause a number of other symptoms including, but not limited to, nerve irritation and vertebrobasilar insufficiency with associated vertigo, tinnitus, dizziness, facial pain, arm pain, and migraine headaches. In the lower cervical spine (C3-C7), this can cause muscle spasms, crepitation, and/or paresthesia in addition to chronic neck pain. In either case, the presence of excessive motion between two adjacent cervical vertebrae and these associated symptoms is described as cervical instability. Therefore, we propose that in many cases of chronic neck pain, the cause may be underlying joint instability due to capsular ligament laxity. Currently, curative treatment options for this type of cervical instability are inconclusive and inadequate. Based on clinical studies and experience with patients who have visited our chronic pain clinic with complaints of chronic neck pain, we contend that prolotherapy offers a potentially curative treatment option for chronic neck pain related to capsular ligament laxity and underlying cervical instability.

A valid pre-manipulative screening tool is needed

The Australian Physiotherapy Association's Clinical Guidelines for Pre-Manipulative Procedures for the Cervical Spine represent a positive step towards the goal of reducing the incidence of vertebrobasilar strokes following neck manipulation. Nevertheless, the predictive value of the guidelines is largely contingent upon the validity of the physical screening tests, particularly sustained end-range cervical rotation. The primary issue is the sensitivity of the tests for detecting patients with vertebral artery occlusion and vertebrobasilar insufficiency, and who are at high risk of experiencing significant forces during manipulation which could result in intimal dissection.

Changes in vertebral artery blood flow following various head positions and cervical spine manipulation

OBJECTIVE

The objective of the study was to investigate the cerebrovascular hemodynamic response of cervical spine positions including rotation and cervical spine manipulation in vivo using magnetic resonance imaging technology on the vertebral artery (VA).

METHODS

This pilot study was conducted as a blinded examiner cohort with 4 randomized clinical tasks. Ten healthy male participants aged 24 to 30 years (mean, 26.8 years) volunteered to participate in the study. None of the participants had a history of disabling neck, arm, or headache pain within the last 6 months. They did not have any current or history of neurologic symptoms. In a neutral head position, physiologic measures of VA blood flow and velocity at the C1-2 spinal level were obtained using phase-contrast magnetic resonance imaging after 3 different head positions and a chiropractic upper cervical spinal manipulation. A total of 30 flow-encoded phase-contrast images were collected over the cardiac cycle, in each of the 4 conditions, and were used to provide a blood flow profile for one complete cardiac cycle. Differences between flow (in milliliters per second) and velocity (in centimeters per second) variables were evaluated using repeated-measures analysis of variance.

RESULTS

The side-to-side difference between ipsilateral and contralateral VA velocities was not significant for either velocities (P = .14) or flows (P = .19) throughout the conditions. There were no other interactions or trends toward a difference for any of the other blood flow or velocity variables.

CONCLUSIONS

There were no significant changes in blood flow or velocity in the vertebral arteries of healthy young male adults after various head positions and cervical spine manipulations.

Vertebral Artery Blood flow Velocity Changes Associated with Cervical Spine rotation: A Meta-Analysis of the Evidence with implications for Professional Practice

Many studies of vertebral artery (VA) blood flow changes related to cervical spine rotation have been published, but the findings are controversial and the evidence unconvincing. Recent Doppler measurements suggest that contralateral VA blood flow is compromised on full rotation in both healthy subjects and patients. More rigorous research is needed, and it was the aim of this study to conduct a meta-analysis of published data to inform professional practice. A systematic literature search, including only Doppler studies of VA blood flow velocity associated with cervical spine rotation in adults, yielded nine reports with published data. Using weighted means of the pooled data, the magnitude of the effect size (Cohen's d) was calculated for differences between patients and subjects, sitting or lying supine for testing, the parts of the VA insonated, and the changes recorded after cervical spine rotation. From this meta-analysis, VA blood flow velocity was found to be compromised more in patients than healthy individuals, on contralateral rotation, with the subject sitting, and more in the intracranial compared to the cervical part of the VA. Possible reasons for these findings are suggested, and it is advised that sustained end-of-range rotation and quick-thrust rotational manipulations be avoided until there is a stronger evidence base for clinical practice.

Enhanced external counterpulsation and traction therapy ameliorates rotational vertebral artery flow insufficiency resulting from cervical spondylosis

STUDY DESIGN

Clinical trial of patients with rotational vertebrobasilar insufficiency (VBI) resulting from cervical spondylosis.

OBJECTIVE

To investigate the effectiveness of enhanced external counterpulsation (EECP) and traction therapy for these patients.

SUMMARY OF BACKGROUND DATA

EECP would reduce arterial stiffness and vascular resistance, and increase regional blood flow of vertebral arteries, thus may ameliorate symptoms in these patients.

METHODS

One hundred sixty-three patients who were clinically suspected rotational VBI caused by cervical spondylosis were enrolled in this study. They were randomly allocated into 3 groups: EECP + traction, EECP, and traction group. All patients and 50 healthy volunteers received transcranial color Doppler examination of the vertebral artery and basilar artery in both a neutral cervical spine position and a rotational position.

RESULTS

Within 3 days after treatment, 47 (84%) patients in EECP + traction group, 32 (61%) patients in EECP group, and 8 (15%) patients in traction group achieved successful outcomes, while at 3 months' follow-up, 45 (80%) patients in EECP + traction group, 34 (64%) in EECP group, and 3 (6%) in traction group achieved successful outcomes. With head rotation, the percentage of reduction of blood flow velocities of the vertebrobasilar artery (VBA) in patients was much greater than that of the healthy volunteers (P < 0.01). After treatment, rotational blood flow velocity reduction percentage of VBA in each treatment group was much lower than that of each group before treatment. EECP + traction group experienced the greatest decrease of rotational blood flow velocity reduction percentage of VBA, while EECP group experienced second greatest.

CONCLUSION

EECP and traction therapy can relieve the symptoms of rotational VBI, improve the rotational reduction of vertebrobasilar blood flow, and reduce the increased arterial impedance.

Atypical suboccipital vertebral artery blood flow in healthy subjects: case studies using real-time ultrasound

Manual therapists and other professionals are using real-time ultrasound increasingly to visualize vessels and determine their diameter and blood flow. Four case studies are presented to show atypical ultrasound profiles of the suboccipital vertebral artery (VA3) in healthy, young individuals. VA3 diameters and blood flow velocities were measured with the subjects sitting, and the cervical spine in the neutral position then with active, full-range rotation to the left and right. None of the subjects reported any signs or symptoms of vertebrobasilar ischemia (VBI) during the measurement procedure, despite an absence of typical VA3 ultrasound profiles on one side in two of the individuals and a decreased unilateral VA3 blood flow in the other two subjects. Possible reasons for the atypical findings are proposed. Anatomical variations of VA3 and conditions such as obesity may give rise to atypical real-time ultrasound measurements of VA3 blood flow, particularly when associated with cervical spine rotation. The possibility of altered VA3 blood flow because of such factors, which may give rise to false-positive or false-negative findings in the standard VBI test, should be considered by manual therapists in pretreatment assessments and treatment programs in professional practice.

Pre-manipulative testing and the use of the velocimeter

Manipulation of the cervical spine remains a common intervention for neck pain and dysfunction, despite the well-documented associated risk of vertebrobasilar stroke. The currently advocated pre-manipulative risk assessment protocols include the use of provocative positional tests to challenge the integrity of the vascular supply to the brain. This paper critically evaluates the validity of these pre-manipulative provocative tests in the light of ultrasonographic blood flow studies of the vertebral arteries. It also critically evaluates the evidence concerning the clinical utility of a portable continuous wave Doppler device (or velocimeter) to examine vertebral artery blood flow prior to neck manipulation. There is clear evidence that the provocative tests may produce both false positive and false negative findings. Initial research regarding the clinical use of a velocimeter suggests this device may provide a more objective assessment of vertebral artery blood flow than the provocative tests. However, the sensitivity, specificity and reliability of the use of the velocimeter in identifying abnormal vascular flow in the vertebral arteries, and therefore its clinical utility, has not yet been fully established.

Is mechanical deformation of the suboccipital vertebral artery during cervical spine rotation responsible for vertebrobasilar insufficiency?

PURPOSE

The atlanto-axial region of the vertebral artery (VA) has traditionally been considered at risk for injury during cervical spine rotation, leading to compromised blood flow to the hindbrain and vertebrobasilar insufficiency or ischaemia (VBI). The anatomical relationships of the suboccipital VA (VA3) and related haemodynamic changes associated with cervical spine movements have been neglected, however. The present review aims to provide a new perspective on possible causes of reduced blood flow to the hindbrain, with particular reference to the functional anatomy of VA3 and related biomechanics of cervical spine rotation, to inform evidence-based practice.

METHOD

To support the hypothesis that it is VA3, not the VA in the atlanto-axial region, that is compressed or stretched during cervical spine rotation, current studies of blood flow changes in the VA distal to the region of rotation and possible arterial deformation were retrieved, using AMED, CINAHL, Embase, Pedro and PubMed, and reviewed.

RESULTS

Possible sites for VA3 deformation, based on a re-examination of its anatomy and biomechanics, are described. However, no research reports of VA3 blood flow measurements associated with cervical spine rotation have been published to date. Five studies on blood flow changes in the intracranial VA after cervical spine rotation were reviewed. The subjects for four of these reports were young, healthy individuals, and the fifth included older patients and young non-patients. The analysis of these studies demonstrated that more rigorous control of variables is necessary before meaningful conclusions can be made.

CONCLUSION

The paucity of studies of VA3 emphasises the need for research based on informed understanding of the anatomy and biomechanics of this area. This view on mechanical deformation of VA3 associated with cervical spine rotation as a possible cause of compromised blood flow to the hindbrain and VBI provides further argument for avoiding full-range or sustained cervical spine rotation in clinical practice.

Posterior ponticles and rotational stenosis of vertebral arteries. A pilot study using Doppler ultrasound velocimetry and magnetic resonance angiography

OBJECTIVE

To determine whether the presence of posterior ponticles markedly increases by 30% or more, the incidence of major rotational stenosis of vertebral arteries.

METHODS

Doppler ultrasound studies were performed in 3 private chiropractic clinics and in the radiology department of a public hospital, and magnetic resonance angiography (MRA) studies were made in the latter location. Thirty-two chiropractic patients had Doppler velocimetery, and 16 of these patients had MRA scanning. The outcome measures included changes in Doppler velocimetry signals and MRA images indicative of marked rotational stenosis of vertebral arteries.

RESULTS

All vertebral arteries from the 32 patients displayed no signs indicative of marked rotational stenosis.

CONCLUSION

The findings of this study show that the incidence of major rotational stenosis of vertebral arteries is not markedly increased by the presence of posterior ponticles.

Is it time to stop functional pre-manipulation testing of the cervical spine?

The combined extended and rotated cervical spine position has been postulated to affect vertebral artery blood flow by primarily causing a narrowing of the vessel lumen, usually within the artery contralateral to the side of head rotation. The production of brainstem symptoms during the manoeuvre has generally been considered to be a positive test result. As a consequence, functional pre-manipulation testing of the cervical spine has been part of clinical screening undertaken by chiropractors and other manual practitioners to rule out the risk of possible injury to the vertebral artery. To date, these testing procedures are taught to students and carried out in daily clinical practice, despite the considerable controversy that exists about their validity. This paper considers and discusses the usefulness of functional pre-manipulation testing for clinical scenarios, involving dissection, spasm or stenosis of the vertebral artery, and makes the following recommendations: (1) Practitioners must assess the patient thoroughly, through careful history taking and physical examination, for the possibility of vertebral artery dissection. It is important to note that vertebral artery dissection (VAD) may present as pain only, and may not be associated with symptoms and signs of brainstem ischaemia. (2) If there is a strong likelihood of VAD, provocative pre-manipulation tests should not be performed, and the patient must be referred appropriately. (3) In the patient presenting with symptoms of brainstem ischaemia due to non-dissection stenotic vertebral artery pathologies, provocative testing is very unlikely to provide any useful additional diagnostic information. (4) In the patient with unapparent vertebral artery pathology, where spinal manipulative therapy (SMT) is considered as the treatment of choice, provocative testing is very unlikely to provide any useful information in assessing the probability of manipulation induced vertebral artery injury.

Vertebral arteries and cervical movement: Doppler ultrasound velocimetry for screening before manipulation

OBJECTIVE

It has been proposed that Doppler velocimetry, which is noninvasive, quick, and relatively inexpensive, should be used when the screening vertebral arteries before manipulation to reduce the risk of cervical manipulation-related injury to these vessels. The objective of this analysis of the literature is to study the evidence of the suitability of Doppler velocimetry for this purpose.

DATA SELECTION

Studies were examined that dealt with the incidence of stroke after manipulation, the proposed mechanisms for this clinical entity, the validity of the provocational tests that have been used in screening before manipulation, the validity and reliability of Doppler velocimetry of vertebral arteries, and the biomechanics of vertebral arteries.

RESULTS

There is a suspicion of increased risk for vertebrobasilar stroke for vertebral arteries that have markedly reduced patency in the neutral position and/or stenosis during cervical rotation. There is evidence that provocational tests lack validity and that Doppler velocimetry is valid in assessing the patency of vertebral arteries in the neutral position and during cervical rotation. Interexaminer reliability of the Doppler technique has been shown to be high. Doppler ultrasound screening also seems to be able to provide an indirect assessment of the mechanical stresses to the artery during cervical movements.

CONCLUSION

There is strong evidence to suggest that Doppler velocimetry should be included in the screening of vertebral arteries before manipulation.

Uneventful upper cervical manipulation in the presence of a damaged vertebral artery

OBJECTIVE

To discuss a case in which a patient with a previously injured vertebral artery underwent manipulation in the upper cervical spine without alteration of her symptom pattern. The literature concerning the relative safety of specific upper cervical manipulative techniques is reviewed.

CLINICAL FEATURES

A 42-year-old woman had a 3-week history of unilateral suboccipital pain that she related to a sudden twisting of her head and neck that occurred while she was putting sheets of drywall on top of her car. Subsequent examination by a neurologist 2 weeks later was unremarkable, and a tension-type headache was diagnosed. Approximately 10 days later (3 weeks after injury), a single high-velocity upper-cervical manipulation (incorporating slight rotation and full lateral flexion) was performed with no change in her symptom pattern. Two weeks after that, the patient had development of a lateral medullary syndrome (also known as Wallenberg syndrome) after she briefly extended and rotated her upper cervical spine while painting a ceiling.

INTERVENTION AND OUTCOME

The patient was treated with anticoagulant therapy, and the lateral medullary infarct healed without incident. The spinocerebellar and subtle motor symptoms also resolved, but the ipsilateral suboccipital headache and the loss of temperature sensation associated with the spinothalamic tract lesion were still present 9 months later.

CONCLUSION

This case report demonstrates that vigorous manipulation of the upper cervical spine is possible without injuring an already damaged vertebral artery. It is suggested that the line of drive used during the single manipulation, almost pure lateral flexion with slight rotation, was responsible for the apparent innocuous response. Guidelines for the evaluation and management of vertebral artery dissection are reviewed. Because it is currently impossible to identify patients at risk of having a dissected vertebral artery with standard in-office examination procedures, rotational manipulation of the upper cervical spine should be abandoned by all practitioners, and schools should remove such techniques from their curriculums.

Vertebral arteries and cervical rotation: modeling and magnetic resonance angiography studies

OBJECTIVE

To determine whether lumen narrowing in vertebral arteries during atlanto-axial rotation is due to stretch or localized compression.

DESIGN AND SETTING

Experiments with models were made in a private chiropractic clinic, whereas studies of cadaveric specimens were performed in an anatomy laboratory. Doppler ultrasound and magnetic resonance angiography (MRA) studies were carried out in the radiology department of a public hospital.

PATIENTS

Eight patients had their vertebral arteries examined by use of a Doppler velocimeter and MRA.

MAIN OUTCOME MEASURE

Stenosis of the vertebral arteries caused by stretch, localized compression, or kinking.

RESULTS

All 16 vertebral arteries from the 8 patients displayed no changes in their lumen dimensions with full cervical rotation, although curves in each of the arteries did change. The model and cadaveric vertebral arteries demonstrated localized compression or kinking of the vessel wall with atlanto-axial rotation contralaterally but revealed no evidence of major contribution of stretching to stenosis.

CONCLUSION

The lumen of vertebral arteries is usually unaffected by atlanto-axial rotation. In cases where there is stenosis, this is mainly due to localized compression or kinking. These findings are relevant to premanipulative screening of vertebral arteries with Doppler ultrasound scanning.

Causes of complications from cervical spine manipulation

Cervical manipulation occasionally causes serious vertebrobasilar complications. The usual cause is vertebral artery dissection, however in some cases there has been no obvious arterial injury. The present paper reviews the mechanisms by which complications occur, particularly when the applied force is trivial or there is no injury to the vertebral arteries, and the factors that increase risk of complications. In addition, implications are drawn for use of the recently revised Australian Physiotherapy Association (APA) guidelines. In the absence of vertebral artery rupture, complications are proposed to arise from vasospasm, haemostasis, endothelial injury or turbulent flow. These mechanisms have a sound scientific basis but have yet to be demonstrated as specifically causing vertebrobasilar complications. The most important risk factors for vertebrobasilar complications appear to be prior trauma to the vertebral arteries and symptoms of vertebrobasilar ischaemia from previous manipulation. There is weak evidence that hypoplasia of the vertebral arteries also increases the risk of complications. Neither general vascular factors nor pre-existing degenerative conditions of the cervical spine increase risk of vertebrobasilar complications. The procedures described in the APA guidelines test adequacy of total cerebral perfusion during cervical movements rather than patency of the vertebral arteries or their susceptibility to injury. The guidelines may therefore indicate potential for surviving a complication from manipulation. They may also identify patients at risk of complications from minor trauma. It is recommended that the procedures described in the APA guidelines be applied prior to every manipulation, and that manipulation be avoided in the presence of any signs of vertebrobasilar insufficiency.

Color duplex sonographic findings in human vertebral arteries during cervical rotation

PURPOSE

The aims of this study were to determine whether vertebral artery blood flow velocity changes during contralateral cervical rotation, to determine the extent of rotation necessary to affect the velocity, and to find direct evidence of stretching or compression of the vertebral arteries during cervical rotation.

METHODS

Color duplex sonography was used to measure the blood flow velocities and diameters of the vertebral arteries in 20 patients. Measurements were taken with the patients' heads in the neutral position and at 10 degrees increments of contralateral neck rotation (determined using a cervical range of motion goniometer) to the end-range.

RESULTS

The data showed no significant change in the mean blood flow velocity for the entire study population during cervical rotation. However, there were marked changes in the blood flow velocities in 7 vertebral arteries toward the end-range of rotation. No arteries displayed any evidence of major stretching of the arterial walls, although localized compression of 2 arteries was observed.

CONCLUSIONS

The results of this study suggest that vertebral arteries are usually unaffected by contralateral cervical rotation and that Doppler sonography may provide an indirect assessment of mechanical stresses to the arterial wall.

Vertebral arteries and neck rotation: Doppler velocimeter interexaminer reliability

The purpose of this study was to test the interexaminer reliability of Doppler ultrasound (US) velocimeter examination of vertebral arteries during contralateral cervical rotation. Vertebral arteries from 20 adults 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 data obtained by two examiners, regarding persistence or major reduction in Doppler signals, were compared. There was 93% agreement between the data from the two examiners, and the kappa score was 0.78 at p = 0.05. These results provide evidence to support the interexaminer reliability of bidirectional Doppler velocimeter examination for the purpose of assessing the effects of contralateral rotation on vertebral artery blood flow.