Sonography of vertebral arteries in De Kleyn's position in subjects and in patients with vertebrobasilar transient ischemic attacks

Asymptomatic rotational vertebral artery compression in a child due to head positioning for cranial surgery: illustrative case

BACKGROUND

The authors recently reported a series of children with vertebral artery (VA) compression during head turning who presented with recurrent posterior circulation stroke. Whether VA compression occurs during head positioning for cranial surgery is unknown.

OBSERVATIONS

The authors report a case of a child with incidental rotational occlusion of the VA observed during surgical head positioning for treatment of an intracranial arteriovenous fistula. Intraoperative angiography showed dynamic V₃ occlusion at the level of C2 with distal reconstitution via a muscular branch “jump” collateral, supplying reduced flow to the V₄ segment. She had no clinical history or imaging suggesting acute or prior stroke. Sequential postoperative magnetic resonance imaging scans demonstrated signal abnormality of the left rectus capitus muscle, suggesting ischemic edema.

LESSONS

This report demonstrates that rotational VA compression during neurosurgical head positioning can occur in children but may be asymptomatic due to the presence of muscular VA–VA “jump” collaterals and contralateral VA flow. Although unilateral VA compression may be tolerated by children with codominant VAs, diligence when rotating the head away from a dominant VA is prudent during patient positioning to avoid posterior circulation ischemia or thromboembolism.

Effect of cervical manipulation on vertebral artery and cerebral haemodynamics in patients with chronic neck pain: a crossover randomised controlled trial

OBJECTIVE

It is hypothesised that cervical manipulation may increase the risk of cerebrovascular accidents. We aimed to determine whether cervical spine manipulation is associated with changes in vertebral artery and cerebrovascular haemodynamics measured with MRI compared with neutral neck position and maximum neck rotation in patients with chronic neck pain.

SETTING

The Imaging Research Centre at St. Joseph's Hospital in Hamilton, Ontario, Canada.

PARTICIPANTS

Twenty patients were included. The mean age was 32 years (SD ±12.5), mean neck pain duration was 5.3 years (SD ±5.7) and mean neck disability index score was 13/50 (SD ±6.4).

INTERVENTIONS

Following baseline measurement of cerebrovascular haemodynamics, we randomised participants to: (1) maximal neck rotation followed by cervical manipulation or (2) cervical manipulation followed by maximal neck rotation. The primary outcome, vertebral arteries and cerebral haemodynamics, was measured after each intervention and was obtained by measuring three-dimensional T1-weighted high-resolution anatomical images, arterial spin labelling and phase-contrast flow encoded MRI. Our secondary outcome was functional connectivity within the default mode network measured with resting state functional MRI.

RESULTS

Compared with neutral neck position, we found a significant change in contralateral blood flow following maximal neck rotation. There was also a significant change in contralateral vertebral artery blood velocity following maximal neck rotation and cervical manipulation. We found no significant changes within the cerebral haemodynamics following cervical manipulation or maximal neck rotation. However, we observed significant increases in functional connectivity in the posterior cerebrum and cerebellum (resting state MRI) after manipulation and maximum rotation.

CONCLUSION

Our results are in accordance with previous work, which has shown a decrease in blood flow and velocity in the contralateral vertebral artery with head rotation. This may explain why we also observed a decrease in blood velocity with manipulation because it involves neck rotation. Our work is the first to show that cervical manipulation does not result in brain perfusion changes compared with a neutral neck position or maximal neck rotation. The changes observed were found to not be clinically meaningful and suggests that cervical manipulation may not increase the risk of cerebrovascular events through a haemodynamic mechanism.

TRIAL REGISTRATION NUMBER

NCT02667821.

Reliability and validity of clinical tests to assess the anatomical integrity of the cervical spine in adults with neck pain and its associated disorders: Part 1-A systematic review from the Cervical Assessment and Diagnosis Research Evaluation (CADRE) Collaboration

OBJECTIVE

To determine the reliability and validity of clinical tests to assess the anatomical integrity of the cervical spine in adults with neck pain and its associated disorders.

METHODS

We updated the systematic review of the 2000-2010 Bone and Joint Decade Task Force on Neck Pain and its Associated Disorders. We also searched the literature to identify studies on the reliability and validity of Doppler velocimetry for the evaluation of cervical arteries. Two independent reviewers screened and critically appraised studies. We conducted a best evidence synthesis of low risk of bias studies and ranked the phases of investigations using the classification proposed by Sackett and Haynes.

RESULTS

We screened 9022 articles and critically appraised 8 studies; all 8 studies had low risk of bias (three reliability and five validity Phase II-III studies). Preliminary evidence suggests that the extension-rotation test may be reliable and has adequate validity to rule out pain arising from facet joints. The evidence suggests variable reliability and preliminary validity for the evaluation of cervical radiculopathy including neurological examination (manual motor testing, dermatomal sensory testing, deep tendon reflexes, and pathological reflex testing), Spurling's and the upper limb neurodynamic tests. No evidence was found for doppler velocimetry.

CONCLUSIONS

Little evidence exists to support the use of clinical tests to evaluate the anatomical integrity of the cervical spine in adults with neck pain and its associated disorders. We found preliminary evidence to support the use of the extension-rotation test, neurological examination, Spurling's and the upper limb neurodynamic tests.

Effect of selected manual therapy interventions for mechanical neck pain on vertebral and internal carotid arterial blood flow and cerebral inflow

BACKGROUND

Manual therapy of the cervical spine has occasionally been associated with serious adverse events involving compromise of the craniocervical arteries. Ultrasound studies have shown certain neck positions can alter craniocervical arterial blood flow velocities; however, findings are conflicting. Knowledge about the effects of neck position on blood flow may assist clinicians in avoiding potentially hazardous practices.

OBJECTIVE

The purpose of this study was to examine the effects of selected manual therapeutic interventions on blood flow in the craniocervical arteries and blood supply to the brain using magnetic resonance angiography (MRA).

DESIGN

This was an experimental, observational magnetic resonance imaging study.

METHOD

Twenty adult participants who were healthy and had a mean age of 33 years were imaged using MRA in the following neck positions: neutral, rotation, rotation/distraction (similar to a Cyriax manipulation), C1-C2 rotation (similar to a Maitland or osteopathic manipulation), and distraction.

RESULTS

The participants were imaged using 3T MRA. All participants had normal vascular anatomy. Average inflow to the brain in neutral was 6.98 mL/s and was not significantly changed by any of the test positions. There was no significant difference in flow in any of the 4 arteries in any position from neutral, despite large individual variations.

LIMITATIONS

Only individuals who were asymptomatic were investigated, and a short section of the arteries only were imaged.

CONCLUSIONS

Blood flow to the brain does not appear to be compromised by positions commonly used in manual therapy. Positions using end-range neck rotation and distraction do not appear to be more hazardous to cerebral circulation than more segmentally localized techniques.

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.

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.

Pre-manipulative testing of the cervical spine review, revision and new clinical guidelines

Members of the Manipulative Physiotherapists Association of Australia (now Musculoskeletal Physiotherapy Australia) were surveyed to determine their use of cervical manipulation, compliance with and attitudes to the Australian Physiotherapy Association's (APA) Protocol for Pre-manipulative Testing of the Cervical Spine, and the incidence of adverse effects from cervical manipulation. The questionnaire was mailed to 740 members and returned by 480 members (65%). Cervical manipulation (84.5%) and passive mobilization (99.8%) were used by a high percentage of respondents. Most were familiar with the protocol with 63% supporting its continued endorsement. Adverse effects were reported at a rate of one per 1000 years of practice (or 0.003/week). The most common effects were symptoms potentially related to VBI (94.4% responses), with no reported major complications. Only 37.1% of respondents always informed the patient about potential dangers of cervical manipulation and consent was sought on every occasion by 33% of respondents. The results suggest that the use and interpretation of the protocol are variable among members of MPA. The risk of adverse effects from manipulative (musculoskeletal) physiotherapy practice, including cervical manipulation, appears to be very low. Recommendations for revision of the protocol were made on the basis of results of the survey and treatment diary, in addition to a review of the literature related to testing for vertebro-basilar insufficiency, adverse incidents related to cervical mobilizing and manipulative technique, differentiating features of VBI related dizziness and vertigo related to benign paroxysmal positional vertigo (BPPV) and current issues surrounding informed consent. Finally, a summary of the content of the new Clinical Guidelines for Pre-Manipulative Testing of the Cervical Spine (APA, 2000) is provided.

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.

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.

Measurement of blood flow in the vertebral artery using colour duplex Doppler ultrasound: establishment of the reliability of selected parameters

This study was designed to determine the reliability of the ultrasound testing procedure for evaluating vertebral artery blood flow, and to determine a robust testing protocol for future studies. Blood flow parameters were tested in ten asymptomatic subjects (mean age 33 years, standard deviation 6 years 8 months) using colour duplex Doppler imaging. Volume flow rate data at C5-6 demonstrated good reliability from a single measurement (Intraclass correlation coefficient [ICC]=0.81). Peak velocity sampled at C1-2 showed poor reliability if a single measurement was used (ICC=0.26) improving to fair levels with three measurements (ICC=0.77). Reliability for this parameter was good if five measurements were taken (ICC=0.83-0.84). Systolic/diastolic ratio measured at C5-6 showed poor reliability (ICC=0.57) if a single measurement was taken in the manner of Thiel et al. (1994). This improved to fair reliability (ICC=0.75) if the mean of three measurements was used. There was no further improvement if five measures were sampled. Sampling at C2-3 in the manner of Refshauge (1994) was found to be technically difficult and it was not possible to detect a Doppler shift in three of the ten subjects at this level. Reliability of peak velocity at C2-3 was found to be poor, regardless of whether single or multiple averaged measurements were taken (ICC=0.37-0.63). Mean (time averaged) velocity measurements at C2-3 showed poor reliability if a single measurement was taken (ICC=0.39), fair reliability if the first three measurements were averaged (ICC=0.73) and good to high reliability levels if five measurements were sampled (ICC=0.88-0.91). A review of the literature suggests that sampling volume flow rate at C5-6 and peak velocity at C1-2 represents a clinically meaningful combination of parameters to detect narrowing in the VA. The results of this current study indicate the desirability of taking a single measurement of volume flow rate at C5-6 and the mean of three measurements of peak velocity at C1-2, with the additional calculation of the standard error of measurement, if reliable results are to be achieved.

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.

Basilar artery blood flow during head rotation in vertebrobasilar ischemia

PATIENTS AND METHODS

Forty-six patients with vertebrobasilar ischemia and 40 control subjects were examined during head rotation using transcranial Doppler ultrasonography.

RESULTS

In the control group, no difference in blood flow velocity through the BA was found between the neutral and rotated positions. Based on these data, a blood flow reduction in the BA of more than 20% was considered to be significantly abnormal (p < 0.01). In three of 46 patients no signal was detectable in the BA using TCD. The reduction in blood flow velocity through the BA during head rotation was strongly dependent on the condition of the VA; none of 23 patients without atherosclerotic lesions or hypoplasia of the VA developed a significant reduction in blood flow through the BA. Two of 11 patients with unilateral VA lesions had significantly reduced blood flow in the BA (27% and 31%), although both were asymptomatic. Five of nine patients with bilateral VA lesions showed a significant reduction in blood flow through the BA (mean = 52%, minimum = 30%), and four of these developed clinical symptoms such as vertigo or diplopia during the rotation maneuver.

CONCLUSION

These data suggest that patients with uni- or bilateral lesions of the VA are at risk for developing clinically relevant reductions in blood flow through the BA during head rotation. Because not all patients with VA lesions developed reduced blood flow velocity, we conclude that individual vascular mechanisms must play an important compensatory role.

Influence of extreme head rotations on brainstem auditory evoked potentials (BAEP)

The influence of extreme head rotations on BAEP was studied in 47 patients who had vertebral artery angiogram. Patients with and without unilateral hypoplasia of the vertebral artery (VA) lumen were identified and all patients were further divided into two groups: with and without hypertension. The subjects underwent a BAEP examination in three head positions: neutral position, extreme right and extreme left rotation. In the subgroup of patients with hypertension and unilateral VA hypoplasia, and following the rotation away from the non-hypoplastic vessel a statistically significant decrease in the PV wave amplitude and prolonged PV wave latency was found. Head maneuvers in subjects with normal blood pressure or in hypertensive patients with symmetrical VA did not cause significant changes in BAEP. These results document the effect of head rotation in subjects with potentially impaired collateral flow. An increase in the PV wave latency and decrease in its amplitude may reflect subtle changes in the brainstem perfusion in hypertensive patients. These changes maybe due to a reduced capacity to compensate for dynamic obstruction of VA following the head rotations.

Blood flow velocities in basilar artery during rotation of the head

The authors measured blood flow velocities with transcranial Doppler ultrasonography in the basilar artery after extreme rotations of the head. Studied subjects were divided in two groups according to the degree of asymmetry of the vertebral artery lumens. Rotation of the head caused significant reduction of the mean flow velocity in the basilar artery in the subjects with asymmetry of the vertebral arteries of more than 75%. The decline occurred only after the rotation ipsilaterally to the hypoplastic vertebral artery. This study confirms the importance of the collateral flow in the compensation of dynamic compression of the vertebral artery.

Transient ischemic attacks: an update

This is a review of extant concepts of transient ischemic attacks (TIAs), their definitions, prognostic significance, pathogenesis, physiology, and management. The natural history of TIAs depends upon the risk factors of the population group studied, so that therapeutic trials should be controlled and randomized and not dependent upon published natural history data. A strong association between TIAs and coronary artery disease has now been established. It may be difficult to establish the cause or pathogenesis of TIAs in any given patient in view of the relatively poor correlation between the patient's symptoms and location of arterial plaques. Recent studies have suggested mechanisms aside from impaired perfusion or embolization from carotid plaques or vertebral basilar disease. There are no proven indications for carotid endarterectomy, a procedure which has been excessively used in the United States, but presently ongoing prospective, randomized, controlled multi-center studies will likely resolve this important issue. Neither is there scientific validation for the use of long-term anticoagulants, but data support the efficacy of ASA in reducing the incidence of stroke and myocardial infarction in patients with TIAs.