Continuous-wave Doppler of vertebral arteries in noninvasive diagnosis and management of vertebro-basilar TIAs

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.

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.

Vertebrobasilar insufficiency: correlation of clinical and radiologic findings

Radiological and clinical findings of 20 cases with angiographically proven stenosis or occlusion of the vertebrobasilar system and with clinical signs and symptoms attributable to posterior circulation disorder were studied. A simplified classification of vertebrobasilar arterial disease was presented; type I refers to stenosis of the vertebrobasilar system or subclavian artery, type II refers to vertebrobasilar occlusion, and type III refers to vertebrobasilar branch disease. Type I lesions were further subdivided into types Ia and Ib; type Ia cases showed no infarction in the posterior territory, whereas type Ib cases showed one or more infarctions on computed tomography or magnetic resonance imaging. This angiographic classification is based on treatment options that can be adopted to specific types of lesion. In type I cases, lesions are usually amenable to surgical or angiographic intervention. In type II cases, short-term anticoagulation is the treatment of choice. In type III cases, treatment is primarily aimed at prevention of complication and further stroke.

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

Two groups of subjects, matched for age, were studied. The first group consisted of 190 healthy subjects, the second, of 60 patients with vertebrobasilar transient ischemic attacks (TIAs), 22 of whom underwent angiography. After it was ascertained that the findings from continuous-wave (cw) Doppler of carotid and vertebral arteries, performed in the standard position, were normal, the examination was then done in De Kleyn's position, the velocity signal being detected at the mastoidal slopes. The abnormal findings were classified into two groups: "loss of diastolic velocity signal" and "absence of velocity signal." In the control group, changes of flow were detected in 6.31%, whereas in the group of patients abnormal Doppler parameters were detected in 33.33%. None of the patients who were submitted to angiography showed abnormal hemodynamic findings. The authors suggest that the detection of the velocity signal of the vertebral arteries in De Kleyn's position could be of help in revealing conditions that could cause, in time, signs and/or symptoms of vertebrobasilar insufficiency in subjects with possible asymptomatic anomalies of the circle of Willis.