Vertebral Artery Test
The vertebral artery test is used in physiotherapy to test the vertebral artery blood flow, searching for symptoms of vertebral artery disease. Vertebral artery disease is also known as vertebrobasilar ischaemia (VBI).
Clinicallly Relevant Anatomy. It branches from the subclavian artery, where it arises from the posterosuperior portion of the subclavian artery. It ascends thought the foramina of the transverse processes of the sixth cervical vertebrae. Then, it winds behind the superior articular process of the atlas. It enters the cranium through the foramen magnum where it unites with the opposite vertebral artery to form the basilar artery (at the lower border of the pons).
The vertebral artery can be divided into four divisions: The first division runs posterocranial between the longus colli and the m. scalenus anterior. The first division is also called the ‘pre-foraminal division’. The second division runs cranial through the foramina in the cervical transverse processes of the cervical vertebrae C2. The second division is also called the foraminal division. The third division is defined as the part that rises from C2. It rises from the latter foramen on the medial side of the rectus capitis lateralis, and curves behind the superior articular process of the atlas. Then, it lies in the
groove on the upper surface of the posterior arch of the atlas, and enters the vertebral canal by passing beneath the posterior atlantoöccipital membrane. The fourth part pierces the dura mater and inclines medial to the front of the medulla oblongata.
The vertebral artery test is used to test the vertebral artery blood flow, searching for symptoms of vertebral artery disease. A reduction of blood flow may result in a transient ischiamic attack (TIA), a critical harbinger of impending stroke. It could mean that, if the disease isn’t quickly diagnosed, there is a risk of missing the opportunity to prevent permanent disability or even death. According to ‘Johnston et al, 2000’, the 90-day risk of stroke after a transient ischaemic attack has been estimated to approximately 10%. 50% of these strokes occur within the first two days after a TIA. Therefore, it is important to send a person with a positive test score to the hospital, where he can be examined furtherly.
TIA is often misdiagnosed as migraine, seizure, peripheral neuropathy or anxiety.
Vertebral artery disease is also known as ‘vertebrobasilar ischaemia’ (VBI).
To test the blood flow in the vertebral artery (VA), one should put the patient on his back and perform an passive extension, followed by a passive rotation of the neck. The rotation should be performed in both directions.
The manoeuvre causes a reduction of the lumen at the third division of the vertebral artery, resulting in de decreased blood flow of the intracranial VA of the contralateral side. It causes an ischemia due to blood loss in the pons and the medulla oblongata of the brain. This results in dizziness, nausea, syncope, dysarthria, dysphagia, and disturbances of the hearing or vision, paresis or paralysis of patients with VBI.
Below is an alternate vertebral artery test, that may be used in certain settings. For example, in the assessment of an individual with suspected BPPV.
The test is commonly used for over the past 30 years. The reduction of the lumen has been reported by many authors, but a lot of these studies were not sufficient enough because of lack of good samples of healthy people and VBI patients over a wide range of age. Therefore, those results may be controversial.
There are also a lot of inconsistencies in the today’s literature. The review of Mitchell et al.,2007 found that, from the twenty studies it reviewed, four studies measured the blood flow in the transverse part of the VA (first division), eleven in the second division, none in the third division and five in the fourth division. In 7 of the 20 studies, there was not found any loss of blood flow in the VA1. Because of the inconsistency in the literature, there will be false positive/negative blood flow results in cervical spine rotation. Thus, the controversial findings in today’s literature cannot be used to guide evidence-based practice except to support the need for educated caution and authority in the pre-treatment screening and treatment of the patients.
‘Côté et al.’ sais that the positive predictive value of this test(the proportion of subjects with a positive test who are correctly diagnosed) is 0%, and the negative predictive value of this test ranged from 63%-97%. The test was found not valid enough to detect a reduced blood flow in the VA. Therefore, the value of this test is questionable.
| || Current Best Evidence: VBI and Cervical Manipulation
This presentation, created by Kahn Nirschi as part of the Evidence In Motion OMPT Fellowship, discusses the current best evidence for vertebral cervical insufficiency and cervical manipulation.
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 Jeanette Mitchell; Doppler insonation of vertebral artery blood flow changes associated with cervical spine rotation: Implications for manual therapists; Physiotherapy Theory and Practice; 2007; 23(6):303-313
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 R. Grant; Vertebral Artery Testing – the Australian Association protocol after 6 years; Manual Therapy; 1996; 1; 149-153
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 Jeanette A. Mitchell; Changes in vertebral artery flow following normal rotation of the cervical spine; Journal of Manipulative and Physiological Therapeutics; 347-351, 2002
- ↑ 4.0 4.1 4.2 Jeanette A. Mitchell; Is cervical spine rotation, as used in the standard vertebrobasilar insufficiency test, associated with a measureable change in intracranial vertebral artery blood flow?; Manual Therapy; 2004; 9 ; 220–227
- ↑ 5.0 5.1 5.2 http://home.comcast.net/~wnor/lesson5.htm
- ↑ 6.0 6.1 6.2 6.3 6.4 6.5 http://education.yahoo.com/reference/gray/subjects/subject/148
- ↑ Albers GW, Caplan LR, Easton JD, Fayad PB, Mohr JP, Saver JL, et al.; Transient ischemic attack—proposal for a new definition.; N Engl J Med. 2002;347:1713–6.[A2]
- ↑ 8.0 8.1 Hiroaki Naritomi, MD; Fumihiko Sakai, MD; John Stirling Meyer, MD; fckLRPathogenesis of Transient Ischemic Attacks Within the Vertebrobasilar Arterial System; Arch Neurol. 1979;36(3):121-128.[B]
- ↑ Johnston CS, Gress DR, Browner WS, Sidney S. Short-term prognosis after emergency department diagnosis of TIA. JAMA. 2000;284:2901–6.[B]
- ↑ Côté P et al.; The validity of the extension-rotation test as a clinical screening procedure before neck manipulation: a secondary analysis; J Manipulative Physiol Ther;. 1996 Mar-Apr;19(3):159-64[A2]
Evidence Based Practice
Learn about Evidence Based Practice in this month's members learn topic with book chapters from Practical Evidence-Based Physiotherapy 2012 & Evidence-Based Practice Across the Health Professions 2013