1. Chapter 21
The Vertebral Artery

2. Overview
The first studies of the vertebral artery were recorded as far back as 1844
Since that time the importance of the vertebral artery has grown considerably in stature, and is now discussed in more detail than any other artery by physical therapists

3. Anatomy
The vertebral artery appears during the fifth to sixth week of intra-uterine development, from a posterior costal anastomosis between the upper six cervical and posterior-lateral intersegmental arteries
Along its course, the artery can be viewed as four portions: the proximal, transverse, suboccipital and intracranial portions

4. Anatomy The Proximal Portion
This portion runs from the origin of the artery to its point of entry to the cervical spine
The vertebral artery usually originates from the posterior surface of the subclavian artery, but it can also originate from the aortic arch and common carotid artery
It runs vertically, slightly medial and posteriorly, lateral to the longus colli and medial to the anterior scalene, to reach the transverse foramen of the lower cervical spine, although its exact direction is dependent on its exact point of origin

5. Anatomy Proximal portion
Tortuosity and compression of this portion of the artery is common
The tortuosity and compression can be congenital, muscular (due to compression by the longus colli and scalene) or because of advancing years

6. Anatomy Transverse Portion
The transverse portion of the vertebral artery runs from the point of entry at the spinal column to the transverse foramen of C 2
Throughout this section of the spinal column, the artery travels vertically, in a true canal called the transverse canal
The transverse canal is formed by the bony transverse foramina at each spinal level, the overlying anterior and posterior intertransverse muscles, and the scaleni and longus coli muscles

7. Anatomy Transverse portion
Tortuosity of this portion of the artery can also occur due to an abnormal origin of the artery from the aorta
The tortuosity is characterized by looping within the intervertebral foramina, to the extent of causing pedicle erosion, and a widening of the intervertebral foramen with nerve root compression, and even a fracture of the neural arch

8. Anatomy Suboccipital Portion
This portion of the artery extends from its exit at the axis to its point of penetration into the spinal canal
The vertebral artery is most vulnerable to compression and stretching at the C1-C2 level because of the amount of cervical rotation that can occur at the atlantoaxial joint

9. Anatomy The Intracranial Portion
This portion of the vertebral artery runs from its penetration of the dura mater into the arachnoid space at the level of the foramen magnum, to the formation of the basilar artery by the midline union of the two arteries at the lower border of the pons
A major change in the structure of the artery occurs as it becomes intracranial
The tunica adventitia and tunica media become thinner, and there is a gross reduction in the number of elastic fibers in these coats

10. Anatomy Intracranial portion
Due to these structural changes the intracranial portion of the artery is prone to mechanical obstructions to the artery, including atherosclerotic plaques or stenosis

11. Pathology
Damage and occlusion of the vertebral arteries is felt to occur because of the close proximity of the vertebral artery and the bony and ligamentous structures of the cervical spine
Trauma to this area may lead to thrombosis, dissection, transection, transmural hematoma, pseudoaneurysm, and spasm of the vertebral artery
Vertebral artery compromise may also occur because of atherosclerotic involvement of the artery, sickle cell disease, rheumatoid arthritis, arterial fibroplasias, an arteriovenous fistula, and a number of congenital syndromes

12. Examination
Clinicians need to be aware of the signs and symptoms and consider vertebral artery dissection early in the differential diagnosis because of the potential devastating neurological consequences and in order to decrease morbidity and mortality

13. Examination
The testing of the vertebral artery has been a routine part of patient screening by manual therapists for many years, being first described by Maitland in 1968
Traditionally, clinicians have relied solely on existing manual pre-manipulative tests to determine the appropriateness of a Grade V technique, although it is not clear how sensitive these tests are

14. Examination
In those cases where the clinician is to perform cervical mobilizations of Grade I-IV, rather than a Grade V thrust technique, the Australian Physiotherapy Association’s Protocol for Pre-manipulative Testing of the Cervical Spine is recommended

15. Examination
A positive vertebral artery test is one in which signs or symptoms change, especially if the changes evoked include upper motor neuron signs and/or symptoms

16. Examination Upper motor neuron signs and symptoms Dysphasia Diplopia
Hemianopia
Ataxia
Hyperreflexia
Babinski response
Positive Hoffman or Oppenheim test

17. Examination Other UMN signs and symptoms Flexor withdrawal Nystagmus
Quadrilateral paresthesia
Bilateral upper limb paresthesia
Peri-oral anesthesia
Drop attacks
Wallenberg syndrome

18. Intervention
Following a positive vertebral artery test, or positive responses in the history, the patient must be handled very carefully, and further intervention, particularly manipulation of the cervical spine should not be delivered
The patient should not under any circumstance, be allowed to leave the clinic until their physician has been contacted, and until the necessary arrangements have been made for the safe transport of the patient to an appropriate facility