Spinal manipulation, particularly when performed on the cervical spine, is frequently associated with mild to moderate adverse effects. It can also result in serious complications such as vertebral artery and internal carotid artery dissection followed by stroke. These terms are coined with other vascular conditions to be known as cervical artery dysfunction (CAD) which manual therapists should be aware of before performing manual techniques onto the cervical spine region. This blog will go through risk factors and assessment strategies to help identify signs of CAD to help build a clinical picture of your patient and whether manual therapy or further referral is appropriate.
The Vertro-basiliar (cervical) arterial system provides blood ﬂow to the hind-brain (i.e. brain-stem, Medulla Oblongata, Pons, Cerebellum, and Vestibular apparatus). The left and right vertebral arteries arise from the subclavian arteries and pass through the transverse foramina of cervical vertebral levels 6 to 1, during rotation, the contralateral vessel may be stretched therefore potentially affecting blood ﬂow. Once inside the skull, the two vertebral arteries join each other to form the basilar artery, which in turn flows into the circle of Willis. The internal carotid artery supplies the anterior part of the brain, the eye and its appendages, and sends branches to the forehead and nose. Its size, in the adult, is equal to that of the external carotid, though, in the child, it is larger than that vessel. When there is a reduction of blood supply to speciﬁc parts of the brain, certain signs and symptoms are displayed. This is what can be referred to as Vertebral Basiliar Insuffiency (VBI).
Trauma or damage to cervical blood vessels is generally classified as either dissection resulting from direct trauma to the vessel, or localised thrombogenesis and embolus formation in response to endothelial damage. Either of these pathological states may lead to a stroke. Arterial dissection may occur after trivial trauma to the vessel, or spontaneously. This may be related to pre-existing, congenital weakness of the vessel wall or acquired vascular pathology (atherosclerosis). The mechanisms are thought to be arterial dissection with an intra-mural haematoma, resulting in vessel lumen narrowing which causes a reduction in blood flow and ischaemia; an extending dissection, leading to subarachnoid haemorrhage; and/or dissection leading to thrombus formation with secondary emboli, and stroke (Kerry et al, 2008).
Risk factors for CAD
The following risk factors are associated with an increased risk of either internal carotid or vertebrobasilar arterial pathology and should be thoroughly assessed during the subjective history (Rushton et al, 2012).
- Past history of trauma to cervical spine / cervical vessels
- History of migraine-type headache
- Hypercholesterolemia / hyperlipidemia
- Cardiac disease, vascular disease, previous cerebrovascular accident or transient ischaemic attack
- Diabetes mellitus
- Blood clotting disorders / alterations in blood properties (e.g. hyperhomocysteinemia)
- Anticoagulant therapy
- Long-term use of steroids
- History of smoking
- Recent infection
- Immediately post partum
- Trivial head or neck trauma (Haneline and Lewkovich, 2005; Thomas et al, 2011)
- Absence of a plausible mechanical explanation for the patient’s symptoms.
- 5 D’s (dizziness, diplopia, dysarthria, dysphagia, drop attacks)
- 3 N’s (nausea, numbness, nystagmus)
Upper Cervical Instability
This condition is also linked to trauma etc and needs to be differentiated as a possible cause of the patients symptoms. The following risk factors are associated with the potential for bony or ligamentous compromise of the upper cervical spine (Cook et al 2005):
- History of trauma (e.g. whiplash, rugby neck injury)
- Throat infection
- Congenital collagenous compromise (e.g. syndromes: Down’s, Ehlers-Danlos, Grisel, Morquio)
- Inflammatory arthritides (e.g. rheumatoid arthritis, ankylosing spondylitis)
- Recent neck/head/dental surgery.
Posture, Gait disturbances, subtle signs of disequilibrium, upper motor neuron signs and behaviour suggestive of upper cervical instability (e.g. anxiety, supporting head/neck).
Hypertension or high blood pressure is a risk factor for CAD normal rages are:
Myotomes, dermatomes, reflexes
Cranial Nerve Assessment
The cranial nerves run closely to the vertebral and internal carotid arteries so examination of these can help to show if early signs of CAD are present.
Cervical Instability Testing
Palpation of the carotid artery
Asymmetry between left and right vessels is considered. A pulsatile, expandable mass is typical of arterial aneurysm. Such a finding should be considered in the context of other findings from the clinical assessment. It is possible for dissections and disease of the carotid arteries to exist in the absence of aneurysm formation, therefore a negative finding should not be used to refute the hypothesis of arterial dysfunction.
Differential Diagnosis examples:
Also a fantastic podcast by Roger Kerry a leading clinician and researcher in this field can be listened to here:
CAD is a serious condition that needs to be assessed and even though the incidence of this condition is very rare, it still needs to be kept in mind when patients present with headaches and neck pain. By looking for relevant risk factors from the patient’s history and also during the objective assessment the risks of adverse events from manual therapy to the cervical spine can be reduced and also knowing when to refer a patient on for further examination can aid this further.
Kerry, R, Taylor, A.J, Mitchell, J. and McCarthy, C. 2008. Cervical arterial dysfunction and manual therapy: A critical literature review to inform professional practice, Manual Therapy 13, 278–288.
Mintken,P.E, Metrick, L. and Flynn, T.W. 2008. Upper cervical ligament testing in a patient with os odontoideum presenting with headaches. Journal of Orthopaedic and Sports Physical Therapy (Impact Factor: 2.95; 38(8):465-75. DOI:10.2519/jospt.2008.2747.
Rushton, A, Rivett, D, Carlesso, L, Flynn, T, Hing, W. and Kerry, R. 2013. International Framework for Examination of the Cervical Region for potential of Cervical Arterial Dysfunction prior to Orthopaedic Manual Therapy Intervention. Man Ther.(13)00192-6. doi: 10.1016/j.math.2013.11.005.