Craniocervical artery dissection (CAD), a tearing of the intimal, medial or adventitial layers of the wall of the internal carotid or vertebral arteries, is a major cause of ischaemic stroke in young to middle aged individuals in the fourth and fifth decades [1, 2], perhaps accounting for up to 10-25 % of ischaemic stroke in this age group . CAD has an annual incidence of 2.5-3:100,000 [3–5], however this may be an underestimate as cases with mild clinical signs and symptoms may not always be recognised and dissections may resolve spontaneously .
The aetiology of CAD is not fully understood and many cases are described as occurring spontaneously when no obvious mechanism or trigger can be identified. However, it has been suggested that for dissection to occur there is a contribution from both intrinsic and extrinsic factors. It has been proposed that the mechanism involves both a pre-existing intrinsic susceptibility such as an underlying arteriopathy, and a precipitating event which may be fairly innocuous [2, 3, 6, 7]. The underlying arteriopathy may be in the form of a vascular anomaly, a genetic pre-disposition  such as a subclinical connective tissue disease, or may be a transient situation perhaps caused by an infection or pro-inflammatory state giving rise to a temporary friability of the vessel wall [9, 10]. In patients with such an existing susceptibility, exposure to a precipitating event such as minor mechanical trauma or activities imparting some stress to the neck [11, 12] may trigger a dissection of the artery . Such minor trauma is usually innocuous, such as might occur during the course of normal daily activities. Frank trauma, such as may happen during a motor vehicle accident has not usually been reported [14, 15].
Cervical spine manual therapy has been hypothesised as one type of minor trauma or neck stress which may be a trigger for CAD. This has raised concerns amongst manual practitioners as to whether the nature of manipulative techniques is responsible for reported cases or whether some patients already have CAD in its early stages when it is difficult to diagnose. Notably, the clinical presentation of CAD usually includes neck pain and headache, which may in many cases mimic a musculoskeletal disorder or migraine [2, 3, 7]. It is therefore possible that CAD might not be recognised early in its presentation, particularly in the absence of clear ischaemic (or neurological) features. This may lead the patient to seek pain treatment from their primary care practitioner or manual therapist for the painful symptoms which are in reality resulting from a dissection in progress .
Previous reviews have often included a number of retrospective studies of CAD [2, 3, 17] some of which have shown conflicting findings in respect of the presence of particular risk factors . Exposure to minor mechanical trauma of the neck has been shown to be associated with CAD by a number of authors [4, 13, 18, 19], however detailed characterisation of the types of trauma and direction of force application has been limited. Retrospective studies are often limited and biased by the information available in hospital databases, highlighting the need for prospective studies which include interviews of patients close to the time of their dissection.
Previous prospective studies have tended to be from large hospital series and were therefore medically focussed, again relying on routine information in the hospital records and did not always use a face to face interview [13–15, 20, 21]. They may have therefore been subject to selection bias if investigators were able to choose whether or not to include participants based on information available in the records [15, 22]. Some previous studies have also lacked age limitations so may have included older patients with atherosclerosis or other age related conditions. Moreover, they did not always include a control group for comparison. In particular, they generally report limited information or historical details about preceding activities and events, as well as occurrence of any transient ischaemic features in the weeks preceding hospitalisation which might facilitate early recognition of CAD. These details are of particular interest to primary care practitioners to assist them to more readily identify those patients at risk of CAD or who may be presenting with early symptoms.
It has been argued that the timely recognition of potential risk factors and more subtle early presenting neurological signs or symptoms of CAD is critical [2, 23] so that the patient is not exposed to inappropriate manual treatment of the neck. Early recognition is also critical in the case of a patient presenting with a dissection in progress, so that referral for appropriate medical management can be made promptly. There is also a need to characterise the presenting features of vertebral and internal carotid artery dissection, in particular ischaemic features, with more descriptive detail, so as to aid recognition of the significance of early signs and symptoms.
In manual therapy texts and guidelines on the topic of vertebrobasilar insufficiency (VBI) , an insufficiency of blood flow to the hindbrain, much emphasis has been placed on the presence of dizziness as an indicator of VBI. However it is possible that other clinical features may be earlier or more useful indicators of the presence of dissection and associated VBI. Identification of early clinical features related to dissection of craniocervical arteries may help in the prompt recognition of these conditions in patients presenting to physiotherapists and other practitioners.
A recent retrospective study of risk factors and clinical features of CAD by our research group examined the medical records of 47 patients ≤ 55 years who had suffered a vertebral or internal carotid dissection, and found that 64 % had a recent history of minor mechanical trauma to the neck . Other preceding events and proposed risk factors such as recent infection and hypertension were less well documented. This retrospective study was however limited by inconsistent recording of data in the medical records. Hence we have designed a prospective study to further investigate the risk factors and presenting clinical features of CAD patients in the Hunter region of New South Wales, Australia.
The purpose of the proposed study is therefore to prospectively investigate the presenting clinical features and pre-existing health status of CAD patients ≤ 55 years in order to identify risk factors and describe the common early clinical features.
Aims and hypotheses
The specific aims of the study are to test the following hypotheses in a prospective cohort of patients with radiologically confirmed CAD:
That the following risk factors will be independently associated with vertebral or internal carotid arterial dissection:
That patients presenting with craniocervical arterial dissection pain will have no antecedent ischaemic neurological features.
recent minor mechanical trauma to the head or neck
cervical spine manual therapy, specifically high velocity thrust manipulation or end-range rotational mobilisation techniques or deep upper cervical soft tissue massage
recent infection, febrile illness or clinical markers of pro − inflammatory states