Lucy C. Thomas

Risk factors and clinical features of craniocervical arterial dissection

Craniocervical arterial dissection is one of the most common causes of ischaemic stroke in young people and is occasionally associated with neck manipulation. Identification of individuals at risk will guide risk management. Early recognition of dissection in progress will expedite medical intervention. Study aims were to identify risk factors and presenting features of craniocervical arterial dissection. Medical records of patients from the Hunter region of New South Wales, Australia aged ≤ 55 years with radiographically confirmed or suspected vertebral or internal carotid artery dissection, were retrospectively compared with matched controls with stroke from some other cause. Records were inspected for details of clinical features, presenting signs and symptoms and preceding events. Records of 47 dissection patients (27 males, mean age 37.6 years) and 43 controls (22 males, mean age 42.6 years) were inspected. Thirty (64%) dissection patients but only three (7%) controls reported an episode of mild mechanical trauma, including manual therapy, to the cervical spine within the preceding three weeks. Mild mechanical trauma to the head and neck was significantly associated with craniocervical arterial dissection (OR 23.53). Cardiovascular risk factors for stroke were less evident in the dissection group (<1 factor per case) compared to the controls (>3).

Risk factors and clinical presentation of craniocervical arterial dissection : a prospective study

BackgroundCraniocervical arterial dissection is a major cause of ischaemic stroke in young adults. The pathogenesis is not fully understood but is thought to be related to a combination of an intrinsic weakness in the arterial wall and an external trigger. Intrinsic susceptibility is thought to be a generalised arteriopathy, vascular anomaly or genetic predisposition. Proposed extrinsic factors include recent viral infection and minor mechanical trauma to the neck, including neck manipulation, which has raised concerns amongst manual practitioners in particular as to the appropriate screening of patients and avoidance of more vigorous therapeutic techniques. The presenting features of dissection may mimic a musculoskeletal presentation, creating a diagnostic dilemma for primary care practitioners. Early recognition is critical so that appropriate management can be commenced.The aims of this study are to prospectively investigate young patients ≤55 years admitted to hospital with radiologically diagnosed craniocervical arterial dissection compared to matched controls with stroke but not dissection, to identify risk factors and early presenting clinical features, so these may be more readily identified by primary care practitioners.MethodsPatients ≤ 55 years presenting to hospital with craniocervical arterial dissection and controls will have their medical records reviewed and be interviewed and questioned about possible risk factors, preceding events to admission such as recent neck trauma, and presenting clinical features including any preceding transient ischaemic features. Clinical assessment will include a connective tissue screening examination to identify subclinical connective tissue disorders. Radiology and blood screening will be reviewed for typical features and inflammatory markers. Functional outcome will be reviewed to determine the burden of the stroke.DiscussionThis study will provide descriptive and comparative data on intrinsic and extrinsic risk factors for craniocervical arterial dissection and outline the typical clinical presentation, including the nature of early presenting features which might assist practitioners to identify those patients for whom vigorous manual therapy of the neck is inappropriate and alert them to those for whom immediate urgent medical care should be sought.

Risk Factors and Clinical Presentation of Cervical Arterial Dissection: Preliminary Results of a Prospective Case-Control Study

STUDY DESIGN Cross-sectional case-control study. OBJECTIVES To identify risk factors and clinical presentation of individuals with cervical arterial dissection. BACKGROUND Cervical arterial dissection is a common cause of stroke in young people and has in rare cases been associated with cervical manipulative therapy. The mechanism is considered to involve pre-existing arterial susceptibility and a precipitating event, such as minor trauma. Identification of individuals at risk or early recognition of a dissection in progress could help expedite medical intervention and avoid inappropriate treatment. METHODS Participants were individuals 55 years of age or younger from the Hunter region of New South Wales, Australia with radiologically confirmed vertebral or internal carotid artery dissection and an age- and sex-matched comparison group. Participants were interviewed about risk factors, preceding events, and clinical features of their stroke. Physical examination of joint mobility and soft tissue compliance was undertaken. RESULTS Twenty-four participants with cervical arterial dissection and 21 matched comparisons with ischemic stroke but not dissection were included in the study. Seventeen (71%) of the 24 participants with dissection reported a recent history of minor mechanical neck trauma or strain, with 4 of these 17 reporting recent neck manipulative therapy treatment. Cardiovascular risk factors were uncommon, with the exception of diagnosed migraine. Among the participants with dissection, 67% reported transient ischemic features in the month prior to their admission for dissection. CONCLUSION Recent minor mechanical trauma or strain to the head or neck appears to be associated with cervical arterial dissection. General cardiovascular risk factors, with the exception of migraine, were not important risk factors for dissection in this cohort. Preceding transient neurological symptoms appear to occur commonly and may assist in the identification of this serious pathology. LEVEL OF EVIDENCE Prognosis, level 4.

Effect of Selected Manual Therapy Interventions for Mechanical Neck Pain on Vertebral and Internal Carotid Arterial Blood Flow and Cerebral Inflow

Background Manual therapy of the cervical spine has occasionally been associated with serious adverse events involving compromise of the craniocervical arteries. Ultrasound studies have shown certain neck positions can alter craniocervical arterial blood flow velocities; however, findings are conflicting. Knowledge about the effects of neck position on blood flow may assist clinicians in avoiding potentially hazardous practices. Objective The purpose of this study was to examine the effects of selected manual therapeutic interventions on blood flow in the craniocervical arteries and blood supply to the brain using magnetic resonance angiography (MRA). Design This was an experimental, observational magnetic resonance imaging study. Method Twenty adult participants who were healthy and had a mean age of 33 years were imaged using MRA in the following neck positions: neutral, rotation, rotation/distraction (similar to a Cyriax manipulation), C1–C2 rotation (similar to a Maitland or osteopathic manipulation), and distraction. Results The participants were imaged using 3T MRA. All participants had normal vascular anatomy. Average inflow to the brain in neutral was 6.98 mL/s and was not significantly changed by any of the test positions. There was no significant difference in flow in any of the 4 arteries in any position from neutral, despite large individual variations. Limitations Only individuals who were asymptomatic were investigated, and a short section of the arteries only were imaged. Conclusions Blood flow to the brain does not appear to be compromised by positions commonly used in manual therapy. Positions using end-range neck rotation and distraction do not appear to be more hazardous to cerebral circulation than more segmentally localized techniques.

Validity of the Doppler velocimeter in examination of vertebral artery blood flow and its use in pre-manipulative screening of the neck

Pre-existing compromise of one or both vertebral arteries is considered a contraindication to neck manipulation. Current pre-manipulative screening tests may not adequately identify individuals with such compromise. It has been proposed that using a continuous wave ultrasound device (Doppler velocimeter) may assist in identifying patients presenting with flow abnormalities. The aim of this study was to determine the validity and reliability of the use of a velocimeter in detecting altered vertebral artery blood flow. Blood flow in the atlanto-axial segment of seated healthy adult volunteers (n=60) was examined in the neutral and end-range contralateral rotation positions. Duplex ultrasound scans were performed (n=58) and identified 17 volunteers (29.3%) with abnormal flow according to pre-determined criteria. Three trained physiotherapists blinded to the duplex examination results used a velocimeter to examine the vertebral arteries of the volunteers. The specificity of the velocimeter examination to detect abnormal flow identified by the duplex examination was fair to good (range 0.78-0.88). However, its sensitivity was poor (range 0.25-0.38) and the inter-examiner reliability was poor (kappa ranged from 0.15 to 0.26). This study suggests that the velocimeter may be neither a valid or reliable tool for the detection of abnormal blood flow in the vertebral arteries.

Cervical arterial dissection: An overview and implications for manipulative therapy practice

INTRODUCTION Cervical arterial dissection (CAD) is a common cause of stroke in young people under 55 years. It can occur spontaneously or subsequent to minor trauma or infection. The incidence is difficult to determine accurately as not all CAD progress to stroke. CAD is the most catastrophic adverse event associated with cervical manipulative therapy but it is rare. Early features of CAD can mimic a painful musculoskeletal presentation and a patient may present for treatment of neck pain and headache with a dissection in progress. Whether the manipulative technique is responsible for dissection or whether the diagnosis of CAD has been missed is unclear. Identification of individuals at risk, or early recognition of CAD could help expedite medical intervention and avoid inappropriate treatment. PURPOSE The aims of this masterclass are to outline current research into the pathophysiology, aetiology and clinical presentation of CAD, to place the risk in context in a manipulative therapy setting and to discuss its possible clinical recognition. IMPLICATIONS For those patients presenting with recent onset, moderate to severe unusual headache or neck pain, clinicians should perform a careful history, in particular questioning about recent exposure to head/neck trauma or neck strain. Cardiovascular factors may not be particularly useful indicators of risk of dissection. Clinicians should also be alert to reports of transient neurological dysfunction such as visual disturbance and balance deficits, arm paraesthesia and speech deficits, as these may be subtle. If clinicians suspect arterial dissection is in progress patients should be urgently referred for medical evaluation.

Risk factors, radiological features, and infarct topography of craniocervical arterial dissection

Background Craniocervical arterial dissection is a common cause of ischemic stroke in the young to middle-aged population. There have been a number of previous studies where radiological features have been described but few with detailed mapping of infarct topography and none where these features have been related to the reported risk factors. Aims The aims of this study were to describe the radiological characteristics of dissection patients ≤55 years and relate these to reported risk factors. Methods Craniocervical arterial dissection cases ≤55 years, and age- and gender-matched controls were identified from a medical records database between 1998 and 2009. Control cases had stroke from another cause than dissection. Records and radiology were reviewed. Results Thirty-six radiologically confirmed dissection cases [20 (56%) vertebral artery, 16 (44%) internal carotid], and 43 controls were identified. Dissections were extracranial with intracranial extension in 10 (28%) cases. Infarction was demonstrated in 22 (61%) dissection cases. The most common wall deficit identified was an intimal flap. Twenty-three (64%) dissection cases had a recent history of neck trauma (P > 0·000) and 13 (36%) had vascular variants (P = 0·013). Conclusion Craniocervical arterial dissection cases, particularly vertebral artery, were more likely to have a history of neck trauma. Dissections were most commonly extracranial, in the upper cervical region, with intracranial extension in 28%. Dissection cases with trauma more commonly had a dissection flap and evidence of infarction in the lateral medulla, anterior or posterior inferior cerebellar artery territory. Close inspection of the V3 segment of the vertebral or skull base for internal carotid artery may be warranted with a history of neck trauma.

Shear wave elastography of the cervical arteries: A novel approach to the assessment of cervical arterial wall stiffness. An investigation of psychometric properties and intra-rater reliability

BACKGROUND Cervical arterial dissection, can occur spontaneously and is a rare but catastrophic adverse event associated with neck manipulation. Pathophysiology involves altered integrity of the arterial wall increasing its vulnerability to minor trauma. Those at risk are difficult to detect. Previous screening investigated blood flow but altered mechanical properties as stiffness of cervical arterial wall could provide a more valid indication of arterial integrity or even early dissection. OBJECTIVES To investigate suitability and intra-rater reliability of shear wave ultrasound elastography to measure mechanical properties of the cervical arterial wall. Suitability was assessed by ability to track arteries along their length and measurement accuracy. DESIGN Observational and intra-rater reliability study. METHODS Internal carotid (ICA) and vertebral arteries (VA) of healthy participants were examined with shear wave elastography. Shear wave velocity (m/s) indicative of wall stiffness was measured with the head in the neutral position: proximally (C3-4) and distally (C1-2) where injuries have been more commonly reported. Proximal measures were repeated to assess intra-rater reliability. RESULTS Thirty healthy participants (13 female), mean age of 29 (±12.8) years were imaged. Mean VA wall stiffness (3.4 m/s) was greater than ICA (2.3 m/s) (p < 0.000). Intra-rater reliability for ICA was ICC 0.81 (CI 0.52 to 0.92) and for VA ICC 0.76 (CI 0.38 to 0.9). Standard error of measurement was 0.16 for ICA and 0.34 for VA. CONCLUSIONS Shear wave ultrasound elastography appears a suitable and reliable method to measure cervical arterial wall stiffness, justifying further research into its use for screening arterial integrity.

Seasonal Variation in Spontaneous Cervical Artery Dissection: Comparing between UK and Australian Sites

BACKGROUND Cervical artery dissection (CAD) is a leading cause of stroke among middle-aged adults, but the etiology is unclear. Some reports of seasonal variation in CAD incidence have been suggested but may reflect extreme climatic conditions. Seasonal variation may implicate more transient seasonal causes such as proinflammatory or hypercoagulable states. This study aimed to assess whether CAD incidence varied with season between UK and Australian sites. Also, this study aimed to determine whether there was a different pattern of seasonal variation between arteries (carotid and vertebral) and any association between CAD incidence and clinical factors. METHODS This was a retrospective observational study of patients older than 18 years with radiological diagnosis of internal carotid or vertebral arterial dissection, from sites in Australia and the UK. Clinical variables were compared between autumn-winter and spring-summer and site of dissection. RESULTS A total of 133 CAD cases were documented in Australia and 242 in the UK. There was a seasonal pattern to CAD incidence in countries in both the northern and the southern hemispheres, with a trend for dissection to occur more commonly in autumn, winter, and spring than in summer (incidence rate ratios [IRR] 1.4-1.5, P < .05). CAD counts were also slightly higher in internal carotid than in vertebral artery (IRRs 1.168, 1.43, and 1.127, respectively). Neither systolic blood pressure nor pulse pressure was significantly associated with CAD counts. CONCLUSIONS CAD occurs more commonly in cooler months regardless of geographical location, suggesting transient seasonal causes may be important in the pathophysiology. This effect was slightly higher in internal carotid than in vertebral artery, suggesting differing trigger mechanisms between dissection sites.

The effect of end-range cervical rotation on vertebral and internal carotid arterial blood flow and cerebral inflow: A sub analysis of an MRI study

INTRODUCTION Cervical spine manual therapy has been associated with a small risk of serious adverse neurovascular events, particularly to the vertebral arteries. Sustained end-range rotation is recommended clinically as a pre-manipulative screening tool; however ultrasound studies have yielded conflicting results about the effect of rotation on blood flow in the vertebral arteries. There has been little research on internal carotid arterial flow or utilising the reference standard of angiography. OBJECTIVES To evaluate the mean effect of cervical rotation on blood flow in the craniocervical arteries and blood supply to the brain, as well as individual variation. DESIGN This was an observational study. METHOD Magnetic resonance angiography was used to measure average blood flow volume in the vertebral arteries, internal carotid arteries, and total cerebral inflow, in three neck positions: neutral, end-range left rotation and end-range right rotation in healthy adults. RESULTS Twenty participants were evaluated. There was a decrease in average blood flow volume in the vertebral and internal carotid arteries on contralateral rotation, compared to neutral. This was statistically significant on left rotation only. Ipsilateral rotation had no effect on average blood flow volume in any artery. Total cerebral inflow was not significantly affected by rotation in either direction. CONCLUSIONS It appears that in healthy adults the cerebral vasculature can compensate for decreased flow in one or more arteries by increasing flow in other arteries, to maintain cerebral perfusion. Sustained end-range rotation may therefore reflect the compensatory capacity of the system as a whole rather than isolated vertebrobasilar function.