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Seasonal Variation in Spontaneous Cervical Artery Dissection: Comparing between UK and Australian Sites
Lucy C Thomas1, Lesley Ann Hall2, John R Attia3
1Faculty of Health and Medicine, The University of Newcastle, New South Wales, Australia; School of Health and Rehabilitation Sciences, The University of Queensland, Brisbane, Queensland, Australia.
Insights
Cervical artery dissection (CAD) occurs more frequently in cooler months across both hemispheres. This suggests seasonal factors, possibly related to inflammation or clotting, may contribute to the condition
Area of Science:
- Neurology
- Vascular Medicine
- Epidemiology
Background:
- Cervical artery dissection (CAD) is a primary cause of stroke in middle-aged adults, with unknown etiology.
- Previous studies suggested seasonal variation in CAD, potentially linked to extreme weather.
- Seasonal influences may involve transient proinflammatory or hypercoagulable states.
Purpose of the Study:
- To investigate seasonal variations in CAD incidence across UK and Australian populations.
- To determine if seasonal patterns differ between carotid and vertebral artery dissections.
- To explore associations between CAD incidence and clinical factors.
Main Methods:
- Retrospective observational study including adult patients (18+ years) with diagnosed internal carotid or vertebral artery dissection.
- Data collected from Australian and UK sites.
- Comparison of clinical variables between seasons (autumn-winter vs. spring-summer) and dissection sites.
Main Results:
- A total of 375 CAD cases were analyzed (133 Australia, 242 UK).
- A significant seasonal pattern was observed, with higher CAD incidence in autumn, winter, and spring compared to summer (IRR 1.4-1.5, P < .05).
- Internal carotid artery dissections were slightly more frequent than vertebral artery dissections (IRRs 1.168, 1.43, 1.127); blood pressure was not significantly associated.
Conclusions:
- Cervical artery dissection incidence is higher during cooler months, irrespective of hemisphere, indicating potential transient seasonal triggers.
- The slightly higher incidence in internal carotid artery dissections suggests distinct mechanisms compared to vertebral artery dissections.
- Findings support the role of seasonal factors in CAD pathophysiology.
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.
