Patients with Epilepsy Are at an Increased Risk of Subsequent Stroke: A Population-Based Cohort Study
Introduction from Dr Markus Reuber, editor-in-chief of Seizure
Last year a key publication in Seizure highlighted the risk of developing epilepsy after transient ischaemic attacks and different types of ischaemic and haemorrhagic stroke (1). In view of the facts that life expectancy is increasing, that the incidence of epilepsy is now highest in older adults and that cerebrovascular disease is the commonest cause of epilepsy in the patient population, cerebrovascular disease should be a topic of considerable interest to health professionals involved in the treatment of epilepsy. Of course, it has long been recognized that strokes can cause epilepsy. However, there is also increasing evidence that the reverse may be true: having epilepsy may increase the risk of subsequent stroke.
At first sight, this link between epilepsy and stroke may seem unintuitive – perhaps leaving aside the scenario of cerebrovascular disease presenting with epileptic seizures (2). However, there are many ways in which epilepsy could increase the risk of subsequent stroke. There is accumulating evidence that many antiepileptic drugs can cause or contribute to atherosclerosis (3). Epilepsy is also associated with lower social status and income, perhaps creating an indirect link with poorer diets, less healthy lifestyles and a higher prevalence of smoking. The fact that epilepsy could also be an aetiologically unrelated association of stroke risk factors well recognized in the general population makes it difficult to understand the specific contribution of epilepsy to the risk of subsequent stroke. Conceivably, factors putting people at risk of developing both – epilepsy and premature cerebrovascular disease – may be commoner than one might assume. Rare diseases such as some of the mitochondrial disorders are an example.
My editor’s choice from this issue of seizure is a paper by C-S Chang et al. who carried out a population-based study using Taiwan National Health Insurance claims data (4). They identified 3812 patients newly diagnosed with epilepsy between 2000 and 2008 and age and 15 248 age and gender people with no history of epilepsy. They found that the stroke incidence of the epilepsy cohort was three times higher than that of the comparison cohort. The age-specific results indicated that the risk was the highest for the youngest group (20-39 y).
As much good research, this paper poses as many questions as it answers. This paper particular paper is an invitation to find out more about the reasons why epilepsy (or the treatment for it) seems to increase the risk of stroke so substantially.
(1) Conrad J, Pawlowski M, Dogan M, Kovac S, Ritter MA, Evers S. Seizures after cerebrovascular events: Risk factors and clinical features. Seizure 2013;22:275–282
(2) Cleary P, Shorvon S, Tallis R. Late-onset seizures as a predictor of subsequent
stroke. Lancet 2004;363:1184–1186.
(3) Tan TY, Lu CH, Chuang HY, et al. Long-term antiepileptic drug therapy contributes to the acceleration of atherosclerosis. Epilepsia 2009;50:1579–1586.
Chang C-S, Liao C-C, Lane H-Y et al. Patients with Epilepsy Are at an Increased Risk of Subsequent Stroke: A Population-Based Cohort Study