There are no official guidelines on how to manage stroke-related seizures. In a prospective multicentre study, the incidence of seizures in relation to stroke was 8.9%, with a frequency of 10.6 and 8.6% in haemorrhagic and ischaemic stroke, respectively. In subarachnoid haemorrhage the incidence is 8.5%. Due to the fact that infarcts are significantly more frequent than haemorrhages, seizures are mainly related to occlusive vascular disease of the brain.1 The general view is to consider stroke-related seizures as harmless complications in the course of a prolonged vascular disease involving the heart and brain.
Seizures can be classified as those of early and those of late onset in a paradigm comparable to post-traumatic epilepsy, with an arbitrary dividing point of two weeks after the event. Most early-onset seizures occur during the first day after the stroke. Late-onset seizures occur three times more often than early-onset ones. A first late-onset epileptic event is most likely to take place between six months and two years after the stroke. However, up to 28% of patients develop their first seizure several years later.
Simple partial seizures, with or without secondary generalisation, account for about 50% of total seizures, while complex partial spells, with or without secondary generalisation, and primary generalised tonic–clonic insults account for approximately 25% each. Status epilepticus occurs in 12% of stroke patients, but the recurrence rate after an initial status epilepticus is not higher than after a single seizure.2 Inhibitory seizures, mimicking transient ischaemic attacks, are observed in 7.1% of cases.
Early-onset seizures in ischaemic stroke are mainly found in patients with large cortical lesions, decreased consciousness and additional haemodynamic and metabolic – mainly renal – disturbances. In haemorrhagic stroke, the products of blood metabolism, such as haemosiderin, may cause a focal cerebral irritation, leading to seizures.
In the Seizures After Stroke Study (SASS), the main predictors for late-onset seizures after an ischaemic stroke were the severity of the initial neurological deficit and the presence of a large cortical infarct.1 In our series we found that the only clinical predictor of late-onset seizures was the initial presentation of partial anterior circulation syndrome due to a territorial infarct. Patients with total anterior circulation syndrome had less chance of developing epileptic spells, not only due to their shorter life expectancy but also due to the fact that the large infarcts are sharply demarcated in these patients.