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EMBOLIC STROKE LINKED WITH HIGH RISK OF SEIZURES AND POOR OUTCOME
PHILADELPHIA—Patients with clearly defined embolic stroke experience a higher incidence of poststroke seizures and epilepsy than previously reported, according to results of a recent retrospective study undertaken by Adriana Palade, MD, and colleagues at Allegheny General Hospital in Pittsburgh.
In previous clinical studies, estimates of the incidence of seizures or epilepsy following a stroke have varied considerably. Dr. Palade and her colleagues attempted to provide a better estimate of the risk of seizures or epilepsy by rigorously identifying the source of the embolus in patients with a recent embolic stroke.
MORE ACCURATE ESTIMATES OF SEIZURE RISK
The investigators performed a retrospective chart review of patients with embolic stroke who were admitted to the inpatient service of Allegheny General Hospital’s Department of Neurology during a three-year period. Only patients whose strokes had been clinically diagnosed and confirmed by magnetic resonance imaging as being embolic in nature were considered. This aspect of the study was particularly important in that it allowed a more accurate estimate of seizure and epilepsy occurrence following embolic stroke by selecting only patients with confirmed, identifiable embolus sources. The results were reported at the 53rd Annual Meeting of the American Academy of Neurology.
One hundred fifty patients with a confirmed diagnosis of embolic stroke were identified. The study required that the source of the embolus for each stroke be clearly identifiable by esophageal echocardiogram and/or carotid Doppler imaging. Seizure activity and epilepsy were defined clinically, on electroencephalogram, or by both methods.
Thirty-two of the 150 patients who had suffered embolic stroke were excluded from the retrospective analysis because of carotid dissection, an occlusion or high-grade carotid stenosis ipsilateral to the stroke, transformation of the embolic stroke to hemorrhagic stroke, or seizure activity that was considered questionable. Among the 118 remaining patients with confirmed embolic stroke, 46 strokes were due to patent foramen ovale; an additional 34 strokes, to patent foramen ovale associated with atrial septal aneurysm; 19, to intracardiac thrombus; 13, to atrial fibrillation; four, to severe atheromatous disease of the aorta; and two, to post–carotid endarterectomy hematoma.
Seizure activity occurring within one week after stroke was reported in 15 patients (12.7%), and five of those patients presented in complex partial status epilepticus. The etiology of strokes in these 15 individuals included five cases with intracardiac thrombus, five cases with atrial fibrillation, one case with severe aortic atheromatous disease, three cases with patent foramen ovale, and one case with post–carotid endarterectomy hematoma. At a mean follow-up of 17 months, five of these 15 patients (4.3% of the test group; mean age, 48.6) had developed epilepsy. Of the remaining 10 patients, after a mean follow-up of 14.8 months, seven patients (mean age 62.8) had suffered one late seizure (occurring one or more weeks after stroke), and three had died soon after hospital admission.
Of the five patients with poststroke seizures who had originally presented in complex partial status epilepticus, by the end of the follow-up period, two had developed epilepsy, two had died, and one patient had had limited follow-up.
EMBOLIC STROKE PREDISPOSES FOR SEIZURE AND EPILEPSY
Based on these results, the researchers concluded that patients with clearly defined embolic strokes have a higher incidence of poststroke seizures and epilepsy than previously reported. For patients who presented in complex partial status epilepticus after a stroke, clinical outcomes were poor and included death and development of epilepsy.
Stroke is the most common cause of seizures in patients over the age of 64. Seizures may result from hemorrhagic or ischemic cerebrovascular disease, or they may be due to cerebral emboli, often from a cardiac source or carotid atheromatous plaque. While within the general population a person’s lifetime risk of having a seizure is 10%, and the lifetime risk of developing epilepsy is 3% to 4%, the incidence of poststroke seizure disorders has been generally approximated at 6%, with the greatest risk in patients who suffered cortical infarction, intracranial hemorrhage, or embolic stroke. In contrast to these commonly reported results, this retrospective study demonstrated a 12.7% incidence of poststroke seizure and a 4.3% incidence of poststroke epilepsy in patients with clearly defined embolic stroke.
According to Dr. Palade, while the results of this retrospective study were somewhat surprising, “We set out to demonstrate that careful identification of the source of the embolus would allow a more accurate estimate of the frequency of poststroke seizures and epilepsy than previously reported. Our goal was to increase awareness of the efficacy of this approach.”
NR
—Kim Buscemi
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