Risk Factors for Seizures, Epilepsy After Stroke

Daniel M. Keller, PhD

October 10, 2017

KYOTO, Japan — The rate of seizures or epilepsy after thrombolysis for the treatment of ischemic stroke is similar to the rates in the decades before the use of thrombolysis, a retrospective study shows.

"Hemorrhagic transformation and degree of neurological compromise after thrombolysis, but not before, were independently associated with seizures or post-stroke epilepsy," lead author, Marino Bianchin, MD, PhD, Hospital Clínicas de Porto Alegre, Brazil, reported.

In the new analysis, presented at the XXIII World Congress of Neurology (WCN), researchers also reported several factors potentially associated with unfavorable outcome and found that seizures were among them.

Seizures and epilepsy affect a substantial proportion of patients after they have had a stroke. In fact, stroke is the leading cause of diagnosis of new-onset epilepsy in patients older than 65 years, Dr Bianchin said.

To evaluate the risk factors, the researchers performed a retrospective study of 153 consecutive patients who received thrombolysis using tissue plasminogen activator (tPA) for the treatment of acute ischemic stroke between 2005 and 2011. Patients were followed for at least 2 years after the stroke, and those with epilepsy had at least two prolonged electroencephalograms.

The cohort consisted of 74 women and 79 men, had a mean age of 67.2 ± 13.1 years, and initial and 3-month National Institutes of Health Stroke Scale (NIHSS) mean scores of 10.95 ± 6.25  and 2.09 ± 3.55, respectively.

General health and metabolic variables as well as stroke-specific ones were evaluated as risk factors, including age, sex, ethnicity, hypertension, diabetes mellitus, hypercholesterolemia, smoking, alcohol use, atrial fibrillation, NIHSS score, stroke cause, vascular territories, stroke severity, hemorrhagic transformation, and outcome of thrombolysis.

Response to treatment was assessed by using the NIHSS and modified Rankin Scale (mRS) 3 months after the stroke. A good outcome was considered to be an mRS score of 0 or 1, and a bad outcome was defined as an mRS score of 2 or greater. Bleeding was defined as any central nervous system bleeding according to radiologic criteria.

Of the 153 patients, 21 (13.7%) had seizures and 15 (9.8%) had epilepsy. The researchers found that of the variables evaluated, only hemorrhagic transformation and mRS score of 2 or greater were significant independent risk factors for seizures or for epilepsy.  

There was no significant effect of NIHSS score or glucose on admission, systolic blood pressure at onset, diabetes, or hypercholesterolemia.

Table 1. Independent Risk Factors for Seizures or Epilepsy After Thrombolysis

Endpoint

Independent Risk Factors for Seizures

Independent Risk Factors for Epilepsy

Adjusted Odds Ratio (95% Confidence Interval)

P Value

Adjusted Odds Ratio (95% Confidence Interval)

P Value

Hemorrhagic transformation

3.55 (1.11 - 11.34)

.033

3.26 (1.08 - 9.78)

.035

MRS score ≥ 2 at 3 mo after stroke

5.82 (1.45 - 23.42)

.013

3.51 (1.20 - 10.32)

.022

 

Age, NIHSS score, and seizure were independent risk factors for unfavorable outcome (mRS score of 2 or greater).

Table 2. Independent Risk Factors for Unfavorable Outcome (mRS Score ≥ 2)

Variable

Adjusted Odds Ratio (95% Confidence Interval)

P Value

Age

1.03 (1.01 - 1.06)

.011

NIHSS score

1.08 (1.03 - 1.14)

.001

Hemorrhagic transformation

0.43 (0.21 - 0.90)

.024

Seizure

3.07 (1.22 - 7.75)

.018

Large cortical area (Alberta Stroke Program Early CT score [ASPECTS] ≤ 7)  

0.49 (0.26 - 0.96)

.036

 

Dr Bianchin said that late seizures were an independent risk factor associated with worse outcome after thrombolytic therapy. He noted that the rates or seizures or post-stroke epilepsy seen in this cohort that received thrombolysis were similar to rates before the use of thrombolysis.

Not comparing the cohort that had thrombolysis to one not receiving thrombolysis made it "very difficult then to interpret the results in those that had had thrombolysis…because there's no presentation against a reference cohort," Isobel Hubbard, PhD, from the School of Medicine and Public Health at the University of Newcastle, Australia, commented to Medscape Medical News. She said she was not sure how to apply these results to clinical practice.

A question also arises as to the underlying mechanism of the outcomes seen "because there is some toxicity with tPA," she said.

There was no commercial funding for the study. Dr Bianchin and Dr Hubbard have disclosed no relevant financial relationships.

XXIII World Congress of Neurology (WCN). Abstract 378. Presented September 18, 2017.

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