Impact of poststroke seizures on neurological deficits: magnetic resonance diffusion-weighted imaging study

The impact of poststroke seizures on the neurological deficits related to ischemic stroke is not well known. It has been reported that following poststroke epilepsy, transient or long-lasting worsening of the poststroke sequelae may develop, but the underlying mechanism of deficit worsening has not been systematically studied by magnetic resonance diffusion-weighted imaging (MRI-DWI).

From 2008 to 2009, 1,010 ischemic stroke patients were admitted to our stroke unit at the Ege University Hospital with first-time strokes. Of these, 76 (7.5%) patients developed delayed seizures in a follow-up period of 18 months. We extracted the clinical and imaging data of the patients from our Stroke Registry databases and other medical records, and evaluated brain MRI, including spin-echo DWI with apparent diffusion coefficient (ADC) maps, FLAIR and T2-weighted images.

There were 15 (20%) patients who had long-lasting worsening of the previous neurological sequelae, which we called long-lasting neurological worsening (LLW); 38 (50%) had transient neurological worsening (TNW) and 23 (30%) were without neurological worsening (WNW) after poststroke seizures. DWI findings were present in 3/23 (13%) patients with simple partial-type seizure, in 4/17 (29%) patients with complex partial-type seizure, and in 7/13 (54%) patients with generalized toni-clonic type seizure (p = 0.002). Patients with LLW showed more frequent changes on DWI than those with TNW (53 vs. 16%; p = 0.009). Forty percent of patients with LLW and 5% of those with TNW had ADC decrease (p = 0.004). Patients with LLW had DWI changes in the occipital region more frequently than those with TNW (57 vs. 18%; p = 0.05). Correlation analysis found a significant association between LLW and DWI changes, multiple DWI lesions, ADC decrease, and recurrent seizures. In the control MRI-DWI 1 month after the poststroke seizure, no signal abnormalities were detected in neuroimaging studies of all patients. Despite no functional outcome differences between the groups before the seizure, the functional scales 1 week after the seizure (National Institutes of Health Stroke Scale, Modified Rankin Scale and Barthel Index) showed significantly worse neurological functional statements in the patients with LLW than those with TNW and WNW (p = 0.001).

Poststroke seizures may affect poststroke sequelae transiently, which we see more often, but some seizure types may prolong the duration of deficits. Multiple DWI changes and LLW following recurrent and longer poststroke seizures were strongly associated, and this may be due to the effect of seizures causing additional metabolical changes.