Long-term risk of seizures and epilepsy in patients with posterior reversible encephalopathy syndrome

Summary Objective Seizures are common in patients with posterior reversible encephalopathy syndrome (PRES), which is reported in up to 70% of cases, and antiepileptic drugs (AEDs) are commonly prescribed. There is a paucity of data regarding the risk of subsequent seizures following resolution of PRES, and therefore the optimal duration of treatment with AEDs is currently unknown. The objective of this study was to identify the frequency of recurrent seizures and epilepsy following recovery from PRES. Methods We performed a retrospective review of consecutive adults diagnosed with PRES between 2000 and 2010. Results One hundred twenty-seven patients, median age 53 years (interquartile range [IQR] 37-64), were included in the analysis. The most common causes of PRES were hypertension (72%) and immunosuppression (20%). Renal failure was present in 47%. Eighty-four patients (66%) had seizures at presentation (39 focal, 45 generalized), and 13 (15%) of them presented with status epilepticus. Median duration of follow-up was 3.2 years (IQR 4 months to 6.9 years). Patients with seizures were treated with AEDs for a median of 3 months (IQR 2-7). Fifteen patients (12%) had provoked seizures during the follow-up period; in eight (53%) patients seizures were caused by recurrent PRES. Only three patients had subsequent unprovoked seizures, one of whom was considered to have developed epilepsy. Significance We conclude that unprovoked seizures and epilepsy are uncommon in patients who have recovered from PRES. Discontinuation of AEDs following resolution of PRES should be considered, provided there is adequate control of risk factors, and absence of factors that could substantially lower the seizure threshold.