Postencephalitic epilepsy and drug‐resistant epilepsy after infectious and antibody‐associated encephalitis in childhood: Clinical and etiologic risk factors

Summary To define the risk factors for postencephalitic epilepsy ( PE ) and drug‐resistant epilepsy ( DRE ) in childhood following infectious and autoimmune encephalitis, we included 147 acute encephalitis patients with a median follow‐up of 7.3 years (range 2–15.8 years). PE was defined as the use of antiepileptic drugs ( AED s) for ≥24 months, and DRE was defined as the persistence of seizures despite ≥2 appropriate AED s at final follow‐up. PE and DRE were diagnosed in 31 (21%) and 15 (10%) of patients, respectively. The features during acute encephalitis predictive of DRE (presented as odds ratio [ OR ] with confidence intervals [ CI s]) were status epilepticus ( OR 10.8, CI 3.4–34.3), visual disturbance (6.4, 1.4–29.9), focal seizures (6.2, 1.9–20.6), magnetic resonance imaging ( MRI ) hippocampal/amygdala involvement (5.0, 1.7–15.4), intensive care admission (4.7, 1.4–15.4), use of >3 AED s (4.5, 1.2–16.1), MRI gadolinium enhancement (4.1, 1.2–14.2), any seizure (3.9, 1.1–14.4), and electroencephalography ( EEG ) epileptiform discharges (3.9, 1.3–12.0). On multivariable regression analysis, only status epilepticus remained predictive of DRE in all models. DRE was common in herpes simplex virus (3/9, 33%) and unknown (8/40, 20%) encephalitis, but absent in acute disseminated encephalomyelitis ( ADEM ) (0/32, 0%), enterovirus (0/18), and anti‐ N ‐methyl‐ d ‐aspartate receptor– NMDAR encephalitis (0/9). We have identified risk factors for DRE and demonstrated “high‐risk,” and “low‐risk” etiologies.