NEFL and epilepsy: Elevated levels of serum NfL have previously been reported in DRE versus MCE and healthy controls.20 The study observed that a small number of patients with DRE exhibited abnormally high NfL levels, similar to our previous study where we also found abnormal plasma NfL in a subset of patients with epilepsy.20,22 In both studies, the potential effects of injury such as trauma or stroke, were controlled for suggesting the changes seen in NfL may reflect a neurodegenerative process or brain injury directly related to the drug-resistant status of the epilepsy.