NEFL and multiple sclerosis: NfL levels in blood are increased in patients with traumatic brain injury (Shahim 2016, Zetterberg 2016), axonal injury due to multiple sclerosis (Khalil 2018), and sports-related concussion (Shahim 2018), but even uneventful anaesthesia has been associated with increased blood levels of NfL (Evered 2018).