To evaluate the utility of cerebrospinal fluid (CSF) tau as a biomarker in cryptogenic New Onset Refractory Status Epilepticus (cNORSE).

Tau has been implicated in the pathophysiology of many neurological conditions, such as Alzheimer’s dementia and traumatic brain injury. Earlier studies of tau in status epilepticus yield conflicting results regarding its usefulness as a prognostic biomarker, and tau has not previously been studied specifically in cNORSE. 

A retrospective review of adult cNORSE patients admitted to a national referral center in South Korea was conducted. These patients had CSF total tau (t-tau) and phosphorylated tau 181 (p-tau) levels performed on CSF samples obtained within 7 days of NORSE onset. Paraclinical data and clinical outcome measures were obtained, and t-tau and p-tau levels were compared with controls.

Nineteen cNORSE patients were studied: 9 (47.4%) were male, median age 35.0 [IQR:27.0-54.3] years with median premorbid mRS being 0 [0-0]. Five (26.3%) presented with non-convulsive status epilepticus. The median duration of ICU stay was 28.0 [16.8-45.5] days in this cohort. cNORSE patients had higher CSF t-tau levels than controls (p=0.001) but both cNORSE patients and controls did not have elevated p-tau181. High CSF t-tau was found to be associated with hippocampal atrophy on interval imaging (p= 0.044). Higher t-tau levels also appeared to correlate with a higher number of anti-seizure medications used (p=0.031 in multivariate analysis) and less improvement in CASE scores one month after NORSE onset (p=0.066).

CSF t-tau levels performed early after cNORSE onset may be a useful marker of initial brain injury by cNORSE and predict subsequent hippocampal atrophy.