Cerebrospinal fluid tau as a marker of neuronal damage after epileptic seizure

PURPOSE Whether repeated brief seizures can cause neuronal damage is controversial. Cerebrospinal fluid (CSF) total tau (T-tau) and phosphorylated tau (P-tau) measurements have been suggested for the diagnosis of Alzheimer's disease, and T-tau may also be a marker of axonal damage and neuronal degeneration. We studied T-tau and P-tau levels and P-tau/T-tau ratio in CSF after epileptic seizures in order to determine whether they are increased after seizures. METHODS A total of 54 patients with tonic-clonic or partial secondarily generalized seizures due to various etiologies were studied and CSF obtained within 48h after the seizure. RESULTS There were no statistical differences in the levels of T-tau (p=0.09, ANOVA) or P-tau (p=0.60) between different etiologic groups or controls. No patients with epilepsy of unknown origin had abnormal CSF T-tau whereas 11 patients with acute or remote symptomatic seizures had abnormal T-tau levels and the P-tau/T-tau ratio showed significant differences between the groups and controls (p=0.003). CONCLUSIONS Epileptic seizures with unknown etiology did not increase CSF tau levels. Abnormal tau levels were associated with either acute or remote symptomatic seizures with known etiology. The presence of elevated CSF tau increases the probability of symptomatic cause in a patient with a seizure.