NEFL and pseudotumor cerebri: To evaluate the validity of this hypothesis, the current study aims 1) to investigate the association of NfL in serum (S-NfL), CSF-NfL and QNfL values with lumbar puncture opening pressure in IIH patients, 2) to compare NfL measures of IIH patients with those of appropriate control groups, and 3) to validate QNfL findings by measuring an additional protein of CNS origin, glial fibrillary acidic protein (GFAP), in serum and CSF.