There are two reasons justifying our choice: 1) Lumbar puncture is not routine in the diagnosis of patients with CNS tumors, thus the Local Bioethics Committee gave permission for CSF collection only within neurosurgery; 2) To compare CSF Nogo-A concentrations between tumoral and non-tumoral individuals, cerebrospinal fluid should be collected from the same CNS interspace; so our samples were relatively homogenous. Here, RTN4 is linked to central nervous system neoplasm.