Endoscopic third ventriculostomy (ETV) is an option for hydrocephalus treatment in patients with myelomeningocele, mostly after a previous shunt dysfunction. Late failure of ETV is a rare event, traditionally associated with dramatic symptoms of intracranial hypertension. In patients with myelodysplasia and neurogenic bladder dysfunction, urodynamic deterioration can be a signal of neurologic worsening as a consequence of tethered cord or shunt problems.