title: Posterior reversible encephalopathy syndrome (PRES): a rare condition after resection of posterior fossa tumors: two new cases and review of the literature.
abstract: BACKGROUND
  In 1996, Hinchey and colleagues coined the term "Posterior reversible encephalopathy syndrome" (PRES) to describe a condition seen in patients with acute neurological symptoms and reversible subcortical vasogenic edema predominantly involving parieto-occipital areas demonstrated in brain MRI. The occurrence of this phenomenon after surgical resection of CNS tumors is typically linked to pediatric cases.
  
  
  METHODS
  Two new cases of PRES after posterior fossa surgery are reported. A thorough review of the literature is carried out with the purpose of updating and summarizing the main features regarding PRES in similar cases. Seven cases of PRES after resection of a posterior fossa tumor have been hitherto reported (4 patients were <20 years old). There is another pediatric case described after a ventriculoperitoneal shunting procedure in a patient with fourth ventricle ependymoma. Two resected tumors were ependymomas, 2 hemangiopericytomas in one patient, 1 pilocyticastrocytoma, 1 vestibular schwannoma, and 1 of the reported cases did not describe the final pathology diagnosis.
  
  
  METHODS
  We present 2 new cases of PRES after surgical resection of a posterior fossa tumor (medulloblastoma in case 1 and ependymoma in case 2) in pediatric patients. Case 1 developed delayed seizures and altered mental status(10 days after surgical resection) after receiving treatment with bromocriptine for cerebellar mutism. Case 2 presented with generalized seizures and altered mental status within the first 48 postoperative hours followed by right hemiparesis. Both patients fully recovered and returned to neurological baseline status. A thorough review of the literature was carried out with the purpose of updating and summarizing the main features regarding PRES in similar cases.
  
  
  CONCLUSIONS
  We report 2 new pediatric cases of posterior reversible encephalopathy syndrome (PRES) that developed after surgical resection of a posterior fossa tumor. Appropriate management includes supportive measures, antihypertensive agents, and antiepileptic drugs, if needed. Full recovery is the most likely outcome in line with previous articles.
authors.affiliation: Department of Pediatric Neurosurgery, Hospital General 12 de Octubre, Madrid, Spain. lainhermesgq@gmail.com.|Department of Neurosurgery, HGU Gregorio Marañón, Calle Doctor Esquerdo número 46, C.P, 28007, Madrid, Spain. lainhermesgq@gmail.com.
authors.forename: Lain Hermes
authors.initials: LH
authors.lastname: González Quarante
authors.affiliation: Department of Pediatric Neurosurgery, Hospital General 12 de Octubre, Madrid, Spain.
authors.forename: José Hinojosa
authors.initials: JH
authors.lastname: Mena-Bernal
authors.affiliation: Department of Pediatric Neurosurgery, Hospital General 12 de Octubre, Madrid, Spain.
authors.forename: Beatriz Pascual
authors.initials: BP
authors.lastname: Martín
authors.affiliation: Department of Pediatric Neurosurgery, Hospital General 12 de Octubre, Madrid, Spain.
authors.forename: Marta
authors.initials: M
authors.lastname: Ramírez Carrasco
authors.affiliation: Department of Pediatric Neurosurgery, Hospital General 12 de Octubre, Madrid, Spain.
authors.forename: María Jesús
authors.initials: MJ
authors.lastname: Muñoz Casado
authors.affiliation: Department of Neuroradiology, Hospital General 12 de Octubre, Madrid, Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Martínez de Aragón
authors.affiliation: Department of Pediatric Neurology, Hospital General 12 de Octubre, Madrid, Spain.
authors.forename: Rogelio Simón
authors.initials: RS
authors.lastname: de las Heras
mesh_terms: D000293:Adolescent; D002675:Child, Preschool; D006801:Humans; D015192:Infratentorial Neoplasms / Q000000981:diagnostic imaging / Q000601:surgery*; D008279:Magnetic Resonance Imaging; D008297:Male; D008527:Medulloblastoma / Q000000981:diagnostic imaging / Q000601:surgery*; D019635:Neurosurgical Procedures / Q000009:adverse effects*; D054038:Posterior Leukoencephalopathy Syndrome / Q000000981:diagnostic imaging / Q000209:etiology*; D016896:Treatment Outcome
keywords: Ependymoma; Medulloblastoma; PRES; Posterior fossa surgery; Posterior reversible encephalopathy syndrome