title: Occipital WHO grade II gliomas: oncological, surgical and functional considerations.
abstract: BACKGROUND
  Diffuse WHO grade II glioma (GIIG) involving the occipital lobe is a rare entity. Its surgical resection remains controversial as it implies inducing a permanent visual deficit. For the first time to our knowledge, we report a consecutive surgical series of patients who underwent an occipital lobectomy for an LGG invading visual structures.
  
  
  METHODS
  Six right-handed patients harboring a GIIG revealed by seizures (normal examination except a quadrantanopsia in one case) and located within the occipital lobe (4 left and 2 right tumors) were submitted to surgery. Before making this decision, the benefit-to-risk ratio of the resection was extensively discussed with the patient and his/her family, especially concerning the price to pay to remove the tumor, that is, to voluntarily generate a permanent hemianopsia. All the procedures were performed under awake condition using intraoperative electrostimulation, in order to pursue the resection until sensory-motor and/or language structures were encountered.
  
  
  RESULTS
  An extensive occipital lobectomy was achieved in the six patients, with identification and preservation of sensory-motor pathways in the two cases with a right tumor and detection of language pathways in the four cases with a left tumor. The mean extent of resection was 93% (range: 91-100%). All patients experienced an expected postoperative deficit of the visual field (homonymous hemianopsia). Nonetheless, the six patients resumed a normal social and professional life (KPS at 90 in the 6 cases) with a mean follow-up of 58 months (range: 3-147 months)--with adjuvant treatment in three cases (in addition to a reoperation in two of them).
  
  
  CONCLUSIONS
  Our findings suggest that, despite a definitive hemianopsia, an extensive surgical resection can be considered in the rare cases of occipital GIIG involving the primary visual structures, with patients able to maintain a normal life--except regarding the medico-legal problem of driving.
authors.affiliation: Department of Neurosurgery, Hospital Garcia de Orta, Almada, Portugal.
authors.forename: Catarina
authors.initials: C
authors.lastname: Viegas
authors.forename: Sylvie
authors.initials: S
authors.lastname: Moritz-Gasser
authors.forename: Valérie
authors.initials: V
authors.lastname: Rigau
authors.forename: Hugues
authors.initials: H
authors.lastname: Duffau
mesh_terms: D000328:Adult; D001932:Brain Neoplasms / Q000145:classification* / Q000503:physiopathology / Q000601:surgery*; D005260:Female; D005910:Glioma / Q000145:classification* / Q000503:physiopathology / Q000601:surgery*; D006423:Hemianopsia / Q000209:etiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D019635:Neurosurgical Procedures / Q000379:methods; D009778:Occipital Lobe / Q000473:pathology* / Q000503:physiopathology / Q000601:surgery*; D012189:Retrospective Studies; D018570:Risk Assessment; D016896:Treatment Outcome; D014944:World Health Organization