title: Application of diffusion tensor imaging and tractography of the optic radiation in anterior temporal lobe resection for epilepsy: a systematic review.
abstract: BACKGROUND
  Approximately 50-100% of patients with temporal lobe epilepsy undergoing anterior temporal lobe resection (ATLR) will suffer a postoperative visual field defect (VFD) due to disruption of the optic radiation (OpR).
  
  
  OBJECTIVE
  We conducted a systematic review of the literature to examine the role of DTI and tractography in ATLR and its potential in reducing the incidence of postoperative VFD.
  
  
  METHODS
  We conducted an electronic literature search using PubMed, Embase, Web of Science and BMJ case report databases. Eligibility for study inclusion was determined on abstract screening using the following criteria: the study must have been (1) an original investigation or case report in humans; (2) investigating the OpR with DTI in cases of ATLR in temporal lobe epilepsy; (3) investigating postoperative VFD. All forms of ATLR and ways of assessing VFD were included to reflect clinical practice.
  
  
  RESULTS
  13 studies (four case reports, eight prospective observational studies, one prospective comparative trial) were included in the review, 179 (mean±SD, 13.8±12.6; range, 1-48) subjects were investigated using DTI. The time of postoperative VFD measurement differed between the detected studies, ranging from two weeks to nine years following ATLR. A modest number of studies and insufficient statistical homogeneity precluded meta-analysis. However, DTI methods were consistently accurate at quantifying and predicting postoperative damage to the OpR. These methods revealed a correlation between the extent of OpR damage and the severity of postoperative VFD. The first and only trial with 15 subjects compared to 23 controls reported that using intraoperative tractography in ATLR significantly reduces the occurrence of postoperative VFD on comparison to conventional surgical planning.
  
  
  CONCLUSIONS
  DTI shows potential to be an effective method used in planning ATLR. Findings from a single modest sized study suggest that tractography may be employed as part of intraoperative navigation techniques in order to avoid injury to the OpR. Further research needs to be conducted to ensure the applicability and effectiveness of this technology before implementation in routine clinical practice.
authors.affiliation: College of Medicine and Veterinary Medicine, University of Edinburgh, Chancellor's Building, 49 Little France Crescent, Edinburgh EH16 4SB, UK; Muir Maxwell Epilepsy Centre, Child Life and Health, School of Clinical Sciences and Community Health, The Royal Hospital for Sick Children, University of Edinburgh, 20 Sylvan Place, Edinburgh EH9 1UW, UK. Electronic address: R.J.Piper@sms.ed.ac.uk.
authors.forename: Rory J
authors.initials: RJ
authors.lastname: Piper
authors.affiliation: College of Medicine and Veterinary Medicine, University of Edinburgh, Chancellor's Building, 49 Little France Crescent, Edinburgh EH16 4SB, UK; Muir Maxwell Epilepsy Centre, Child Life and Health, School of Clinical Sciences and Community Health, The Royal Hospital for Sick Children, University of Edinburgh, 20 Sylvan Place, Edinburgh EH9 1UW, UK; Department of Paediatric Neurosciences, Royal Hospital for Sick Children, 9 Sciennes Road, Edinburgh EH9 1LF, UK.
authors.forename: Michael M
authors.initials: MM
authors.lastname: Yoong
authors.affiliation: Department of Paediatric Neurosciences, Royal Hospital for Sick Children, 9 Sciennes Road, Edinburgh EH9 1LF, UK.
authors.forename: Jothy
authors.initials: J
authors.lastname: Kandasamy
authors.affiliation: College of Medicine and Veterinary Medicine, University of Edinburgh, Chancellor's Building, 49 Little France Crescent, Edinburgh EH16 4SB, UK; Muir Maxwell Epilepsy Centre, Child Life and Health, School of Clinical Sciences and Community Health, The Royal Hospital for Sick Children, University of Edinburgh, 20 Sylvan Place, Edinburgh EH9 1UW, UK; Department of Paediatric Neurosciences, Royal Hospital for Sick Children, 9 Sciennes Road, Edinburgh EH9 1LF, UK.
authors.forename: Richard F
authors.initials: RF
authors.lastname: Chin
mesh_terms: D038481:Anterior Temporal Lobectomy / Q000009:adverse effects*; D056324:Diffusion Tensor Imaging / Q000379:methods*; D004833:Epilepsy, Temporal Lobe / Q000601:surgery*; D005829:Geniculate Bodies / Q000293:injuries*; D006801:Humans; D011183:Postoperative Complications / Q000175:diagnosis* / Q000209:etiology; D014786:Vision Disorders / Q000175:diagnosis* / Q000209:etiology
keywords: Anterior temporal lobectomy; Diffusion tensor imaging; Epilepsy surgery; Tractography; Visual field defects