title: [Change in visual evoked potential by radiotherapy of nasopharyngeal carcinoma].
abstract: OBJECTIVE
  To study the effect of radiotherapy of nasopharyngeal carcinoma on visual evoked potential (VEP).
  
  
  METHODS
  VEP of 63 patients with nasopharyngeal carcinoma were tested before, at the end of, half a year, one year, 2 years and 3 years after their radiotherapy.
  
  
  RESULTS
  Within the male group, one year after radiotherapy, the latency of VEP was significantly delayed than that before and at the end of radiotherapy, while the amplitude was decreased significantly. Two years after radiotherapy, the latency of VEP was significantly delayed more than that before radiotherapy. However there was no significant difference among VEP at the end of, half a year and 3 years after radiotherapy. Within the female group, 2 years after radiotherapy, the latency of VEP was significantly delayed than that before radiotherapy. Three years after radiotherapy, the latency of VEP was significantly delayed than that before, at the end of, half a year and one year after radiotherapy. There was no significant difference in VEP amplitudes before and after radiotherapy.
  
  
  CONCLUSIONS
  Within the male group, the abnormal delay of VEP latency mostly happens one or two years after radiotherapy. Within the female group, the significant delay of VEP latency happens at the end of radiotherapy and lasts for 3 years, while the VEP amplitude does not change significantly during the 3 years after radiotherapy. The result indicates that the sustained radiation damage within the female visual nerve system starts at the end of radiotherapy, but to a lesser degree. It was shown that radiotherapy of nasopharyngeal carcinoma certainly damages the visual nerve system, though there is sex difference in the impairment.
authors.affiliation: Department of Radiation Oncology, Cancer Center, Sun Yat-Sen University, Guangzhou 510060, China.
authors.forename: Weihan
authors.initials: W
authors.lastname: Hu
authors.forename: Minzhong
authors.initials: M
authors.lastname: Yu
authors.forename: Shixian
authors.initials: S
authors.lastname: Long
authors.forename: Shizhou
authors.initials: S
authors.lastname: Huang
authors.forename: Mofa
authors.initials: M
authors.lastname: Gu
authors.forename: Lansun
authors.initials: L
authors.lastname: Zhou
authors.forename: Dezheng
authors.initials: D
authors.lastname: Wu
mesh_terms: D000328:Adult; D005074:Evoked Potentials, Visual / Q000528:radiation effects*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009303:Nasopharyngeal Neoplasms / Q000532:radiotherapy*; D012737:Sex Factors; D013997:Time Factors