Impairment of optic path due to radiotherapy for nasopharyngeal carcinoma.

PURPOSE: To evaluate the impairment of optic path caused by radiotherapy for nasopharyngeal carcinoma (NPC). METHODS: Visual evoked potential was used to evaluate the functional impairment of optic path by an 8 MV linear accelerator or 60Co gamma-ray radiotherapy in 63 (23 women and 40 men) patients with nasopharyngeal carcinoma before radiotherapy, at the end of radiotherapy, 6 months and 1, 2 and 3 years after their radiotherapy respectively. RESULTS: In the female group, the latency of VEP elicited by the three types of elements significantly delayed 2 and 3 years after radiotherapy than that before radiotherapy, at the end of radiotherapy, 6 months and 1 year after radiotherapy; there were no significant difference among VEP amplitudes elicited by the three types of elements before and after radiotherapy. In the male group, the latency of VEP elicited by the medium and the small elements significantly delayed 1 year after radiotherapy than that before radiotherapy and at the end of radiotherapy, the VEP latency elicited by the small elements was significantly prolonged 3 years after radiotherapy compared to that just after radiotherapy, while the VEP amplitude elicited by the large elements was significantly attenuated 1 year after radiotherapy compared to those before and just after radiotherapy. CONCLUSIONS: In the female group, the significant prolongation of VEP latency happened at the end of radiotherapy and lasted for 3 years, while the VEP amplitude did not change significantly during the 3 years after radiotherapy. It indicates that the sustained impairment by radiation within the female visual nerve system starts at the end of radiotherapy, but the impairment was mild. In the male group, the significant prolongation of VEP latency mostly happened 1 or 2 years after radiotherapy. It was shown that the radiotherapy for nasopharyngeal carcinoma certainly injured the optic path, and there was difference in the impairment between the two sexes.

[Study on prevention and treatment of radiotherapy caused post-visual pathway injury in nasopharyngeal carcinoma patients by traditional Chinese medicine].

OBJECTIVE: To study the effect of TCM in preventing and treating post-visual pathway injury caused by radiotherapy (RT) for nasopharyngeal carcinoma (NPC). METHODS: Thirty-five patients of NPC were randomly divided into the RT group (n = 17) and the RT + TCM group (n = 18), they were all received RT, but the latter was treated additionally with Jingming recipe, a Chinese recipe. The latent period and amplitude of evoked potential (EP) were measured before and after ending of RT, using multi-focusing visual evoked potential inspector. RESULTS: The latent time of EP, both upper and lower visual field, was prolonged significantly after RT in the RT group (P < 0.05), but not in the RT + TCM group (P > 0.05); the amplitude of EP of upper visual field lowered significantly (P < 0.05) in the RT group but insignificantly in the RT + TCM group (P > 0.05); as for the EP amplitude of lower visual field, it was unaltered in RT group after RT (P > 0.05), but increased in the RT + TCM group (P < 0.05). CONCLUSION: The Chinese medicine Jingming recipe was effective in preventing and treating RT induced post-visual pathway injury.