Radiation-induced oscillopsia in nasopharyngeal carcinoma patients.
OBJECTIVE
To apply a battery of audiovestibular function tests and magnetic resonance imaging (MRI) to investigate the causes of oscillopsia in nasopharyngeal carcinoma (NPC) patients after irradiation (RT).


METHODS
Of 300 NPC patients, 12 (4%) developed oscillopsia after RT. The mean accumulated radiation dose to the nasopharynx was 112 +/- 30 Gy. Each patient underwent a battery of audiovestibular function tests, including audiometry and the dynamic illegible E, caloric, and rotational tests.


RESULTS
Excluding 3 patients with neck fibrosis who could not perform the head turning movement, the remaining 9 patients displayed 100% abnormal dynamic illegible E test results and 100% abnormal refixation saccades. All 12 patients presented with bilateral hearing loss, caloric reductions, and reduced gains of the vestibular ocular reflex (VOR) on the rotational test, indicating bilateral VOR loss. After excluding tumor relapse and radiation necrosis of the brain by MRI, the oscillopsia in these 12 irradiated NPC patients was attributed to bilateral VOR loss.


CONCLUSIONS
Radiation-induced oscillopsia in our NPC patients was attributed to bilateral VOR loss, possibly as a result of higher radiation doses. Hence, the therapeutic benefits of a second course of RT are associated with the potential risk of oscillopsia after RT.
Chen
Peir-Rong
PR
Department of Otolaryngology, Buddhist Tzu-Chi General Hospital, Hualien, Taiwan.
Hsu
Lee-Ping
LP
Tu
Chuan-En
CE
Young
Yi-Ho
YH
D000368:Aged; D016009:Chi-Square Distribution; D007758:Ear, Inner / Q000528:radiation effects; D005260:Female; D034381:Hearing Loss / Q000209:etiology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009303:Nasopharyngeal Neoplasms / Q000532:radiotherapy*; D011832:Radiation Injuries / Q000150:complications; D011879:Radiotherapy Dosage; D014724:Vestibular Function Tests; D014786:Vision Disorders / Q000209:etiology*