Vestibular Apparatus Dysfunction after External Beam Radiation Therapy for Head and Neck Cancers

Abstract

Objectives: Radiation therapy (RT) for head and neck cancers (HNC) may be associated with vestibular dysfunction (VD). The goal of this study is to examine the post-RT incidence of VD in HNC patients receiving RT +/- chemotherapy (chemo) and its association with patient and treatment related factors. Methods: Pre and post-RT records of 376 HNC patients were retrospectively assessed for the presence of possible VD. Dose received by vestibular apparatus was estimated using the CT-based treatment plan for the patient. Uni- and multivariate analyses evaluated the association between various variables and incidence of VD. Results: Subjective vertigo or dizziness was reported in 53(14.5%) patients over a median time of 16 months (range 0 to 36 months). Abnormal elecronystagmography was observed in 41 of 49 (83.6%) tested patients: 24 (48.9%) bithermal caloric stimulation, 8 (16.3%) sinusoidal tracking, and 5 (10.2%) with both. Doses received by vestibular apparatus varied between 45 to 80 Gy. Vestibular RT dose was significantly associated with VD ( P < 0.05), but age (>60), gender, fractionation were not. Use of chemo was marginally associated with VD ( P = 0.056). Conclusions: Radiation dose to the vestibular apparatus appears to be the primary determinant of VD in HNC patients treated with RT. Further prospective investigation is needed to better understand the effects of RT and chemo-RT on vestibular apparatus.