Purpose. It has been assumed that postirradiated nasopharyngeal carcinoma (NPC) patients are prone to benign paroxysmal positional vertigo (BPPV). The purpose of this study was to better understand this clinical entity. Materials and Methods. From September 2003 to June 2011, we conducted a retrospective study of 11 irradiated NPC patients with BPPV in our institute. During the same period, 11 irradiated NPC patients without BPPV were randomly selected and enrolled as the control group. All medical records of these patients were evaluated. Results. The risk of BPPV rises significantly when the patient undergoes radiotherapy (RT) twice and the threshold radiation dose is >120？Gy ( ). The occurrence of postirradiated BPPV was significantly related to incidences of otitis media and sensorineural hearing loss (SNHL) ( and 0.009, resp.). All the patients responded well to repositioning maneuvers. Conclusion. A second course of RT, postirradiated otitis media, or SNHL is associated with the potential risk of radiation-induced BPPV. Repositioning maneuvers were safe and effective for relief of this disease. 1. Introduction Nasopharyngeal carcinoma (NPC) is a tumor arising from the epithelial cells that cover the surface and line of the nasopharynx. Radiotherapy (RT) is by far the most primary treatment of NPC. Due to complex anatomy, exposure of adjacent and nontarget organs during irradiation of the nasopharynx areas is frequently unavoidable. Ondrey et al. [1] studied the radiation exposure of otologic structures in head and neck cancer and implied that the temporal bone received a significant dose of radiation. Consequently, with the increasing number of irradiated NPC survivors, more and more patients are experiencing otologic and neurotologic complications, such as otitis media with effusion, sensorineural hearing loss (SNHL), dizziness/vertigo, and oscillopsia [2–5]. However, benign paroxysmal positional vertigo (BPPV) in irradiated NPC patients remains scarcely reported [6]. BPPV is a syndrome characterized by short-lived episodes of vertigo (a sensation of instability, often with a sensation of rotation) in association with rapid changes in head position. There are a number of aetiologies associated with BPPV, such as vertebrobasilar ischaemia, labyrinthitis, ear surgery, head trauma, and vestibular neuritis [7]. Because the radiation portals for NPC consist of the bilateral temporal bones, whether it is radiation damage to the inner ear that leads to BPPV in irradiated NPC patients remains unexplored. The purpose of this study is to investigate the
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