Introduction
Nasopharyngeal carcinoma (NPC) is the most common type of tumor
originating in the epithelium of the nasopharynx and a distinct tumor of
head and neck region which is primarily treated with external beam
radiation therapy, with or without concurrent cisplatin
chemotherapy.1,2 External beam radiation to the head
and neck region is notorious for its otologic complications including
external otitis, otitis media, sensorineural hearing loss (SNHL) and
osteoradionecrosis of the temporal bone.3,4 Post
irradiation middle ear effusion (MEE), is associated with conductive
hearing loss. If not identified and managed properly, it may progress to
full atelectasis of the ear drum associated ossicular bone erosion,
hearing loss deterioration and
cholesteatoma.5,6 Therefore, evaluation of NPC
patients for the presence of MEE is mandatory.
In the late 1990’s new radiation modalities were introduced to decrease
the radio-toxicity related to the radiation therapy (RT), one of which
is intensity-modulated radiotherapy (IMRT).7,8 IMRT is
superior to the traditional 2D radiation due to its three-dimensional
properties which allow a more precise planning of the irradiated tumor
volume, sparing non-involved regions. As such, in patients with NPC it
may allow reducing the otologic complications.9,10 The
main structures associated with normal middle ear function are the
Eustachian tube (ET), the Levator veli-palatini (LVP) and Tensor
veli-palatine (TVP) muscles which function as the ET dilators, and are
therefore crucial for its normal function and patency.
The primary objective of this study was to perform a comprehensive
analysis of patient, tumor and treatment parameters as risk factors for
post radiation MEE in NPC patients. Specifically, irradiation parameters
of the middle ear, ET, TVP and LVP regions were investigated as well as
potential contributors.