DISCUSSION
Hearing impairment remains the most common complication in long-term
survivors after comprehensive treatment for NPC. Currently, CI is the
only method implemented for the rehabilitation severe to profound SNHL
in cases of insufficient compensation effect of the HA. However, various
postradiotherapy complications increase the difficulties of surgery, and
have negative effect on postoperative recovery. Therefore, the
evaluation performed only by otorhinolaryngologists of the condition of
such patients was not sufficient, and thus MDT was used to make the
diagnosis and provide the treatment plan for each of the patients
included in the present study.
According to the CSCO clinical guidelines for NPC, post-treatment
follow-up of NPC is very important. In this study, the relevant
examinations were strictly completed following the guidelines, and MDT
evaluated the situation of tumor control jointly by specialists from
different departments. The results showed that NPC in all 11 patients
was controlled completely.
Huang et al.17 divided the postirradiated NPC patients
into three categories: mild, moderate and severe. Different from our
study, they recommended that patients of severe category underwent
subtotal temporal bone resection (STBR), external auditory canal
elimination, CI simultaneously or by stage because they suffered
recurrent suppurative otitis media and mastoiditis, combined with the
external moist EAC with defect of skin and bear dead bones, and serious
or severe radiation osteomyelitis by CT/MRI. The results showed that CI
for postirradiated ears of NPC is safe and feasible following specific
surgical methods aiming to three categories.
In this study, we classified ORNTB into localized type and diffuse type
referring to Ramsden classification.11 On the basis of
Ramsden classification, our center’s experience demonstrated the
importance of the thickness and integrity of the cortical bone of the
posterior and superior wall of the EAC. This was due to the fact that
the intact EAC can protect the cochlear electrode array, preventing the
occurrence of infection and electrode exposure. Thus, we recommended
that the patients of grade (c) underwent STP, external auditory canal
elimination, mastoid cavity obliteration by fat graft or
musculoperiosteal flaps and CI simultaneously. Prasad et
al.18 reported that STP is indicated in
osteoradionecrosis while STBR is usually used on the temporal bone
malignancies. In the present study we initially excluded the residues,
recurrence, or metastasis of the primary lesion based on perioperative
MDT discussion. Therefore, STP was selected to eliminate potential
infection, reduce the risk of postoperative complications and achieve
rapid postoperative recovery. It is worth noticing that the
aforementioned cochlear implant was dysfunctional because of the total
detached electrode from the round window. Considering the history of
radiotherapy for NPC and diffuse ORNTB, conservative management would
have exposed the patient to a high risk of infection. Therefore, the
patient underwent a second surgery, as mentioned earlier. Chua et
al.19 performed conservative treatment with close
clinical surveillance as a reasonable option faced with electrode array
extrusion post-CI in a post-irradiated patient. In contrast, we suggest
a positive surgical treatment in case of electrode extrusion. Besides,
MDT precisely predicted the risk of electrode exposure in this patient,
reflecting the potential of MDT to reduce the incidence of medical
errors.
Several studies have revealed marked improvements in the hearing of
cochlear implant recipients who had previously received radiotherapy for
head and neck cancers. In this regard, Soh et al.20,
Chang et al.21, and Low et al.22established that there were no obvious differences in the effectiveness
of CI in post-irradiated NPC patients with hearing impairment as
compared with non-NPC patients with profound SNHL. However, whether REP,
which is regarded as a severe post-irradiation complication, affects
postoperative hearing outcome remains unclear. Besides, there are no
clear guidelines for the diagnosis and treatment of REP. In our study,
it was shown that the postoperative hearing and speech rehabilitation
effects of all 11 patients were significantly better than those before
surgery, regardless of the presence or absence of REP.