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.