Surgical management of hearing disabilities in nasopharyngeal carcinoma patients

Abstract

Nasopharyngeal carcinoma (NPC) is a common head and neck cancer in our locality, with an incidence of 15 per 100 000 males. Despite improvement in toxicities profile, many survivors develop long-term adverse effects, such as hearing impairment, that impact their quality of life (QOL). A cross-sectional QOL survey of 114 patients using the Functional Assessment of Cancer Therapy- Nasopharyngeal Cancer Subscale (FACT-NP) showed that the QOL deteriorated progressively, and the long-term survivors (> 10 years) have the worst QOL scores. The hearing impairment score also started to drop after the completion of primary treatment and continued to deteriorate with time. Otologic problems including otitis media with effusion (OME) occur in up to 60% of patients as their first presenting symptom. Decades ago, myringotomy and grommet insertion (M&G) was the treatment of choice with the risk of persistent otorrhoea and eardrum perforation. In the modern era of better radiation technique, a prospective cohort study was conducted to investigate the efficacy of pre-treatment M&G. When M&G were performed for early T-stage patients with OME, the risk of adverse otologic outcomes was significantly lower (p<0.005) than for advanced T-stage tumours at 6 months and 3 years. Although observation for pre-treatment OME was safe, M&G for early T-stage patients could alleviate the frustrating otologic symptoms. Maxillary swing nasopharyngectomy for local recurrence has been performed for decades. The original idea of M&G during nasopharyngectomy to prevent OME and its complications has never been verified. A retrospective review showed that up to 32% had otorrhoea and perforated eardrums at one year. When only myringotomy is performed, the risk of otorrhoea drops to 10% at one year. However, the problem of chronic suppurative otitis media (CSOM) remained between the two groups even at one year after the procedure. The use of Eustachian tube (ET) stenting instead of M&G during maxillary swing nasopharyngectomy was studied to see if it could prevent subsequent otologic complications. An Angiocath was used as the stent and inserted through the remnant of the ET after nasopharyngectomy. 71% of patients had no OME and had better audiologic results at one year. The stenting procedure should theoretically provide similar results for other nasopharyngectomy using endoscopes or surgical robots. Profound sensorineural hearing loss (SNHL) patients are not aidable with hearing aids unless cochlear implantation. NPC patients with previous radiotherapy carry higher surgical risks and radiation damage to the retrocochlear pathway can cause poor audiologic outcome. A classification to guide surgical approaches for cochlear implantation was proposed. When the guidelines were followed, the risk of surgical complication was minimal. The outcome of various speech perception assessments using the Hong Kong Speech Perception Test Manual (HKSPTM) at one year or longer after implantation showed significant improvement, with some scores up to 80%. The findings contributed to the knowledge of cochlear implantation in Cantonese-speaking NPC patients. Although many hearing disabilities of NPC could have been treated without surgery, surgical intervention remains necessary to provide immediate relief or when no other alternatives are effective in the restoration of hearing.