Discussion

Eustachian tube dysfunction with middle-ear effusion is a known and common complication after receiving RT to the head and neck region. The incidence of Eustachian tube dysfunction with middle-ear effusion is reported to be 20–40 per cent in patients who have received RT.^{Reference Bhandare, Antonelli, Morris, Malapaya and Mendenhall2,Reference Jereczek-Fossa, Zorowski, Milani and Orrechia3} This is believed to be caused by mucosal oedema and loss of Eustachian tube function. The effect may be transient or permanent.^{Reference Schwarz, Manogaran and Danial1}

Currently, there is no ideal treatment for post-RT Eustachian tube dysfunction with middle-ear effusion. Xu et al. have compared three management methods: simple myringo-puncture with aspiration, tympanic membrane fenestration and cauterisation, and myringotomy with grommet insertion.^{Reference Xu, Ou, Zheng, Chen and Ji9} Myringotomy with grommet insertion yields the highest cure rate, but it is also associated with the highest rate of complications, such as eardrum perforation and chronic suppurative otitis media. The risk for complications is reported to be as high as 20–30 per cent.^{Reference Xu, Ou, Zheng, Chen and Ji9}

Patients suffering from this condition must live with significant morbidity in the form of ear discomfort, tinnitus, varying degrees of pain and discomfort, and poor hearing. Treatment choices all come with additional morbidities. Some patients accept the situation and opt for hearing aids to assist with their hearing. It is hoped that the recent advancement of balloon Eustachian tube dilatation may offer an additional option to treat this condition, without any associated morbidity.

Balloon Eustachian tube dilatation was first performed on cadavers in 2010.^{Reference Ockermann, Reineke, Upile, Ebmeyer and Sudhoff10} It was shown to be easily performed without any damage to essential structures. Since then, multiple reports have been published on the efficacy and safety of balloon Eustachian tube dilatation. Poe et al. compared the outcomes of 342 patients divided into a control group and those who underwent the procedure.^{Reference Poe, Anand, Dean, Roberts, Stolovitzky and Hoffmann7} The outcomes favoured the balloon Eustachian tube dilatation group with respect to normalisation of the tympanogram after six weeks and symptom improvement.

There were no significant adverse effects associated with the use of balloon Eustachian tube dilatation. Most adverse effects were mild and self-limiting, such as minor nosebleed, mild pain, rhinitis and tinnitus.^{Reference Poe, Silvola and Pyykko4,Reference Catalano, Jonnalagadda and Yu6,Reference Poe, Anand, Dean, Roberts, Stolovitzky and Hoffmann7}

Within the literature, there have been no reported cases of injury to the internal carotid artery, which lies close to the Eustachian tube. Abdel-Aziz et al. concluded from their retrospective study that pre-operative high-resolution computed tomography (CT) of the temporal bone does not predict intra-operative or post-operative difficulty in performing balloon Eustachian tube dilatation.^{Reference Abdel-Aziz, Schroder, Lehmann, Gehl, Ebmeyer and Sudhoff11} Accordingly, a routine temporal high-resolution CT scan is not needed for all patients.

To the best of our knowledge, there has been no published case or study on the use of balloon Eustachian tube dilatation to treat post-RT Eustachian tube dysfunction. Preliminary results from a limited number of patients have shown that patients with long-standing Eustachian tube dysfunction following RT do not respond well to balloon Eustachian tube dilatation. Balloon Eustachian tube dilatation is founded on the idea that the balloon-mediated crushing of diseased mucosa will cause normal mucosa to heal over the affected area.^{Reference Catalano, Jonnalagadda and Yu6} However, in post-RT patients, the damaged segment of the Eustachian tube may be fibrosed and stenosed, hence the ineffectiveness of the balloon.

In the present study, the decision to recruit patients to the nasopharyngeal carcinoma group only six months after RT is based on the possibility that Eustachian tube dysfunction may resolve spontaneously, and this may occur at any point up to six months after initial onset.^{Reference Jereczek-Fossa, Zorowski, Milani and Orrechia3} Further studies will be needed to explore the possibility of earlier intervention to prevent stenosis. The outcomes for non-nasopharyngeal carcinoma patients fell within the expectations as described in the available literature.^{Reference Huisman, Verdam, Stegeman and de Ru12}

In this study, there was a single patient who showed a full recovery following balloon Eustachian tube dilatation. This patient was treated with balloon Eustachian tube dilatation about six months after RT for stage I nasopharyngeal carcinoma (Table 5). Though it is difficult to draw conclusions from a single patient, it is possible that the early timing of intervention, before fibrosis and mature scarring had occurred, may have led to a better outcome. Another possible explanation is the early stage of cancer diagnosis in this patient. This could indicate the presence of a less extensive tumour, which may have preserved the normal functional nasopharyngeal structures compared with more extensive disease progression in the other patients.

Table 5.

NPC patient characteristics and outcome

NPC = nasopharyngeal cancer; pt no. = patient number; RT = radiotherapy; ETDQ-7 = seven-item Eustachian Tube Dysfunction Questionnaire

The preliminary findings in five patients who underwent balloon Eustachian tube dilatation for post-RT Eustachian tube dysfunction do not show a clear benefit clinically. A larger sample size would be appropriate to assess the feasibility of a full randomised, controlled study. The statistical significance of these preliminary data should be interpreted with caution given the small sample size.