Discussion
To the best of our knowledge, this is the first report to describe the otorhinolaryngological management in Taiwanese patients with MPS. Our results emphasize that otorhinolaryngological management is important for patients with MPS as they have problems of language development and poor quality of life due to the high frequency of ear disorders [17]. For better prognosis of MPS, it is important to treat in early stage. The otorhinolaryngologist and audiologists play important roles in follow-up and treatment of MPS patients. Patients need better and long-term follow-ups due to high incidence of recurrent serous otitis media with conductive hearing loss and progress to sensorineural hearing loss.
In previous studies, an average of 75% of cases (range 59.7% to 89%) have hearing loss [18]. Various types and degrees of hearing loss can be seen in MPS patients [7-8, 19-21]. Conductive hearing losses are more common in MPS patients due to frequent chronic middle ear effusion and Eustachian tube dysfunction. The incidence and etiology of sensorineural hearing losses are unknown [7]. In our study, conductive hearing losses are more than sensorineural hearing losses (19.0% v.s. 16.7%). Although conductive hearing loss can be improved by adenoidectomy and tympanostomy with ventilation tube [21], sensorineural hearing loss is still a problem to be overcome. In our study, 34.3% of patients had improved hearing after surgery. Besides, according to the infection score system, we noticed that the severity of respiratory tract and otological infections improved after ENT surgery. It may cause by the improvement of adenoid hypertrophy, tonsillar hypertrophy and OME with decreased infection risk.
Ventilation tubes are advised to apply in MPS patients with recurrent OME and hearing loss. However, some families rejected to undergo ventilation tubes insertion because they were afraid of the risk of general anesthesia during operation. In some cases, the operation was very difficult or impossible because of the severe deformity of external ear canal that the ear drum was difficult to approach. And in some cases, we advised patients to apply hearing aids, but the socioeconomical inadequacy made them hard to come to follow-ups and obtain these aids. This is the reason that some patients still have conductive hearing loss after ERT. Besides, ERT could not improve sensorineural hearing loss [22].
Whereas otologic problems influence the quality of life, upper airway obstruction can cause serious morbidity and mortality. Most respiratory problems are caused by the changes of soft tissue of the tonsils, adenoids, tongue, lingual tonsils and the stiffness of oropharynx and temporomandibular joint. Oropharyngeal stiffness and collapse become severe when the disease deteriorates and can cause significant airway obstruction [23]. The degree of upper airway obstruction may range from OSA to life-threatening airway emergencies, and airway evaluation is necessary and challenging. The results of airway examinations vary in case-by-case patients [24]. In our study, the upper airway obstruction (patients who had stridor, suprasternal retractions, and change of voice) rate was 76.2%, compared with 38% [20], 48% [18], and 92% [25] in other studies. All types of MPS patients had similar symptoms. Consequently, it is necessary to perform adenoidectomy in patients with purulent, recurrent, and chronic symptoms such as OME, snoring and sleep apnea [14]. Though tonsillectomy and adenoidectomy can help those with OSA at first, they may need nocturnal oxygen treatment, and even tracheostomy in advanced cases [26]. Anesthetic risks increase in patients with MPS because they have macroglossia, temporomandibular joint stiffness, difficult or failed intubations, abnormal laryngeal anatomy, trachea deformity and subglottic narrowing [27, 28]. Before surgery, these patients need examination using a flexible bronchoscope to survey the exact extent and severity of airway obstruction [7, 9].
The patient history and physical examination are necessary for evaluation of OSA initially, but the degree of obstruction before and after surgery should be studied by polysomnography and laryngobronchoscopy [25,29]. In our study, 28.6% of our patients still had OSA after adenotonsillectomy due to macroglossia and oropharyngeal stiffness. This condition is also found in other OSA patients without MPS. The reason may be that even though the structure and the tension of upper airway improved after surgery, it could deteriorate after years. We should also pay attention to whether the dose of ERT is enough or not. ENT care and airway evaluations should be provided before we take these patients to the operation room and it could provide more safe intubation and extubation. Choosing the suitable size of endotracheal tube and the method of intubation potentially decrease the risk of complications related to intubation during general anesthesia and surgery [30].
This study has several limitations. We had only 42 patients in this study because they had complete medical histories of otorhinolaryngological treatments. Besides, we did not perform sleep studies in every patient because this study was designed for medical retrospect. It is necessary to complete their examinations in the future. It is also needed to evaluate the quality of life of patients formally by visual analogue scale (VAS) as previous study [16].