Introduction
Mucopolysaccharidoses (MPSs) are one group of lysosomal storage disorders. Most of their inheritance patterns are autosomal recessive, except MPS type II that is X-linked recessive. These diseases are manifestations of a deficiency of the enzymes that break down glycosaminoglycans (GAGs). There are eleven kinds of enzymes deficiency in MPSs, and MPS is classified into seven types (I, II, III, IV, VI, VII and IX) [1,2]. Due to accumulation of GAGs in lysosomes, dysfunction of cells, tissues, and organs occurs. This results in coarse facial features, hepatosplenomegaly, bone deformities with limitation of joint movement, variable intellectual disability, cardiac anomalies, and corneal clouding [3,4].
Ear, nose, and throat (ENT) problems frequently occur in MPS I, II, and VI and are often the earliest clinical manifestations of these diseases [5,6]. As there are abnormal accumulations of GAGs in the middle ear mucosa, nasal mucosa, and eustachian tubes, potential of stiffness and obstruction in eustachian tube was predicted. MPS patients usually have otitis media with effusion (OME), which could cause conductive hearing loss [7,8]. It is also believed that infiltration of the cochlear nerve, afferent cochlear nerve and stria vascularis in cochlear with GAGs causes sensorineural hearing loss [5]. However, most hearing loss patterns of MPS VI patients are conductive [9]. It means that Eustachian tubes play the dominant mechanism with conductive hearing loss in MPS VI. Other ENT disorders such as persistent copious nasal discharge, chronic recurrent rhinitis [10], and adenotonsillar hypertrophy often occur in MPS patients [7].
Upper airway complications and obstructive sleep apnea (OSA) can be caused by macroglossia and stiffness of oropharynx, temporomandibular joint stiffness, nasal dysmorphism, flaccid and redundant supra-arytenoid soft tissue, and tracheomalacia [9-12]. Even though obstructed airways can be improved by conservative treatment, (such as positive airway pressure devices), early adenotonsillectomy, and even tracheostomy may be needed [7,13].
This retrospective study aimed to determine the occurrence of ENT manifestations in MPS patients in Taiwan, and to analyze the prognosis of surgical intervention, including the effect on symptoms and quality of life.