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.