Disordered breathing during sleep in patients with mucopolysaccharidoses

Pediatric Sleep Respiratory Disorders: A Narrative Review of Epidemiology and Risk Factors

Sleep is a fundamental biological necessity, the lack of which has severe repercussions on the mental and physical well-being in individuals of all ages. The phrase "sleep-disordered breathing (SDB)" indicates a wide array of conditions characterized by snoring and/or respiratory distress due to increased upper airway resistance and pharyngeal collapsibility; these range from primary snoring to obstructive sleep apnea (OSA) and occur in all age groups. In the general pediatric population, the prevalence of OSA varies between 2% and 5%, but in some particular clinical conditions, it can be much higher. While adenotonsillar hypertrophy ("classic phenotype") is the main cause of OSA in preschool age (3-5 years), obesity ("adult phenotype") is the most common cause in adolescence. There is also a "congenital-structural" phenotype that is characterized by a high prevalence of OSA, appearing from the earliest ages of life, supported by morpho-structural abnormalities or craniofacial changes and associated with genetic syndromes such as Pierre Robin syndrome, Prader-Willi, achondroplasia, and Down syndrome. Neuromuscular disorders and lysosomal storage disorders are also frequently accompanied by a high prevalence of OSA in all life ages. Early recognition and proper treatment are crucial to avoid major neuro-cognitive, cardiovascular, and metabolic morbidities.

Childhood Dementia: A Collective Clinical Approach to Advance Therapeutic Development and Care

Childhood dementias are a group of over 100 rare and ultra-rare pediatric conditions that are clinically characterized by chronic global neurocognitive decline. This decline is associated with a progressive loss of skills and shortened life expectancy. With an estimated incidence of one in 2800 births and less than 5% of the conditions having disease-modifying therapies, the impact is profound for patients and their families. Traditional research, care, and advocacy efforts have focused on individual disorders, or groups classified by molecular pathogenesis, and this has established robust foundations for further progress and collaboration. This review describes the shared and disease-specific clinical changes contributing to childhood dementia and considers these as potential indicators of underlying pathophysiologic processes. Like adult neurodegenerative syndromes, the heterogeneous phenotypes extend beyond cognitive decline and may involve changes in eating, motor function, pain, sleep, and behavior, mediated by physiological changes in neural networks. Importantly, these physiological phenotypes are associated with significant carer stress, anxiety, and challenges in care. These phenotypes are also pertinent for the development of therapeutics and optimization of best practice management. A collective approach to childhood dementia is anticipated to identify relevant biomarkers of prognosis or therapeutic efficacy, streamline the path from preclinical studies to clinical trials, increase opportunities for the development of multiple therapeutics, and refine clinical care.

Sanfilippo syndrome: consensus guidelines for clinical care

Sanfilippo syndrome is a group of rare, complex, and progressive neurodegenerative lysosomal storage disorders that is characterized by childhood dementia. The clinical management of patients with progressive neurological decline and multisystem involvement requires a multidisciplinary team with experience in the management of neurodegenerative disorders. Best practice guidelines for the clinical management of patients with these types of rare disorders are critical to ensure prompt diagnosis and initiation of appropriate care. However, there are no published standard global clinical care guidelines for patients with Sanfilippo syndrome. To address this, a literature review was conducted to evaluate the current evidence base and to identify evidence gaps. The findings were reviewed by an international steering committee composed of clinical experts with extensive experience in managing patients with Sanfilippo syndrome. The goal was to create a consensus set of basic clinical guidelines that will be accessible to and informed by clinicians globally, as well as providing a practical resource for families to share with their local care team who may not have experience with this rare disease. This review distills 178 guideline statements into an easily digestible document that provides evidence-based, expert-led recommendations for how to approach common management challenges and appropriate monitoring schedules in the care of patients with Sanfilippo syndrome.

Quantifying medical manifestations in Hurler syndrome with the infant physical symptom score: associations with long-term physical and adaptive outcomes

BACKGROUND

A physical symptom score (PSS) for the mucopolysaccharidosis (MPS) disorders has been developed to quantitate the somatic burden of disease across multiple organ systems. Studies have demonstrated the sensitivity and its relationship to age, IQ and adaptive functioning of the PSS in older children. With the onset of newborn screening, there is an increased need to characterize the somatic symptoms in the earliest stages of life, especially for young children under 36 months of age. Consequently, a new scale, Infant Physical Symptom Score (IPSS), was developed to score physical symptoms in infants and toddlers.

OBJECTIVE

Part I. To create a measure to quantify somatic burden in patients with MPS disorders under 36 months of age. The IPSS assess outcomes and changes in somatic disease in individuals with MPS disorders diagnosed very early in life. Part II. To determine the relationship between IPSS and other measures to evaluate its validity and utility, a) we evaluated the relationship between the IPSS and PSS in the same patients with MPS I over time to determine if the two scales are measuring the same concepts, and b) we evaluated the association between IPSS and a functional adaptive measure over time with a focus on the age at first treatment (under 36 months) to determine if the IPSS has predictive value.

METHODS

Part I. The Infant Physical Symptom Score (IPSS) for the infant population in MPS disorders was established using data from 39 patients enrolled in the Lysosomal Disease Network longitudinal MPS I study (U54NS065768). All of these patients had Hurler syndrome (MPS IH) and underwent hematopoietic stem cell transplant (HSCT) at the University of Minnesota. Items for the IPSS were selected by reviewing CRFs prepared for the MPS I longitudinal study and examining medical records of these patients prior to HSCT based on the knowledge gained from the development of the PSS. Part II. Of those 39 patients, a subset of 19 were all seen 9 to 12 years post HSCT. Having retrospectively calculated their IPSS prior to HSCT, we categorized them by age at HSCT, and examined their most recent PSS along with Composite and Daily Living Skills scores on the Vineland Adaptive Behavior Scales - Second Edition (VABS-II).

RESULTS AND CONCLUSION

The total score on the IPSS collected prior to transplant differed by patient's age at transplant, as expected in this progressive condition. Those transplanted at ≤12 months of age had a mean score of 7.4, which was significantly lower, suggesting less somatic disease burden, compared to those transplanted at >12 to ≤24 months (mean 11.8) and > 24 to ≤36 months (mean 13.6). Higher IPSS reflects more evidence of somatic disease burden and lower IPSS reflects less evidence of disease burden. Nine to 12 years later, the severity level as measured by the PSS was comparable to severity on the IPSS suggesting that the two scales are measuring similar concepts. Retrospectively calculated pre-transplant IPSS were negatively associated with higher VABS-II Composite scores 9-12 years later (p value-0.015) and to a lesser extent Daily Living Skills scores (p value-0.081). We conclude that the IPSS appears to be a useful approach to quantifying the somatic disease burden of MPS IH patients under 36 months of age.

Non-cardiac Manifestations in Adult Patients With Mucopolysaccharidosis

Mucopolysaccharidoses (MPS) are a heterogeneous group of disorders that results in the absence or deficiency of lysosomal enzymes, leading to an inappropriate storage of glycosaminoglycans (GAGs) in various tissues of the body such as bones, cartilage, heart valves, arteries, upper airways, cornea, teeth, liver and nervous system. Clinical manifestations can become progressively exacerbated with age and affect their quality of life. Developments in advanced supportive treatment options such as enzyme replacement therapy (ERT), hematopoietic stem cell transplantation (HSCT) may have improved patients' life span. Adult MPS patients require specialist clinical surveillance long-term. In many cases, in addition to the MPS-related health problems, they may develop age-related complications. Considering the complexity of their clinical manifestations and lack of guidelines on the management of adult MPS disorders, multispecialty and multidisciplinary teams' care is essential to diagnose and treat health problems that are likely to be encountered. This review presents non-cardiac clinical manifestations, their pathophysiology, management and long-term outcomes in adult MPS patients.

Increased Alveolar Heparan Sulphate and Reduced Pulmonary Surfactant Amount and Function in the Mucopolysaccharidosis IIIA Mouse

Mucopolysaccharidosis IIIA (MPS IIIA) is a lysosomal storage disease with significant neurological and skeletal pathologies. Respiratory dysfunction is a secondary pathology contributing to mortality in MPS IIIA patients. Pulmonary surfactant is crucial to optimal lung function and has not been investigated in MPS IIIA. We measured heparan sulphate (HS), lipids and surfactant proteins (SP) in pulmonary tissue and bronchoalveolar lavage fluid (BALF), and surfactant activity in healthy and diseased mice (20 weeks of age). Heparan sulphate, ganglioside GM3 and bis(monoacylglycero)phosphate (BMP) were increased in MPS IIIA lung tissue. There was an increase in HS and a decrease in BMP and cholesteryl esters (CE) in MPS IIIA BALF. Phospholipid composition remained unchanged, but BALF total phospholipids were reduced (49.70%) in MPS IIIA. There was a reduction in SP-A, -C and -D mRNA, SP-D protein in tissue and SP-A, -C and -D protein in BALF of MPS IIIA mice. Captive bubble surfactometry showed an increase in minimum and maximum surface tension and percent surface area compression, as well as a higher compressibility and hysteresis in MPS IIIA surfactant upon dynamic cycling. Collectively these biochemical and biophysical changes in alveolar surfactant are likely to be detrimental to lung function in MPS IIIA.

Pulmonary Manifestations of Endocrine and Metabolic Diseases in Children

Advances in technology, methodology, and deep phenotyping are increasingly driving the understanding of the pathologic basis of disease. Improvements in patient identification and treatment are impacting survival. This is true in endocrinology and inborn errors of metabolism, where disease-modifying therapies are developing. Inherent to this evolution is the increasing awareness of the respiratory manifestations of these rare diseases. This review updates clinicians, stratifying diseases spirometerically; pulmonary hypertension and diseases with a predisposition to recurrent pulmonary infection are discussed. This division is artificial; many diseases have multiple pathologic effects on respiration. This review does not cover the impact of obesity.

Oral health of Brazilian individuals with mucopolyssaccaridosis

PURPOSE

This study described and compared the oral characteristics of Brazilian individuals with mucopolysaccharidosis (MPS) and without MPS.

METHODS

A cross-sectional study was performed with 29 individuals with MPS and 29 without MPS and their parents/guardians. The individuals were aged between 3 and 21 years and attended at two hospitals in Belo Horizonte, southeastern Brazil. The dental characteristics were evaluated by clinical examination of dental caries, gingivitis, malocclusion, dental anomalies and developmental defects of enamel. The parents/guardians answered a questionnaire about the sociodemographic and behavioural aspects of their children. The study was approved by the Research Ethics Committee of the Federal University of Minas Gerais.

RESULTS

The average age of the individuals was 13.9 years (± 7.2). The majority were male (58.6%), had black/brown skin (70.7%) and were from favored economic class (89.7%). Dental caries, gingivitis, malocclusion and dental anomalies were more prevalent in the MPS group (p < 0.05).

CONCLUSION

The individuals with MPS had a higher prevalence of oral diseases and dental anomalies than the group without MPS.

Otorhinolaryngological Management in Taiwanese Patients with Mucopolysaccharidoses

Background: Mucopolysaccharidoses (MPSs) are lysosomal storage disorders wherein glycosaminoglycans accumulate because the enzymes that degrade them are insufficient. The earliest symptoms, which are the main reasons for seeking consultation, are otorhinolaryngological and commonly occur in MPS I, II, IV, and VI. This retrospective study aimed to determine the occurrence of otorhinolaryngological manifestations in MPS patients in Taiwan and to analyze the prognosis of surgical intervention, including its effect on symptoms. Methods: We reviewed 42 patients (30 males and 12 females), with a median age of 20.5 years, who had MPS (16.7% type I, 35.7% type II, 19.0% type IIIB, 21.4% type IVA, and 7.2% type VI). The following otorhinolaryngological manifestations were collected: annual number of upper respiratory tract infections (URTIs) and otitis media with effusion (OME) episodes, adenoid size, tonsillar size, and apnea-hypopnea index (AHI). Results: Among 42 patients, we found recurrent otitis media in 42.9% of the patients, hearing loss in 83.3% (mixed: 52.4%, conductive: 21.4%, and sensorineural: 9.5%), frequent URTIs in 47.6%, and obstructive sleep apnea syndrome in 35.7%. Moreover, 76% of the patients underwent ear, nose, and throat (ENT) surgery, including adenoidectomy, tonsillectomy, tympanostomy with ventilation tube insertion, tracheotomy, and supraglottoplasty. Conclusions: MPS patients had a high incidence of ENT problems. ENT surgery reduced the severity of hearing loss, degree of symptoms related to upper airway obstruction, and severity of respiratory tract and otological infections of patients with MPS.

The abnormal accumulation of heparan sulfate in patients with mucopolysaccharidosis prevents the elastolytic activity of cathepsin V

Mucopolysaccharidosis (MPS) are rare inherited diseases characterized by accumulation of lysosomal glycosaminoglycans, including heparan sulfate (HS). Patients exhibit progressive multi-visceral dysfunction and shortened lifespan mainly due to a severe cardiac/respiratory decline. Cathepsin V (CatV) is a potent elastolytic protease implicated in extracellular matrix (ECM) remodeling. Whether CatV is inactivated by HS in lungs from MPS patients remained unknown. Herein, CatV colocalized with HS in MPS bronchial epithelial cells. HS level correlated positively with the severity of respiratory symptoms and negatively to the overall endopeptidase activity of cysteine cathepsins. HS bound tightly to CatV and impaired its activity. Withdrawal of HS by glycosidases preserved exogenous CatV activity, while addition of Surfen, a HS antagonist, restored elastolytic CatV-like activity in MPS samples. Our data suggest that the pathophysiological accumulation of HS may be deleterious for CatV-mediated ECM remodeling and for lung tissue homeostasis, thus contributing to respiratory disorders associated to MPS diseases.

Challenging behavior in mucopolysaccharidoses types I-III and day-to-day coping strategies: a cross sectional explorative study

BACKGROUND

Challenging behavior represents a core symptom in neuropathological mucopolysaccharidoses (MPS) and puts major strain on affected families. Although multimodal approaches including behavioral strategies to treatment could be valuable, there is lack of research to the effectiveness of specific measures. This explorative, cross-sectional study is aimed at the collection of parental experiences regarding effective day-to-day measures against challenging behavior in MPS and focuses on 4 major research questions: First: What is challenging behavior in MPS? Second: Which strategies are helpful in the day-to-day coping with challenging behavior? Third: How strong is parental acceptance of illness and the disorder's impact on family relationships? Fourth: What are beneficial personal and interfamilial strategies for generally coping with the disorder?

METHODS

A semi structured questionnaire was designed de novo in cooperation with affected families. 37/268 questionnaires were returned (rate: 13.8%), of which 34 (MPS I: n = 8, MPS II: n = 8; MPS III: n = 18) could be included in data analysis in accordance with inclusion criteria. Assessment of challenging symptoms was based on perceived frequency, parent- and child stress. Exploration of possible coping strategies for challenging behavior and general illness-related strain included the evaluation of perceived effectiveness. Questionnaires were completed by patient's relatives and analyzed for strategies to cope with challenging behavior and the disorder's impact. STROBE criteria were respected.

RESULTS

MPS I was reported to show lower frequency and better perceived manageability of challenging behavior than MPS II and -III. Sleep disturbance, hyperactivity, agitation, aggression and orality seemed relevant symptoms regarding frequency and/or parent stress. Reported measures were manifold, worthwhile approaches against challenging behavior appeared to be aiming at distraction, relief and environmental changes. Medication and non-medication approaches were rated similarly effective. Social exchange, private space and networking with other affected families seemed highly important for personal and interfamilial well-being.

CONCLUSIONS

Multimodal mentoring for affected families could be based on the following equivalent pillars: (1) Medication therapy for challenging behavior including evaluation of cost and benefit (2) Guided implementation and re-evaluation of specific behavioral measures against challenging behavior. (3) Psychosocial support of MPS-families, including options for strengthening parental well-being and family functioning. Trial registration This study was registered at clinicaltrials.gov prior to study start (NCT-Number: NCT03161171, Date: 2017/05/19).

Improvement in functional gait parameters following corrective thoracolumbar surgery in children affected by Mucopolysaccharidosis 1 (Hurler syndrome)

OBJECTIVE

Thoracolumbar kyphosis is a common indication for spinal surgery in children with Mucopolysaccharidosis. Functional outcome of spinal surgical intervention has never been published in patients with this rare disease. We present a cohort of patients with Mucopolysaccharidosis 1(Hurler syndrome) who underwent thoraco-lumbar spinal deformity correction and functional outcome assessed by pre-operative and post-operative gait analysis. This study represents the first attempt at presenting a functional assessment of surgical outcome in any Mucopolysaccharidosis subtype.

METHODS

A retrospective analysis of prospectively collected data was carried out from 11 children diagnosed with this subtype of Mucopolysaccharidosis. All patients underwent thoracolumbar kyphosis correction between the years 2013 to 2016. Gait assessment was performed using GAITRite™ electronic walkway pre-operatively and post-operatively within 9 to 24 months from the index surgery. Walking distance, cadence and gait velocity were the three spatio-temporal parameters analysed. Wilcoxon signed rank test was used to analyse the data and P-Value ≤0.05 was deemed significant.

RESULTS

There was a statistically significant improvement in walking distance in 9 out of 11 patient post-operatively with a mean increase of 232.06 cms (P = 0.05). There was marginal improvement in cadence by 6.33 steps/min post-operatively (P-value 0.79). Gait velocity also showed a marginal increase by 8.73 cms/sec post-operatively (P-value 0.32).

CONCLUSION

The results of our study suggest that correction of thoracolumbar kyphosis in children with Mucopolysaccharidosis 1 resulted in a significant improvement of walking distance with a trend towards improved gait in the other parameters. Post-operative change in cadence was not statistically significant suggesting that physiological maturation of gait had minimal effect in the specified post-operative assessment timeframe. This study emphasizes that outcomes of spinal surgery in children with Mucopolysaccharidosis 1 should be determined by functional measures aiming to maintain or improve quality of life.

Mucopolysaccharidosis Type I

Mucopolysaccharidosis type I (MPS I) is caused by the deficiency of α-l-iduronidase, leading to the storage of dermatan and heparan sulfate. There is a broad phenotypical spectrum with the presence or absence of neurological impairment. The classical form is known as Hurler syndrome, the intermediate form as Hurler-Scheie, and the most attenuated form is known as Scheie syndrome. Phenotype seems to be largely influenced by genotype. Patients usually develop several somatic symptoms such as abdominal hernias, extensive dermal melanocytosis, thoracolumbar kyphosis odontoid dysplasia, arthropathy, coxa valga and genu valgum, coarse facial features, respiratory and cardiac impairment. The diagnosis is based on the quantification of α-l-iduronidase coupled with glycosaminoglycan analysis and gene sequencing. Guidelines for treatment recommend hematopoietic stem cell transplantation for young Hurler patients (usually at less than 30 months of age). Intravenous enzyme replacement is approved and is the standard of care for attenuated-Hurler-Scheie and Scheie-forms (without cognitive impairment) and for the late-diagnosed severe-Hurler-cases. Intrathecal enzyme replacement therapy is under evaluation, but it seems to be safe and effective. Other therapeutic approaches such as gene therapy, gene editing, stop codon read through, and therapy with small molecules are under development. Newborn screening is now allowing the early identification of MPS I patients, who can then be treated within their first days of life, potentially leading to a dramatic change in the disease's progression. Supportive care is very important to improve quality of life and might include several surgeries throughout the life course.

Respiratory Dysfunction in Children and Adolescents with Mucopolysaccharidosis Types I, II, IVA, and VI

Mucopolysaccharidosis (MPS) is a rare genetic disease involving active storage of glycosaminoglycans (GAGs). Accumulation of GAGs in the connective tissues of airways leads to progressive pulmonary dysfunction. Studies conducted in Taiwan revealed mainly restrictive pulmonary dysfunction, whereas the same studies in Egypt and California revealed obstructive pulmonary dysfunction. The contradictory results and lack of studies of respiratory system in patients with MPS in Asian populations are an indication to study pulmonary impairment in patients with MPS in Kazakhstan. The prospective study of respiratory system in patients with MPS was conducted in the Scientific Centre of Paediatrics and Paediatric Surgery. Patients with MPS (n = 11) were examined for respiratory function. Different types of pulmonary dysfunction were present in MPS patients, they were mainly of a restrictive pathology. One patient with MPS II had obstructive dysfunction. Enzyme replacement therapy was provided for an average duration of four years, leading to improvements in respiratory function in two patients with total normalization in one. All observed patients had respiratory dysfunction, mainly of the restrictive type. Pulmonary impairment in patients with MPS is the main reason for death. Thus, it is necessary to follow up with pulmonary function assessments in children with MPS.

Respiratory complications of metabolic disease in the paediatric population: A review of presentation, diagnosis and therapeutic options

Inborn errors of metabolism (IEMs) whilst individually rare, as a group constitute a field which is increasingly demands on pulmonologists. With the advent of new therapies such as enzyme replacement and gene therapy, early diagnosis and treatment of these conditions can impact on long term outcome, making their timely recognition and appropriate investigation increasingly important. Conversely, with improved treatment, survival of these patients is increasing, with the emergence of previously unknown respiratory phenotypes. It is thus important that pulmonologists are aware of and appropriately monitor and manage these complications. This review aims to highlight the respiratory manifestations which can occur. It isdivided into conditions resulting primarily in obstructive airway and lung disease, restrictive lung disease such as interstitial lung disease or pulmonary alveolar proteinosis and pulmonary hypertension, whilst acknowledging that some diseases have the potential to cause all three. The review focuses on general phenotypes of IEMs, their known respiratory complications and the basic metabolic investigations which should be performed where an IEM is suspected.

Mucopolysaccharidosis type II (Hunter syndrome): Clinical and biochemical aspects of the disease and approaches to its diagnosis and treatment

Mucopolysaccharidosis type II (MPS II, Hunter syndrome) is a rare X-linked lysosomal storage disease caused by mutations of the gene encoding the lysosomal enzyme iduronate-2-sulfatase (IDS), the role of which is to hydrolytically remove O-linked sulfates from the two glycosaminoglycans (GAGs) heparan sulfate (HS) and dermatan sulfate (DS). HS and DS are linear, heterogeneous polysaccharides composed of repeating disaccharide subunits of l-iduronic acid (IdoA) or d-glucuronic acid, (1→4)-linked to d-glucosamine (for HS), or (1→3)-linked to 2-acetamido-2-deoxy-d-galactose (N-acetyl-d-galactosamine) (for DS). In healthy cells, IDS cleaves the sulfo group found at the C-2 position of terminal non-reducing end IdoA residues in HS and DS. The loss of IDS enzyme activity leads to progressive lysosomal storage of HS and DS in tissues and organs such as the brain, liver, spleen, heart, bone, joints and airways. Consequently, this leads to the phenotypic features characteristic of the disease. This review provides an overview of the disease profile and clinical manifestation, with a particular focus on the biochemical basis of the disease and chemical approaches to the development of new diagnostics, as well as discussing current treatment options and emerging new therapies.

ENT and mucopolysaccharidoses

The mucopolysaccharidoses (MPS) are a heterogeneous group of inherited metabolic disorders, each associated with a deficiency in one of the enzymes involved in glycosaminoglycan (GAG) catabolism. Over time, GAGs accumulate in cells and tissues causing progressive damage, a variety of multi-organ clinical manifestations, and premature death. Ear, nose, and throat (ENT) disorders affect more than 90% of MPS patients and appear in the early stage of MPS; also reported are recurrent otitis media and persistent otitis media with effusion, macroglossia, adenotonsillar hypertrophy, nasal obstruction, obstructive sleep apnoea syndrome (OSAS), hearing loss, and progressive respiratory disorders. Undiagnosed MPS patients are frequently referred to otolaryngologists before the diagnosis of MPS is confirmed. Otolaryngologists thus have an early opportunity to recognize MPS and they can play an increasingly integral role in the multidisciplinary approach to the diagnosis and management of many children with MPS. The ENT commitment is therefore to suspect MPS when non-specific ENT pathologies are associated with repeated surgical treatments, unexplainable worsening of diseases despite correct treatment, and with signs, symptoms, and pathological conditions such as hepatomegaly, inguinal hernia, macrocephaly, macroglossia, coarse facial features, hydrocephalous, joint stiffness, bone deformities, valvular cardiomyopathy, carpal tunnel syndrome, and posture and visual disorders.

Sleep-disordered breathing in paediatric setting: existing and upcoming of the genetic disorders

Childhood obstructive sleep apnea syndrome (OSAS) is characterized by anatomical and functional upper airway abnormalities as pathophysiological determinants, and clinical symptoms are frequently clear. OSAS is widely described in rare genetic disorders, such as achondroplasia, Down syndrome, Prader-Willi syndrome, Pierre Robin sequence, and mucopolysaccharidosis. Craniofacial and upper airway involvement is frequently morbid conditions. In children with genetic diseases, the clinical symptoms of OSAS are often slight or absent, and related morbidities are usually more severe and can be observed at any age. The present review is aimed to updating the discoveries regarding OSAS on Achondroplasia, Down syndrome, Prader-Willi syndrome, Pierre Robin sequence, Sickle cell disease, or encountered in our clinical practice (Ehlers-Danlos syndrome, Ellis-van Creveld syndrome, Noonan syndrome). Two additional groups of genetic disorders will be focused (mucopolysaccharidoses and osteogenesis imperfecta). The flowing items are covered for each disease: (I) what is the pathophysiology of OSAS? (II) What is the incidence/prevalence of OSAS? (III) What result from the management and prognosis? (IV) What are the recommendations? Considering the worries of OSAS, such as inattention and behavioural problems, daytime sleepiness, failure to thrive, cardiological and metabolic complications, the benefit of a widespread screening and the treatment in children with genetic diseases is undoubtful. The goals of the further efforts can be the inclusion of various genetic diseases into guidelines for the screening of OSAS, updating the shreds of evidence based on the research progression.

Mucopolysaccharidosis VI and effects on growth of the apical bases: a case report

OBJECTIVE

Mucopolysaccharidosis (MPS) VI is a rare disorder caused by an autosomal recessive mutation in the short arm of chromosome 5 (5q12-13) leading to an N-acetylgalactosamine-sulfatase lysosomal enzyme deficiency and numerous systemic clinical changes. The oral and maxillofacial complex may exhibit tooth eruption anomalies, macroglossia, gingival hypertrophy, mouth breathing, increased lower facial height, open bite, retrognathia, and progressive TMJ arthrosis. This report describes craniofacial growth changes in two MPS VI patients, sisters and daughters of outbred parents, who were longitudinally monitored from 11 to 15 years of age.

STUDY DESIGN

Skull lateral teleradiography and cephalometric tracings were performed. The measurements were assessed in the anteroposterior and vertical directions based on protocols by McNamara and Usp/Unicamp and compared to the normal reported ranges.

RESULTS

A similar skeletal class III malocclusion was observed in both patients. The jaw was retruded, the anterior skull base decreased, and the mandibular body was normal or larger than normal. The vertical growth direction differed between the patients; one was hyperdivergent, while the other was hypodivergent.

CONCLUSIONS

By understanding the craniofacial growth changes in MPS VI patients, new treatment options may be developed for affected patients.

Pathophysiology, evaluation, and management of sleep disorders in the mucopolysaccharidoses

The mucopolysaccharidoses (MPS) represent a heterogeneous group of lysosomal storage disorders, each one associated with a deficiency in one of the enzymes involved in glycosaminoglycan degradation. Sleep disorders are a frequent manifestation of all types of MPS. Underlying causes are diverse and comprised of both respiratory and central nervous system (CNS) abnormalities. Sleep disordered breathing such as obstructive sleep apnea and nocturnal hypoventilation can arise in patients with upper airway obstruction and/or with alterations in respiratory mechanics, causing restrictive pulmonary disease. MPS patients with CNS disease can also develop sleep disturbances unrelated to ventilatory impairments, often associated with severe behavioral problems or night-time epileptic seizures. The present review discusses the pathophysiology, evaluation, and management of sleep disorders in MPS based on information from a meeting on the brain in MPS, attended by an international group of experts (April 28-30, 2016, Stockholm, Sweden), and additional literature searches.

Practical management of behavioral problems in mucopolysaccharidoses disorders

The mucopolysaccharidosis (MPS) disorders are caused by deficiencies of specific lysosomal enzymes, resulting in progressive glycosaminoglycan (GAG) accumulation in cells and tissues throughout the body. Excessive GAG storage can lead to a variety of somatic manifestations as well as primary and secondary neurological symptoms. Behavioral problems (like hyperactivity, attention difficulties, and severe frustration) and sleeping problems are typical primary neurological symptoms of MPS caused by GAG accumulation in neurons, and are frequently observed in patients with MPS I, II, III, and VII. As these problems often place a significant burden on the family, proper management is important. This review summarizes current insights into behavioral and sleeping problems in MPS disorders and the most optimal management approaches, as presented and discussed during a meeting of an international group of experts with extensive experience in managing and treating MPS.

Sleep Disorders in Childhood Neurogenetic Disorders

enetic advances in the past three decades have transformed our understanding and treatment of many human diseases including neurogenetic disorders. Most neurogenetic disorders can be classified as "rare disease," but collectively neurogenetic disorders are not rare and are commonly encountered in general pediatric practice. The authors decided to select eight relatively well-known neurogenetic disorders including Down syndrome, Angelman syndrome, Prader-Willi syndrome, Smith-Magenis syndrome, congenital central hypoventilation syndrome, achondroplasia, mucopolysaccharidoses, and Duchenne muscular dystrophy. Each disorder is presented in the following format: overview, clinical characteristics, developmental aspects, associated sleep disorders, management and research/future directions.

Presentation and Treatments for Mucopolysaccharidosis Type II (MPS II; Hunter Syndrome)

INTRODUCTION

Mucopolysaccharidosis Type II (MPS II; Hunter syndrome) is an X- linked lysosomal storage disorder caused by a deficiency of iduronate-2-sulfatase (IDS). IDS deficiency leads to primary accumulation of dermatan sulfate (DS) and heparan sulfate (HS). MPS II is both multi-systemic and progressive. Phenotypes are classified as either attenuated or severe (based on absence or presence of central nervous system impairment, respectively).

AREAS COVERED

Current treatments available are intravenous enzyme replacement therapy (ERT), hematopoietic stem cell transplantation (HSCT), anti-inflammatory treatment, and palliative care with symptomatic surgeries. Clinical trials are being conducted for intrathecal ERT and gene therapy is under pre-clinical investigation. Treatment approaches differ based on age, clinical severity, prognosis, availability and feasibility of therapy, and health insurance.This review provides a historical account of MPS II treatment as well as treatment development with insights into benefits and/or limitations of each specific treatment.

EXPERT OPINION

Conventional ERT and HSCT coupled with surgical intervention and palliative therapy are currently the treatment options available to MPS II patients. Intrathecal ERT and gene therapy are currently under investigation as future therapies. These investigative treatments are critical to address the limitations in treatment of the central nervous system (CNS).

Impact of long-term elosulfase alfa treatment on respiratory function in patients with Morquio A syndrome

OBJECTIVE

To present long-term respiratory function outcomes from an open-label, multi-center, phase 3 extension study (MOR-005) of elosulfase alfa enzyme replacement therapy (ERT) in patients with Morquio A syndrome.

METHODS

In part 1 of MOR-005, patients initially randomized to ERT in the 24-week pivotal study (MOR-004) remained on their regimen (2.0 mg/kg/week or every other week); placebo patients were re-randomized to one of the two regimens. During part 2, all patients received elosulfase alfa 2.0 mg/kg/week. Respiratory function was one of the efficacy endpoints evaluated in MOR-005. Change from MOR-004 baseline to 120 weeks of treatment for the combined population was determined and compared with results from untreated patients from a Morquio A natural history study (MorCAP).

RESULTS

Maximum voluntary ventilation (MVV) improved up to week 72 and then stabilized; forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV₁) increased continuously over 120 weeks. Mean increases in the modified per-protocol population was 9.2 % for FVC, 8.8 % for FEV₁, and 6.1 % for MVV after 120 weeks. All patients ≤14 years showed respiratory improvements, presumably in part related to growth; however, these were greater in treated patients. For those >14 years, treated patients showed improvements, while deterioration occurred in untreated. Altogether, the improvements were significantly greater (P < 0.05) in treated patients.

CONCLUSIONS

Long-term ERT is associated with sustained improvements in respiratory function in Morquio A. In younger patients (≤14 years), some improvement may be ascribed to growth. In older patients, other mechanisms, e.g., decreased glycosaminoglycan storage, are likely involved.

Unique medical issues in adult patients with mucopolysaccharidoses

The mucopolysaccharidoses are a group of inherited metabolic diseases caused by deficiencies in enzymes involved in the sequential degradation of glycosaminoglycans (GAGs) leading to substrate accumulation in various tissues and organs. GAG accumulation can cause growth retardation and progressive damage to respiratory, cardiovascular, musculoskeletal, nervous, gastrointestinal, auditory, and visual systems. In the past, few people with severe phenotypic mucopolysaccharidosis (MPS) reached adulthood. However, better methods for diagnosis, multi-disciplinary care, and new therapies have extended lifespan, leading to an increasing number of patients surviving beyond childhood. The growing number of adult MPS patients poses significant challenges for clinicians who may not be familiar with the clinical manifestations of MPS. In addition, as new interventions have changed the natural history of these disorders, it is difficult to anticipate both the impact on life expectancy and other complications that may occur as these patients age. Because the MPS disorders are multi-organ diseases, their management requires a coordinated multi-disciplinary approach. Here we discuss the unique pattern of medical issues and multi-organ involvement in adult patients with MPS and identify the challenges that are associated with management of MPS. This review is based on information from an expert investigator meeting with MPS specialists held October 2-4, 2014 in Dublin, Ireland, as well as on current literature searches focusing on MPS and adults.

The impact of laronidase treatment in otolaryngological manifestations of patients with mucopolysaccharidosis

INTRODUCTION

Mucopolysaccharidosis (MPS) is a lysosomal storage disease caused by deficiency of α-l-iduronidase. The otolaryngological findings include hearing loss, otorrhea, recurrent otitis, hypertrophy of tonsils and adenoid, recurrent rhinosinusitis, speech disorders, snoring, oral breathing and nasal obstruction.

OBJECTIVE

To evaluate the impact of enzymatic replacement therapy with laronidase (Aldurazyme(®)) in patients with mucopolysaccharidosis (MPS I), regarding sleep and hearing disorders, and clinical manifestations in the upper respiratory tract (URT).

METHODS

Nine patients with MPS I (8 Hurler-Scheie, and 1 Scheie phenotypes) of both sexes, ages ranging between 3 and 20 years, were included in this study. Patients were evaluated between seven and 11 months before the treatment and between 16 and 22 months after the onset of the enzymatic replacement. They were all submitted to a clinical and otolaryngological evaluation, including nasofibroscopical, polysomnographic and audiologic exams.

RESULTS

The results' data showed decreasing of the frequency of ear, nose and throat infections, with improvement of the rhinorrhea and respiratory quality. No remarkable changes were observed regarding macroglossia and tonsil and adenoid hypertrophy. Audiometric and polysomnographic evaluations did not show statistical significance.

CONCLUSION

Enzymatic replacement therapy in patients with mucopolysaccharidosis I provides control of recurrent URT infections, rhinorrhea and respiratory quality, however it is does not seem to improve audiologic and polisomnographic parameters, with no effect on adenoid and tonsils hypertrophy and macroglossia.

Correlation Between Flexible Fiberoptic Laryngoscopic and Polysomnographic Findings in Patients with Mucopolysaccharidosis Type VI

This study aimed to compare flexible fiberoptic laryngoscopy (FFL) and polysomnography (PSG) findings in patients with mucopolysaccharidosis (MPS) type VI and to describe upper airway anatomical findings and abnormal PSG results in these patients. In this cross-sectional study, all MPS VI patients followed up at the genetic division of a hospital in southern Brazil were included. Overnight PSG was performed, and the results were classified as normal or mildly, moderately, or severely abnormal. FFL was performed between 7 days before and 7 days after PSG. FFL findings were classified as (1) no obstruction, (2) mild obstruction, (3) moderate obstruction, or (4) severe obstruction of the airways, using the highest score obtained in all the regions.Eleven patients with MPS VI were included. FFL detected severe airway obstruction in eight (72.7%) patients, moderate obstruction in two (18.2%), and mild obstruction in one (9.1%). PSG revealed obstructive sleep apnea syndrome (OSAS) in nine (81.8%) patients. Among these, mild OSAS was observed in five (45.5%) patients, moderate OSAS in three (27.2%), and severe OSAS in one (9.1%). Moderate to severe hypertrophy of the nasal turbinates was found in 81.8% of the patients, and 64% had severe infiltration in the supraglottic region. There was no association between FFL and PSG findings (p = 0.454; κ = -0.09; 95%CI = -0.34 to 0.17), indicating no agreement between the two methods. In the present study, all patients with MPS showed some degree of airway obstruction. We suggest performing PSG in MPS patients to determine disease severity.

Sleep disordered breathing in mucopolysaccharidosis I: a multivariate analysis of patient, therapeutic and metabolic correlators modifying long term clinical outcome

Background

The lysosomal storage disorder, mucopolysaccharidosis I (MPS I), commonly manifests with upper airway obstruction and sleep disordered breathing (SDB). The success of current therapies, including haematopoietic stem cell transplantation (HSCT) and enzyme replacement therapy (ERT) may be influenced by a number of factors and monitored using biomarkers of metabolic correction. We describe the pattern of SDB seen in the largest MPS I cohort described to date and determine therapies and biomarkers influencing the severity of long-term airway disease.

Methods

Therapeutic, clinical and biomarker data, including longitudinal outcome parameters from 150 sleep oximetry studies were collected in 61 MPS I (44 Hurler, 17 attenuated) patients between 6 months pre to 16 years post-treatment (median follow-up 22 months). The presence and functional nature of an immune response to ERT was determined using ELISA and a cellular uptake inhibition assay. Multivariate analysis was performed to determine significant correlators of airway disease.

Results

The incidence of SDB in our cohort is 68%, while 16% require therapeutic intervention for airway obstruction. A greater rate of progression (73%) and requirement for intervention is seen amongst ERT patients in contrast to HSCT treated individuals (24%). Multivariate analysis identifies poorer metabolic clearance, as measured by a rise in the biomarker urinary dermatan sulphate: chondroitin sulphate (DS:CS) ratio, as a significant correlator of increased presence and severity of SDB in MPS I patients (p = 0.0017, 0.008). Amongst transplanted Hurler patients, delivered enzyme (leukocyte iduronidase) at one year is significantly raised in those without SDB (p = 0.004). Cellular uptake inhibitory antibodies in ERT treated patients correlate with reduced substrate clearance and occurrence of severe SDB (p = 0.001).

Conclusion

We have identified biochemical and therapeutic factors modifying airway disease across the phenotypic spectrum in MPS I. Interventions maximising substrate reduction correlate with improved long-term SDB, while inhibitory antibodies impact on biochemical and clinical outcomes. Monitoring and tolerisation strategies should be re-evaluated to improve detection and minimise the inhibitory antibody response to ERT in MPS I and other lysosomal storage diseases. Future studies should consider the use of sleep disordered breathing as an objective parameter of clinical and metabolic improvement.

[Obstructive sleep apnea-hypopnea syndrome in children: beyond adenotonsillar hypertrophy]

The prevalence of obstructive sleep apnea-hypopnea syndrome in the general childhood population is 1-2% and the most common cause is adenotonsillar hypertrophy. However, beyond adenotonsillar hypertrophy, there are other highly prevalent causes of this syndrome in children. The causes are often multifactorial and include muscular hypotonia, dentofacial abnormalities, soft tissue hypertrophy of the airway, and neurological disorders). Collaboration between different specialties involved in the care of these children is essential, given the wide variability of conditions and how frequently different factors are involved in their genesis, as well as the different treatments to be applied. We carried out a wide literature review of other causes of obstructive sleep apnea-hypopnea syndrome in children, beyond adenotonsillar hypertrophy. We organised the prevalence of this syndrome in each pathology and the reasons that cause it, as well as their interactions and management, in a consistent manner.

Mucopolysaccharidosis: Otolaryngologic findings, obstructive sleep apnea and accumulation of glucosaminoglycans in lymphatic tissue of the upper airway

OBJECTIVE

The aim of this study is to evaluate otolaryngologic problems (upper airway obstruction, obstructive sleep apnea, restriction of mouth opening, middle ear effusion, hearing and breathing problems) and their treatments on mucopolysaccharidoses (MPS) patients and to investigate accumulation of glucosaminoglycans (GAG) in the upper airway biochemically and pathologically.

METHODS

76 MPS patients were evaluated. Forty-two MPS patients underwent polysomnography (PSG) for obstructive sleep apnea (OSA). Pre- and postoperative PSG results of 18 patients were compared. The success and complications of treatments for OSA in MPS were evaluated. Biochemical and histopathological accumulation of GAG in tonsil and adenoid tissue and middle ear effusion were analyzed and compared with the control group.

RESULTS

Forty patients out of 42 tested with PSG had OSA (95%). Adenoid grade, Mallampati grade, restricted mouth opening, rate of difficult intubation were significantly different among MPS subtypes. MPS types III and IV had significantly lower Mallampati scores; type VI had significantly worse mouth opening; and type III had significantly better mouth opening and higher rate of easy intubation when compared to other MPS types. There was no significant difference between MPS subtypes according to tonsil grade, adenoid grade, rate of otitis media with effusion and OSA severity. Statistically significant difference was found between GAG accumulation in adenoid tissue and middle ear effusion of MPS and control group (p<0.05). However, GAG accumulation in tonsil was not significantly different between MPS and control group. There was a statistically significant improvement in postop Apnea-Hypopnea Index (AHI) compared to preop AHI (p<0.05).

CONCLUSIONS

Most MPS patients have airway obstruction and OSA due to adenotonsillar hypertrophy. Most of these children benefit from adenotonsillectomy, after which OSA significantly improves. They experience high recurrence rate after adenoidectomy; though this is not clinically problematic. They also suffer from conductive hearing loss due to OME, which has to be treated with ventilation tube insertion. However, such operations are usually complicated by difficult endotracheal intubation and restricted mouth opening. Sometimes tracheotomy may be necessary. Tracheotomy is also highly complicated in MPS patients. Significant accumulation of GAG in middle ear fluid and adenoid tissue is present; however, GAG appears not to accumulate in tonsillar tissue.

Pediatric polysomnography for sleep-disordered breathing prior to tonsillectomy: a guideline review

Snoring and other signs of sleep-disordered breathing (SDB) represent a common management challenge for the pediatrician, pulmonologist, anesthesiologist, and otolaryngologist. In 2011, the American Academy of Otolaryngology-Head and Neck Surgery published a clinical practice guideline for the treatment of patients with SDB. This guideline provides indications for polysomnography use in patients with SDB. In this article, we discuss the management of SDB in pediatric patients, which relies on the accurate assessment of symptoms of SDB, identification of comorbidities known to increase the severity of SDB, and appropriate preoperative assessment of the patient.

Tracheostomy in mucopolysaccharidosis type II (Hunter's Syndrome)

OBJECTIVE

Patients with mucopolysaccharidosis type II (MPS II) may develop progressive multi-level upper airway obstruction. Despite the unique challenges presented by these complex patients, tracheostomy remains an important intervention to safeguard the airway when other interventions have failed or when the airway obstruction involves multiple sites. Airway involvement is largely responsible for the significant anaesthetic risk seen in MPS II. We reviewed our tertiary unit's experience of tracheostomies in patients with MPS II.

STUDY DESIGN

Retrospective study.

METHODS

Case note review of MPS II patients requiring tracheostomy at our tertiary institution. The primary outcome measure used for this study was complications following tracheostomy.

RESULTS

We identified 10 MPS II patients requiring tracheostomy to manage upper airway obstruction. Mean age at which tracheostomy was 11 years 2 months (range 4 years 6 months to 28 years 10 months). Tracheostomy insertion was indicated in 3 scenarios: (1) to safeguard an anticipated difficult airway prior to a planned non-ENT surgical procedure, (2) to treat refractory progressive upper airway obstruction and (3) emergency airway management. Complications recorded included infratip and suprastomal granulations, local wound infection and skin ulceration from mechanical trauma. There were no immediate postoperative complications.

CONCLUSIONS

Progressive upper airway obstruction is common in children with MPS II. Tracheostomy is an effective way of managing airway obstruction when less invasive interventions are no longer adequate. Tracheostomy in these patients can be technically difficult and although the complications of tracheostomy in MPS II do not significantly differ from other patient groups, the implications and management complexity vary considerably. The impact of ERT on airway obstruction is not yet fully understood, with tracheostomies likely to remain an important airway adjunct in some patients who fail to respond to ERT, or in those patients surviving into adulthood. It is vital that a multidisciplinary team, comprising clinicians with experience in managing such patients, are involved in airway management of patients with MPS II to enable the best standard of care to be given. The significant additional implications of a tracheostomy in a patient with MPS II, in terms of safety, aftercare and potentially life-threatening complications must be discussed in detail with the patient's family and/or carers.

LEVEL OF EVIDENCE

2c.

Relationship of sleep to pulmonary function in mucopolysaccharidosis II

OBJECTIVE

To study the sleep characteristics, pulmonary function, and their relationships in an enzyme naive population of patients with mucopolysaccharidoses (MPS) II (Hunter syndrome).

STUDY DESIGN

The analyzed subjects (30 patients with MPS II with a median age of 9 years) had been enrolled in an MPS II natural history study and a phase I/II enzyme replacement clinical study in which they underwent standard polysomnography including spirometry and plethysmography, if cooperative. Descriptive statistics and nonparametric correlation were performed for demographic, sleep, and pulmonary function variables.

RESULTS

Median apnea-hypopnea index was 6.4, with obstructive sleep apnea observed in 27/30 subjects. Sleep architecture was characterized by diminished rapid-eye movement sleep duration (median 13%), and decline in sleep efficiency and slow-wave sleep duration in older individuals. Oxygen desaturation below 90% occurred in 26/30 subjects, and hypoventilation above 50 Torr occurred in 11/23 subjects with accurate end-tidal carbon dioxide recordings. Of 15 subjects with reliable spirometry, median forced expiratory volume in 1 second was below 80% predicted in 12/15 subjects. Forced expiratory volume in 1 second in percent-predicted was inversely related to apnea-hypopnea index and increase from baseline end-tidal carbon dioxide (P=.023, rs=-0.58), (P<.001, rs=-0.82).

CONCLUSION

Sleep in MPS II is characterized by obstructive sleep apnea, altered sleep architecture, and impaired gas exchange. Sleep disruption is related to daytime pulmonary function, thus both systems should be evaluated when sleep abnormalities are suspected.

Home sleep study characteristics in patients with mucopolysaccharidosis

BACKGROUND

Mucopolysaccharidoses (MPS) are a group of inherited lysosomal storage disorders caused by the deficiency of hydrolases involved in the degradative pathway of glycosaminoglycans. In MPS, upper airway obstruction may result from multiple causative factors which may impact severely upon morbidity and mortality.

METHODS

We evaluated upper airway obstructive disease and related clinical findings through home sleep study in 19 patients (11 with MPS VI, 4 with MPS I, 4 with MPS II) with MPS followed at Gazi University Pediatric Metabolic Unit. Patients underwent home-based sleep measurements, and sleep respiratory problems were asked in a detailed clinical history. Measurements of apnea, apnea-hypopnea index (AHI), hypopnea index, oxygen desaturation index, and minimal oxygen saturation were obtained through home sleep study.

RESULTS

For 19 children, the disorder was normal in 1, mild (AHI=1.5-5/h) in 5, moderate (AHI=5-10/h) in 2, and severe (AHI>10/h) in 11. The prevalence of OSA was 94.7 % (18/19) in patients with MPS. Snoring, witnessed apnea, pectus carinatum, and macroglossia were the main clinical findings. Echocardiograms showed evidence of pulmonary hypertension in 13 patients.

CONCLUSION

Home sleep study is a quick and accessible screening test to determine the abnormalities of breathing during sleep and enables clinicians to take necessary action for patients with severe manifestations.

Up to five years experience with 11 mucopolysaccharidosis type VI patients

Maroteaux-Lamy syndrome (mucopolysaccharidosis type VI, MPS VI) is a rare progressive metabolic disorder characterized by coarse facial features, hepatosplenomegaly, restrictive pulmonary function, cardiac abnormalities and stiff joints. The disease is caused by a deficiency of the lysosomal enzyme N-acetyl galactosamine 4-sulfatase which leads to glycosaminoglycan (GAG) storage in various tissues. It presents as a clinical spectrum with varying disease progressions and severities. While the phases I/II/III studies proved the effectiveness of enzyme-replacement therapy (ERT) with recombinant human arylsulfatase B, long-term data are still scarce. Over treatment periods ranging from 1.3 to 5.4 years, this prospective open-label follow-up study in 11 Dutch mucopolysaccharidosis type VI patients (age 2-18 years) showed that ERT had significant positive effects on cardiac-wall diameters (IVSd and LVMI), left and right shoulder flexions (p<0.001), liver size and spleen size (p<0.001), urinary GAG excretion (p<0.001), and the scales of quality of life (motor functioning and body functioning). ERT did not affect cardiac valve regurgitation or hearing function; HRQoL decreased slightly in two domains ('anxiety' and 'negative emotions'), and patients with the rapid and slow progressive forms of the disease differed with regard to baseline GAG excretion and GAG decrease during treatment. In conclusion, ERT had an effect on several clinical parameters. This effect was established in an open cohort of young mucopolysaccharidosis type VI patients.

Respiratory and sleep disorders in mucopolysaccharidosis

MPS encompasses a group of rare lysosomal storage disorders that are associated with the accumulation of glycosaminoglycans (GAG) in organs and tissues. This accumulation can lead to the progressive development of a variety of clinical manifestations. Ear, nose, throat (ENT) and respiratory problems are very common in patients with MPS and are often among the first symptoms to appear. Typical features of MPS include upper and lower airway obstruction and restrictive pulmonary disease, which can lead to chronic rhinosinusitis or chronic ear infections, recurrent upper and lower respiratory tract infections, obstructive sleep apnoea, impaired exercise tolerance, and respiratory failure. This review provides a detailed overview of the ENT and respiratory manifestations that can occur in patients with MPS and discusses the issues related to their evaluation and management.

Anaesthesia and airway management in mucopolysaccharidosis

This paper provides a detailed overview and discussion of anaesthesia in patients with mucopolysaccharidosis (MPS), the evaluation of risk factors in these patients and their anaesthetic management, including emergency airway issues. MPS represents a group of rare lysosomal storage disorders associated with an array of clinical manifestations. The high prevalence of airway obstruction and restrictive pulmonary disease in combination with cardiovascular manifestations poses a high anaesthetic risk to these patients. Typical anaesthetic problems include airway obstruction after induction or extubation, intubation difficulties or failure [can't intubate, can't ventilate (CICV)], possible emergency tracheostomy and cardiovascular and cervical spine issues. Because of the high anaesthetic risk, the benefits of a procedure in patients with MPS should always be balanced against the associated risks. Therefore, careful evaluation of anaesthetic risk factors should be made before the procedure, involving evaluation of airways and cardiorespiratory and cervical spine problems. In addition, information on the specific type of MPS, prior history of anaesthesia, presence of cervical instability and range of motion of the temporomandibular joint are important and may be pivotal to prevent complications during anaesthesia. Knowledge of these risk factors allows the anaesthetist to anticipate potential problems that may arise during or after the procedure. Anaesthesia in MPS patients should be preferably done by an experienced (paediatric) anaesthetist, supported by a multidisciplinary team (ear, nose, throat surgeon and intensive care team), with access to all necessary equipment and support.

Combined mucopolysaccharidosis type VI and congenital adrenal hyperplasia in a child: Anesthetic considerations

We present a child posted for magnetic resonance imaging of brain under general anesthesia with the rare combination of mucopolysachharidosis type VI and congenital adrenal hyperplasia. The presence of both these disorders has important anesthetic implications. The pathophysiology of this rare combination of disease is reviewed with emphasis on the anesthesia management.

Mucopolysaccharidosis type VI: a cardiologist's guide to diagnosis and treatment

Mucopolysaccharidosis type VI (MPS VI, Maroteaux-Lamy syndrome) is an inborn error of metabolism, with incidences at birth ranging from 1 in 1.5 million to 1 in 43,000 live births. This disorder is rarely considered when evaluating patients with common populational cardiovascular diseases. A significant number of MPS VI patients, however, do present cardiovascular disease and MPS VI should be considered as a potential differential diagnosis for other cardiovascular disorders. This article reviews the clinical features, diagnostic tests and treatment options for MPS VI. Although MPS VI affects many organs and systems of the human body this review focuses on MPS VI diseases of the heart and vessels. The most characteristic cardiac presentation of MPS VI is valvular disease, but heart failure, pulmonary hypertension, cardiomyopathy, fibroelastosis and cardiac conduction system disorders may also occur. Cardiovascular disease in MPS VI patients may emerge silently. An early diagnosis is difficult due to joint stiffness, respiratory system involvement or skeletal malformations that limit exercise capacity and mask the underlining heart failure. This article is supposed to serve as a very practical reference for cardiologists who may come across MPS VI in their daily practices. A greater awareness of cardiovascular manifestations of MPS VI among cardiologists can help to reduce misdiagnosis and promote early detection of this inborn disorder and aid the implementation of adequate therapy at the earliest stage possible which is crucial for its efficacy.

Successful noninvasive ventilation and enzyme replacement therapy in an adult patient with morbus hunter

M. Hunter is characterized by an accumulation of mucopolysaccharides in cells, blood, and connective tissue as a consequence of a deficiency of the enzyme iduronate-2-sulfatase. Unlike enzyme replacement therapy with idursulfase in children, there is limited long-term experience in adult patients with Morbus Hunter.The case presented here describes the development of a man born in 1971 who was admitted to Hemer Lung Clinic in 2005 with severe obstructive sleep apnea, pulmonary functional impairment, and ventilatory failure (FEV 1: 0.8 L, VC: 1.0 L; pO(2): 52 mmHg; pCO(2): 81 mmHg, 6 MWT: 100 m). Initially, the patient received symptomatic treatment with noninvasive ventilation, which achieved a considerable improvement in pulmonary function and a normalization of blood gasses. Since February 2008, the patient received additional enzyme replacement therapy with idursulfase, which resulted in a further significant functional improvement (FEV1: 1.6; VC: 2.3 L; VO(2)max: 1,350 mL or 28.1 mL/kg body weight), in a normalization of prior elevated pulmonary artery pressures and also in impressive changes in the physiognomy and joint mobility. In November 2010, the polysomnography and nocturnal blood gas analysis without NIV showed only a mild obstructive sleep-related breathing disorder with no sign of hypoventilation. Therapy was changed to nocturnal CPAP therapy with a constant pressure of 6 cm H(2)O. Additional administration of oxygen was not required. With this therapy, the patient has been asymptomatic up to September 2011.Adult Hunter patients also benefit from enzyme replacement therapy and, in restrictive ventilatory defects with hypoventilation, from symptomatic therapy with noninvasive ventilation.

Mucopolysaccharidosis type II: European recommendations for the diagnosis and multidisciplinary management of a rare disease

Mucopolysaccharidosis type II (MPS II) is a rare, life-limiting, X-linked recessive disease characterised by deficiency of the lysosomal enzyme iduronate-2-sulfatase. Consequent accumulation of glycosaminoglycans leads to pathological changes in multiple body systems. Age at onset, signs and symptoms, and disease progression are heterogeneous, and patients may present with many different manifestations to a wide range of specialists. Expertise in diagnosing and managing MPS II varies widely between countries, and substantial delays between disease onset and diagnosis can occur. In recent years, disease-specific treatments such as enzyme replacement therapy and stem cell transplantation have helped to address the underlying enzyme deficiency in patients with MPS II. However, the multisystem nature of this disorder and the irreversibility of some manifestations mean that most patients require substantial medical support from many different specialists, even if they are receiving treatment. This article presents an overview of how to recognise, diagnose, and care for patients with MPS II. Particular focus is given to the multidisciplinary nature of patient management, which requires input from paediatricians, specialist nurses, otorhinolaryngologists, orthopaedic surgeons, ophthalmologists, cardiologists, pneumologists, anaesthesiologists, neurologists, physiotherapists, occupational therapists, speech therapists, psychologists, social workers, homecare companies and patient societies.

Take-home message

Expertise in recognising and treating patients with MPS II varies widely between countries. This article presents pan-European recommendations for the diagnosis and management of this life-limiting disease.

Clinical practice guideline: Polysomnography for sleep-disordered breathing prior to tonsillectomy in children

OBJECTIVE

This guideline provides otolaryngologists with evidence-based recommendations for using polysomnography in assessing children, aged 2 to 18 years, with sleep-disordered breathing and are candidates for tonsillectomy, with or without adenoidectomy. Polysomnography is the electrographic recording of simultaneous physiologic variables during sleep and is currently considered the gold standard for objectively assessing sleep disorders.

PURPOSE

There is no current consensus or guideline on when children 2 to 18 years of age, who are candidates for tonsillectomy, are recommended to have polysomnography. The primary purpose of this guideline is to improve referral patterns for polysomnography among these patients. In creating this guideline, the American Academy of Otolaryngology--Head and Neck Surgery Foundation selected a panel representing the fields of anesthesiology, pulmonology medicine, otolaryngology-head and neck surgery, pediatrics, and sleep medicine.

RESULTS

The committee made the following recommendations: (1) before determining the need for tonsillectomy, the clinician should refer children with sleep-disordered breathing for polysomnography if they exhibit certain complex medical conditions such as obesity, Down syndrome, craniofacial abnormalities, neuromuscular disorders, sickle cell disease, or mucopolysaccharidoses. (2) The clinician should advocate for polysomnography prior to tonsillectomy for sleep-disordered breathing in children without any of the comorbidities listed in statement 1 for whom the need for surgery is uncertain or when there is discordance between tonsillar size on physical examination and the reported severity of sleep-disordered breathing. (3) Clinicians should communicate polysomnography results to the anesthesiologist prior to the induction of anesthesia for tonsillectomy in a child with sleep-disordered breathing. (4) Clinicians should admit children with obstructive sleep apnea documented on polysomnography for inpatient, overnight monitoring after tonsillectomy if they are younger than age 3 or have severe obstructive sleep apnea (apnea-hypopnea index of 10 or more obstructive events/hour, oxygen saturation nadir less than 80%, or both). (5) In children for whom polysomnography is indicated to assess sleep-disordered breathing prior to tonsillectomy, clinicians should obtain laboratory-based polysomnography, when available.