Successful use of nasal-CPAP for obstructive sleep apnea in Hunter syndrome with diffuse airway involvement

Safety and efficacy of idursulfase in the treatment of mucopolysaccharidosis II (Hunter syndrome): a post-marketing study in Japan

OBJECTIVES

Enzyme replacement therapy with idursulfase has been shown to improve somatic signs and symptoms of mucopolysaccharidosis type II (MPS II). Idursulfase is available in Japan (since 2007), based on the outcome of clinical trials conducted in the United States, but data from Japanese patients are limited.

METHODS

This was a postmarketing study of Japanese MPS II patients treated with 0.5 mg/kg intravenous idursulfase weekly, conducted over a period of 8 years after initial administration. Assessments included the safety profile, survival rate, degree of clinical improvement, change in urinary uronic acid (UA) concentration, and 6-minute walk test (6MWT).

RESULTS

The safety and efficacy analysis populations included 145 and 143 patients, respectively. The incidence of serious adverse events was 42.8% and the incidence of adverse drug reactions was 48.3%. The 7-year survival rate was 82.7%. Improvements in the clinical features of hepatosplenomegaly, skin, joint, and respiratory disorders were reported (per investigator's assessment). The mean change in urinary UA concentration was -128.39 mg/g creatinine, and that of 6MWT walking distance was +31.8 m.

CONCLUSION

Long-term idursulfase treatment was well tolerated, and effective in improving clinical features, reducing urinary UA, and slowing disease progression in Japanese MPS II patients.

Recommendations for the management of MPS VI: systematic evidence- and consensus-based guidance

Introduction

Mucopolysaccharidosis (MPS) VI or Maroteaux-Lamy syndrome (253200) is an autosomal recessive lysosomal storage disorder caused by deficiency in N-acetylgalactosamine-4-sulfatase (arylsulfatase B). The heterogeneity and progressive nature of MPS VI necessitates a multidisciplinary team approach and there is a need for robust guidance to achieve optimal management. This programme was convened to develop evidence-based, expert-agreed recommendations for the general principles of management, routine monitoring requirements and the use of medical and surgical interventions in patients with MPS VI.

Methods

26 international healthcare professionals from various disciplines, all with expertise in managing MPS VI, and three patient advocates formed the Steering Committee group (SC) and contributed to the development of this guidance. Members from six Patient Advocacy Groups (PAGs) acted as advisors and attended interviews to ensure representation of the patient perspective. A modified-Delphi methodology was used to demonstrate consensus among a wider group of healthcare professionals with expertise and experience managing patients with MPS VI and the manuscript has been evaluated against the validated Appraisal of Guidelines for Research and Evaluation (AGREE II) instrument by three independent reviewers.

Results

A total of 93 guidance statements were developed covering five domains: (1) general management principles; (2) recommended routine monitoring and assessments; (3) enzyme replacement therapy (ERT) and hematopoietic stem cell transplantation (HSCT); (4) interventions to support respiratory and sleep disorders; (5) anaesthetics and surgical interventions. Consensus was reached on all statements after two rounds of voting. The greatest challenges faced by patients as relayed by consultation with PAGs were deficits in endurance, dexterity, hearing, vision and respiratory function. The overall guideline AGREE II assessment score obtained for the development of the guidance was 5.3/7 (where 1 represents the lowest quality and 7 represents the highest quality of guidance).

Conclusion

This manuscript provides evidence- and consensus-based recommendations for the management of patients with MPS VI and is for use by healthcare professionals that manage the holistic care of patients with the intention to improve clinical- and patient-reported outcomes and enhance patient quality of life. It is recognised that the guidance provided represents a point in time and further research is required to address current knowledge and evidence gaps.

Electronic supplementary material

The online version of this article (10.1186/s13023-019-1080-y) contains supplementary material, which is available to authorized users.

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.

Comparison of treatment modalities in syndromic children with obstructive sleep apnea--a randomized cohort study

INTRODUCTION

Obstructive Sleep Apnea (OSA) is a common medical problem in adults that is becoming increasingly recognized in children. It occurs in the pediatric age group, from newborns to teens. More recently, many specialists have estimated OSA prevalence to be between 5 and 6%. However, in syndromic children, the prevalence of OSA can be from 50 to 100%, having a significant effect on their Quality-of-Life. As they are a challenging population for management, it is essential to evaluate them thoroughly before planning appropriate intervention.

OBJECTIVE

To compare the efficacy of Adenotonsillectomy (T&A) and Continuous Positive Airway Pressure (CPAP) in syndromic children [Down syndrome (DS) and Mucopolysaccharidoses (MPS)] with Obstructive Sleep Apnea (OSA).

MATERIALS AND METHODS

In a prospective, randomized, cohort comparative study, 124 syndromic children (DS and MPS) aged between 6 and 12 years were recruited from a private MPS support group and the Down Syndrome Society, Chennai. A standard assessment was performed on all children who entered the study including a full overnight Polysomnogram (PSG), Epworth Sleepiness Scale-Children (ESS-C) and Quality-of-Life (QOL) tool OSA-18. The children with positive PSG who consented for the study (n = 80) were randomly distributed to two groups, T&A group & CPAP group. The children were followed up with repeat PSG, clinical evaluation, ESS-C and Quality-of-Life (QOL) tool OSA-18 for a period of 1 year.

OBSERVATION AND RESULTS

Follow-up was available for 73 syndromic children. Both the groups, T&A group and CPAP group, showed statistically significant (p < 0.05) improvement in Apnea-Hypoapnea Index (AHI), ESS-C, QOL from the intervention. In our study, T&A showed equal outcome compared to CPAP. The contrasting feature between the two groups was that CPAP use gave immediate sustained improvement while T&A gave gradual progressive improvement of symptoms over a period of 1 year.

CONCLUSION

On average, T&A gives equal outcomes as CPAP and it can be suggested as a first-line treatment in this group of syndromic children.

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.

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.

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.

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.

Multidisciplinary management of Hunter syndrome

Hunter syndrome is a rare, X-linked disorder caused by a deficiency of the lysosomal enzyme iduronate-2-sulfatase. In the absence of sufficient enzyme activity, glycosaminoglycans accumulate in the lysosomes of many tissues and organs and contribute to the multisystem, progressive pathologies seen in Hunter syndrome. The nervous, cardiovascular, respiratory, and musculoskeletal systems can be involved in individuals with Hunter syndrome. Although the management of some clinical problems associated with the disease may seem routine, the management is typically complex and requires the physician to be aware of the special issues surrounding the patient with Hunter syndrome, and a multidisciplinary approach should be taken. Subspecialties such as otorhinolaryngology, neurosurgery, orthopedics, cardiology, anesthesiology, pulmonology, and neurodevelopment will all have a role in management, as will specialty areas such as physiotherapy, audiology, and others. The important management topics are discussed in this review, and the use of enzyme-replacement therapy with recombinant human iduronate-2-sulfatase as a specific treatment for Hunter syndrome is presented.

Diagnosis and management of respiratory involvement in Hunter syndrome

Respiratory problems are frequently encountered by patients with Hunter syndrome and contribute to the premature mortality seen in individuals with the disease. Progressive deposition of glycosaminoglycans in the soft tissue of the throat and trachea is thought to be responsible for the airway dysfunction and obstruction, which characterize the syndrome. Other physical characteristics, including abnormalities in the shape and structure of the ribs, abdominal organ enlargement, short neck and immobile jaw, further contribute to the respiratory problems. New measurement systems specifically tailored to paediatric patients now allow clinicians to follow the progressive deterioration of lung function, which was previously challenging in this population. Sleep apnoea is another common feature of Hunter syndrome, which can lead to a reduction in oxygen saturation of the blood and severely disrupts sleep. In our clinic, continuous positive airway pressure (CPAP), in which inspired air at elevated pressure is delivered through a specially designed mask, has proved to be effective for reducing sleep apnoea in patients with Hunter syndrome. As a consequence of the anatomical and pathological changes in the upper airways of patients with Hunter syndrome, general anaesthesia - especially intubation - is a difficult and potentially high-risk procedure. Consequently, such procedures should be performed by an anaesthetist - ideally accompanied by a paediatric pneumologist/intensivist - with experience in managing patients with Hunter syndrome.

CONCLUSION

Respiratory abnormalities are a major contributor to the premature mortality seen in Hunter syndrome. Treatment of these respiratory problems requires the careful attention of clinicians skilled in the recognition, diagnosis, management and treatment of Hunter syndrome.

Skeletal dysplasias and their effect on the respiratory system

Children with skeletal dysplasia frequently have pulmonary disease which can be life threatening. These pulmonary problems are due to multiple aetiologies including thoracic and craniofacial anomalies predisposing to restrictive lung disease, upper airway obstruction and central apnoea. Recognition of pulmonary disease and early intervention improves the survival and quality of life for these children.

Disordered breathing during sleep in patients with mucopolysaccharidoses

OBJECTIVE

Obstructive sleep apnoea (OSA) has been reported as a feature of children with mucopolysaccharidoses (MPS). However, the incidence and severity of OSA with respect to disease type is poorly defined. The aim of the present study was to measure objectively the degree of OSA in a group of children with a range of MPS syndromes.

METHODS

In a cross-sectional study, cardiopulmonary sleep studies were performed during unsedated sleep in 26 children with MPS over a period of 2 years. Scores of OSA severity based upon clinical history and upon objective sleep study data were made in each case and compared.

RESULTS

OSA was present in 24/26 patients, and ranged in severity from mild to severe. OSA was most marked in MPS type IH (Hurler syndrome) followed by types IHS (Hurler--Scheie syndrome) and II (Hunter syndrome). Frequent arousals and poor sleep quality, not suspected clinically, were noted in several patients. There was agreement between the clinical and objective scoring systems in only 17/26 patients (65%) with clinical history scores tending to underestimate the most severe cases (5/26 cases) and overestimate the severity in the mild cases (4/26 cases).

CONCLUSIONS

Obstructive respiratory problems are frequent in MPS patients and there are differences in severity of OSA between the different MPS types. Assessments of the severity of OSA based upon clinical history alone are inadequate. Our results suggest that objective sleep studies are necessary to evaluate these cases, to monitor clinical outcome and to assess the effects of therapeutic intervention. Prospective studies in larger numbers of patients are needed to validate these observations.