Failure to control the airway in a patient with Hunter's syndrome

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).

Management of Life-Threatening Tracheal Stenosis and Tracheomalacia in Patients with Mucopolysaccharidoses

Several different lysosomal storage diseases, mainly mucopolysaccharidosis (MPS) type I, II, and VI, are complicated by severe obstruction of the upper airways, tracheobronchial malacia, and/or stenosis of the lower airways. Although enzyme replacement therapies (ERTs) are available, the impact of these on tracheobronchial alterations has not been reported. By extending the life expectancy of MPS patients with ERTs, airway problems may become more prevalent at advanced ages. These airway abnormalities can result in severe, potentially fatal, difficulties during anesthetic procedures. Usually, upper airway obstruction is treated by tracheostomy. However, with lower airway malacia and/or stenosis, there are no procedures available to date to address these difficulties. We report the first cases using a new technique of tracheal stenting in patients with MPS type VI (Maroteaux-Lamy syndrome) and type II (Hunter syndrome) who had almost complete tracheal occlusion and total airway collapse. An updated literature review is also reported.

A retrospective audit of anesthetic techniques and complications in children with mucopolysaccharidoses

OBJECTIVES AND AIMS

To document the incidence of difficult airway management and difficult intubation in the era of replacement therapy for Australian children with mucopolysaccharidosis (MPS).

BACKGROUND

Medical treatment for MPS has developed significantly since 1980's with a large number of patients now being offered either bone marrow transplant or enzyme replacement. The impact of these therapies on the incidence of difficult airway management has not been adequately documented. Similarly, anesthesia techniques and airway devices have been developed, which are thought to have greatly increased the safety of managing these patients under anesthesia but their role in children with MPS has not been systematically described.

METHODS

A retrospective chart review of 17 patients with MPS who had received anesthetics at the Royal Children's Hospital during the time frame January 1998-January 2011. The primary outcome was the incidence of difficult or failed intubation. Secondary outcomes were the relationship between the incidence of difficult intubation and treatment with enzyme replacement therapy (ERT) or bone marrow transplantation.

RESULTS

Seventeen patients received 141 anesthetics for 214 procedures. Difficult face mask ventilation occurred in 20 anesthetics (14.2%). Difficult intubation occurred in 40 anesthetics (25%). Failed intubation occurred in two cases (1.6%).The incidence of difficult intubation was 12% in MPS I, 35% MPS II, 86.7% in MPS VI, and 0% in MPS III and IV.

CONCLUSIONS

Hematopoietic stem cell transplantation prior to 2 years of age reduces the incidence of difficult mask ventilation and difficult intubation in children with MPS I. ERT was initiated late in the clinical course of MPS II and VI and induced improvements in upper airway patency but did not reduce the incidence of difficult airway management.

Importance of surgical history in diagnosing mucopolysaccharidosis type II (Hunter syndrome): data from the Hunter Outcome Survey

PURPOSE

To characterize surgical histories typical of patients with mucopolysaccharidosis type II, thereby broadening understanding of the natural history of these patients and helping physicians recognize the disease.

METHODS

Data on surgical interventions from the Hunter Outcome Survey--a multinational, observational database of patients with mucopolysaccharidosis type II-were analyzed. The study population comprised 527 patients for whom surgical data were reported on/before July 23, 2009.

RESULTS

Surgical interventions were performed in 83.7% of the study population. Patients underwent their first operation at a median age of 2.6 years. Tympanostomies, repairs of inguinal hernias, and operations for carpal tunnel syndrome were performed in a greater proportion of the study population than the general population. A median of 3.0 operations was performed per patient; repeat operations for hernia or carpal tunnel syndrome were common. The majority of patients (221/389) underwent at least one surgical intervention before diagnosis of mucopolysaccharidosis type II.

CONCLUSION

Patients with mucopolysaccharidosis type II typically undergo surgical intervention at a young age, often before diagnosis. Repeated early surgical interventions, particularly for hernias or carpal tunnel syndrome, are characteristic of patients with mucopolysaccharidosis type II. We recommend that such patients are carefully examined for manifestations of mucopolysaccharidosis disorders and referred for diagnostic testing.

Respiratory manifestations in mucopolysaccharidoses

Mucopolysaccharidoses (MPS) are a group of inherited, metabolic diseases caused by deficiency of lysosomal enzymes that degrade glycosaminoglycans (GAG). Loss of enzyme activity results in cellular accumulation of GAG fragments leading to the progressive multi-system manifestations. MPS are classified into seven clinical types based on eleven known lysosomal enzyme deficiencies of GAG metabolism. Respiratory involvement is seen in most MPS types with recurrent respiratory infections, upper and lower airway obstruction, tracheomalacia, restrictive lung disease, and sleep disturbances. Patients with airway obstruction are at high risk for anaesthetic complications. In this review, we present the respiratory manifestations in various MPS types and stages, evaluation of respiratory involvement, and treatment options for the progressive respiratory failure that occurs in MPS patients.

Analysis of the upper airway by the acoustic reflection method in children with mucopolysaccharidosis

BACKGROUND

Upper airway obstruction is common in children with mucopolysaccharidosis. The acoustic reflection method is a noninvasive technique that can analyze the caliber of the upper airways. The aim of the study was to evaluate the feasibility of the acoustic reflection method in children with mucopolysaccharidosis, and to compare the characteristics of the upper airways evaluated by the acoustic reflection method in patients with mucopolysaccharidosis to matched healthy counterparts.

METHODS

Open, single center, prospective, study.

RESULTS

Accurate acoustic reflection measurements could be obtained in 7 of 10 patients (mean age: 10.4 ± 3.9 years; mucopolysaccharidosis type II (n = 3); type IV (n = 2), type VI (n = 1), and fucosidosis (n = 1)). The mean minimum cross-sectional area was lower in mucopolysaccharidosis patients (1.6 ± 0.3 cm(2) ) as compared to 14 healthy counterparts (1.8 ± 0.3 cm(2); P = 0.03). The mean resistance of the airways was significantly higher in the MPS group (7.9 ± 1.8 cmH(2) O l(-1) sec) as compared to the controls (5.5 ± 1.2 cmH(2) O l(-1) sec; P = 0.006).

CONCLUSION

This study is the first to analyze the upper airways by the noninvasive acoustic reflection method in children with mucopolysaccharidosis. Due to a lack of cooperation, reliable measurements could only be obtained in 70% of a selected group of patients. Children with mucopolysaccharidosis have significant upper airway obstruction as assessed by the reduction of the minimal cross-sectional area of the upper airways and the increase in airway resistance.

Mucopolysaccharidosis type II (Hunter syndrome): a clinical review and recommendations for treatment in the era of enzyme replacement therapy

Mucopolysaccharidosis type II (MPS II; Hunter syndrome) is a rare X-linked recessive disease caused by deficiency of the lysosomal enzyme iduronate-2-sulphatase, leading to progressive accumulation of glycosaminoglycans in nearly all cell types, tissues and organs. Clinical manifestations include severe airway obstruction, skeletal deformities, cardiomyopathy and, in most patients, neurological decline. Death usually occurs in the second decade of life, although some patients with less severe disease have survived into their fifth or sixth decade. Until recently, there has been no effective therapy for MPS II, and care has been palliative. Enzyme replacement therapy (ERT) with recombinant human iduronate-2-sulphatase (idursulfase), however, has now been introduced. Weekly intravenous infusions of idursulfase have been shown to improve many of the signs and symptoms and overall wellbeing in patients with MPS II. This paper provides an overview of the clinical manifestations, diagnosis and symptomatic management of patients with MPS II and provides recommendations for the use of ERT. The issue of treating very young patients and those with CNS involvement is also discussed. ERT with idursulfase has the potential to benefit many patients with MPS II, especially if started early in the course of the disease.