Children with mucopolysaccharidosis: perioperative care, morbidity, mortality, and new findings

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.

Anesthetic Concerns of Children With Skeletal Dysplasia

Children with skeletal dysplasia present unique challenges for safe anesthetic care including differences in the anatomy of the respiratory system, possibility of cervical spine instability or spinal stenosis, and a unique body habitus. Even seemly routine anesthesia can result in respiratory arrest or spinal cord injury. These complications can largely be avoided by proper planning such as appropriate techniques for the intubation of difficult airways, recognition of cervical instability, neuromonitoring for any anesthesia over an hour in patients with severe spinal stenosis, and preoperative assessment of the trachea and avoidance of neuraxial anesthesia in children with Morquio syndrome.

Mucopolysaccharidosis Type I: Current Treatments, Limitations, and Prospects for Improvement

Mucopolysaccharidosis type I (MPS I) is a lysosomal disease, caused by a deficiency of the enzyme alpha-L-iduronidase (IDUA). IDUA catalyzes the degradation of the glycosaminoglycans dermatan and heparan sulfate (DS and HS, respectively). Lack of the enzyme leads to pathologic accumulation of undegraded HS and DS with subsequent disease manifestations in multiple organs. The disease can be divided into severe (Hurler syndrome) and attenuated (Hurler-Scheie, Scheie) forms. Currently approved treatments consist of enzyme replacement therapy (ERT) and/or hematopoietic stem cell transplantation (HSCT). Patients with attenuated disease are often treated with ERT alone, while the recommended therapy for patients with Hurler syndrome consists of HSCT. While these treatments significantly improve disease manifestations and prolong life, a considerable burden of disease remains. Notably, treatment can partially prevent, but not significantly improve, clinical manifestations, necessitating early diagnosis of disease and commencement of treatment. This review discusses these standard therapies and their impact on common disease manifestations in patients with MPS I. Where relevant, results of animal models of MPS I will be included. Finally, we highlight alternative and emerging treatments for the most common disease manifestations.

Case Report: Cerebral Revascularization in a Child With Mucopolysaccharidosis Type I

Mucopolysaccharidosis (MPS) type I is a rare lysosomal storage disorder caused by an accumulation of glycosaminoglycans (GAGs) resulting in multisystem disease. Neurological morbidity includes hydrocephalus, spinal cord compression, and cognitive decline. While many neurological symptoms have been described, stroke is not a widely-recognized manifestation of MPS I. Accordingly, patients with MPS I are not routinely evaluated for stroke, and there are no guidelines for managing stroke in patients with this disease. We report the case of a child diagnosed with MPS I who presented with overt stroke and repeated neurological symptoms with imaging findings for severe ventriculomegaly, infarction, and bilateral terminal carotid artery stenosis. Direct intracranial pressure evaluation proved negative for hydrocephalus. The patient was subsequently treated with cerebral revascularization and at a 3-year follow-up, the patient reported no further neurological events or new ischemia on cerebral imaging. Cerebral arteriopathy in patients with MPS I may be associated with GAG accumulation within the cerebrovascular system and may predispose patients to recurrent strokes. However, further studies are required to elucidate the etiology of cerebrovascular arteriopathy in the setting of MPS I. Although the natural history of steno-occlusive arteriopathy in patients with MPS I remains unclear, our findings suggest that cerebral revascularization is a safe treatment option that may mitigate the risk of future strokes and should be strongly considered within the overall management guidelines for patients with MPS I.

Mucopolysaccharidosis Type I: A Review of the Natural History and Molecular Pathology

Mucopolysaccharidosis type I (MPS I) is a rare autosomal recessive inherited disease, caused by deficiency of the enzyme α-L-iduronidase, resulting in accumulation of the glycosaminoglycans (GAGs) dermatan and heparan sulfate in organs and tissues. If untreated, patients with the severe phenotype die within the first decade of life. Early diagnosis is crucial to prevent the development of fatal disease manifestations, prominently cardiac and respiratory disease, as well as cognitive impairment. However, the initial symptoms are nonspecific and impede early diagnosis. This review discusses common phenotypic manifestations in the order in which they develop. Similarities and differences in the three animal models for MPS I are highlighted. Earliest symptoms, which present during the first 6 months of life, include hernias, coarse facial features, recurrent rhinitis and/or upper airway obstructions in the absence of infection, and thoracolumbar kyphosis. During the next 6 months, loss of hearing, corneal clouding, and further musculoskeletal dysplasias develop. Finally, late manifestations including lower airway obstructions and cognitive decline emerge. Cardiac symptoms are common in MPS I and can develop in infancy. The underlying pathogenesis is in the intra- and extracellular accumulation of partially degraded GAGs and infiltration of cells with enlarged lysosomes causing tissue expansion and bone deformities. These interfere with the proper arrangement of collagen fibrils, disrupt nerve fibers, and cause devastating secondary pathophysiological cascades including inflammation, oxidative stress, and other disruptions to intracellular and extracellular homeostasis. A greater understanding of the natural history of MPS I will allow early diagnosis and timely management of the disease facilitating better treatment outcomes.

Airway management and perioperative adverse events in children with mucopolysaccharidoses and mucolipidoses: A retrospective cohort study

BACKGROUND

Children suffering from mucopolysaccharidoses (subtypes I, II, III, IV, VI, and VII) or mucolipidoses often require anesthesia, but are at high risk for perioperative adverse events. However, the impact of the disease subtype and the standard of care for airway management are still unclear.

AIMS

This study aimed to assess independent risk factors for perioperative adverse events in individuals with mucopolysaccharidoses/mucolipidoses and to analyze the interaction with the primary airway technique implemented.

METHODS

This retrospective study included individuals with mucopolysaccharidoses/mucolipidoses who underwent anesthesia at two high-volume centers from 2002 to 2016. The data were analyzed in a multivariate hierarchical model, accounting for repeated anesthesia procedures within the same patient and for multiple events within a single anesthesia.

RESULTS

Of 141 identified inpatients, 67 (63 mucopolysaccharidoses and 4 mucolipidoses) underwent 269 anesthesia procedures (study cases) for 353 surgical or diagnostic interventions. At least one perioperative adverse event occurred in 25.6% of the cases. The risk for perioperative adverse events was higher in mucopolysaccharidoses type I (OR 8.0 [1.5-42.7]; P = .014) or type II (OR 8.8 [1.3-58.6]; P = .025) than in type III. Fiberoptic intubation through a supraglottic airway was associated with the lowest risk for perioperative adverse events and lowest conversion rate. Direct laryngoscopy was associated with a significantly higher risk for airway management problems than indirect techniques (estimated event rates 47.8% vs 10.1%, OR 24.05 [5.20-111.24]; P < .001). The risk for respiratory adverse events was significantly higher for supraglottic airway (22.6%; OR 31.53 [2.79-355.88]; P = .001) and direct laryngoscopy (14.8%; OR 14.70 [1.32-163.44]; P = .029) than for fiberoptic intubation through a supraglottic airway (2.1%).

CONCLUSIONS

The disease subtype and primary airway technique were the most important independent risk factors for perioperative adverse events. Our findings indicate that in MPS/ML children with predicted difficult airway indirect techniques should be favored for the first tracheal intubation attempt.

Laryngeal, Tracheal, and Bronchial Disease in the Mucopolysaccharidoses: Endoscopic Study

Mucopolysaccharidoses (MPS) are genetically determined diseases, leading to a deficiency of enzymes in the glycosaminoglycan (GAG) degradation pathway. The accumulation of GAG occurs in connective tissue in various organs and systems of the body, including the larynx, trachea, and bronchi. Respiratory symptoms are common and severe in these patients, and respiratory disease is a frequent cause of death. A cross-sectional study with flexible bronchoscopy was conducted in 30 MPS patients (6 MPS I, 8 MPS II, 2 MPS III, 3 MPS IV-A, and 11 MPS VI). Only four patients (13.33%) had a normal airway; nine (30%) had mild to moderate disease, 12 (40%) moderate to severe, and five patients (16.67%) had severe disease. Of particular interest, neuronopathic MPS II had the largest proportion of tracheostomized patients who died due to respiratory complications; in MPS IV-A, all patients had significant tracheobronchial deformity with associated tracheomalacia, despite lacking laryngeal involvement. Laryngotracheobronchial disease (LTBD) was associated to longer disease history and was significantly more severe in older patients. Longer use of enzyme replacement therapy did not prevent the progression of LTBD, although the age of therapy introduction may be a crucial factor in lower airway involvement.

Neonatal Onset Interstitial Lung Disease as a Primary Presenting Manifestation of Mucopolysaccharidosis Type I

We describe two cases of neonatal onset interstitial lung disease eventually diagnosed as mucopolysaccharidosis type I (MPS I). In both cases, evaluation led to lung biopsy, pathology review, and identification of glycogen deposition. Pulmonary interstitial glycogenosis (PIG) was considered as a clinical diagnosis in case one; however, further review of electron microscopy (EM) was more consistent with MPS I rather than PIG. Both cases were confirmed to have MPS I by enzyme and molecular analysis. Neonatal interstitial lung disease is an atypical presentation for MPS I which is likely under-recognized. Diagnosis through clinical guidelines and a multidisciplinary approach had a major impact on patient management. The diagnosis of MPS I prompted timely initiation of enzyme replacement therapy (ERT) and the patients ultimately underwent hematopoietic stem cell transplantation (HSCT) to improve symptomatic outcomes. In addition to treatment, immediate precautionary recommendations were made to avoid potentially catastrophic outcomes associated with cervical instability. These cases add to the clinical spectrum of MPS I in the newborn period. They further illustrate the difficulties in early recognition of the disease, and importance of a definitive diagnosis of MPS I in infants with interstitial lung disease.

Mediastinal Tracheostoma for Treatment of Tracheostenosis after Tracheostomy in a Patient with Mucopolysaccharidosis-Induced Tracheomalacia

Background

Treatment of tracheostenosis after tracheostomy in pediatric patients is often difficult. Mucopolysaccharidosis is a lysosomal storage disease that may induce obstruction of the airways.

Case Presentation

A 16-year-old male patient underwent long-term follow-up after postnatal diagnosis of type II mucopolysaccharidosis. At 11 years of age, tracheostomy was performed for mucopolysaccharidosis-induced laryngeal stenosis. One week prior to presentation, he was admitted to another hospital on an emergency basis for major dyspnea. He was diagnosed with tracheostenosis caused by granulation. The patient was then referred to our institution. The peripheral view of his airway was difficult because of mucopolysaccharidosis-induced tracheomalacia. For airway management, a mediastinal tracheostoma was created with extracorporeal membrane oxygenation. To maintain the blood flow, the skin incision for the mediastinal tracheal hole was sharply cut without an electrotome. The postoperative course was uneventful, and the patient was weaned from the ventilator on postoperative day 19. He was discharged 1.5 months postoperatively. Although he was referred to another institution because of respiratory failure caused by his primary disease 6 months postoperatively, his airway management remained successful for 1.5 years postoperatively.

Conclusion

Mediastinal tracheostomy was useful for treatment of tracheostenosis caused by granulation tissue formation after a tracheostomy.

Does orthopaedic surgery improve quality of life and function in patients with mucopolysaccharidoses?

PURPOSE

Mucopolysaccharidoses (MPS) are a group of rare lysosomal storage disorders associated with involvement of multiple organs along with a generalised skeletal dysplasia. Both haematopoetic stem cell transplant and enzyme replacement therapy have improved the outlook for patients while surgery remains high-risk and there is little information on clinical or functional outcome to justify many of the surgical procedures performed. This paper aims to summarise the orthopaedic surgical procedures in MPS patients for which quality of life (QoL) and functional data are available and to describe additional QoL and functional measurement tools of relevance to the assessment of orthopaedic outcomes in MPS.

METHODS

We reviewed the available literature to look for reported outcomes of orthopaedic surgery to lower and upper limbs and the spine. In addition, we describe the general and MPS-specific health measures that might be of relevance to the orthopaedic surgeon.

RESULTS

There is some evidence in the literature that orthopaedic surgery may improve QoL and function in some specific aspects of the MPS condition (in relation to genu valgum, carpal tunnel syndrome and trigger digits); however, the literature is sparse and consists of level 4/5 studies only. Further studies of these conditions should include QoL and functional assessment in order to confirm or refute these reports. In other areas (spine and hip), outcomes are judged largely on radiographic appearances with little clinical correlation and short follow-up; however, one long-term study of function following hip dysplasia surgery suggests poor outcomes. Anaesthetic morbidity/mortality is not insignificant in these complex patients with multi-organ involvement. Careful assessment is required, particularly when there is neurological involvement.

CONCLUSIONS

Orthopaedic surgeons involved with MPS patients should be encouraged to use and report measures of QoL and function with respect to musculoskeletal manifestations and response to surgery, recognising that such assessments in these complex and challenging patients may require a multidisciplinary approach.

Sleep and the Cardiovascular System in Children

Subspecialty pediatric practice provides comprehensive medical care for a range of ages, from premature infants to children, and often includes adults with complex medical and surgical issues that warrant multidisciplinary care. Normal physiologic variations involving different body systems occur during sleep and these vary with age, stage of sleep, and underlying health conditions. This article is a concise review of the cardiovascular (CV) physiology and pathophysiology in children, sleep-disordered breathing (SDB) contributing to CV morbidity, congenital and acquired CV pathology resulting in SDB, and the relationship between SDB and CV morbidity in different clinical syndromes and systemic diseases in the expanded pediatric population.

Mucopolysaccharidosis IVA and glycosaminoglycans

Mucopolysaccharidosis IVA (MPS IVA; Morquio A: OMIM 253000) is a lysosomal storage disease with an autosomal recessive trait caused by the deficiency of N-acetylgalactosamine-6-sulfate sulfatase. Deficiency of this enzyme leads to accumulation of specific glycosaminoglycans (GAGs): chondroitin-6-sulfate (C6S) and keratan sulfate (KS). C6S and KS are mainly produced in the cartilage. Therefore, the undegraded substrates are stored primarily in cartilage and in its extracellular matrix (ECM), leading to a direct impact on cartilage and bone development, and successive systemic skeletal dysplasia. Chondrogenesis, the earliest phase of skeletal formation, is maintained by cellular interactions with the ECM, growth and differentiation factors, signaling pathways, and transcription factors in a temporal-spatial manner. In patients with MPS IVA, the cartilage is disrupted at birth as a consequence of abnormal chondrogenesis and/or endochondral ossification. The unique skeletal features are distinguished by a disproportional short stature, odontoid hypoplasia, spinal cord compression, tracheal obstruction, pectus carinatum, kyphoscoliosis, platyspondyly, coxa valga, genu valgum, waddling gait, and laxity of joints. In spite of many descriptions of these unique clinical features, delay of diagnosis still happens. The pathogenesis and treatment of systemic skeletal dysplasia in MPS IVA remains an unmet challenge. In this review article, we comprehensively describe historical aspect, property of GAGs, diagnosis, screening, pathogenesis, and current and future therapies of MPS IVA.

Anesthetic care and perioperative complications in children with Sanfilipo Syndrome Type A

BACKGROUND

Patients with mucopolysaccharidoses (MPS) are generally considered high risk for anesthesia care, owing to disease-related factors. Sanfilippo syndrome type A (MPS IIIA) is the most frequently occurring MPS. Anesthesia-specific information for MPS IIIA is not readily available in the literature.

OBJECTIVES

To report post hoc analyses on anesthesia care and outcomes from a 2-year study of the natural history of patients with untreated MPS IIIA (NCT01047306).

METHODS

Subjects were ≥1 year of age, developmental age ≥1 year, and without significant central nervous system impairment (other than that due to MPS IIIA) or issues that would preclude study procedures. Procedures requiring general anesthesia included brain/abdominal magnetic resonance imaging, lumbar puncture, and echocardiography. Sedation, intubation, and extubation procedures as well as postoperative airway problems were recorded at baseline and 6, 12, and 24 months of age.

RESULTS

Twenty-five patients (baseline age, 13-220 months) received a total of 94 general anesthetics. Patients successfully received oral sedation prior to 76 of 94 anesthetics. No patients required airway intervention or oxygen supplementation during sedation. All anesthesia providers described facemask ventilation and endotracheal intubations as 'easy'. All subjects were successfully extubated after completion of the procedures. No patients required reintubation. Six (24%) patients had episodes of postoperative airway problems: wheezing (7/94, 7.4%), croup (6/94, 6.4%), and laryngospasm (2/94, 2.1%).

CONCLUSION

We found no change in the modified Cormack-Lehane intubation grades in 25 Sanfilippo syndrome type A children over the 2-year study period.

Alterations of mucosa of the larynx and hypopharynx in patients with mucopolysaccharidoses

OBJECTIVE

This study aimed to: assess the mucosal alterations of the larynx and hypopharynx typical for mucopolysaccharidoses, in a standardised manner; compare the severity in different subtypes of mucopolysaccharidoses; and monitor the effect of an enzyme replacement therapy.

METHODS

A classification for mucosal alterations of the larynx and hypopharynx was developed and utilised in 55 patients with mucopolysaccharidoses. Fifteen patients who started treatment with enzyme replacement therapy were followed longitudinally.

RESULTS

The most severe alterations were seen in the posterior region of the larynx and the arytenoids, and in the region of the false vocal folds. The alterations were most severe in patients with mucopolysaccharidosis II. No clear trend was observed in the patients who received enzyme replacement therapy.

CONCLUSION

Quantification of mucosal alterations of the hypopharynx and larynx in mucopolysaccharidoses patients can provide information about the disease's natural process and about the efficacy of enzyme replacement therapy.

Effects of neonatal enzyme replacement therapy and simvastatin treatment on cervical spine disease in mucopolysaccharidosis I dogs

Mucopolysaccharidosis I (MPS I) is a lysosomal storage disease characterized by deficient α-L-iduronidase activity, leading to the accumulation of poorly degraded glycosaminoglycans (GAGs). Children with MPS I exhibit high incidence of spine disease, including accelerated disc degeneration and vertebral dysplasia, which in turn lead to spinal cord compression and kyphoscoliosis. In this study we investigated the efficacy of neonatal enzyme replacement therapy (ERT), alone or in combination with oral simvastatin (ERT + SIM) for attenuating cervical spine disease progression in MPS I, using a canine model. Four groups were studied: normal controls; MPS I untreated; MPS I ERT-treated; and MPS I ERT + SIM-treated. Animals were euthanized at age 1 year. Intervertebral disc condition and spinal cord compression were evaluated from magnetic resonance imaging (MRI) images and plain radiographs, vertebral bone condition and odontoid hypoplasia were evaluated using micro-computed tomography (µCT), and epiphyseal cartilage to bone conversion was evaluated histologically. Untreated MPS I animals exhibited more advanced disc degeneration and more severe spinal cord compression than normal animals. Both treatment groups resulted in partial preservation of disc condition and cord compression, with ERT + SIM not significantly better than ERT alone. Untreated MPS I animals had significantly lower vertebral trabecular bone volume and mineral density, whereas ERT treatment resulted in partial preservation of these properties. ERT + SIM treatment demonstrated similar, but not greater, efficacy. Both treatment groups partially normalized endochondral ossification in the vertebral epiphyses (as indicated by absence of persistent growth plate cartilage), and odontoid process size and morphology. These results indicate that ERT begun from a very early age attenuates the severity of cervical spine disease in MPS I, particularly for the vertebral bone and odontoid process, and that additional treatment with simvastatin does not provide a significant additional benefit over ERT alone.

Musculoskeletal function in patients with mucopolysaccharidosis using the pediatric outcomes data collection instrument

BACKGROUND

Musculoskeletal function is often the limiting factor in quality of life in patients with mucopolysaccharidosis (MPS). The Pediatric Outcomes Data Collection Instrument (PODCI) is a validated tool to be used in children aged 2 to 18 years with chronic musculoskeletal disorders and is freely available to any investigator. The goal of this study is to establish normative data for patients with MPS.

METHODS

Of our 25 patients with MPS, 16 had PODCI's performed at initial evaluation. This included 4 patients with MPS IH (Hurler), 7 patients with MPS II (Hunter), 4 patients with MPS IV (Morquio), and 1 patient with MPS VI (Maroteaux-Lamy). Differences in PODCI scores among children with MPS IH (Hurler), II (Hunter), and IV were estimated using a Kruskal-Wallis test.

RESULTS

With the exception of upper extremity and physical functioning function in MPS IV, all domains for our MPS patients measured below average for typically developing children. We found a statistically significant difference among the groups in the upper extremity and physical function scale [H (2) = 8.16, P = 0.02]. The single MPS VI patient had the highest scores overall. MPS IV patients scored better than the MPS IH patients, and the MPS II patients scored lowest.

CONCLUSIONS

This study demonstrates the limited musculoskeletal function in patients with MPS and the differences among different MPS diagnoses.

CLINICAL RELEVANCE

The data establishes a basic understanding of musculoskeletal function in patients with MPS and should provide comparative data for future studies in which musculoskeletal function is measured as an objective outcome. It can also serve as a better objective measure for interventions, as previous models have only served as proxies to musculoskeletal function.

Mucopolysaccharidoses

The mucopolysaccharidoses (MPSs) are a group of rare genetic disorders of glycosaminoglycan catabolism, caused by a deficiency of lysosomal enzymes required for GAG degradation. Incomplete breakdown of glycosaminoglycans leads to progressive accumulation of these substances in many tissues throughout the body. Different residual enzymatic activity can result in different phenotypes of the same MPS disorder, from severe to attenuated. Musculoskeletal manifestations are common across all forms of MPS. Skeletal and joint abnormalities are prominent features of many MPS disorders, particularly attenuated phenotypes. However, diagnostic delays occur frequently for patients with an MPS, especially those with more attenuated forms of disease. In the absence of appropriate treatment, these conditions are chronic, progressive and often debilitating, but treatment for many types of MPS is now available. Therefore, increasing awareness of MPS among rheumatologists is extremely important.

Perioperative complications in patients diagnosed with mucopolysaccharidosis and the impact of enzyme replacement therapy followed by hematopoietic stem cell transplantation at early age

BACKGROUND

Mucopolysaccharidoses (MPS) are hereditary storage diseases; airway management typically worsens in these patients with the progression of the disease.

OBJECTIVE(S)

To assess the incidence of perioperative complications in children with MPS and the impact of enzyme replacement therapy (ERT) followed by hematopoietic stem cell transplantation (HSCT).

METHODS

The records of patients with MPS treated with ERT followed by HSCT, who received anesthesia at the Wilhelmina Children's Hospital between 2003 and 2012, were reviewed. Data were collected on incidence of perioperative respiratory and cardiovascular complications and the impact of treatment and age.

RESULTS

Nineteen children with MPS were identified (including 17 Hurler patients), who received ERT treatment followed by HSCT. Median age at start of treatment was 14 (range: 7-43) months. Patients were anesthetized 136 times. The incidence of respiratory and cardiovascular complications was 24% and 4%, respectively. Airway management by face mask was difficult in 7%. There were no problems with the laryngeal mask airway. Tracheal intubation was difficult in 25% and failed in 10%; using a video laryngoscope was most successful (89%), followed by classic laryngoscope (67%) and fiber-optic scope (20%). Multivariate logistic regression analyses showed that the incidence of perioperative respiratory problems did not increase with age or decrease after start of treatment.

CONCLUSION

Perioperative airway management was most successful using a laryngeal mask airway or video laryngoscope. Treatment with ERT followed by HSCT and patient age did not influence the incidence of perioperative respiratory problems.

Feasibility of cochlear implantation in Mucopolysaccharidosis

Mucopolysaccharidoses (MPS) are a group of rare inherited metabolic disorders resulting from deficiencies of particular enzymes involved in the breakdown of glycosaminoglycans. Amongst the manifestations of MPS within the head and neck patients may develop conductive, mixed or sensorineural hearing loss.

OBJECTIVE

The main objective of this paper is to describe the management of profound sensorineural hearing loss in children with Mucopolysaccaridosis. The primary outcome measures for this case series were improvement in auditory performance and speech perception scores following cochlear implantation. Secondary outcome measures included surgical complications.

METHODS

We carried out a casenote review of the first two cases of cochlear implantation (CI) to rehabilitate profound sensory neural hearing loss in Mucopolysaccharidoses. Improvement in auditory performance was measured by categories of auditory performance (CAP) score, speech reception score (SRS) and the IHR McCormick toy discrimination test.

RESULTS

Both patients with MPS had demonstrable benefit from CI in terms of auditory performance and speech perception. The first patient improved from pre-operatively only managing to recognise environmental sounds to understanding conversation without lip-reading with a familiar talker. Following CI, the second patient can discriminate speech in noisy environments to a degree, without lip-reading. No peri-operative complications were noted in either patient.

CONCLUSION

As the medical management of the MPS has progressed there is likely to be a corresponding increase in survival. This increased life-expectancy will likely lead to greater numbers of patients with MPS surviving long enough to develop profound hearing loss. Likewise, when considering the risks and benefits of quality of life interventions such as CI in patients with MPS, it is more likely that the risks of surgery and general anaesthesia will be considered acceptable. Clinicians managing such patients will need to be aware of these developments.

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.

Postnatal progression of bone disease in the cervical spines of mucopolysaccharidosis I dogs

INTRODUCTION

Mucopolysaccharidosis I (MPS I) is a lysosomal storage disorder characterized by deficient α-l-iduronidase activity leading to accumulation of poorly degraded dermatan and heparan sulfate glycosaminoglycans (GAGs). MPS I is associated with significant cervical spine disease, including vertebral dysplasia, odontoid hypoplasia, and accelerated disk degeneration, leading to spinal cord compression and kypho-scoliosis. The objective of this study was to establish the nature and rate of progression of cervical vertebral bone disease in MPS I using a canine model.

METHODS

C2 vertebrae were obtained post-mortem from normal and MPS I dogs at 3, 6 and 12 months-of-age. Morphometric parameters and mineral density for the vertebral trabecular bone and odontoid process were determined using micro-computed tomography. Vertebrae were then processed for paraffin histology, and cartilage area in both the vertebral epiphyses and odontoid process were quantified.

RESULTS

Vertebral bodies of MPS I dogs had lower trabecular bone volume/total volume (BV/TV), trabecular thickness (Tb.Th), trabecular number (Tb.N) and bone mineral density (BMD) than normals at all ages. For MPS I dogs, BV/TV, Tb.Th and BMD plateaued after 6 months-of-age. The odontoid process appeared morphologically abnormal for MPS I dogs at 6 and 12 months-of-age, although BV/TV and BMD were not significantly different from normals. MPS I dogs had significantly more cartilage in the vertebral epiphyses at both 3 and 6 months-of-age. At 12 months-of-age, epiphyseal growth plates in normal dogs were absent, but in MPS I dogs they persisted.

CONCLUSIONS

In this study we report reduced trabecular bone content and mineralization, and delayed cartilage to bone conversion in MPS I dogs from 3 months-of-age, which may increase vertebral fracture risk and contribute to progressive deformity. The abnormalities of the odontoid process we describe likely contribute to increased incidence of atlanto-axial subluxation observed clinically. Therapeutic strategies that enhance bone formation may decrease incidence of spine disease in MPS I patients.

Bronchoscopy and airway management in patients with mucopolysaccharidoses (MPS)

INTRODUCTION

Mucopolysaccharidoses (MPS) are a group of lysosomal storage disorders characterized by tissue deposition of glycosaminoglycans (GAG). Their musculoskeletal abnormalities and the GAG storage in the airway result in increased risk for patients undergoing anesthesia. This study evaluates a multi-disciplinary airway management approach and reports upper and lower airway findings of flexible bronchoscopy performed during these procedures.

METHODS

This is a retrospective study over 10 years evaluating approaches to and outcomes of airway management and bronchoscopic findings in this patient group.

RESULTS

Thirty-one patients underwent a total of 105 anesthetic events of which 74 involved multiple surgical services. The majority of patients were either MPS I (n = 9) or MPS II (n = 19). The median age was 8.6 years (range 1.1-24 years). Airway management by anesthesiologists alone occurred in 31 cases including natural airway (n = 7), perilaryngeal airway (n = 7), oral or nasal intubation (n = 7) or tracheostomy (n = 6) and emergent fiberoptic intubation in four cases. In 74 of the procedures, flexible bronchoscopy was performed which included fiberoptic intubation in 22 cases. Post-operative complications occurred in eight cases mostly when prolonged airway instrumentation had occurred. The most frequent findings on bronchoscopy were GAG deposits/adenoid hypertrophy in 72%, laryngomalacia in 31% and lower airway deposits and/or tracheobronchomalacia in 46% of procedures. Deposits of GAG were seen in patients as young as 4 years of age.

CONCLUSION

Our experience demonstrates that a multidisciplinary approach and combined surgeries in MPS provides for safe airway management and allows diagnostic assessments for further patient care without added risks. Significant, multi-factorial airway compromise may occur already in early childhood including upper and lower airway GAG deposits.

Clinical overview and treatment options for non-skeletal manifestations of mucopolysaccharidosis type IVA

Mucopolysaccharidosis type IVA (MPS IVA) or Morquio syndrome is a multisystem disorder caused by galactosamine-6-sulfatase deficiency. Skeletal manifestations, including short stature, skeletal dysplasia, cervical instability, and joint destruction, are known to be associated with this condition. Due to the severity of these skeletal manifestations, the non-skeletal manifestations are frequently overlooked despite their significant contribution to disease progression and impact on quality of life. This review provides detailed information regarding the non-skeletal manifestations and suggests long-term assessment guidelines. The visual, auditory, digestive, cardiovascular, and respiratory systems are addressed and overall quality of life as measured by endurance and other functional abilities is discussed. Impairments such as corneal clouding, astigmatism, glaucoma, hearing loss, hernias, hepatomegaly, dental abnormalities, cardiac valve thickening and regurgitation, obstructive sleep apnea, tracheomalacia, restrictive and obstructive respiratory compromise, and muscular weakness are discussed. Increased awareness of these non-skeletal features is needed to improve patient care.

Spinal involvement in mucopolysaccharidosis IVA (Morquio-Brailsford or Morquio A syndrome): presentation, diagnosis and management

Mucopolysaccharidosis IVA (MPS IVA), also known as Morquio-Brailsford or Morquio A syndrome, is a lysosomal storage disorder caused by a deficiency of the enzyme N-acetyl-galactosamine-6-sulphate sulphatase (GALNS). MPS IVA is multisystemic but manifests primarily as a progressive skeletal dysplasia. Spinal involvement is a major cause of morbidity and mortality in MPS IVA. Early diagnosis and timely treatment of problems involving the spine are critical in preventing or arresting neurological deterioration and loss of function. This review details the spinal manifestations of MPS IVA and describes the tools used to diagnose and monitor spinal involvement. The relative utility of radiography, computed tomography (CT) and magnetic resonance imaging (MRI) for the evaluation of cervical spine instability, stenosis, and cord compression is discussed. Surgical interventions, anaesthetic considerations, and the use of neurophysiological monitoring during procedures performed under general anaesthesia are reviewed. Recommendations for regular radiological imaging and neurologic assessments are presented, and the need for a more standardized approach for evaluating and managing spinal involvement in MPS IVA is addressed.

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.

Clinical guidelines for diagnosing and managing ocular manifestations in children with mucopolysaccharidosis

The mucopolysaccharidoses (MPS) are a group of rare lysosomal storage disorders characterized by the accumulation of glycosaminoglycans in several tissues and organs. This accumulation results in an array of clinical manifestations and premature death in severe cases. Ocular problems are very common in children with MPS and may involve the cornea, sclera, trabecular meshwork, retina, optic nerve and also the posterior visual pathways. The aims of this study are to give an overview of ocular problems in MPS and to provide clinical guidelines for paediatric ophthalmologists for early diagnosis and management of ocular manifestations in children with MPS. Diagnostic problems may arise in children with severe corneal clouding, hampering visualization of the fundus. Intraocular pressures may be falsely high, even leading to suspicion and unnecessary pressure-lowering treatment. Simple interventions such as the use of prescription glasses or photochromatic glasses can considerably improve quality of life in children with MPS.

Prevalence and development of orthopaedic symptoms in the dutch hurler patient population after haematopoietic stem cell transplantation

Hurler syndrome (MPS-IH) is a rare autosomal recessive lysosomal storage disease. Besides a variety of other features, Hurler syndrome is characterized by a range of skeletal abnormalities known as dysostosis multiplex. Despite the successful effect of haematopoietic stem cell transplantation on the other features, dysostosis remains a disabling symptom of the disease. This study analyzed the status and development of the orthopaedic manifestations of 14 Dutch Hurler patients after stem cell transplantation.Data were obtained retrospectively by reviewing patients' charts, radiographs and MRIs. Existing methods to measure the deficiencies were modified to optimally address the dysostosis. These measurements were done by two of the authors independently. The odontoïd/body ratio, kyphotic angle, scoliotic angle and parameters for hip dysplasia and genu valgum were measured and plotted against age. The degree of progression was determined. The intraclass correlation coefficient (ICC) was calculated to determine the reliability of the measurements.All patients showed hypoplasia of the odontoïd, which significantly improved during growth. Kyphosis in the thoracolumbar area was present in 13 patients and proved to be progressive. Scoliosis was observed in eight patients. Hip dysplasia was present in all patients and showed no tendency of improvement. In all but one patient, knee valgus remained more than two standard deviations above normal.Dysostosis remains a major problem after haematopoietic stem cell transplantation in Hurler patients. Moreover, except for dens hypoplasia, it appears to be progressive and therefore surgical interventions may be necessary in the majority of these patients.

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.

Paediatric airway management in mucopolysaccharidosis 1: a retrospective case review

CONTEXT

Airway management in children suffering from mucopolysaccharidosis 1 (Hurler syndrome) remains challenging despite advances in both treatment and airway management techniques.

OBJECTIVES

Forty-one anaesthetic charts following ten children over a 6-year period (2004-2010) were reviewed with emphasis on airway problems.

RESULTS

All children had early stem cell transplantation at the age of 2 years or earlier. Mean (SD) age was 5 (4.3) years. Mask ventilation was difficult in five of 41 (12%) anaesthetics or in three of ten children. There were 29 intubations. Direct laryngoscopy was described as difficult (Cormack and Lehane ≥3) on 11 occasions in five of ten children. There were three of 26 (12%) failed intubations with direct laryngoscopy. These situations were resolved by a fibre-optic procedure, by laryngeal mask airway (LMA) insertion or by use of a videolaryngoscope. A laryngeal mask airway was used 11 times to avoid invasive airway management and once when direct laryngoscopy was impossible.

CONCLUSION

The airway management of children with mucopolysaccharidosis 1 remains critical, despite advances in both treatment and airway management techniques. Problems did not seem to increase as children grew older. We assume that technical improvements such as standardised use of the laryngeal mask airway or attached tube channel videolaryngoscopes as well as a stem cell transplantation treatment of the disease helped the management of older children with mucopolysaccharidosis 1.

High rate of postoperative mortality in patients with mucopolysaccharidosis I: findings from the MPS I Registry

BACKGROUND/PURPOSE

Mucopolysaccharidosis I (MPS I) is a rare lysosomal storage disorder caused by deficiency of α-L-iduronidase, which results in progressive multisystemic disease. Patients with MPS I often require multiple common and uncommon surgeries and are at risk for surgical and anesthetic complications because of respiratory and cardiac disease. Surgery often precedes diagnosis; thus, surgeons and anesthesiologists may be unaware of potential risks.

METHODS

We analyzed data from the MPS I Registry, a voluntary observational database, for deaths occurring within 1 month of a surgical procedure among the 932 patients enrolled as of July 2010.

RESULTS

Among the 196 deceased patients, 186 reported 1 surgery or more, and 32 had 1 surgery or more within 1 month of death, including 20 who had 1 surgery or more within 10 days of death. Surgeries before death included hernia repair, central line placement, spinal surgery, tracheostomy, and ventriculo-peritoneal shunt. Most patients (28/32) had severe MPS I (Hurler), and 20 of 32 patients (all Hurler) died at 3 years or younger. In 6 of 32 patients, surgery was directly noted in the cause of death, including 4 patients with an attenuated form of MPS I.

CONCLUSIONS

Patients with mucopolysaccharidosis have a high postoperative mortality because of underlying respiratory and cardiac diseases.

Orthopaedic aspects of mucopolysaccharidoses

Skeletal abnormalities are an early and prominent feature of most mucopolysaccharide (MPS) disorders, with the degree of skeletal involvement varying between and within MPS subtypes. Most patients exhibit a constellation of radiographic abnormalities known as dysostosis multiplex, consisting of abnormally shaped vertebrae and ribs, enlarged skull, spatulate ribs, hypoplastic epiphyses, thickened diaphyses and bullet-shaped metacarpals. Thoracolumbar kyphosis or the gibbus deformity is often a key diagnostic clue. Also common are hip dysplasia, genu valgum and, later in the course of the disease, spinal cord compression, which can be life-threatening. Short stature is ubiquitous. Treatment of skeletal manifestations usually involves surgical intervention. All patients with MPS should be considered at high risk for surgical intervention requiring anaesthesia because of airway and cardiac disease manifestations. Regular imaging of the cervical, thoracic and lumbar spine, the hips and the lower extremities is recommended for patients with MPS.

Mucopolysaccharidosis type I Hurler-Scheie syndrome affecting two sisters

Mucopolysaccharidosis I (MPS I) is a rare inherited disorder characterized by physical deformities and developmental anomalies. Part of a group of clinically progressive disorders, it is caused by the deficiency of the lysosomal enzyme, α-L -iduronidase, which results in intralysosomal accumulation of dermatan sulfate and heparan sulfate and in turn causes cell dysfunction. Two sisters, one 11 years old and the other 7, both MPS type I H/S, came to our diagnostic center. Hand-wrist radiographs revealed bullet-shaped phalanges with proximal pointing of the second to fifth metacarpals. Ultrasonographic examination showed splenomegaly in the younger child. Radiography of the pelvis showed a narrow pelvis with flared iliac wings. A skull skiagram showed J-shaped sella.

Orthopaedic management of Hurler's disease after hematopoietic stem cell transplantation: a systematic review

OBJECTIVE

The introduction of hematopoietic stem cell transplantation (HSCT) has significantly improved the life-span of Hurler patients (mucopolysaccharidosis type I-H, MPS I-H). Yet, the musculoskeletal manifestations seem largely unresponsive to HSCT. In order to facilitate evidence based management, the aim of the current study was to give a systematic overview of the orthopaedic complications and motor functioning of Hurler's patients after HSCT.

METHODS

A systematic review was conducted of the medical literature published from January 1981 to June 2010. Two reviewers independently assessed all eligible citations, as identified from the Pubmed and Embase databases. A pre-developed data extraction form was used to systematically collect information on the prevalence of radiological and clinical signs, and on the orthopaedic treatments and outcomes.

RESULTS

A total of 32 studies, including 399 patient reports were identified. The most frequent musculoskeletal abnormalities were odontoid hypoplasia (72%), thoracolumbar kyphosis (81%), genu valgum (70%), hip dysplasia (90%) and carpal tunnel syndrome (63%), which were often treated surgically during the first decade of life. The overall complication rate of surgical interventions was 13.5%. Motor functioning was further hampered due to reduced joint mobility, hand dexterity, motor development and longitudinal growth.

CONCLUSION

Stem cell transplantation does not halt the progression of a large range of disabling musculoskeletal abnormalities in Hurler's disease. Although prospective data on the quantification, progression and treatment of these deformities were very limited, early surgical intervention is often advocated. Prospective data collection will be mandatory to achieve better evidence on the effect of treatment strategies.

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.

Transplant outcomes in mucopolysaccharidoses

The mucopolysaccharidoses (MPSs) are inherited metabolic disorders (IMDs) caused by single-gene defects leading to progressive cellular accumulation of glycosaminoglycans (GAGs) and damage to multiple organs, including the central nervous, musculoskeletal, cardiorespiratory, and other systems. Hurler syndrome (MPS IH), the most severe form, is the prototypical model. Enzyme replacement therapy (ERT), available for MPS I, II, and VI, is beneficial in some patients. However, ERT does not improve neurocognitive function because of its inability to cross the blood-brain barrier. In contrast, allogeneic hematopoietic stem cell transplantation (HSCT) allows donor-derived, enzyme-producing cells to migrate to the brain and other organs to provide permanent enzyme therapy and thus help somatic organs, improve neurocognitive function and quality of life, and prolong survival, particularly when performed early in the course of the disease. Bone marrow has been the graft source in the past. However, in the last 5 years many patients have been treated with unrelated donor (URD) umbilical cord blood transplant (UCBT), allowing rapid and increased access to transplantation with favorable outcomes. This review describes published and our institutional clinical experiences, discusses the current status of the field, and provides therapy guidelines for patients with MPS.

Role of the pediatric otolaryngologist in diagnosis and management of children with mucopolysaccharidoses

OBJECTIVE

Mucopolysaacharidoses (MPS) represent a spectrum of disorders characterized by the genetic deficiency of specific lysosomal enzymes occurring in as many as 1 in 10,000 live births and resulting in the accumulation of glycosaminoglycans within cells throughout the body. Children have highly variable, multi-systemic involvement that nearly always involves manifestations of the head and neck including recurrent otitis, hearing loss, upper airway obstruction, and characteristic coarse facial features. This places the otolaryngologist in a prime position for early recognition and initiation of treatment. We sought to examine our own experience in dealing with this diverse and often quite devastating clinical entity.

METHODS

Retrospective chart review of children with mucopolysaccharidoses seen in our tertiary care pediatric otolaryngology clinic accompanied by review of the literature.

RESULTS

Nine children were identified--five with Hurler syndrome, three with Hunter syndrome, and one with Maroteaux-Lamy syndrome. The median age of diagnosis/genetics referral was 15 months, while median age of presentation to an otolaryngologist was 12 months. Three patients were referred for genetics evaluation based upon initial evaluation/suspicion by an otolaryngologist. Two were diagnosed early because of an affected older sibling. All patients in the series had varying degrees of hearing loss, recurrent otitis, chronic effusions or abnormal facial features, and all patients required placement of at least one set of ventilation tubes.

CONCLUSIONS

Otolaryngologists have an opportunity to play an increasingly integral role in the multidisciplinary approach to the diagnosis and management of many children with mucopolysaccharidoses. Clinical suspicion, early recognition, and prompt diagnosis of these challenging disorders is crucial, as outcomes of treatment in many cases appear time-sensitive, with better results being achieved when intervention is initiated at a younger age or prior to progression of the disease.

Pre-transplant risk factors affecting outcome in Hurler syndrome

Allogeneic transplantation remains the standard of care for patients with Hurler syndrome. As enzyme replacement therapy (ERT) has become available, controversy has emerged in regards to whether the use of enzyme in the peri-transplant period is appropriate. An analysis was performed on 74 patients with Hurler syndrome transplanted at the University of Minnesota between 1990 and 2003, before our use of ERT associated with transplant, with the intention of determining if patients at higher risk during the transplant can be identified based on evaluations and events before transplantation. Age, the presence of hydrocephalus, a history of cardiovascular issues or upper airway obstruction before transplant was not associated with significant differences in survival. In contrast, patients who had a history of lower airway disease, including reactive airway disease or bronchiolitis, or a history of pneumonia, had a significantly inferior outcome based on OS. The risk for serious respiratory complications was also assessed by evaluating the incidence of intubation. Overall, 31% of these patients were intubated. The risk of intubation was higher in older patients and in those with a history of lower airway disease. These findings have implications for the care of patients with high-risk features.

Musculoskeletal complications encountered in the lysosomal storage disorders

The lysosomal storage disorders are a heterogeneous group of inherited metabolic diseases resulting from defects in the degradation or transport of several distinct by-products of cellular turnover. The various subtypes are characterized by multi-systemic involvement; the wide range in patient ages at symptom onset is only partly explained by the underlying mutation(s). Neurodegenerative features and musculoskeletal complications are often seen in the most severe variants, and are features of the disease that have the most significant impact on patients' physical and functional well-being. Until recently, the care of affected individuals relied mainly on palliative or supportive measures. The introduction of therapies directed at correcting the primary defect (i.e., deficient enzyme activity) in several of these disorders has led to modification of the phenotype and natural history or disease course; however, clinical problems arising from brain and bone involvement remain major sources of morbidity. Factors that might influence therapeutic outcome include pre-existing pathology at the time of treatment initiation, drug access to tissues sites of pathology, and - in the case of enzyme therapy - antibody formation. Increasing understanding of the pathogenesis or relevant mechanism(s) of diseases is providing insights into additional therapeutic targets, enabling the potential for optimized patient outcomes with the use of adjunctive or supplemental agents. Physical and occupational therapy remain critical components of a comprehensive approach to patient care.