Physical performance testing in mucopolysaccharidosis I: a pilot study

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.

Timed Floor to Stand-Natural: Reference Data for School Age Children

PURPOSE

To collect reference data for the Timed Floor to Stand-Natural (TFTS-N) on a large, diverse sample of school children who are typically developing, taking into account age, sex, and body mass index (BMI).

METHODS

Five physical therapists administered the TFTS-N on a sample of convenience of 1476 school children who were typically developing, aged 5 to 14 years (male = 637, female = 839), using previously tested, standardized reliable procedures.

RESULTS

The average time ranged from 7.91 ± 1.65 seconds to 8.98 ± 1.62 seconds; 8 year-old students were the quickest and the 13-year-old students were the slowest. The mean difference between males and females was clinically negligible at 0.38 seconds. Post hoc analyses revealed no significant differences among BMI categories.

CONCLUSIONS

Reference data for the TFTS-N test are now available. Neither sex nor BMI affects the timing of the task in this age range.

Reliability and validity of the Timed Floor To Stand Test-Natural in school-aged children

PURPOSE

To establish reliability for the Timed Floor to Stand-Natural (TFTS-N) test as a stand-alone measure for schoolchildren with typical development (TD) in preparation for normative data collection.

METHODS

Five physical therapists working in schools standardized testing procedures for a "natural" pace version of the TFTS. Time data were collected using a repeated-measures design.

RESULTS

Twenty-two students with TD (8 years 7 months to 12 years 7 months; (Equation is included in full-text article.)= 10 years, SD = 1.13) completed the TFTS-N in 6.27 (SD = 0.30) to 8.45 (SD = 0.68) seconds. Intraclass correlation coefficients (ICCs) (3,1) ranged from 0.713 to 0.800 for intrarater reliability and was 0.988 for interrater reliability. The ICC (3,3) was 0.871 for test-retest reliability.

CONCLUSION

The TFTS-N has high intra-, inter-, and test-retest reliability. TFTS-N has face validity as the task frequently occurs in school settings. The test procedures are reliable for trained physical therapists to establish individual baseline measures of schoolchildren with TD.

Isokinetic muscle strength differences in patients with mucopolysaccharidosis I, II, and VI

PURPOSE

To determine muscular strength differences in patients with MPS-I, II, and VI versus age- and sex-matched healthy controls.

METHODS

Dominant leg isokinetic knee extension strength was measured at 90 and 120 degrees per second (d/s) using a dynamometer in 30 subjects with MPS and 42 controls (5-16 yrs). MPS-I was further divided into MPS-IA (attenuated) and MPS-IH (severe). Strength measures analyzed were peak torque (PkT), peak torque per unit body weight (PkT/BW) and per unit lean body mass (PkT/LBM), and average power (AP).

RESULTS

Following adjusting strength measures for age, MPS-IH and MPS-II had significantly lower strength measures for all variables at both angular velocities. MPS-VI had significantly lower PkT, PkT/LBM, and AP compared to controls at 90 and 120d/s. In contrast, MPS-IA was not significantly different from controls for any strength variable at either angular velocity.

CONCLUSION

The results of this study suggest that decrements in skeletal muscle strength depend on MPS diagnosis and severity of disease. Children with MPS-IH demonstrate the greatest difference in muscular strength compared to healthy controls.

The 6-minute walk test and other clinical endpoints in duchenne muscular dystrophy: reliability, concurrent validity, and minimal clinically important differences from a multicenter study

INTRODUCTION

An international clinical trial enrolled 174 ambulatory males ≥5 years old with nonsense mutation Duchenne muscular dystrophy (nmDMD). Pretreatment data provide insight into reliability, concurrent validity, and minimal clinically important differences (MCIDs) of the 6-minute walk test (6MWT) and other endpoints.

METHODS

Screening and baseline evaluations included the 6-minute walk distance (6MWD), timed function tests (TFTs), quantitative strength by myometry, the PedsQL, heart rate-determined energy expenditure index, and other exploratory endpoints.

RESULTS

The 6MWT proved feasible and reliable in a multicenter context. Concurrent validity with other endpoints was excellent. The MCID for 6MWD was 28.5 and 31.7 meters based on 2 statistical distribution methods.

CONCLUSIONS

The ratio of MCID to baseline mean is lower for 6MWD than for other endpoints. The 6MWD is an optimal primary endpoint for Duchenne muscular dystrophy (DMD) clinical trials that are focused therapeutically on preservation of ambulation and slowing of disease progression.

Behavioural phenotypes of the mucopolysaccharide disorders: a systematic literature review of cognitive, motor, social, linguistic and behavioural presentation in the MPS disorders

BACKGROUND

The mucopolysaccharide disorders (MPS) are a group of recessively inherited metabolic disorders resulting in progressive physical and cognitive decline.

MATERIALS AND METHODS

MEDLINE, PsycINFO and Embase databases were searched, alongside manual screening, to identify relevant literature. Papers were included in the review if they were published in a peer reviewed journal and conducted empirical research into cognitive, motor, social or linguistic development or behaviour in one or more MPS disorders.

RESULTS

Twenty-five papers were reviewed. Two papers used methodology of a sufficiently high standard to demonstrate a behavioural phenotype; both found sleep disturbance to be part of the phenotype of MPS III. Fearfulness and sleep disturbance were frequently observed in people with MPS I and II. Cognitive and motor impairment and decline, and challenging behaviour were highly prevalent in the severe form of MPS II. Cognitive decline and severe behavioural problems relating to aggression, hyperactivity, orality, unusual affect and temper tantrums were seen in MPS III.

CONCLUSIONS

Sleep disturbance is part of the behavioural phenotype of MPS III, and challenging behaviour is highly prevalent in MPS II and MPS III, therefore the efficacy of behavioural interventions for these populations should be investigated. Further research into the behaviour and adaptive skills of children with MPS III and MPS IV is required.

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.

Evolução motora de paciente com mucopolissacaridose tipo 1

OBJETIVO: Relatar os aspectos funcionais de uma criança com mucopolissacaridose tipo 1, descrevendo suas principais alterações após breve tratamento fisioterapêutico. DESCRIÇÃO DE CASO: Criança com 34 meses, portadora de mucopolissacaridose tipo 1 iniciou tratamento fisioterapêutico, duas vezes por semana, durante 50 minutos, sendo avaliada mensalmente por meio das atividades propostas pela Escala de Desenvolvimento Motor (EDM), que analisa a motricidade fina e global, o equilíbrio, o esquema corporal e a organização temporal e espacial. Na primeira avaliação, a criança apresentava-se com 34 meses de idade cronológica e 18 meses de idade motora geral, com melhor pontuação no item organização espacial, segundo a EDM. Após quatro meses, a idade motora geral era de 20 meses; porém, houve melhora da motricidade global. COMETÁRIOS: A análise das atividades funcionais do paciente relatado demonstrou atraso no desenvolvimento motor. A intervenção terapêutica possibilitou evolução favorável, principalmente na motricidade global, mesmo tratando-se de um portador de doença evolutiva.

Combined enzyme replacement and haematopoietic stem cell transplantation in Hurler syndrome

We report the long-term follow-up of successful treatment of mucopolysaccharidosis type I H (MPS IH, Hurler syndrome) with combined enzyme replacement therapy and haematopoietic progenitor stem cell transplant.

Mobility in Hurler syndrome

Hurler syndrome is an autosomal recessive metabolic storage disease. Hematopoietic stem cell transplant increases life expectancy, but the effects on associated musculoskeletal abnormalities remains unclear, and long-term data are limited. We detail the follow-up of 23 patients at a mean of 8.5 years after successful hematopoietic stem cell transplant. All patients underwent clinical examination at an annual multidisciplinary clinic. Serial radiological studies were reviewed to assess development and management of hip dysplasia and genu valgum. All patients demonstrated characteristic acetabular dysplasia and failure of ossification of the superolateral femoral head. Eight patients underwent bilateral pelvic and femoral derotation (mean age at surgery, 4.4 years); 4 patients had pelvic osteotomy only. Mean preoperative acetabular angle was 34 degrees. Genu valgum of variable severity due to failure of ossification of the lateral aspect of the proximal tibial metaphysis was observed early, and 6 patients underwent medial epiphyseal stapling, decreasing tibiofemoral angle by a mean of 8 degrees. Clinically, all patients were independently mobile, with restriction of internal hip rotation being the most significant clinical finding. Valgus knees and pronated feet were a typical finding. This cohort represents one of the largest available for study, and ongoing review will clarify the progression of musculoskeletal problems and determine the effectiveness of orthopaedic intervention.

Temporal and spatial gait characteristics of children with Hurler syndrome after umbilical cord blood transplantation

BACKGROUND AND PURPOSE

Recent medical advances are increasing the life expectancy of children with Hurler syndrome; however, little is known about the motor abilities of children who have received these medical interventions. The purpose of this study was to describe the temporal and spatial gait parameters of children with Hurler syndrome following umbilical cord blood transplantation (UCBT) in reference to gait parameters of children with typical development.

SUBJECTS

The group with Hurler syndrome consisted of 18 children between 19.6 and 96.8 months of age who were examined 1 to 4 times between 2.9 and 72.2 months after UCBT. Four hundred thirty-eight children with typical development between the ages of 14.4 and 131.8 months served as a comparison group.

METHODS

Temporal and spatial gait parameters were assessed using a GAITRite electronic walkway. Step length, gait speed, and cadence were normalized for body stature.

RESULTS

Children with Hurler syndrome had slower gait speeds and shorter step lengths than children with typical development at 2 and 3 years of age. Time since transplantation was a predictor of gait speed and step length.

DISCUSSION AND CONCLUSION

Children with Hurler syndrome after UCBT were delayed in maturation of temporal and spatial gait parameters.

Rheumatologic aspects of lysosomal storage diseases

Lysosomal storage diseases are rare metabolic disorders, some of which can now be treated using enzyme replacement therapies. Because the time point of treatment initiation significantly influences the outcome in Gaucher disease, Fabry disease, and mucopolysaccharidosis type I, early diagnosis is of utmost importance. All three disorders can present with musculoskeletal symptoms in early stages, therefore, the rheumatologist may be the first to be contacted by these patients. Here, we present three characteristic lysosomal storage disease cases to increase awareness in the rheumatological community of the typical symptom constellations associated with these rare but treatable disorders.

Limitations of enzyme replacement therapy: current and future

Orphan drug legislation passed in the USA in 1983 and in Europe in 1999 has encouraged biotechnology companies to develop treatments for diseases that the industry previously ignored because they affect only small numbers of people and promised only limited profitability. Incentives, exclusivity and the freedom to charge sufficient to cover development costs has led to a niche market, and patients with lysosomal storage disorders have been one of the main beneficiaries of these developments. The recombinant production of highly purified enzymes that are modified to improve tissue targeting has been a direct result of this legislation. The spectacular clinical and financial success of Cerezyme (and previously Ceredase, Genzyme) for the treatment of Gaucher disease has led to the development of enzyme replacement treatment(s) for Fabry disease and mucopolysaccharidoses types I and VI. A number of other enzyme replacement therapies are at an earlier stage in development and the next 12 months could see the launch of therapies for mucopolysaccharidosis type II and Pompe disease. Like all medical treatments, this approach has some limitations. Not all patients are suitable for treatment, some organs and tissues are corrected more readily than others, and there are problems with gauging efficacy in these highly variable disorders. Finally, the therapies are expensive, limiting access to patients from those countries that are able to afford expensive health care.

The first 5 years of clinical experience with laronidase enzyme replacement therapy for mucopolysaccharidosis I

Mucopolysaccharidosis I (MPS I, McKusick 25280) is caused by the deficiency or absence of the lysosomal enzyme, alpha-L-iduronidase (EC 3.2.1.76). This inherited disease causes progressive cellular, tissue and organ damage across the entire phenotypic spectrum. Disabling, multi-organ disease is the rule, and generally results in death between the first and fourth decades of life. Recently, laronidase (Aldurazyme) [Genzyme], a specific recombinant human alpha-L-iduronidase) became commercially available as long-term enzyme replacement therapy. Results from the Phase I/II and III extended clinical studies have shown that laronidase safely and effectively alleviates many systemic signs and symptoms of this progressive multisystemic disease. Clinically meaningful and sustained improvements in pulmonary function and functional capacity have been observed in Phase III study patients. Significant and sustained reductions in urinary glysosaminoglycan (GAG) excretion and hepatomegaly have also been observed. Improvements in sleep apnoea and joint range of motion occurred in patients with the most severe symptoms at baseline. Improvements in Disability Index scores as measured using the CHAQ and HAQ questionnaires were modest, which may have been related to the fact that these disability measuring tools are not disease-specific. Anecdotal reports of improvements in the performance of daily activities further add to the therapeutic benefits, as do case histories pointing at stabilisation or improvement of symptomatology in various organs, such as the eyes, heart, and muscles. With the availability of specific treatment, the importance of early recognition of the disease and appropriate therapeutic intervention has increased. The variability in clinical symptomatology is reviewed in detail and may allow for a better understanding of the diagnostic and therapeutic challenges. Results of the clinical trials and their initial extension periods, as well as the anecdotal experiences of physicians with laronidase in non-study settings, are discussed.

Musculoskeletal complications associated with lysosomal storage disorders: Gaucher disease and Hurler-Scheie syndrome (mucopolysaccharidosis type I)

PURPOSE OF REVIEW

Enzyme therapy for lysosomal storage disorders directed at correcting the underlying cause of disease represents the most significant recent advance in patient management. This review focuses on two disease groups: glycosphingolipidoses and mucopolysaccharidoses. Specifically, Gaucher disease and Hurler-Scheie syndrome have been selected as the prototypical disorder for each respective class.

RECENT FINDINGS

Musculoskeletal complications are encountered in several of the lysosomal storage disorders and often represent a major source of extraneurologic morbidity, particularly in the subacute or chronic variants. Enzyme therapy has led to improvements in physical and functional well-being. However, bone involvement remains a recalcitrant feature, especially among patients with established disease before institution of therapy.

SUMMARY

Early diagnosis and appropriate timely intervention are critical in achieving the best therapeutic results. A better understanding of the fundamental mechanisms of bone pathology may enable the identification of complementary approaches (eg, the use of bisphosphonates for severe osteopenia) for optimized outcomes. Symptomatic care and rigorous physical and occupational therapy remain critical components of a comprehensive management approach.

The emerging role of the pediatric physical therapist in evaluation and intervention for individuals with lysosomal storage diseases

PURPOSE

The purposes of this article are to describe the pathology, medical implications, and typical impairments of individuals with various lysosomal storage diseases (LSDs), summarize results of recent clinical trials on medical interventions relevant to physical therapy practice, report new advances in functional measurement, and suggest a framework for physical therapy management and intervention.

SUMMARY OF KEY POINTS

Medical and surgical interventions are enabling individuals with LSDs to not only survive but to improve their daily functioning and quality of life. This is likely to become an increasing area of emphasis in pediatric physical therapy, as the intervention emphasis for some individuals will shift from maintenance to restorative programs.

RECOMMENDATIONS

We recommend that pediatric physical therapists become familiar with new LSD therapeutics, play a major role in evaluating impairment and functional limitation changes in individuals with LSDs, and become knowledgeable about the indications and precautions for restorative physical therapy programs.