Spinal Muscular Atrophy: Survival Pattern and Functional Status

Abstract

ABSTRACT. Objective. Spinal muscular atrophy (SMA) is common. The prevalence of SMA in southern Chinese is 1 in 53 000. The clinical course is variable. The traditional classification of SMA includes age of onset, age of death, achievement of motor milestones, and ambulatory status as criteria. There was a lack of inclusion of the best lifetime functional status of any child with SMA. With the advances in medical care, the life expectancy and ambulatory status of patients with SMA have improved. The objective of this study was to assess the survival pattern, ambulatory status, and functional status of children with SMA.Methods. Patients with SMA were recruited from the neuromuscular clinic of the Duchess of Kent Children's Hospital, which is a university-affiliated hospital, and the Families of SMA in Hong Kong. By September 2002, 102 SMA cases had been registered in the Duchess of Kent Children's Hospital neuromuscular clinic and Families of SMA registry, and 83 patients were analyzed. Among them, 39 were recruited for the administration of Functional Independence Measure for Children (WeeFIM), an assessment tool for functional status that has been previously validated by us for Chinese children. The diagnosis of SMA was made from clinical history, serum muscle enzyme, electromyography, muscle biopsy, and, recently, by molecular studies. In Hong Kong, molecular tests of the survivor motor neuron gene was available since 1995. A total of 36 in our cohort of 83 patients had the diagnosis confirmed with molecular analyses. We adopted the classification of SMA from previous studies in which the criteria were based on the International SMA consortium (1992) with modifications according to the 59th European Neuromuscular Center International Workshops. As only SMA patients with childhood onset were studied, we did not include any type IV patients in our study. Parents were interviewed and records were reviewed for demographic and clinical data, including age of onset, gender, family history, motor milestones, disease progression, loss of motor function, and involvement of respiratory or bulbar muscles. We define the age of disease onset as the age in which the first abnormalities were obvious from the medical records or from the descriptions of the parents about the first signs of weakness, eg, age of achievement of certain motor milestones or loss of functions. For the ambulatory status, we define "being ambulatory" as having the ability to walk for 100 meters, either with assistance such as calipers or walkers or without assistance. Actuarial survival curves were obtained by using the Kaplan-Meier method for calculating survival probabilities and probabilities of remaining ambulatory. The parents or the chief caregivers were interviewed for functional status using WeeFIM at the last registered date in September 2002. The WeeFIM consists of 3 domains: 1) self-care, 2) mobility, and 3) cognition. The self-care domain consists of 8 items, namely eating, grooming, bathing, dressing (upper body), dressing (lower body), ...

Mutational and structural analysis of Japanese patients with mucopolysaccharidosis type II

“…Previous study using the classification according to the severity regarding intelligence and the skeletal findings could suggest the more precise phenotype classification, including an intermediate type (Hiraizumi et al 1989), but it required an experienced examiner. Recently, new disability scores such as the Functional Independence Measure, which can be easily applied by the general physician, have been used to delineate the complex phenotype classification in genetic diseases (Colvin et al 2003;Chung et al 2004). Further molecular investigations with a reliable disability score should be performed to better understand genotype-phenotype correlation for future therapeutic approaches.…”

A modified Hammersmith functional motor scale for use in multi-center research on spinal muscular atrophy

“…On the other hand, functional motor scales may be more appropriate for young children, as motivation for maximum performance need not depend upon comprehension of the purpose of the task. Thus, scales targeted to assess functional ability with disease-specific and strength-specific tasks may have the potential to exceed direct measures of power in sensitivity and reliability [10][11][12]. In addition, functional testing to ascertain efficacy and monitor natural history has value [13,14].…”

“…More recently the EK scale [20] was developed for non-ambulatory patients with Duchenne's muscular dystrophy (DMD) and SMA, the Wee Fim was utilized to quantify function in children with SMA in Hong Kong [11] and the functional research scale for ALS (FRS-ALS) scale was utilized in clinical trials with adult patients with ALS [21,22]. These scales are typically used as primary outcome measures for a treatment trial only when direct measure of power is not possible, though their use as a secondary measure is common [5,6,[23][24][25][26].…”

Rehabilitation Considerations for Children Dependent on Long-Term Mechanical Ventilation

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