Survival in SMA type I: a prospective analysis of 34 consecutive cases

The impact of three SMN2 gene copies on clinical characteristics and effect of disease-modifying treatment in patients with spinal muscular atrophy: a systematic literature review

Objective

To review the clinical characteristics and effect of treatment in patients with spinal muscular atrophy (SMA) and three copies of the SMN2 gene.

Methods

We conducted a literature search in October 2022 to identify English-language clinical research on SMA that included SMN2 copy number according to PRISMA guidelines.

Results

Our search identified 44 studies examining the impact of three SMN2 copies on clinical characteristics (21 on phenotype, 13 on natural history, and 15 on functional status and other signs/symptoms). In children with type I SMA or presymptomatic infants with an SMN1 deletion, three SMN2 copies was associated with later symptom onset, slower decline in motor function and longer survival compared with two SMN2 copies. In patients with SMA type II or III, three SMN2 copies is associated with earlier symptom onset, loss of ambulation, and ventilator dependence compared with four SMN2 copies. Eleven studies examined treatment effects with nusinersen (nine studies), onasemnogene abeparvovec (one study), and a range of treatments (one study) in patients with three SMN2 copies. In presymptomatic infants, early treatment delayed the onset of symptoms and maintained motor function in those with three SMN2 copies. The impact of copy number on treatment response in symptomatic patients is still unclear.

Conclusion

SMN2 copy number is strongly correlated with SMA phenotype in patients with SMN1 deletion, while no correlation was found in patients with an SMN1 mutation. Patients with three SMN2 copies show a highly variable clinical phenotype. Early initiation of treatment is highly effective in presymptomatic patients with three SMN2 copies.

Significant healthcare burden and life cost of spinal muscular atrophy: real-world data

OBJECTIVES

The aim of this study is to quantify the mortality rate, direct healthcare costs, and cumulative life costs of pediatric patients with spinal muscular atrophy (SMA) type 1, type 2, and type 3 born in Hong Kong.

METHODS

Data were collected from genetically confirmed SMA patients born in or after 2000 from the Hospital Authority medical database. Patients were followed up from birth until they died, left Hong Kong, reached 18 years, or initiated disease-modifying treatment. Study outcomes included incidence risks of mortality, cumulative direct medical costs-attendances of special outpatient clinics, emergency department, allied health services, and mean length of stay in hospitals over time. Total direct medical costs were calculated as unit costs multiplied by utilization frequencies of corresponding healthcare services at each age.

RESULTS

Seventy-one patients with SMA were included. Over a median follow-up period of 6 years, the overall incidence rate of death was 5.422/100 person-years (95%CI 3.542-7.945/100 person-years). 67.7% and 11% of deaths occurred in SMA1 and SMA2 groups, respectively. The median age of death was 0.8 years in SMA1 and 10.9 years in SMA2. The mean cumulative direct medical costs in overall SMA, SMA1, SMA2 and SMA3 groups per patient were US$935,570, US$2,393,250, US$413,165, and US$40,735, respectively.

INTERPRETATION

Our results confirmed a significantly raised mortality and extremely high healthcare burden for patients with SMA especially SMA type 1 and 2 without disease-modifying treatment. Study evaluating health and economic impact of newborn screening and early treatment is needed.

Changes in pNFH Levels in Cerebrospinal Fluid and Motor Evolution after the Loading Dose with Nusinersen in Different Types of Spinal Muscular Atrophy

Aim and Objectives: The objective of our retrospective study was to investigate the changes in pNFH levels in cerebrospinal fluid, which is a reliable marker of neuronal damage, after the loading dose of nusinersen in different types of spinal muscular atrophy. Materials and Methods: We analyzed the spinal muscular atrophy types, the number of copies of the SMN2 gene, and the progression of the motor status using specific motor function scales in a group of 38 patients with spinal muscular atrophy types 1, 2, and 3. Results: We found a significant inverse correlation between pNFH levels and patient age, progress on functional motor scales, and nusinersen administration. Our results also revealed that the neurofilament levels in the cerebrospinal fluid were higher in patients with 2 SMN2 copies than those with more than 2 copies, although the association was not statistically significant due to the abnormal distribution of the values. Conclusions: We identified several predictors of favorable evolution under nusinersen treatment, including spinal muscular atrophy type 1, children aged ≤ 30 months, and the presence of only 2 copies of SMN2. Our study provides important insights into the use of pNFH as a biomarker to monitor disease progression and responses to treatment in patients with spinal muscular atrophy.

Base editing rescue of spinal muscular atrophy in cells and in mice

Spinal muscular atrophy (SMA), the leading genetic cause of infant mortality, arises from survival motor neuron (SMN) protein insufficiency resulting from SMN1 loss. Approved therapies circumvent endogenous SMN regulation and require repeated dosing or may wane. We describe genome editing of SMN2, an insufficient copy of SMN1 harboring a C6>T mutation, to permanently restore SMN protein levels and rescue SMA phenotypes. We used nucleases or base editors to modify five SMN2 regulatory regions. Base editing converted SMN2 T6>C, restoring SMN protein levels to wild type. Adeno-associated virus serotype 9-mediated base editor delivery in Δ7SMA mice yielded 87% average T6>C conversion, improved motor function, and extended average life span, which was enhanced by one-time base editor and nusinersen coadministration (111 versus 17 days untreated). These findings demonstrate the potential of a one-time base editing treatment for SMA.

The First Report of Iranian Registry of Patients with Spinal Muscular Atrophy

BACKGROUND

Insufficient amounts of survival motor neuron protein is leading to one of the most disabling neuromuscular diseases, spinal muscular atrophy (SMA). Before the current study, the detailed characteristics of Iranian patients with SMA had not been determined.

OBJECTIVE

To describe the key demographic, clinical, and genetic characteristics of patients with SMA registered in the Iranian Registry of SMA (IRSMA).

METHODS

IRSMA has been established since 2018, and the demographic, clinical, and genetic characteristics of patients with SMA were recorded according to the methods of treat neuromuscular disease (TREAT-NMD) project.

RESULTS

By October 1, 2022, 781 patients with 5q SMA were registered. Of them, 164 patients died, the majority of them had SMA type 1 and died during the first 20 months of life. The median survival of patients with type 1 SMA was 23 months. The consanguinity rate in 617 alive patients was 52.4%, while merely 24.8% of them had a positive family history. The most common type of SMA in live patients was type 3. Morbidities were defined as having scoliosis (44.1%), wheelchair dependency (36.8%), tube feeding (8.1%), and requiring mechanical ventilation (9.9%). Most of the registered patients had a homozygous deletion of SMN1, while the frequency of patients with higher copy numbers of SMN2, was less in more severe types of the disease. Earlier onset of the disease was significantly seen in patients with lower copy numbers of SMN2. The neuronal apoptosis inhibitory protein (NAIP) gene deletion was associated with a higher incidence of more severe types of SMA, higher dependency on ventilators, tube feeding, and earlier onset of the disease.

CONCLUSIONS

The IRSMA is the first established Iranian nationwide registry of patients with SMA. Using this registry, decision-makers, researchers, and practitioners can precisely understand the epidemiology, characteristics, and genetics of patients with SMA in Iran.

An open-label phase 1 clinical trial of the allogeneic side population adipose-derived mesenchymal stem cells in SMA type 1 patients

INTRODUCTION

Spinal muscular atrophy (SMA), an autosomal recessive neurodegenerative disorder of alpha motor neurons of spinal cord associated with progressive muscle weakness and hypotonia, is the most common genetic cause of infant mortality. Although there is few promising treatment for SMA, but the field of translational research is active in it, and stem cell-based therapy clinical trials or case studies are ongoing. Combination of different therapeutic approaches for noncurative treatments may increase their effectiveness and compliance of patients. We present a phase 1 clinical trial in patients with SMA1 who received side population adipose-derived mesenchymal stem cells (SPADMSCs).

METHODS

The intervention group received three intrathecal administrations of escalating doses of SPADMSCs and followed until 24 months or the survival time. The safety analysis was assessed by controlling the side effects and efficacy evaluations performed by the Hammersmith Infant Neurological Examination (HINE), Ballard score, and electrodiagnostic (EDX) evaluation. These evaluations were performed before intervention and at the end of the follow-up.

RESULTS

The treatment was safe and well tolerated, without any adverse event related to the stem cell administration. One of the patients in the intervention group was alive after 24 months of study follow-up. He is a non-sitter 62-month-old boy with appropriate weight gain and need for noninvasive ventilation (NIV) for about 8 h per day. Clinical scores, need for supportive ventilation, and number of hospitalizations were not meaningful parameters in the response of patients in the intervention and control groups. All five patients in the intervention group showed significant improvement in the motor amplitude response of the tibial nerve (0.56mV; p: 0.029).

CONCLUSION

This study showed that SPADMSCs therapy is tolerable and safe with promising efficacy in SMA I. Probably same as other treatment strategies, early intervention will increase its efficacy and prepare time for more injections. We suggest EDX evaluation for the follow-up of treatment efficacy.

Antisense Oligonucleotide Therapies for Neurodegenerative Diseases

Antisense oligonucleotides represent a novel therapeutic platform for the discovery of medicines that have the potential to treat most neurodegenerative diseases. Antisense drugs are currently in development for the treatment of amyotrophic lateral sclerosis, Huntington's disease, and Alzheimer's disease, and multiple research programs are underway for additional neurodegenerative diseases. One antisense drug, nusinersen, has been approved for the treatment of spinal muscular atrophy. Importantly, nusinersen improves disease symptoms when administered to symptomatic patients rather than just slowing the progression of the disease. In addition to the benefit to spinal muscular atrophy patients, there are discoveries from nusinersen that can be applied to other neurological diseases, including method of delivery, doses, tolerability of intrathecally delivered antisense drugs, and the biodistribution of intrathecal dosed antisense drugs. Based in part on the early success of nusinersen, antisense drugs hold great promise as a therapeutic platform for the treatment of neurological diseases.

Population-based analysis of survival in spinal muscular atrophy

OBJECTIVE

To investigate probabilities of survival and its surrogate, that is, mechanical ventilation, in patients with spinal muscular atrophy (SMA).

METHODS

We studied survival in a population-based cohort on clinical prevalence of genetically confirmed, treatment-naive patients with SMA, stratified for best acquired motor milestone (i.e., none: type 1a/b; head control in supine position or rolling: type 1c; sitting independently: type 2a; standing: type 2b; walking: type 3a/b; adult onset: type 4). We also assessed the need for mechanical ventilation as a surrogate endpoint for survival.

RESULTS

We included 307 patients with a total follow-up of 7,141 person-years. Median survival was 9 days in SMA type 1a, 7.7 months in type 1b, and 17.0 years in type 1c. Patients with type 2a had endpoint-free survival probabilities of 74.2% and 61.5% at ages 40 and 60 years, respectively. Endpoint-free survival of SMA types 2b, 3, and 4 was relatively normal, at least within the first 60 years of life. Patients with SMA types 1c and 2a required mechanical ventilation more frequently and from younger ages compared to patients with milder SMA types. In our cohort, patients ventilated up to 12 h/d progressed not gradually, but abruptly, to ≥16 h/d.

CONCLUSIONS

Shortened endpoint-free survival is an important characteristic of SMA types 1 and 2a, but not types 2b, 3, and 4. For SMA types 1c and 2a, the age at which initiation of mechanical ventilation is necessary may be a more suitable endpoint than the arbitrarily set 16 h/d.

Drug treatment for spinal muscular atrophy type I

BACKGROUND

Spinal muscular atrophy (SMA) is caused by a homozygous deletion of the survival motor neuron 1 (SMN1) gene on chromosome 5, or a heterozygous deletion in combination with a point mutation in the second SMN1 allele. This results in degeneration of anterior horn cells, which leads to progressive muscle weakness. By definition, children with SMA type I are never able to sit without support and usually die or become ventilator dependent before the age of two years. There have until very recently been no drug treatments to influence the course of SMA. We undertook this updated review to evaluate new evidence on emerging treatments for SMA type I. The review was first published in 2009 and previously updated in 2011.

OBJECTIVES

To assess the efficacy and safety of any drug therapy designed to slow or arrest progression of spinal muscular atrophy (SMA) type I.

SEARCH METHODS

We searched the Cochrane Neuromuscular Specialised Register, CENTRAL, MEDLINE, Embase, and ISI Web of Science conference proceedings in October 2018. We also searched two trials registries to identify unpublished trials (October 2018).

SELECTION CRITERIA

We sought all randomised controlled trials (RCTs) or quasi-RCTs that examined the efficacy of drug treatment for SMA type I. Included participants had to fulfil clinical criteria and have a genetically confirmed deletion or mutation of the SMN1 gene (5q11.2-13.2). The primary outcome measure was age at death or full-time ventilation. Secondary outcome measures were acquisition of motor milestones, i.e. head control, rolling, sitting or standing, motor milestone response on disability scores within one year after the onset of treatment, and adverse events and serious adverse events attributable to treatment during the trial period. Treatment strategies involving SMN1 gene replacement with viral vectors are out of the scope of this review.

DATA COLLECTION AND ANALYSIS

We followed standard Cochrane methodology.

MAIN RESULTS

We identified two RCTs: one trial of intrathecal nusinersen in comparison to a sham (control) procedure in 121 randomised infants with SMA type I, which was newly included at this update, and one small trial comparing riluzole treatment to placebo in 10 children with SMA type I. The RCT of intrathecally-injected nusinersen was stopped early for efficacy (based on a predefined Hammersmith Infant Neurological Examination-Section 2 (HINE-2) response). At the interim analyses after 183 days of treatment, 41% (21/51) of nusinersen-treated infants showed a predefined improvement on HINE-2, compared to 0% (0/27) of participants in the control group. This trial was largely at low risk of bias. Final analyses (ranging from 6 months to 13 months of treatment), showed that fewer participants died or required full-time ventilation (defined as more than 16 hours daily for 21 days or more) in the nusinersen-treated group than the control group (hazard ratio (HR) 0.53, 95% confidence interval (CI) 0.32 to 0.89; N = 121; a 47% lower risk; moderate-certainty evidence). A proportion of infants in the nusinersen group and none of 37 infants in the control group achieved motor milestones: 37/73 nusinersen-treated infants (51%) achieved a motor milestone response on HINE-2 (risk ratio (RR) 38.51, 95% CI 2.43 to 610.14; N = 110; moderate-certainty evidence); 16/73 achieved head control (RR 16.95, 95% CI 1.04 to 274.84; moderate-certainty evidence); 6/73 achieved independent sitting (RR 6.68, 95% CI 0.39 to 115.38; moderate-certainty evidence); 7/73 achieved rolling over (RR 7.70, 95% CI 0.45 to 131.29); and 1/73 achieved standing (RR 1.54, 95% CI 0.06 to 36.92; moderate-certainty evidence). Seventy-one per cent of nusinersen-treated infants versus 3% of infants in the control group were responders on the Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP INTEND) measure of motor disability (RR 26.36, 95% CI 3.79 to 183.18; N = 110; moderate-certainty evidence). Adverse events and serious adverse events occurred in the majority of infants but were no more frequent in the nusinersen-treated group than the control group (RR 0.99, 95% CI 0.92 to 1.05 and RR 0.70, 95% CI 0.55 to 0.89, respectively; N = 121; moderate-certainty evidence). In the riluzole trial, three of seven children treated with riluzole were still alive at the ages of 30, 48, and 64 months, whereas all three children in the placebo group died. None of the children in the riluzole or placebo group developed the ability to sit, which was the only milestone reported. There were no adverse effects. The certainty of the evidence for all measured outcomes from this study was very low, because the study was too small to detect or rule out an effect, and had serious limitations, including baseline differences. This trial was stopped prematurely because the pharmaceutical company withdrew funding. Various trials and studies investigating treatment strategies other than nusinersen, such as SMN2 augmentation by small molecules, are ongoing.

AUTHORS' CONCLUSIONS

Based on the very limited evidence currently available regarding drug treatments for SMA type 1, intrathecal nusinersen probably prolongs ventilation-free and overall survival in infants with SMA type I. It is also probable that a greater proportion of infants treated with nusinersen than with a sham procedure achieve motor milestones and can be classed as responders to treatment on clinical assessments (HINE-2 and CHOP INTEND). The proportion of children experiencing adverse events and serious adverse events on nusinersen is no higher with nusinersen treatment than with a sham procedure, based on evidence of moderate certainty. It is uncertain whether riluzole has any effect in patients with SMA type I, based on the limited available evidence. Future trials could provide more high-certainty, longer-term evidence to confirm this result, or focus on comparing new treatments to nusinersen or evaluate them as an add-on therapy to nusinersen.

Thoracic circumference: A new outcome measure in spinal muscular atrophy type 1?

Since respiratory insufficiency is the first cause of morbidity and mortality in spinal muscular atrophy type 1 (SMA 1), specific respiratory outcome measures are needed to evaluate changes and assess innovative therapies. In this study, thoracic circumference (TC) was used as a proxy for chest growth and an indirect measurement of respiratory function. The anthropometric parameters including TC and head-circumference (HC) were evaluated from birth to 13 months in 19 infants with SMA 1 and 124 control infants. TC was significantly decreased in the SMA 1 group from the first weeks of life. The control group TC/HC ratio = 1 (± 0.04), and was not found to be associated with age. By contrast, it decreased with time in all infants with SMA 1 and those with a TC/HC ratio <0.85 died within 3 months. TC is a simple measurement that provided an index of chest growth and was used as evidence of early, progressive respiratory failure and under-development of the rib-cage in SMA 1. The TC/HC ratio decreased in all patients over time, reflecting the progression of the disease suggesting that TC/HC ratio could be a new measure for SMA 1 for measuring disease severity and prognosis.

The role of sleep diagnostics and non-invasive ventilation in children with spinal muscular atrophy

Spinal muscular atrophy (SMA) is a degenerative motor neurone disorder causing progressive muscular weakness. Without assisted ventilation or novel therapies, most children with SMA type 1 die before the second year of life due to respiratory failure as the respiratory muscles and bulbar function are severely affected. Active respiratory treatment (mechanically assisted cough, invasive or non-invasive ventilation) has improved survival significantly in recent decades, but often at the cost of becoming ventilator dependent. The advent of a new oligonucleotide based therapy (Nusinersen) has created new optimism for improving motor function. However, the long-term effect on respiratory function is unclear and non-invasive respiratory support will remain an important part of medical management in patients with SMA. This review summarises the existing knowledge about sleep-disordered breathing and respiratory failure in patients with SMA, especially type 1, as well as the evidence of improved outcome and survival in patients treated with non-invasive or invasive ventilation. Practical considerations and ethical concerns are delineated with discussion on how these may be affected by the advent of new therapies such as Nusinersen.

Relationships between long-term observations of motor milestones and genotype analysis results in childhood-onset Japanese spinal muscular atrophy patients

AIM

To clarify the long-term natural history of SMA in Japanese patients by investigating the peak motor milestones of cases 7months through 57years of age, in efforts to contribute to evaluating outcomes of new therapeutic interventions.

METHODS

We sub-classified 112 SMA type I-III cases into type Ia, type Ib, type IIa, type IIb, type IIIa and type IIIb, according to peak motor milestone achieved, and analyzed the SMN1, SMN2 and NAIP genes in relation to clinical subtypes.

RESULTS

In type I cases, there was a significant difference (p<0.0001), depending on whether or not head control was obtained, in the time of ventilation support being required. In type II cases as well, the time at which the ability to maintain the sitting position independently was lost also differed significantly (p<0.01) between those acquiring the ability to sit unaided within eight months after birth and those acquiring this ability after eight months of age. In type III cases, being able versus unable to climb stairs was associated with a significant difference (p=0.02) in the median time until loss of walking independently. Positive correlations were also seen between copy numbers and the clinical severity of SMA.

CONCLUSION

Our long-term results show peak motor milestone evaluations distinguishing between subtypes to be useful not only as outcome measures for assessing treatment efficacy in clinical trials but also for predicting the clinical courses of Japanese SMA patients.

SMN regulation in SMA and in response to stress: new paradigms and therapeutic possibilities

Low levels of the survival of motor neuron (SMN) protein cause the neurodegenerative disease spinal muscular atrophy (SMA). SMA is a pediatric disease characterized by spinal motor neuron degeneration. SMA exhibits several levels of severity ranging from early antenatal fatality to only mild muscular weakness, and disease prognosis is related directly to the amount of functional SMN protein that a patient is able to express. Current therapies are being developed to increase the production of functional SMN protein; however, understanding the effect that natural stresses have on the production and function of SMN is of critical importance to ensuring that these therapies will have the greatest possible effect for patients. Research has shown that SMN, both on the mRNA and protein level, is highly affected by cellular stress. In this review we will summarize the research that highlights the roles of SMN in the disease process and the response of SMN to various environmental stresses.

New insights into SMA pathogenesis: immune dysfunction and neuroinflammation

Spinal muscular atrophy (SMA) is a neuromuscular disorder characterized by motor neuron degeneration, although defects in multiple cell types and tissues have also been implicated. Three independent laboratories recently identified immune organ defects in SMA. We therefore propose a novel pathogenic mechanism contributory to SMA, resulting in higher susceptibility to infection and exacerbated disease progression caused by neuroinflammation. Overall, compromised immune function could significantly affect survival and quality of life of SMA patients. We highlight the recent findings in immune organ defects, their potential consequences on patients, our understanding of neuroinflammation in SMA, and new research hypotheses in SMA pathogenesis.

A Comparative Study of SMN Protein and mRNA in Blood and Fibroblasts in Patients with Spinal Muscular Atrophy and Healthy Controls

Background

Clinical trials to test safety and efficacy of drugs for patients with spinal muscular atrophy (SMA) are currently underway. Biomarkers that document treatment-induced effects are needed because disease progression in childhood forms of SMA is slow and clinical outcome measures may lack sensitivity to detect meaningful changes in motor function in the period of 1–2 years of follow-up during randomized clinical trials.

Objective

To determine and compare SMN protein and mRNA levels in two cell types (i.e. PBMCs and skin-derived fibroblasts) from patients with SMA types 1–4 and healthy controls in relation to clinical characteristics and SMN2 copy numbers.

Materials and methods

We determined SMN1, SMN2-full length (SMN2-FL), SMN2-delta7 (SMN2-Δ7), GAPDH and 18S mRNA levels and SMN protein levels in blood and fibroblasts from a total of 150 patients with SMA and 293 healthy controls using qPCR and ELISA. We analyzed the association with clinical characteristics including disease severity and duration, and SMN2 copy number.

Results

SMN protein levels in PBMCs and fibroblasts were higher in controls than in patients with SMA (p<0.01). Stratification for SMA type did not show differences in SMN protein (p>0.1) or mRNA levels (p>0.05) in either cell type. SMN2 copy number was associated with SMN protein levels in fibroblasts (p = 0.01), but not in PBMCs (p = 0.06). Protein levels in PBMCs declined with age in patients (p<0.01) and controls (p<0.01)(power 1-beta = 0.7). Ratios of SMN2-Δ7/SMN2-FL showed a broad range, primarily explained by the variation in SMN2-Δ7 levels, even in patients with a comparable SMN2 copy number. Levels of SMN2 mRNA did not correlate with SMN2 copy number, SMA type or age in blood (p = 0.7) or fibroblasts (p = 0.09). Paired analysis between blood and fibroblasts did not show a correlation between the two different tissues with respect to the SMN protein or mRNA levels.

Conclusions

SMN protein levels differ considerably between tissues and activity is age dependent in patients and controls. SMN protein levels in fibroblasts correlate with SMN2 copy number and have potential as a biomarker for disease severity.

Disease burden of spinal muscular atrophy in Germany

BACKGROUND

This study aimed at analyzing the economic burden and disease-specific health-related quality of life (HRQOL) of patients with spinal muscular atrophy (SMA) in Germany. SMA is a so far non-curable neuromuscular disease of the anterior nerve cells that causes high rates of morbidity and mortality.

METHODS

In a cross-sectional study we analyzed the cost of illness (COI) and factors that influence the direct, indirect and informal care costs of affected patients and their families by using standardized, self-developed questionnaires. We used the PedsQL™(©) Measurement Model to analyze the disease-specific HRQOL of patients.

RESULTS

One hundred eighty nine patients with SMA types I to III aged <1 to 73 years were enrolled. The average annual COI was estimated at €70,566 per patient in 2013. The highest cost resulted in SMA I with significant lower costs for the milder phenotypes. Inversely, the self-estimated HRQOL increased from SMA I to SMA III. Major cost drivers were informal care cost and indirect cost incurred by patients and their caregivers.

CONCLUSIONS

Although SMA requires high standards of care, there has been a distinct lack of health services research on SMA. Accordingly, our results significantly contribute to a more comprehensive insight into the current burden of SMA and quality of life status as related to SMA health services in Germany. In the light of innovative therapeutic interventions, our results suggest a notable potential for a reduction in overall COI and improvement of HRQOL if the therapeutic intervention leads to a less severe course of the disease.

[Multicentric study of medical care and practices in spinal muscular atrophy type 1 over two 10-year periods]

AIM

Questions about care practices and the role of palliative care in pediatric neurodegenerative diseases have led the Neuromuscular Committee of the French Society of Neurology to conduct a retrospective study in spinal muscular atrophy type 1, a genetic disease most often leading to death before the age of 1 year.

MATERIAL AND METHODS

A retrospective multicenter study from pediatricians included in the reference centers of pediatric neuromuscular diseases was carried out on two 10-year periods (1989-1998 and 1999-2009).

RESULTS

The 1989-1998 period included 12 centers with 106 patients, the 1999-2009 period 13 centers with 116 children. The mean age of onset of clinical signs was 2.1 months (range, 0-5.5 months), the median age at diagnosis was 4 months (range, 0-9 months) vs 3 months. The median age of death was 7.5 months (range, 0-24 months) vs 6 months. The care modalities included physiotherapy (90 %), motor support (61 % vs 26 % for the previous period), enteral nutrition by nasogastric tube (52 % vs 24 %), and 3.4 % of children had a gastrostomy (vs 1.8 %). At home, pharyngeal aspiration was used in 64 % (vs 41 %), oxygen therapy in 8 %, noninvasive ventilatory support in 7 %. The mean age at death was 8.1 months (range, 0-24 months) vs 7 months, the time from diagnosis to death was 4 months vs 3 months. Death occurred at home in 23 % vs 17 %, in a pediatric unit in 62 % vs 41 %. The use of analgesics and sedative drugs was reported in 60 % of cases: 40 % morphine (vs 18 %) and benzodiazepines in 48 % (vs 29 %). Respiratory support was limited mostly to oxygen by nasal tube (55 % vs 54 %), noninvasive ventilation in 9 % of the cases, and intubation and assisted mechanical ventilation (2 %).

DISCUSSION AND CONCLUSION

These results confirm a change in practices and the development of palliative care in children with a French consensus of practices quite different from the standard care in North-America and closer to the thinking of English medical teams. A prospective study within the 2011 national hospital clinical research program (PHRC 2011) is beginning in order to evaluate practices and the role of families and caregivers.

Clinical decision making in hypotonia and gross motor delay: a case report of type 1 spinal muscular atrophy in an infant

BACKGROUND AND PURPOSE

Children often are referred for physical therapy with the diagnosis of hypotonia when the definitive cause of hypotonia is unknown. The purpose of this case report is to describe the clinical decision-making process using the Hypothesis-Oriented Algorithm for Clinicians II (HOAC II) for an infant with hypotonia and gross motor delay.

CASE DESCRIPTION

The patient was a 5-month-old infant who had been evaluated by a neurologist and then referred for physical therapy by his pediatrician. Physical therapist evaluation results and clinical observations of marked hypotonia, significant gross motor delay, tongue fasciculations, feeding difficulties, and respiratory abnormalities prompted necessary referral to specialists. Recognition of developmental, neurologic, and respiratory abnormalities facilitated clinical decision making for determining the appropriate physical therapy plan of care.

OUTCOMES

During the brief episode of physical therapy care, the patient was referred to a feeding specialist and diagnosed with pharyngeal-phase dysphasia and mild aspiration. Continued global weakness, signs and symptoms of type 1 spinal muscular atrophy (SMA), and concerns about increased work of breathing and respiratory compromise were discussed with the referring physician. After inconclusive laboratory testing for metabolic etiologies of hypotonia, a genetics consult was recommended and confirmed the diagnosis of type 1 SMA at 9 months of age.

DISCUSSION

Physical therapists use clinical decision making to determine whether to treat patients or to refer them to other medical professionals. Accurate and timely referral to appropriate specialists may assist families in obtaining a diagnosis for their child and guide necessary interventions. In the case of type 1 SMA, early diagnosis may affect outcomes and survival rate in this pediatric population.

Spinal muscular atrophies

Spinal muscular atrophies (SMA) are genetic disorders characterized by degeneration of lower motor neurons. The most frequent form is caused by mutations of the survival motor neuron 1 gene (SMN1). The identification of this gene greatly improved diagnostic testing and family-planning options of SMA families. SMN plays a key role in metabolism of RNA. However, the link between RNA metabolism and motor neuron degeneration remains unknown. A defect in mRNA processing likely generates either a loss of function of some critical RNA or abnormal transcripts with toxic property for motor neurons. Mutations of SMN in various organisms highlighted an essential role of SMN in motor axon and neuromuscular junction development or maintenance. The quality of life of patients has greatly improved over recent decades through the improvement of care and management of patients. In addition, major advances in translational research have been made in the field of SMA. Various therapeutic strategies have been successfully developed aiming at acting on SMN2, a partially functional copy of the SMN1 gene which remains present in patients. Drugs have been identified and some are already at preclinical stages. Identifying molecules involved in the SMA degenerative process should represent additional attractive targets for therapeutics in SMA.

Pathophysiological insights derived by natural history and motor function of spinal muscular atrophy

OBJECTIVE

To examine the natural history of spinal muscular atrophy (SMA) to gain further insight into the clinical course and pathogenesis.

STUDY DESIGN

Survival pattern, age of onset, and ambulatory status were retrospectively analyzed in 70 patients with SMA with deletions of the survival motor neuron 1 genes that presented to a specialized neuromuscular clinic. The Kaplan-Meier method was used to obtain survival curves. Hammersmith Functional Motor Scale-Expanded and abductor pollicis brevis compound muscle action potential amplitudes were assessed in 25 of the surviving cohort and correlated with survival motor neuron 2 copy number.

RESULTS

Survival probabilities at ages 1, 2, 4, 10, 20, and 40 years were 40%, 25%, 6%, and 0%, respectively, for patients with SMA type 1; 100%, 100%, 97%, 93%, 93%, and 52% for patients with SMA type 2 and all patients with SMA type 3 were alive (age range 7-33 years). There were significant associations between age of onset and long-term outcome, specifically survival in SMA type 1 (P < .01) and Hammersmith Functional Motor Scale-Expanded (P < .0001), and compound muscle action potential (P = .001) in SMA types 2 and 3. Motor function in patients with long-standing SMA reduced over prolonged periods or remained stable. Survival motor neuron 2 copy number related to continuing changes in motor function with age.

CONCLUSION

The natural history of SMA suggests considerable early loss of motor neurons, with severity related to differences in the number of remaining motor neurons. As the ensuing chronic course in milder phenotypes suggests relative stability of remaining motor neurons, the maximal therapeutic window presents early.

Age at disease onset predicts likelihood and rapidity of growth failure among infants and young children with spinal muscular atrophy types 1 and 2

Growth failure is nearly universal in spinal muscular atrophy type 1 and common in type 2, although acuity is often underappreciated at initial diagnosis. We reviewed 44 consecutive spinal muscular atrophy patients (28 type 1, 16 type 2) under 3 years at initial presentation. Growth failure was conventionally defined: weight below the fifth percentile or dropping 2 major percentiles over 6 months. Growth failure differed among subjects stratified by age at disease onset using the Kaplan-Meier method (P = 0.011). Median time to growth failure among subjects with onset between 0 to 3 months of age was 5 months; Only 1 of 22 avoided failure by 22 months of age. Median time to failure with disease onset between 4 to 6 months was 15 months. Most late onset (> 6 months) subjects avoided growth failure. Early clinical symptoms predict feeding dysfunction and growth failure. Immediate, proactive nutritional intervention is indicated for patients with early symptom onset.

International survey of physician recommendation for tracheostomy for Spinal Muscular Atrophy Type I

The ethics of invasive mechanical ventilation for children with the neurodegenerative disease Spinal Muscular Atrophy Type I (SMA I) is highly debated, and wide variability in clinical outcomes exists internationally. We conducted this international survey to identify physician characteristics associated with recommendation for tracheostomy and ventilation for SMA I. A cross-sectional online survey was distributed to 1,772 pediatric pulmonologists and pediatric intensivists from online membership directories of American Thoracic Society, American College of Chest Physicians, and European Respiratory Society. Questions explored physician demographics, attitudes and experience with SMA and end-of-life care, knowledge of consensus guidelines, and recommendations for respiratory care of SMA I. A logistic regression model assessed the independent effects of physician variables on the recommendation for invasive ventilation for SMA I. A total of 367 (21%) physicians completed the survey; 82% were pediatric pulmonologists; and 16% pediatric intensivists. Seventy percent of respondents were from the U.S. Fifty percent of physicians were aware of SMA consensus guidelines. Physicians from Commonwealth countries (U.K., Canada, Australia, etc.) were less likely to recommend tracheostomy/ventilation than U.S. physicians (7% vs. 25%, P = 0.005). Logistic regression modeling identified years of experience, pediatric pulmonology specialty, agreement with a pro-life statement, and recommendation for non-invasive ventilation as predictive of recommendation for long-term invasive ventilation for SMA I. In the largest international survey on this topic, we identified regional differences in physician recommendation for invasive ventilation for children with SMA I. Our data demonstrate a need for increased awareness of consensus guidelines and further dialog about the physician role in variability of care for children with SMA I.

Spinal muscular atrophy type 1: are proactive respiratory interventions associated with longer survival?

CONTEXT

Spinal muscular atrophy type 1, an autosomal recessive motor neuron disease, is a leading genetic cause of death in infancy and early childhood.

OBJECTIVE

To determine whether the early initiation of noninvasive respiratory interventions is associated with longer survival.

DESIGN

Single-institution retrospective cohort study identified children with spinal muscular atrophy type 1 from January 1, 2002 to May 1, 2009 who were followed for 2.3 mean yrs.

SETTING

Tertiary care children's hospital and outpatient clinics in a vertically integrated healthcare system.

PATIENTS OR OTHER PARTICIPANTS

Forty-nine children with spinal muscular atrophy type 1 were grouped according to the level of respiratory support their caregivers chose within the first 3 months after diagnosis: proactive respiratory care (n = 26) and supportive care (n = 23).

INTERVENTIONS

Proactive respiratory care included bilevel noninvasive ventilation during sleep and twice a day cough assist while supportive respiratory care included suctioning, with or without supplemental oxygen.

MEASUREMENTS AND MAIN RESULTS

Kaplan-Meier survival curves were assessed based on intention to treat. Children treated with early proactive respiratory support had statistically longer survival compared to supportive care (log rank 0.047); however, the adjusted hazard ratio for survival was not statistically different (2.44 [95% confidence interval 0.84-7.1]). Children in the proactive group were more likely to be hospitalized for respiratory insufficiency (83% vs. 46%) and had shortened time after diagnosis until first hospital admission for respiratory insufficiency (median 118 vs. 979 days).

CONCLUSION

Longer survival time with spinal muscular atrophy type 1 is associated with early, noninvasive respiratory care interventions after diagnosis.

Drug treatment for spinal muscular atrophy types II and III

BACKGROUND

Spinal muscular atrophy (SMA) is caused by degeneration of anterior horn cells, which leads to progressive muscle weakness. Children with SMA type II do not develop the ability to walk without support and have a shortened life expectancy, whereas children with SMA type III develop the ability to walk and have a normal life expectancy. There are no known efficacious drug treatments that influence the disease course of SMA. This is an update of a review first published in 2009.

OBJECTIVES

To evaluate whether drug treatment is able to slow or arrest the disease progression of SMA types II and III and to assess if such therapy can be given safely. Drug treatment for SMA type I is the topic of a separate updated Cochrane review.

SEARCH METHODS

We searched the Cochrane Neuromuscular Disease Group Specialized Register (8 March 2011), Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2011, Issue 1), MEDLINE (January 1991 to February 2011), EMBASE (January 1991 to February 2011) and ISI Web of Knowledge (January 1991 to March 8 2011). We also searched clinicaltrials.gov to identify as yet unpublished trials (8 March 2011).

SELECTION CRITERIA

We sought all randomised or quasi-randomised trials that examined the efficacy of drug treatment for SMA types II and III. Participants had to fulfil the clinical criteria and have a deletion or mutation of the survival motor neuron 1 (SMN1) gene (5q11.2-13.2) that was confirmed by genetic analysis.The primary outcome measure was to be change in disability score within one year after the onset of treatment. Secondary outcome measures within one year after the onset of treatment were to be change in muscle strength, ability to stand or walk, change in quality of life, time from the start of treatment until death or full time ventilation and adverse events attributable to treatment during the trial period.

DATA COLLECTION AND ANALYSIS

Two authors independently reviewed and extracted data from all potentially relevant trials. Pooled relative risks and pooled standardised mean differences were to be calculated to assess treatment efficacy. Risk of bias was systematically analysed.

MAIN RESULTS

Six randomised placebo-controlled trials on treatment for SMA types II and III were found and included in the review: the four in the original review and two trials added in this update. The treatments were creatine (55 participants), phenylbutyrate (107 participants), gabapentin (84 participants), thyrotropin releasing hormone (9 participants), hydroxyurea (57 participants), and combination therapy with valproate and acetyl-L-carnitine (61 participants). None of these studies were completely free of bias. All studies had adequate blinding, sequence generation and reports of primary outcomes.None of the included trials showed any statistically significant effects on the outcome measures in participants with SMA types II and III. One participant died due to suffocation in the hydroxyurea trial and one participant died in the creatine trial. No participants in any of the other four trials died or reached the state of full time ventilation. Serious side effects were infrequent.

AUTHORS' CONCLUSIONS

There is no proven efficacious drug treatment for SMA types II and III.

Drug treatment for spinal muscular atrophy type I

BACKGROUND

Spinal muscular atrophy (SMA) is caused by degeneration of anterior horn cells of the spinal cord, which leads to progressive muscle weakness. Children with SMA type I will never be able to sit without support and usually die by the age of two years. There are no known efficacious drug treatments that influence the course of the disease. This is an update of a review first published in 2009.

OBJECTIVES

To evaluate whether drug treatment is able to slow or arrest the disease progression of SMA type I, and to assess if such therapy can be given safely. Drug treatment for SMA types II and III is the topic of a separate updated Cochrane review.

SEARCH METHODS

We searched the Cochrane Neuromuscular Disease Group Specialized Register (8 March 2011), CENTRAL (The Cochrane Library 2011, Issue 1), MEDLINE (January 1991 to February 2011), EMBASE (January 1991 to February 2011) and ISI Web of Knowledge (January 1991 to 8 March 2011). We searched the Clinical Trials Registry of the U.S. National Institute of Health (www.ClinicalTrials.gov) (8 March 2011) to identify additional trials that had not yet been published.

SELECTION CRITERIA

We sought all randomised or quasi-randomised trials that examined the efficacy of drug treatment for SMA type I. Participants had to fulfil the clinical criteria and have a deletion or mutation of the SMN1 gene (5q11.2-13.2) confirmed by genetic analysis.The primary outcome measure was time from birth until death or full time ventilation. Secondary outcome measures were development of rolling, sitting or standing within one year after the onset of treatment, and adverse events attributable to treatment during the trial period.

DATA COLLECTION AND ANALYSIS

Two authors (RW and AV) independently reviewed and extracted data from all potentially relevant trials. For included studies, pooled relative risks and standardised mean differences were to be calculated to assess treatment efficacy.

MAIN RESULTS

One small randomised controlled study comparing riluzole treatment to placebo for 10 SMA type 1 children was identified and included in the original review. No further trials were identified for the update in 2011. Regarding the primary outcome measure, three of seven children treated with riluzole were still alive at the ages of 30, 48 and 64 months, whereas all three children in the placebo group died; but the difference was not statistically significant. Regarding the secondary outcome measures, none of the children in the riluzole or placebo group developed the ability to roll, sit or stand, and no adverse effects were observed. For several reasons the overall quality of the study was low, mainly because the study was too small to detect an effect and because of baseline differences. Follow-up of the 10 included children was complete.

AUTHORS' CONCLUSIONS

No drug treatment for SMA type I has been proven to have significant efficacy.

Demographic characteristics of SMA type 1 patients at a tertiary center in Turkey

The aim of this study was to demonstrate demographics of 39 consecutive Spinal Muscular Atrophy (SMA) type 1 patients diagnosed genetically in a tertiary center between June 2006 and June 2009. There was history of consanguineous marriage in 27 (69%) patients. The average patient lifespan was 251 days (30-726 days). The average patient age at diagnosis was 129 days (33-297 days). A statistically significant correlation was found between the age at diagnosis and the lifespan (p = 0.00). No significant correlation was found between the time spent in intensive care and the lifespan (p = 0.43). Routine physical therapy was found to have no significant impact on the lifespan average (p = 0.17). The cause of death in all of our patients was respiratory issues. Genetic counseling was given to 35 families. A second child with SMA was born in three out of the 14 families who declined prenatal diagnosis.

CONCLUSION

A national program is needed in Turkey for SMA prevention and creation of expert teams for the management of these patients.

Drug treatment for spinal muscular atrophy type I

BACKGROUND

Spinal muscular atrophy (SMA) is caused by degeneration of anterior horn cells of the spinal cord, which leads to progressive muscle weakness. Children with SMA type I will never be able to sit without support and usually die by the age of two years. There are no known efficacious drug treatments that influence the course of the disease. This is an update of a review first published in 2009.

OBJECTIVES

To evaluate whether drug treatment is able to slow or arrest the disease progression of SMA type I, and to assess if such therapy can be given safely. Drug treatment for SMA types II and III is the topic of a separate updated Cochrane review.

SEARCH METHODS

We searched the Cochrane Neuromuscular Disease Group Specialized Register (8 March 2011), CENTRAL (The Cochrane Library 2011, Issue 1), MEDLINE (January 1991 to February 2011), EMBASE (January 1991 to February 2011) and ISI Web of Knowledge (January 1991 to 8 March 2011). We searched the Clinical Trials Registry of the U.S. National Institute of Health (www.ClinicalTrials.gov) (8 March 2011) to identify additional trials that had not yet been published.

SELECTION CRITERIA

We sought all randomised or quasi-randomised trials that examined the efficacy of drug treatment for SMA type I. Participants had to fulfil the clinical criteria and have a deletion or mutation of the SMN1 gene (5q11.2-13.2) confirmed by genetic analysis.The primary outcome measure was time from birth until death or full time ventilation. Secondary outcome measures were development of rolling, sitting or standing within one year after the onset of treatment, and adverse events attributable to treatment during the trial period.

DATA COLLECTION AND ANALYSIS

Two authors (RW and AV) independently reviewed and extracted data from all potentially relevant trials. For included studies, pooled relative risks and standardised mean differences were to be calculated to assess treatment efficacy.

MAIN RESULTS

One small randomised controlled study comparing riluzole treatment to placebo for 10 SMA type 1 children was identified and included in the original review. No further trials were identified for the update in 2011. Regarding the primary outcome measure, three of seven children treated with riluzole were still alive at the ages of 30, 48 and 64 months, whereas all three children in the placebo group died; but the difference was not statistically significant. Regarding the secondary outcome measures, none of the children in the riluzole or placebo group developed the ability to roll, sit or stand, and no adverse effects were observed. For several reasons the overall quality of the study was low, mainly because the study was too small to detect an effect and because of baseline differences. Follow-up of the 10 included children was complete.

AUTHORS' CONCLUSIONS

No drug treatment for SMA type I has been proven to have significant efficacy.

Drug treatment for spinal muscular atrophy types II and III

BACKGROUND

Spinal muscular atrophy (SMA) is caused by degeneration of anterior horn cells, which leads to progressive muscle weakness. Children with SMA type II do not develop the ability to walk without support and have a shortened life expectancy, whereas children with SMA type III develop the ability to walk and have a normal life expectancy. There are no known efficacious drug treatments that influence the disease course of SMA. This is an update of a review first published in 2009.

OBJECTIVES

To evaluate whether drug treatment is able to slow or arrest the disease progression of SMA types II and III and to assess if such therapy can be given safely. Drug treatment for SMA type I is the topic of a separate updated Cochrane review.

SEARCH METHODS

We searched the Cochrane Neuromuscular Disease Group Specialized Register (8 March 2011), Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2011, Issue 1), MEDLINE (January 1991 to February 2011), EMBASE (January 1991 to February 2011) and ISI Web of Knowledge (January 1991 to March 8 2011). We also searched clinicaltrials.gov to identify as yet unpublished trials (8 March 2011).

SELECTION CRITERIA

We sought all randomised or quasi-randomised trials that examined the efficacy of drug treatment for SMA types II and III. Participants had to fulfil the clinical criteria and have a deletion or mutation of the survival motor neuron 1 (SMN1) gene (5q11.2-13.2) that was confirmed by genetic analysis.The primary outcome measure was to be change in disability score within one year after the onset of treatment. Secondary outcome measures within one year after the onset of treatment were to be change in muscle strength, ability to stand or walk, change in quality of life, time from the start of treatment until death or full time ventilation and adverse events attributable to treatment during the trial period.

DATA COLLECTION AND ANALYSIS

Two authors independently reviewed and extracted data from all potentially relevant trials. Pooled relative risks and pooled standardised mean differences were to be calculated to assess treatment efficacy. Risk of bias was systematically analysed.

MAIN RESULTS

Six randomised placebo-controlled trials on treatment for SMA types II and III were found and included in the review: the four in the original review and two trials added in this update. The treatments were creatine (55 participants), phenylbutyrate (107 participants), gabapentin (84 participants), thyrotropin releasing hormone (9 participants), hydroxyurea (57 participants), and combination therapy with valproate and acetyl-L-carnitine (61 participants). None of these studies were completely free of bias. All studies had adequate blinding, sequence generation and reports of primary outcomes.None of the included trials showed any statistically significant effects on the outcome measures in participants with SMA types II and III. One participant died due to suffocation in the hydroxyurea trial and one participant died in the creatine trial. No participants in any of the other four trials died or reached the state of full time ventilation. Serious side effects were infrequent.

AUTHORS' CONCLUSIONS

There is no proven efficacious drug treatment for SMA types II and III.

Insights into genotype-phenotype correlations in spinal muscular atrophy: a retrospective study of 103 patients

Spinal muscular atrophy (SMA) is an autosomal recessive disorder associated with homozygous deletion of the survival motor neuron 1 gene (SMN1). Its centromeric copy gene, SMN2, is the major modifying factor. However, the genotype-phenotype correlation is incomplete and is therefore not useful in clinical practice. We studied a cohort of 103 patients in order to refine this correlation. In addition to standard disease severity data, we collected three additional criteria: age at death; brainstem involvement; and loss of ambulation. Gene dosage analysis was conducted by multiplex ligation-dependent probe amplification (MLPA). SMN2 copynumber was highly correlated with survival duration in SMA type I and ambulation conservation or loss in type III. Among SMA severity groups, it was not significantly different in cases with brainstem involvement. Although the SMN2 copynumber could provide prognostic indications, clinical discrepancies still exist among patients, suggesting the existence of unidentified modifying factors.

Survival analysis of spinal muscular atrophy type I

Purpose

The life expectancy of patients with spinal muscular atrophy (SMA) type I is generally considered to be less than 2 years. Recently, with the introduction of proactive treatments, a longer survival and an improved survival rate have been reported. In this study, we analyzed the natural courses and survival statistics of SMA type I patients and compared the clinical characteristics of the patients based on their survival periods.

Methods

We reviewed the medical records of 14 pediatric patients diagnosed with SMA type I during a 9-year period. We examined the demographic and clinical characteristics of these patients, calculated their survival probabilities, and plotted survival curves as on the censoring date, January 1, 2010. We also compared the characteristics of the patients who died before the age of 24 months (early-death, ED group) and those who survived for 24 months or longer (long-survival, LS group).

Results

The mean survival time was 22.8±2.0 months. The survival probabilities at 6 months, 12 months, 18 months, 24 months, and 30 months were 92.9%, 92.9%, 76.0%, 76.0%, and 65.1%, respectively. Birth weight was the only factor that showed a statistically significant difference between the ED and LS groups (P=0.048).

Conclusion

In this study, the survival probabilities at 2 years were far greater than expected. Because of the limited number of patients and information in this study, the contribution of improved supportive care on longer survival could not be clarified; this may be elucidated in larger cohort studies.

Drug treatment for spinal muscular atrophy types II and III

BACKGROUND

Spinal muscular atrophy (SMA) is caused by degeneration of anterior horn cells, which leads to progressive muscle weakness. Children with SMA type II do not develop the ability to walk without support and have a shortened life expectancy, whereas children with SMA type III develop the ability to walk and have a normal life expectancy. There are no known efficacious drug treatments that influence the disease course of SMA.

OBJECTIVES

To evaluate if drug treatment is able to slow or arrest the disease progression of SMA type II and III, and to assess if such therapy can be given safely. Drug treatment for SMA type I will be the topic of a separate Cochrane review.

SEARCH STRATEGY

We searched the Cochrane Neuromuscular Disease Group Trials Register (September 30 2008), The Cochrane Library (Issue 3, 2008), MEDLINE (January 1966 to June 2008), EMBASE (January 1980 to June 2008), ISI (January 1988 to June 2008), and ACP Journal Club (January 1991 to June 2008).

SELECTION CRITERIA

We sought all randomized or quasi-randomized trials that examined the efficacy of drug treatment for SMA type II and III. Participants had to fulfil the clinical criteria and, in studies including genetic analysis to confirm the diagnosis, have a deletion or mutation of the SMN1 gene (5q11.2-13.2)The primary outcome measure was to be change in disability score within one year after the onset of treatment. Secondary outcome measures within one year after the onset of treatment were to be change in muscle strength, ability to stand or walk, change in quality of life, time from the start of treatment until death or full time ventilation, and adverse events attributable to treatment during the trial period.

DATA COLLECTION AND ANALYSIS

Two authors independently reviewed and extracted data from all potentially relevant trials. Pooled relative risks and pooled weighted standardized mean differences were to be calculated to assess treatment efficacy

MAIN RESULTS

Four randomized placebo-controlled trials on treatment for SMA type II and III were found and included in the review. The treatments were creatine, phenylbutyrate, gabapentin and thyrotropin releasing hormone. None of these trials showed any effect on the outcome measures in patients with SMA type II and III. None of the patients in any of the four trials died or reached the state of full time ventilation and serious side effects were infrequent.

AUTHORS' CONCLUSIONS

There is no proven efficacious drug treatment for SMA type II and III.

Drug treatment for spinal muscular atrophy type I

BACKGROUND

Spinal muscular atrophy (SMA) is caused by degeneration of anterior horn cells, which leads to progressive muscle weakness. Children with SMA type I will never be able to sit without support and usually die by the age of two years. There are no known efficacious drug treatments that influence the disease course.

OBJECTIVES

To evaluate if drug treatment is able to slow or arrest the disease progression of SMA type I, and to assess if such therapy can be given safely. Drug treatment for SMA type II and III will be will be the topic of a separate Cochrane review.

SEARCH STRATEGY

We searched the Cochrane Neuromuscular Disease Group Trials Register (September 30 2008, The Cochrane Library (Issue 3, 2008), MEDLINE (January 1966 to June 2008), EMBASE (January 1980 to June 2008), ISI (January 1988 to June 2008), and ACP Journal Club (January 1991 to June 2008).

SELECTION CRITERIA

All randomized or quasi-randomized trials that examined the efficacy of drug treatment for SMA type 1 were sought. Participants had to fulfil clinical criteria and, in studies including genetic analysis to confirm the diagnosis, have a deletion or mutation of the SMN1 gene (5q11.2-13.2)The primary outcome measure was to be time from birth until death or full time ventilation. Secondary outcome measures were to be development of rolling, sitting or standing within one year after the onset of treatment, and adverse events attributable to treatment during the trial period.

DATA COLLECTION AND ANALYSIS

Two authors (WB and AV) independently reviewed and extracted data from all potentially relevant trials. For included studies pooled relative risks and pooled weighted standardized mean differences were to be calculated to assess treatment efficacy

MAIN RESULTS

One small randomized-controlled study comparing riluzole treatment to placebo for SMA type 1 was identified and included in the review. Regarding the primary outcome measure three of seven children treated with riluzole were still alive at the age of 30, 48 and 64 months, whereas all three children in the placebo group died, but the difference was not statistically significant. Regarding the secondary outcome measures none of the patients in the riluzole or placebo group developed the ability to roll, sit or stand, and no adverse effects were observed.

AUTHORS' CONCLUSIONS

No drug treatment for SMA type I has been proven to have significant efficacy.