Chiara Mastella

Survival of Patients With Spinal Muscular Atrophy Type 1

BACKGROUND: Spinal muscular atrophy type 1 (SMA1) is a progressive disease and is usually fatal in the first year of life. METHODS: A retrospective chart review was performed of SMA1 patients and their outcomes according to the following choices: letting nature take its course (NT); tracheostomy and invasive mechanical ventilation (TV); continuous noninvasive respiratory muscle aid (NRA), including noninvasive ventilation; and mechanically assisted cough. RESULTS: Of 194 consecutively referred patients enrolled in this study (103 males, 91 females), NT, TV, and NRA were chosen for 121 (62.3%), 42 (21.7%), and 31 (16%) patients, respectively. Survival at ages 24 and 48 months was higher in TV than NRA users: 95% (95% confidence interval: 81.8%–98.8%) and 67.7% (95% confidence interval: 46.7%–82%) at age 24 months (P < .001) and 89.43% and 45% at age 48 months in the TV and NRA groups, respectively (P < .001). The choice of TV decreased from 50% (1992–1998) to 12.7% (2005–2010) (P < .005) with a nonstatistically significant increase for NT from 50% to 65%. The choice of NRA increased from 8.1% (1999–2004) to 22.7% (2005–2010) (P < .001). CONCLUSIONS: Long-term survival outcome is determined by the choice of the treatment. NRA and TV can prolong survival, with NRA showing a lower survival probability at ages 24 and 48 months.

Bone and Spinal Muscular Atrophy

Spinal Muscular Atrophy (SMA) is an autosomal recessive neuromuscular disease, leading to progressive denervation atrophy in the involved skeletal muscles. Bone status has been poorly studied. We assessed bone metabolism, bone mineral density (BMD) and fractures in 30 children (age range 15-171 months) affected by SMA types 2 and 3. Eighteen children (60%) had higher than normal levels of CTx (bone resorption marker); 25-OH vitamin D was in the lower range of normal (below 20 ng/ml in 9 children and below 12 ng/ml in 2). Lumbar spine BMAD (bone mineral apparent density) Z-score was below -1.5 in 50% of children. According to clinical records, four children had sustained four peripheral fractures; on spine X-rays, we observed 9 previously undiagnosed vertebral fractures in 7 children. There was a significant inverse regression between PTH and 25-OH D levels, and a significant regression between BMC and BMAD values and the scores of motor-functional tests. Even if this study could not establish the pathogenesis of bone derangements in SMA, its main findings - reduced bone density, low 25OH vitamin D levels, increased bone resorption markers and asymptomatic vertebral fractures also in very young patients - strongly suggest that even young subjects affected by SMA should be considered at risk of osteopenia and even osteoporosis and fractures.

Spinal muscular atrophy type 1: Avoidance of hospitalization by respiratory muscle support

Objective: The aim of this study was to report the outcomes of an oximetry protocol using up to continuous full ventilator-setting noninvasive ventilation (NIV) and mechanically assisted coughing (MAC) to avoid episodes of acute respiratory failure and hospitalizations for children with spinal muscular atrophy type 1 under 3 yrs of age. Design: This study was a retrospective chart review of 16 patients with spinal muscular atrophy type 1 under 3 yrs of age consecutively referred for respiratory decompensations resulting in continuous NIV dependence and oxyhemoglobin desaturation. An avoided hospitalization was defined by the need for continuous NIV using high span bilevel positive airway pressure and reversal of desaturations by MAC in the home setting. The protocol included training and equipping parents to use NIV, MAC, and basic life support. Results: There were 49 acute episodes (1.20/patient per year), of which 43 met the criteria for an avoided hospitalization. Therefore, only six episodes (0.15/patient per year) required hospitalization, and four required endotracheal intubation (0.1/patient per year). Three of the four were extubated after 4, 9, and 15 days, respectively, to full NIV support and aggressive MAC. The fourth patient, for whom NIV could not be provided, underwent an emergency intubation at home and died at the age of 40 mos. Conclusions: A protocol including high span bilevel positive airway pressure along with MAC to expel airway secretions and normalize oxyhemoglobin saturation can be used by trained caregivers to avoid episodes of acute respiratory failure and hospitalization for children with spinal muscular atrophy type 1 under 3 yrs of age.

Spontaneous breathing pattern as respiratory functional outcome in children with spinal muscular atrophy (SMA)

Introduction SMA is characterised by progressive motor and respiratory muscle weakness. We aimed to verify if in SMA children 1)each form is characterized by specific ventilatory and thoraco-abdominal pattern(VTAp) during quiet breathing(QB); 2)VTAp is affected by salbutamol therapy, currently suggested as standard treatment, or by the natural history(NH) of SMA; 3)the severity of global motor impairment linearly correlates with VTAp. Materials and methods VTAp was analysed on 32 SMA type I (SMA1,the most severe form), 51 type II (SMA2,the moderate), 8 type III (SMA3,the mildest) and 20 healthy (HC) using opto-electronic plethysmography. Spirometry, cough and motor function were measured in a subgroup of patients. Results In SMA1, a normal ventilation is obtained in supine position by rapid and shallow breathing with paradoxical ribcage motion. In SMA2, ventilation is within a normal range in seated position due to an increased respiratory rate(p<0.05) with reduced tidal volume(p<0.05) secondary to a poor contribution of pulmonary ribcage(%ΔVRC,P, p<0.001). Salbutamol therapy had no effect on VTAp during QB(p>0.05) while tachypnea occurred in type I NH. A linear correlation(p<0.001) was found between motor function scales and VTAp. Conclusion A negative or reduced %ΔVRC,P, indicative of ribcage muscle weakness, is a distinctive feature of SMA1 and SMA2 since infancy. Its quantitative assessment represents a non-invasive, non-volitional index that can be obtained in all children, even uncollaborative, and provides useful information on the action of ribcage muscles that are known to be affected by the disease.Low values of motor function scales indicate impairment of motor but also of respiratory function.

Spinal Muscular Atrophy, types I and II: What are the differences in body composition and resting energy expenditure?

Summary Background & aims Different neuromuscular functional domains in types I and II Spinal Muscular Atrophy (SMAI and SMAII) could lead to differences in body composition (BC) and resting energy expenditure (REE). Their identification could provide the key to defining appropriate strategies in clinical dietary management, but data comparing SMAI and SMAII in terms of BC and REE are not yet available. We measured total and regional fat (FM), lean (LBM), mineral (BMC) masses, body water (total, intra- and extra-cellular, TBW, ICW, ECW) and REE in a sample of SMAI and II children, matched for age and sex, and also adjusting for body size to compare these features of the two SMA phenotypes. Methods 15 SMAI and 15 SMAII children, (M/F = 9/6 vs 9/6, age 3.6 ± 1.9 vs 3.5 ± 1.8 years, p = 0.99), confirmed genetically, were measured as follows: Anthropometric measurements [Body Weight (BW), Supine Length (SL), Arm Length (AL), Femur Length (FL), Tibia Length (TL)], Dual x-ray Energy Absorptiometry (DEXA) [total and segmental FM, LBM, FFM, and BMC], Bioelectrical impedance (BIA) [TBW, ICW, ECW] and Indirect Calorimetry (REE, respiratory quotients) were collected by the same trained dietician. BW, SL and Body Mass Index (BMI) Z-scores were calculated according to CDC Growth Charts (2000). Results SMA children had high percentages of FM and a lower percentage of TBW and ECW compared to the respective reference values for sex and age, whereas the BMC percentages did not differ, even splitting the two phenotypes. SMA I children had a lower BW and BMI-Z score compared to children with SMA II, but similar total and segmental FM. On the contrary, total FFM and LBM were significantly lower in SMAI (7290.0 ± 1729.1 g vs 8410.1 ± 1508.4 g; 6971.8 ± 1637.1 g vs 8041.7 ± 1427.7 g, p = 0.039, p = 0.037, respectively), particularly at the trunk level. Arm BMC also resulted significantly lower in SMAI. The measured REE values were similar (684 ± 143 kcal/day vs 703 ± 122 Kcal/day p = 0.707) whereas REE per FFM unit was higher in SMA I children than in SMA II (95 ± 12 kcal/FFMkg vs 84 ± 11 kcal/FFMkg p = 0.017). Conclusions This study has shown that BW and BMI Z-score measurements alone can be misleading in assessing nutritional status, particularly in SMAI. The differences between SMAI and II in total and regional BC are related only to FFM, LBM and BMC, and seem to be more linked to the magnitude of neurofunctional impairment rather than to the nutritional status derangement. SMA I and SMA II children can have different energy requirements in relation to their specific BC and hypermetabolism of FFM. Based on these results, our recommendation is to use direct BC and REE measurements in the nutritional care process until SMA-specific predictive equations become available.

A New Method for Measuring Bell-Shaped Chest Induced by Impaired Ribcage Muscles in Spinal Muscular Atrophy Children

The involvement of the respiratory muscular pump makes SMA children prone to frequent hospitalization and morbidity, particularly in type 1. Progressive weakness affects ribcage muscles resulting in bell-shaped chest that was never quantified. The aims of the present work were: (1) to quantify the presence of bell-shaped chest in SMA infants and children and to correlate it with the action of ribcage muscles, assessed by the contribution of pulmonary ribcage to tidal volume (ΔVRC, p); (2) to verify if and how the structure of the ribcage and ΔVRC, p change after 1-year in SMA type 2. 91 SMA children were studied in supine position during awake spontaneous breathing: 32 with type 1 (SMA1, median age: 0.8 years), 51 with type 2 (SMA2, 3.7 years), 8 with type 3 (SMA3, 5.4 years) and 20 healthy children (HC, 5.2 years). 14 SMA2 showed negative ΔVRC, p (SMA2px), index of paradoxical inspiratory inward motion. The bell-shaped chest index was defined as the ratio between the distance of the two anterior axillary lines at sternal angle and the distance between the right and left 10th costal cartilage. If this index was < < 1, it indicated bell shape, if ~1 it indicated rectangular shape, while if >> 1 an inverted triangle shape was identified. While the bell-shaped index was similar between HC (0.92) and SMA3 (0.91), it was significantly (p < 0.05) reduced in SMA2 (0.81), SMA2px (0.74) and SMA1 (0.73), being similar between the last two. There was a good correlation (Spearmans rank correlation coefficient, ρ = 0.635, p < 0.001) between ribcage geometry and ΔVRC, p. After 1 year, ΔVRC, p reduced while bell-shaped chest index did not change being significantly lower than HC. The shape of the ribcage was quantified and correlated with the action of ribcage muscles in SMA children. The impaired ribcage muscles function alters the ribcage structure. HC and SMA3 show an almost rectangular ribcage shape, whereas SMA2, SMA2px and SMA1 are characterized by bell-shaped chest. In SMA, therefore, a vicious cycle starts since infancy: the disease progressively affects ribcage muscles resulting in reduced expansion of lung and ribcage that ultimately alters ribcage shape. This puts the respiratory muscles at mechanical disadvantage.

Who Influences Parents’ Decision on Life Support Treatments for Children with Spinal Muscular Atrophy Type 1?

Background: We aimed at assessing the influence of those who are part of the parents’ social network (family, friends and health professionals) when they are making decisions about nutritional and respiratory support treatments for their SMA 1 children. Methods: We prepared a 46-question questionnaire to explore the factors that influence parents’ decisions. The influence of the different persons, the degree of satisfaction with the treatment elected and the consistency between the treatment information and the child’s status were assessed by the parents using a Likert scale of ten (a higher score for a higher influence). Results: The secondary-care physicians have the main influence on parent’s decisions about nutritional support (mean=6.4) and about respiratory support (mean=5.8). This influence is higher among decisions about Percutaneous Endoscopic Gastrostomy (mean=8.0) and among decisions about Tracheostomy Ventilation (mean=8.0). The degree of satisfaction with the chosen treatment is high (mean=7.9), and consistency between information about treatment and development of the illness also has a high score (mean=8.3). The hospital ethics committee was involved in 13.3% of the cases. Conclusions: The secondary-care physician influences parents’ decisions about nutritional and respiratory support, particularly while choosing PEG and TV. The degree of satisfaction is very high regardless of the treatment chosen. The hospital ethics committee is not usually involved in the treatment decisions for SMA1 children. *Correspondence to: Fermín Jesús González-Melado, Pontifical John Paul II Institute for Studies on Marriage and Family, Lateran University, Piazza San Giovanni in Laterano, 4 00120 Vatican City, Rome, Italy, Tel: +34 630-438-796; Fax: +34 924 221 245; E-mail : ferminjgm@hotmail.com

Clinical factors as predictors of survival in spinal muscular atrophy type I

Abstract The aim of this study was to establish whether clinical factors may help to identify subgroups of infants with spinal muscular atrophy (SMA) type I. A questionnaire was retrospectively proposed to 38 families of infants with SMA type I. It included questions regarding possible prenatal and early neonatal signs of motor and/or respiratory weakness, onset and progression of clinical signs, and age at death for those infants who had not survived beyond the age of 30 months. As we also wished to establish whether the severity of onset of clinical signs and their progression are predictors of outcome, and in order to have a homogeneous group, we only included families where the affected child had not received any respiratory support or noninvasive ventilation. In the population of SMA type I patients, statistical analysis of the questionnaire allowed to identify three subgroups of the disease: (1) neonatal SMA; (2) classical SMA type I; (3) SMA intermediate between type I and type II. This would be useful for correct stratification of patient groups and should be considered when establishing inclusion criteria for future trials in SMA type I patients.