乌鸦传媒

Evidence has demonstrated that disease-modifying pharmacotherapeutic treatments (DMTs) can stabilize and improve motor function in people with spinal muscular atrophy (SMA), depending in part on the extent of pretreatment symptoms and the patient鈥檚 age at the start of therapy.^1-3 The potential of DMTs to preserve motor neurons and slow disease progression has created an opportunity for neuromotor habilitation to improve motor function even further over the long-term among young children with SMA.^3-5 Partial body-weight support systems (BWSS), as a tool in neuromotor habilitation, enable children with motor delays to partake in challenging activities in a partial weight-bearing setting.⁶ Conventional BWSS are limited, however, in that they only allow uni-planar movement at prescribed speeds and are typically static and only accessible at medical centers.^7,8

To address these limitations, a team of researchers in Ohio assessed the potential benefit of in-home, portable, multi-planar BWSS in a pilot study among young children treated for SMA. Their findings were published in a recent issue of PLOS ONE.⁹

鈥淭he BWSS used in our study is just one modality that can optimize outcomes in conjunction with DMTs using a collaborative, family-centered approach,鈥� first author Megan Iammarino, PT, DPT, told 乌鸦传媒. Dr. Iammarino is a research physical therapist at The Abigail Wexner Research Institute鈥檚 Center for Gene Therapy, Nationwide Children鈥檚 Hospital, in Columbus, Ohio.

Assessing the utility of family-centered BWSS

The researchers conducted a prospective cohort study, using a 1-group, pretest-posttest design. Between August 2018 and November 2019, study participants were recruited through the Nationwide Children鈥檚 Hospital SMA clinic in Columbus, Ohio, and through other SMA clinics across the United States. Children were included in the study if they had a confirmed heterozygous mutation in SMN1 gene and 2 or 3 copies of SMN2, a body weight of 鈮�50 lbs, previous or current therapy with a DMT for SMA, upright head control, and confirmed motor delay.

Investigators set up the BWSS in the participants鈥� homes and encouraged families to use the BWSS daily for six months. Three physical therapist investigators assessed motor performance at baseline, three months, and six months, within a 2-week time frame of each other. Motor function changes were determined by assessing performance on the Neuromuscular Gross Motor Outcome (GRO), Hammersmith Functional Motor Scale Expanded (HFMSE), Revised Hammersmith Scale (RHS), Gross Motor Subtest of the Bayley Scales of Infant and Toddler Development version 3.0 (Bayley GM), and the World Health Organization Motor Milestone Checklist (WHO).

 At months three and six, activity logs that recorded frequency of BWSS use were collected. At the end of the study, families completed a 5-question survey and rated, on a 5-point Likert scale, their perceptions of how the BWSS impacted their child鈥檚 motor and non-motor skills, how their child enjoyed using the equipment, how easy the device was to use, and whether the BWSS was beneficial to their child.

BWSS may help to optimize motor abilities

Thirty-three children (mean age 2.9 years) were enrolled in the study; one child had no functional follow-up data and was subsequently excluded from the analysis. In the final analysis, 14 children had 2 copies of SMN2, and 19 had 3 copies.

Mean frequency of BWSS use was 4.1 hours/week (range: 0.6鈥�9.5 hours/week) and was comparable between the 2 SMN2 copy number groups. 

No significant difference in the magnitude of change in performance on motor outcomes was apparent between the 2 SMN2 copy number groups. Ten (31%) children achieved 19 new milestones based on the WHO checklist, with crawling, standing with assistance, and walking with assistance being the most commonly gained skills. 

According to linear regression modeling, mean frequency of BWSS use was found to explain 74% to 79% of the variability in change scores after controlling for baseline outcome measures. The authors pointed out that analyses after controlling for baseline scores also suggested that, for each additional hour of BWSS use each week, there was an expected mean change of:

• 0.81 (95% CI 0.64 to 0.97) on the GRO
• 0.85 (95% CI 0.67 to 1.03) on the HFMSE
• 1.02 (95% CI 0.80 to 1.25) on the RHS
• 1.07 (95% CI 0.86 to 1.28) on the Bayley GM-raw

Considering age, more treatment time, time since SMA therapy, and SMN2 copy number 鈥渄id not significantly improve the model fit or explain more variability in the change in outcome scores,鈥� the authors wrote. 

Families, overall, reported a 鈥渉ighly favorable response,鈥� with 114/130 (88%) of responses rated as a 4 or 5 on the Likert scale.

Limitations

This study did have a few limitations. First, the researchers noted the small sample size and shorter duration of the study. Also, data were parent-reported, so the number of hours using the system may not be accurate. Only 26 of the 32 families in the study completed the final satisfaction survey, possibly resulting in a reporting bias.

Also noted was that the three families who did report less satisfaction with ease of use or enjoyment had male children who were also the oldest patients in the study (ages six, six, and nine). Groin discomfort limited the time in the harness, and these participants had the greatest lower extremity contractures compared with the remaining group. Thus, the researchers suggested that 鈥淸l]arger and older individuals with similar characteristics may benefit from an alternative style of harness that would limit discomfort, as they may enjoy the social interaction of being upright and having an independent means of mobility, albeit in a confined space.鈥�

Thinking outside the box

Dr. Iammarino and her colleagues concluded from their study findings that in-home BWSS are useful options to increase the amount of exercise among young children who have been treated for SMA and may help to improve gross motor function.

鈥淭he most apparent take-away from the study findings is that a model of developmental therapy focusing on frequency, intensity, and variability of activity, exercise, and self-driven exploration may have a positive impact on developmental outcomes, both motor and non-motor, in young kids treated for SMA,鈥� Dr. Iammarino commented. 

The BWSS used in the study is just one option, she emphasized. 

鈥淲e encourage both new and experienced clinicians working with young kids treated for SMA to think outside the box and become creative when establishing plans of care,鈥� Dr. Iammarino continued. 鈥淭his new phenotype of SMA has opened the door to a new landscape of possibilities鈥攁nd treatment, whether it be physical therapy, occupational therapy, developmental play, or other supportive habilitative therapy, should therefore include a multi-faceted approach that is viewed through a new lens. This emerging field is open and ready for novel ideas and constructive ways of approaching all aspects of development.鈥�

Published: April 23, 2024