Role Of Rehabilitation in Improving Functional Outcomes Measured by HFMSE In Patients with Spinal Muscular Atrophy

Technical Summary: Role of Rehabilitation in Improving Functional Outcomes Measured by HFMSE in Patients with Spinal Muscular Atrophy

Problem Statement
Spinal Muscular Atrophy (SMA) is a progressive neuromuscular disorder caused by mutations in the SMN1 gene, leading to anterior horn cell degeneration, muscle weakness, and impaired motor function. While recent disease-modifying therapies (e.g., Nusinersen, Risdiplam, gene replacement) have improved survival and stabilized motor function, they do not fully restore motor capacity. Consequently, many patients, particularly those with SMA Types II and III, continue to face limitations in strength, endurance, and functional independence. In regions with limited access to advanced pharmacological treatments, rehabilitation often serves as the primary management strategy. However, there is a paucity of focused literature quantifying the direct impact of structured physiotherapy interventions on standardized functional outcome measures, such as the Hammersmith Functional Motor Scale Expanded (HFMSE), within real-world clinical settings.

Methodology
The study employed a single-group pre–post experimental design to evaluate the efficacy of a structured rehabilitation program.

• Participants: 34 children with genetically confirmed SMA (25 Type II, 9 Type III) were recruited from a tertiary care center in North India. Inclusion criteria required participants to be over 2 years of age, medically stable, and have access to a caregiver and tele-rehabilitation resources.
• Intervention: Participants underwent a 12-week hybrid rehabilitation program adapted from international guidelines. The regimen included:
  • Caregiver-led home exercises (3 days/week).
  • Therapist-supervised tele-rehabilitation (2 days/week).
  • Periodic hospital reassessments.
  • Components included stretching, range of motion, strengthening, postural control, supported standing, balance training, aerobic conditioning, and orthotic support.
• Outcome Measure: Gross motor function was assessed using the HFMSE, a 33-item ordinal scale (0–66 points) validated for SMA Types II and III. Assessments were conducted at baseline and post-intervention.
• Analysis: Data were analyzed using SPSS version 25.0. Pre- and post-intervention scores were compared using descriptive statistics and significance testing (p < 0.05).

Key Results

• Overall Improvement: The structured rehabilitation program resulted in a statistically significant improvement in gross motor function. Mean HFMSE scores increased from 24.76 ± 16.49 at baseline to 26.79 ± 17.11 post-intervention, representing a mean improvement of 2.03 ± 1.06 points (p < 0.001).
• Age-Stratified Outcomes: Analysis revealed significant age-dependent variations in response:
  • Ages 2–6: Demonstrated the highest baseline scores and significant gains (mean increase of 2.43 points; p = 0.001).
  • Ages 7–12: Showed significant functional gains (mean increase of 2.07 points; p = 0.001).
  • Ages 13–18: Showed a modest mean increase of 0.80 points, which was not statistically significant (p = 0.157), indicating a trend toward stabilization rather than substantial functional improvement.
• Stabilization: The minimum HFMSE score remained unchanged (0.00), suggesting that the intervention prevented deterioration in participants with severe functional impairment. The maximum score increased from 53 to 55, indicating enhanced performance in higher-functioning individuals.

Key Contributions

1. Validation of Hybrid Models: The study demonstrates the feasibility and effectiveness of a hybrid rehabilitation model (combining home-based and tele-rehabilitation) in a resource-constrained setting, ensuring continuity of care.
2. Quantification of Rehabilitation Impact: It provides empirical evidence that structured physiotherapy yields measurable improvements in HFMSE scores, even in the absence of disease-modifying drugs, reinforcing rehabilitation as a cornerstone of SMA management.
3. Age-Dependent Responsiveness: The findings highlight that younger children (2–12 years) derive greater functional benefits from rehabilitation compared to adolescents, likely due to greater residual motor neuron reserves and neuroplasticity.
4. Utility of HFMSE: The study reaffirms the HFMSE as a sensitive tool capable of detecting clinically meaningful, albeit modest, changes in motor function resulting from rehabilitation.

Significance and Claims
The authors claim that structured rehabilitation is an essential component of comprehensive SMA care, capable of improving or maintaining functional outcomes. The study emphasizes that:

• Early Intervention is Critical: Timely initiation of rehabilitation is associated with greater functional gains, capitalizing on the developing neuromuscular system's capacity for adaptation and motor learning.
• Stabilization is a Success: In older adolescents and those with advanced disease, the primary therapeutic goal shifts from improvement to the preservation of existing function and the prevention of secondary complications (e.g., contractures, deconditioning). The study posits that preventing deterioration is a significant therapeutic achievement in a progressive disorder.
• Complementary Role: Rehabilitation complements pharmacological treatments by translating physiological improvements into meaningful daily activities and maximizing functional independence.

The authors acknowledge limitations, including the lack of a control group, the small sample size, and the short duration of the study (12 weeks). Consequently, they modestly conclude that while the results support the integration of rehabilitation into standard practice, future multicenter studies with longer follow-ups are necessary to establish long-term sustainability.