Hammersmith Functional Motor Scale and Motor Function Measure-20 in non ambulant SMA patients.

Area of Science:

• Neurology
• Pediatric Neurology
• Rehabilitation Medicine

Background:

• Spinal Muscular Atrophy (SMA) is a progressive neuromuscular disorder affecting motor neurons.
• Assessing functional motor abilities in non-ambulant individuals with SMA is crucial for clinical trials and patient management.
• Standardized outcome measures are needed to reliably track disease progression and treatment efficacy.

Purpose of the Study:

• To evaluate the correlation between the Hammersmith Functional Motor Scale (HFMS) and the 20-item Motor Function Measure (MFM-20) in non-ambulant SMA patients.
• To assess the performance of both scales at baseline and over a 12-month period.
• To determine the suitability of each scale for different severity levels within the non-ambulant SMA population.

Main Methods:

• Prospective, longitudinal, multi-centric study design.
• Inclusion of 74 non-ambulant SMA patients (children and adults) at baseline.
• Assessment using HFMS and MFM-20 at baseline and 12 months for a subset of 49 patients.

Main Results:

• Strong baseline correlation (0.733) between HFMS and MFM-20 scores.
• Moderate correlation (0.48) between the 12-month changes in both scales.
• HFMS demonstrated suitability for stronger non-ambulant patients, while MFM-20 was more sensitive in very weak patients, capturing axial and upper limb activities.

Conclusions:

• Both HFMS and MFM-20 provide valuable information for assessing non-ambulant SMA patients.
• The scales appear to function differently at the extremes of ability spectrum.
• The choice of scale in clinical trials should consider patient inclusion criteria and expected magnitude of change.