Upper extremity strength and function in children with spinal muscular atrophy type II

Area of Science:

• Pediatric Neurology
• Rehabilitation Medicine
• Neuromuscular Disorders

Background:

• Spinal muscular atrophy (SMA) type II is a severe genetic disorder characterized by progressive muscle weakness.
• Understanding the functional capacity and strength deficits in children with SMA type II is crucial for developing targeted interventions.
• Limited data exist on the precise upper extremity strength and functional abilities in this specific pediatric population.

Purpose of the Study:

• To quantify upper extremity strength and functional abilities in children diagnosed with spinal muscular atrophy type II.
• To assess the stability of muscle strength over time in this cohort.
• To investigate the correlation between measurable muscle force and functional independence in activities of daily living (ADL).

Main Methods:

• Manual muscle testing, sphygmomanometry, and pinchometer assessments were employed to evaluate upper extremity strength.
• Functional abilities were documented using self-report forms.
• Repeated-measures analysis of covariance and Fisher exact test were utilized for statistical analysis.

Main Results:

• Children with SMA type II exhibited overall upper extremity strength between 35% and 40% of normal values.
• No significant changes in proximal or distal muscle strength were observed over the study period.
• A significant association (p = .02) was found between the ability to produce measurable pinch or gross grasp force and independence in mobility, hand function, and ADL.

Conclusions:

• Children with SMA type II present with notably weak but stable upper extremity muscle force.
• The capacity to generate even minimal force in grasp is linked to greater independence in functional tasks.
• These findings underscore the importance of strength assessment for predicting functional outcomes in pediatric SMA type II.