Spinal Muscular Atrophy (SMA) is an autosomal recessive neuromuscular disease. Prior to gene replacement therapy (GRT), children with SMA Type I were unable to sit, stand, or walk, with an average life expectancy of 2 years. Dynamic Movement Intervention (DMI) is a therapeutic technique designed to improve motor milestones by targeting autonomic postural responses and stimulating neuroplasticity. The effects of DMI in children with SMA Type I that have undergone GRT is unknown. This case series describes the results of 2 cases who underwent DMI therapy by an Introductory Level B trained DMI therapist over a 25-week span.
A 13-month male diagnosed with 2 copies of SMN2 gene and underwent GRT on DOL24. He started an additional disease modifying agent at 9 months. DMI was initiated at 8 months focusing on neck and trunk extension, independent sitting, transitional skills, and standing, receiving a total of 40 DMI sessions. Functional assessment results showed improvement: Children’s Hospital of Philadelphia- Infant Test of Neurological Disorders (CHOP-Intend) improved from 45 to 54 points, WHO Motor Milestones (WHO MM) improved from 0 to 1.
A 15-month female diagnosed with 2 copies of SMN2 gene and underwent GRT on DOL22. DMI was introduced at 9 months with a total of 16 DMI sessions. Trial of a 4-day intensive was also performed, leading to improvement in gross motor skills: ability to creep for two cycles and stand with unilateral finger support. Functional assessment results showed improvement: CHOP-Intend improved from 54 to 62 points, WHO MM improved from 1 to 2.
The findings demonstrate that children with SMA Type I who undergo GRT can tolerate participation in DMI and may gain motor skills. DMI techniques produced an improvement in functional outcomes and motor milestone attainment in both cases. These successes with DMI techniques suggest that earlier initiation may lead to attainment of gross motor developmental skills. Further research is needed to look at different SMN2 copy numbers, SMA types, and disease-modifying treatments.