Research Report
Population: Pediatric
Laura A Prosser, PT, PhD, Assistant Professor, The Children’s Hospital of Philadelphia prosserl@email.chop.edu
Sudha Kessler, MD, MPH, Neurologist, The Children’s Hospital of Philadelphia kesslers@email.chop.edu
Casey Gorman, BS, Research Assistant, The Children’s Hospital of Philadelphia gormanc@email.chop.edu
Heather Atkinson, PT, NCS, Physical Therapist, The Children’s Hospital of Philadelphia atkinsonh@email.chop.edu
Rebecca Ichord, MD, Neurologist, The Children’s Hospital of Philadelphia ichord@email.chop.edu
Keywords: Plasticity, Hemiplegia, Rehabilitation, TMS
Purpose/Hypothesis: Neuroplasticity after injury is likely different in children compared to adults because of the interaction of neuromaturational processes. The advent of biomarkers of neuroplasticity opens new avenues for studying and predicting individual responses to neurorehabilitation. The objectives of this pilot study were to investigate preliminary motor outcomes of an asymmetrical gait training program in children with chronic hemiplegia from prior stroke, and establish the feasibility of collecting relevant neurophysiological and genetic biomarkers.
Subjects: Eight children and adolescents (mean age 12.0 years) with hemiplegia and a history of unilateral supratentorial stroke at least 6 months prior have been enrolled and randomly assigned to an 8-week conventional physical therapy or asymmetrical gait training program. Data collection is ongoing with a target enrollment of 12 participants.
Methods: Physical therapy was delivered 3 times per week in each group. Conventional therapy activities focused on participant goals, and were documented by type, amount and level of assistance. The asymmetrical gait training program included alternating bouts of walking on a split-belt treadmill with overground walking. The ratio of belt speeds on the treadmill was 2:1 (shorter:longer-stepping leg). Motor outcomes included gait symmetry ratios at self-selected walking speed with 1.0 indicating symmetry. Neural measures included motor threshold of the tibialis anterior muscles stimulated by single-pulse transcranial magnetic stimulation (TMS). These data were collected one month prior to the start of therapy, immediately prior to therapy, after 4 and 8 weeks, and one month after therapy ended. In addition, the presence or absence of two genetic variants (ApoE and BDNF) associated with decreased potential for neuroplasticity was determined from a blood sample.
Results: Consistent with evidence from adults, our preliminary observations suggest that step length symmetry improved in the asymmetrical gait training group but not the conventional therapy group (p=0.020), and symmetry in other gait parameters did not change (p=0.30-0.98). During TMS, active motor threshold was elicited in 5/6 participants on the nonparetic side and 2/6 participants on the paretic side, analysis is ongoing. Seven of 8 participants had an ApoE polymorphism and 3/8 had a BDNF polymorphism.
Conclusions: Asymmetrical gait training may improve step length symmetry in children in hemiplegia. Effect on other gait parameters and on function needs further study. Using TMS to measure corticospinal excitability has potential, but appears more difficult in leg versus arm muscles, and more difficult in children versus adults possibly due to age-related and etiology of injury-related factors.
Clinical Relevance: The identification of biomarkers to measure and predict rehabilitation-induced change will improve physical therapy prognosis and will facilitate the development of physical therapy interventions that optimize neuroplastic potential in children.
Citation:
Prosser, Laura A, PT, PhD; Kessler, Sudha K, MD, MPH; Gorman, Casey , BS; Atkinson, Heather L, PT, NCS; Ichord, Rebecca N, MD. Motor outcomes and neural correlates of asymmetrical gait training in children with acquired hemiplegia.. Poster Presentation. IV STEP Conference, American Physical Therapy Association, Columbus, OH, July 17, 2016. Online. https://u.osu.edu/ivstep/poster/abstracts/070_prosser-et-al/