Browsing by Author "Zewdie, Ephrem Takele"

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    Cortical excitability after pediatric mild traumatic brain injury
    (Elsevier, 2016-11-19) Seeger, Trevor A.; Kirton, Adam; Esser, Michael J.; Gallagher, Clare; Dunn, Jeff F.; Zewdie, Ephrem Takele; Damji, Omar; Ciechanski, Patrick; Barlow, Karen M.
    Introduction: Mild traumatic brain injury (mTBI) outcomes are variable, and 10e15% may suffer from prolonged symptoms beyond 3 months that impair the child's return to normal activities. Neurophysiological mechanisms of mTBI are incompletely understood, particularly in children, but alterations in cortical excitability have been proposed to underlie post-concussion syndrome. Improved understanding is required to advance interventions and improve outcomes. Objective/Hypothesis: To determine if cortical excitability is altered in children with mTBI, and its association with clinical symptoms. Methods: This was a cross-sectional controlled cohort study. School-aged children (8e18 years) with mTBI were compared to healthy controls. Cortical excitability was measured using multiple TMS paradigms in children with (symptomatic) and without (recovered) persistent symptoms one-month post-injury. Primary outcome was the cortical silent period (cSP), a potential neurophysiological biomarker of GABAergic inhibition. Secondary outcomes included additional TMS neurophysiology, safety and tolerability. Associations between neurophysiology parameters and clinical symptoms were evaluated. Results: Fifty-three children with mTBI (55% male; mean age 14.1 SD: 2.4 years; 35 symptomatic and 27 asymptomatic participants) and 28 controls (46% male; mean age 14.3 SD: 3.1 years) were enrolled. cSP duration was similar between groups (F (2, 73) ¼ 0.55, p ¼ 0.582). Log10 long interval intracortical inhibition (LICI) was reduced in symptomatic participants compared to healthy controls (F (2, 59) ¼ 3.83, p ¼ 0.027). Procedures were well tolerated with no serious adverse events. Conclusions: TMS measures of cortical excitability are altered at one month in children with mTBI. Long interval cortical inhibition is decreased in children who remain symptomatic at one month post-injury.
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    The PSTIM Trial: Pediatric Transcranial Static Magnetic Field Stimulation to Improve Motor Learning
    (2019-05-30) Hollis, Asha; Kirton, Adam; Zewdie, Ephrem Takele; Condliffe, Elizabeth G.; Dukelow, Sean P.
    Non-invasive neuromodulation is an emerging therapy for children with early brain injury but is difficult to apply to preschoolers where windows of developmental plasticity are optimal. Transcranial static magnetic field stimulation (tSMS) decreases motor cortex excitability in adults but effects on the developing brain are unstudied. We aimed to determine the effects of tSMS on primary motor cortex (M1) excitability and motor learning in healthy children. Our randomized, sham-controlled, double-blinded, 3-arm, cross-over interventional trial enrolled 24 typically developing school-aged children. We used a linear mixed effects model to examine intervention effects over time. Our results demonstrated that tSMS modulates motor learning. Contralateral (right) tSMS inhibited early motor learning in the trained hand (p<0.01) while ipsilateral (left) tSMS facilitated later stages of motor learning (p<0.01). We did not observe changes in cortical excitability as assessed by transcranial magnetic stimulation (TMS) generated motor-evoked potential (MEP) amplitudes and intracortical neurophysiology paradigms. We demonstrated the feasibility, safety, and favourable tolerability of tSMS in a pediatric population. We conclude that tSMS over motor cortex can modulate motor learning in children with effects specific to both the hemisphere of stimulation and stage of learning. Our findings suggest therapeutic potential for tSMS neuromodulation in young children with cerebral palsy (CP).