Abstract 73: Neurophysiology Of Ipsilateral Corticomotor Projections After Perinatal Stroke
Objectives: Perinatal stroke (PS) causes most hemiparetic cerebral palsy. Persistence of ipsilateral corticomotor connections from unlesioned hemisphere to affected hand are established. Their neurophysiology is not understood and developmental plasticity models suggest they are a therapeutic target. We hypothesized that ipsi projections have distinct neurophysiology that correlates with motor disability.
Methods: Children 6-18 years with PS (arterial or PVI) and hemiparesis were recruited (Alberta Perinatal Stroke Project). Transcranial magnetic stimulation (TMS) protocols were applied to the non-lesioned M1. Outcomes included rest motor thresholds and bilateral stimulus response curves (SRC). Paired pulse TMS at 2 and 10 ms (90% active motor threshold conditioning) explored short-latency intracortical inhibition (SICI) and intracortical facilitation (ICF). Ipsi motor evoked potentials (MEPs) were quantified (≥0.05mV at 120% RMT in ≥5/20 trials). Motor outcomes were Assisting Hand (AHA) and Melbourne (MA) assessments. Ipsi physiology was compared to contra and motor outcome (t-test, (rm)ANOVA). Safety and tolerability was assessed.
Results: Of 35 children (20 male; 55% arterial, 45% PVI), 14 (40%) met ipsi criteria. Presence of ipsi projections correlated with motor disability (AHA, p=0.03, MA p=0.10) but not stroke type. Ipsi intensity correlated with AHA (r=-0.58; p=0.004) and MA (r=-0.45; p=0.013). Ipsi SRC slope was lower than contra (p=0.01). SICI (contra -38.5%, ipsi -30.7%; p<0.05) and ICF (contra +15.4%, ipsi +23.1%; p<0.05) were present and differed between sides (p= 0.004). Procedures were well tolerated.
Conclusions: Cortical physiology of ipsilateral projections can be measured in children with PS. Differences between ipsi and contralateral physiology may be relevant central therapeutic targets.
- © 2012 by American Heart Association, Inc.