OP28 – 2809: Structural MRI, transcranial magnetic stimulation, magnetoencephalography and DTI tractography findings in relation to sensorimotor outcome after perinatal stroke

Abstract

Objective Despite the frequency and importance of sensorimotor deficits after perinatal stroke (PS), the correlation between brain damage and severity of hemiparesis remains unclear. We aimed to investigate inter-relations between stroke topography, (re)organization of motor and sensory pathways, and clinical grade of hemiparesis in children with PS. Methods Seven children (3 boys; age 12–18 years) with mild to profound upper limb impairment (MACS I-V) after left-sided PS were enrolled. 3T structural MRI scans were reviewed to define vascular origin and extent of the infarction. Information about gestational age, delivery, and type of presentation, were collected from patient records. Navigated transcranial magnetic stimulation (nTMS) was used to map cortical hand muscle representations. The integrity of thalamocortical pathways was evaluated with somatosensory evoked magnetic fields to electrical median nerve stimulation and tractography based on regions of interest defined by neuroradiologist. Asymmetry of tract volume (TV), tract mean fractional anisotropy and mean diffusivity (MD) were estimated. Somatosensory responses were assessed by Semmes-Weinstein monofilaments. Results In two children with unilateral truncal middle cerebral artery (MCA) infarctions, moderate to severe hemiparesis (MACS II-III; sensory deficits in one) was associated with ipsilateral motor and contralateral somatosensory representation of the paretic hand. In a child with proximal MCA stroke, profound hemiplegia with sensory impairment (MACS V) was found in relation to purely contralateral motor and somatosensory projections, distinguished by decreased ipsilesional thalamocortical TV and increased MD in comparison to other subjects. While MEG showed contralateral somatosensory representation in four children with periventricular venous infarctions, who had less severe hemiparesis (MACS I-II, no sensory deficits), nTMS revealed bilateral motor representation. Conclusion Distinct (re)organization patterns after different subtypes of PS are demonstrated by modern neuroimaging techniques, which complement structural MRI in the prediction of severity of hemiparesis after PS.