Electronic Thesis and Dissertation Repository

Thesis Format

Monograph

Degree

Master of Science

Program

Neuroscience

Supervisor

Morton, J. Bruce

2nd Supervisor

de Ribaupierre, Sandrine

Co-Supervisor

Abstract

Infants with hydrocephalus are a high-risk group for adverse neurodevelopmental outcomes, including impairments in executive functions such as goal-directed behaviour, focusing, and shifting attention. The current pilot study aimed to profile white matter and executive dysfunction in school-aged children with ventriculoperitoneal (VP) shunted hydrocephalus and age-matched healthy controls using the Behaviour Rating Inventory for Executive Functions and diffusion tensor imaging. To assess the degree of similarity between patient structural networks and controls, probabilistic streamlines between striatal and cortical regions and their respective diffusivity metrics were assessed. For a number of patients with hydrocephalus, white matter in the striatal-executive network showed significant deviation from a healthy control profile. Patients with higher global executive dysfunction also had lower correlations of striatal-executive fractional anisotropy with the healthy control profile. Future studies with larger samples can explore factors such as etiology that are likely to contribute to aberrant white matter and executive dysfunction.

Summary for Lay Audience

Hydrocephalus is a neurological condition characterized by an abnormal accumulation of cerebrospinal fluid within the ventricles of the brain and is the most common reason for brain surgery in children. Infants with hydrocephalus are a high-risk group for adverse neurodevelopmental outcomes, including impairments in executive functioning (EF) skills such as goal-directed behaviour, focusing, and shifting attention. The current pilot study aimed to profile white matter integrity and executive dysfunction in school-aged children with ventriculoperitoneal (VP) shunted hydrocephalus and age-matched healthy controls using parental reports on the Behaviour Rating Inventory for Executive Functions (BRIEF2), and diffusion tensor imaging, a non-invasive MRI technique used to assess white matter microstructure in vivo. To assess the degree of similarity between patient and control structural networks, probabilistic streamlines between striatal and cortical regions of interest and their respective diffusivity metrics were assessed in native diffusion space. For a number of patients with hydrocephalus, white matter connectivity and micro-diffusivity measured by fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), radial diffusivity (RD) and magnetization transfer ratio (MTR) in the striatal-executive network showed significant deviation from a healthy control profile. Overall, patients with hydrocephalus displayed variable executive dysfunction outcome, with at least 5 patients scoring from the potentially clinically elevated to clinically elevated range across indices and another 2 patients scoring within the expected range for children of their age and gender. Patients with higher reported dysfunction on the Global Executive Composite (GEC) scale also had lower correlations of striatal-executive FA with the healthy control profile. Future studies with larger patient samples will be needed to explore factors such as etiology that are likely to contribute to aberrant white matter structure and executive dysfunction outcome.

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