Effects of ventricular volume and cerebral connectivity on neurological outcomes in preterm intraventricular hemorrhage

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PROJECT SUMMARY Despite advances in neonatal and neurosurgical care, post-hemorrhagic hydrocephalus remains among the most frequent, severe neurological complications of very preterm birth (gestational age at birth ≤32 weeks) and now represents the most common cause of pediatric hydrocephalus in North America. It also carries a heavy neurodevelopmental toll, with cognitive deficits and/or cerebral palsy diagnosed in greater than 75% of affected children. After the failure of medical approaches to impact its neurological sequelae, recent research has centered on optimizing neurosurgical treatment of post-hemorrhagic hydrocephalus, with a focus on mitigating ongoing injury due to progressive ventricular distension, a long-recognized risk factor for poor outcomes. The objectives of this proposal are to define the pathophysiological effects of post-hemorrhagic hydrocephalus on cerebral connectivity and neurological outcomes and, more specifically, to determine how ventricular volume modifies these relationships. Our Central Hypotheses are that 1) impaired structural and functional connectivity across key white matter tracts (e.g., corticospinal tracts, optic radiations, corpus callosum) and related functional networks (e.g., somatomotor, visual, default mode networks) are associated with neurological disability in post- hemorrhagic hydrocephalus, 2) ventricular distension contributes to post-hemorrhagic hydrocephalus-related connectivity deficits, and 3) these alterations in connectivity improve with neurosurgical ventricular decompression. Recent advances in MRI now enable characterization of functional and structural connectivity in the developing brain with unparalleled spatial and temporal resolution. Analysis of these data using the highly innovative diffusion basis spectrum imaging approach affords unique capabilities to characterize the complex neuropathological changes underlying these differences in cerebral connectivity. Here, our multidisciplinary team will employ these state-of-the-art MRI techniques in combination with detailed neurodevelopmental assessments to study a large cohort (N=180) that includes very preterm infants with and without post-hemorrhagic hydrocephalus prospectively recruited and followed longitudinally after discharge from the Neonatal Intensive Care Unit. In addition, infants with post-hemorrhagic hydrocephalus will undergo neuroimaging studies both before and after cerebrospinal fluid shunt surgery, characterizing the reversible effects on cerebral connectivity while also defining the role of ventricle size in its pathology. Application of these cutting-edge MRI acquisition and analysis approaches enables unprecedented characterization of the effects of post-hemorrhagic hydrocephalus on the developing brain. Further, we will extend these methods to delineate relationships between imaging measures and neurodevelopmental outcomes, improving our understanding of the modifiable effects of this devastating disease. Critically, these results will address long-standing, clinically important questions related to the care of infants with post-hemorrhagic hydrocephalus and inform development of innovative assessment tools to support clinical trials seeking to thwart the developmental disability observed in this high-risk population.