Psychosocial, Behavioral, and Radiologic Changes Following Radiosurgery for Benign Neurologic Disease

Functional magnetic resonance imaging (fMRI) and diffusion tensor tractography (DTI) have rapidly expanded since its emergence two decades ago. fMRI is well established as the single most powerful method for detecting changes in neural activity in vivo, albeit indirectly by detection of changes in blood oxygenation level dependent (BOLD) signals that reflect hemodynamic changes subsequent to neural activity. A conventional fMRI experiment involves the comparison of two or more brain states followed by statistical tests to identify which brain regions were involved in a particular task. The identification of patterns of highly correlated low-frequency MRI signals in the resting brain provides a powerful approach to delineate and describe neural circuits, and an unprecedented ability to assess the manner in which distributed regions work together to achieve specific functions. Since the first reports of temporal correlations in BOLD baseline signals, several distinct cortical long-range networks have been identified and characterized in the resting state, including a default mode network. Moreover, observations of altered resting state connectivity in several disorders and as a function of behavior or cognitive skills suggest these correlations reflect an important level of brain organization and may play a fundamental role in the execution and maintenance of various brain functions. DTI is also an exceedingly important imaging modality that has elucidated the neural connectivity inherent between various cortical and subcortical structures. DTI is routinely used and has enhanced our understanding of functional connections between various parts of the brain. Prior to interventions, DTI is commonly obtained, so that interventionists can avoid critical circuitry. There is suggestion that both fMRI and DTI imaging is influenced by organic or interventional variables, however this is understudied. The neuroscientists and clinicians would greatly value information that would expand our working knowledge of the basic neural substrates and functional neural changes that occur in patients organically or after interventions. A non-invasive, non-interventional, observational study is needed to show the changes that happen to patients organically or in standard of care settings. A greater working understanding of the neural connectivity and changes that happen in the brain is of great future benefit to patients, science, and society as well as future therapeutic development such as post-stroke care, rehabilitation, post-traumatic brain injury, or post-treatment care in the brain that has previously been influenced by intervention or disease.