1322 Internetwork Functional Connectivity Predicts Hand Dexterity in Patients With Brain Tumors

INTRODUCTION: Brain tumors frequently cause impairments in hand dexterity, and we recently demonstrated that standard manual muscle testing greatly underestimates such dysfunction. Because classical anatomical lesioning studies have not fully explained higher order motor performance, there has been recent interest in examining inter-network brain connectivity as a potentially more direct functional-anatomical relationship. METHODS: 20 patients with contrast enhancing tumors underwent preoperative resting state functional magnetic resonance imaging (rs-fMRI) and a the 9-hole peg test. 9-hole peg test data were normalized to published data accounting for age and sex. A 40-network atlas was used to extract average time series data from the rs-fMRI to calculate functional connectivity. Effects of age, sex, and lesion volume on connectivity were regressed out using a linear model. The functional connectivity between the ipsilesional somatomotor network with the other 39 networks of the brain were entered into a forward stepwise linear regression with alpha set to 0.05 a priori. RESULTS: Data from three participants were excluded because they were unable to complete the 9-hole peg test in <120s. The strongest predictor of declining 9-hole peg test performance was increased connectivity to the ipsilesional salience network (β =-9.70, t=-3.92, p=0.002), followed by decreased connectivity to the contralesional visual network (β =6.62, t=3.33, p=0.005). Together, these connections explained 68.5% of the variance (aR2=0.685, F=18.4, p=0.0001). CONCLUSIONS: Increased connectivity between the ipsilesional somatomotor network and the ipsilesional salience network together with decreased connectivity between the somatomotor network and the contralesional visual network correlate strongly with and explain a high percentage of the variance in hand dexterity in patients with brain tumors. Future studies will examine whether interventional rehabilitation strategies targeting these connections might improve long-term outcomes.