Prediction of Memory Rehabilitation Outcomes in Traumatic Brain Injury by Using Functional Magnetic Resonance Imaging

Strangman GE, O'Neil-Pirozzi TM, Goldstein R, Kelkar K, Katz DI, Burke D, Rauch SL, Savage CR, Glenn MB. Prediction of memory rehabilitation outcomes in traumatic brain injury by using functional magnetic resonance imaging. Objective: To evaluate the ability of functional magnetic resonance imaging (fMRI) measures collected from people with traumatic brain injury (TBI) to provide predictive value for rehabilitation outcomes over and above standard predictors. Design: Prospective study. Setting: Academic medical center. Participants: Persons (N=54) with TBI greater than 1 year postinjury. Intervention: A novel 12-session group rehabilitation program focusing on internal strategies to improve memory. Main Outcome Measure: The Hopkins Verbal Learning Test-Revised (HVLT-R) delayed recall score. Results: fMRI measures were collected while participants performed a strategically directed word memorization task. Prediction models were multiple linear regressions with the following primary predictors of outcome: age, education, injury severity, preintervention HVLT-R, and task-related fMRI activation of the left dorsolateral and left ventrolateral prefrontal cortex (VLPFC). Baseline HVLT-R was a significant predictor of outcome (P=.007), as was injury severity (for severe vs mild, P=.049). We also found a significant quadratic (inverted-U) effect of fMRI in the VLPFC (P=.007). Conclusions: This study supports previous evidence that left prefrontal activity is related to strategic verbal learning, and the magnitude of this activation predicted success in response to cognitive memory rehabilitation strategies. Extreme under- or overactivation of VLPFC was associated with less successful learning after rehabilitation. Further study is necessary to clarify this relationship and to expand and optimize the possible uses of functional imaging to guide rehabilitation therapies.