Brainstem focus of concussive effects from two different kinds of published studies. (A) Computer modeling of sheer stress forces within the brain following a strong blow to the head. The level and location predicted sheer stresses differentiate concussive (left panel) from nonconcussive (right panel) injuries (based on information from Fig. 1 in Mendez CV, Hurley RA, Lassonde M, Zhang L, Taber KH. Mild traumatic brain injury: Neuroimaging of sports-related concussion. J Neuropsychiatry Clin Neurosci. 17:297–303, 2005). (B) Morphometric study of the regions of significant volume reduction (yellow) and increase (blue) in severe TBI between 8 weeks and 12 months post-injury (Reprinted from Sidaros A, Skimminge A, Liptrot MG, Sidaros K, Engberg AW, Herning M, Paulson OB, Jernigan TL, Rostrup E. Long-term global and regional brain volume changes following severe traumatic brain injury: A longitudinal study with clinical correlates. Neuroimage 44(1):1–8, 2009, with permission from Elsevier).