Strain relief from the cerebral ventricles during head impact: experimental studies on natural protection of the brain

Physical models of the parasagittal human skull/brain have been tested to i nvestigate whether the cerebral ventricles provide natural protection of th e brain by relieving strain during head rotation. A sophisticated model inc luded anatomical structures, and a semicircular model consisted of a cylind er divided into two semicircles. Silicone gel simulated the brain and was d etached from the vessel by a layer of liquid paraffin simulating the cerebr ospinal fluid. Both models were run with and without an elliptical inclusio n filled with liquid paraffin simulating a cerebral ventricle. The 2D model s were exposed to angular acceleration by a pendulum impact causing 7600 ra d/s(2) peak rotational acceleration with 6 ms pulse duration. After rotatin g 100 degrees, the models were decelerated during 30 ms. The trajectory of grid markers was analyzed from high-speed video (1000 frames/s). Rigid-body displacement, shear strain and principal strain were determined from the d isplacement of three-point sets inferior and superior to the ventricle. For the subventricular (inferior) region in the sophisticated model, approxima tely 40 % lower peak strain values were obtained in the model with ventricl e than in the one without. Subcortical displacement was reduced by 12%. Cor responding strain reduction in the subcortical (superior) region was approx imately 40% following the acceleration and 25% following the deceleration. Similar but less pronounced effects were found for the semicircular model. The lateral ventricles play an important role as strain relievers and provi de natural protection against blain injury. (C) 2000 Elsevier Science Ltd. All rights reserved.