Rotation of Brain in Head Impact and It's Relation to Concussion

Objective: To analyze the rotational acceleration of the brain in direct head influence and find the areas of brain most vulnerable to concussion.Method: First, the modes of head and brain acceleration are analyzed. Then, formulas are derived to find the values and effects of rotational accelerations and forces acting on the brain. Comparison is made between modes of rotational acceleration.Results: With a direct impact, the head will mainly undergo rotational acceleration in the form of spin and whiplash. Under equal impact moment, spin radial and tangential accelerations are about 3.5 times those of whiplash. Maximum spin radial force is about 3 times that of whiplash. Maximum whiplash tangential force is about 1.14 times that of spin. Model results are conservative relative to realistic brain shape and proportions.Conclusion: Rotational acceleration is responsible for local trauma around the middle and base of the brain. In other words, concussion symptoms related to brain function in these areas can be attributed to rotational effects of head impact. Brain is more vulnerable to spin mode compared to whiplash. The highest radial and tangential force and damage occur in the middle of the brain in head spin, and the base of the brain in whiplash.