Abnormal Motor Response Associated With Concussive Injuries: Biomechanical Comparison Between Impact Seizures and Loss of Consciousness

Abstract

Context Loss of consciousness (LOC) and impact seizures associated with concussion represent different clinical presentations of concussion; however, they are often investigated and treated similarly. The biomechanical parameters differentiating these 2 distinct signs of injury are poorly described. Objective To differentiate between cases of concussions with LOC and those with impact seizures by comparing the impact velocity, peak linear and peak rotational acceleration, as well as brain tissue deformation in the cerebral cortex, white matter, brainstem, cerebellum, thalamus, and corpus callosum. Design Descriptive laboratory study. Patients or Other Participants Elite American football players who sustained an LOC (n = 20) or impact seizures (n = 21). Main Outcome Measure(s) Impact velocity, peak linear and peak rotational acceleration, maximum principal strain, cumulative strain damage measure at 10%, and strain rate (SR). Results The SR in the cerebral white matter was greater in the LOC group than in the impact-seizure group. Similar trends were observed for SRs in the cerebral cortex, brainstem, and corpus callosum. No differences were present between groups for the other variables in this study. Conclusions A lower SR in certain brain regions helps to explain why motor function is preserved and can be observed in patients with impact seizures versus LOC from concussive injuries.