Abstracts

Rationale: Fencing response is a non-epileptic phenomenon and could be a potential immediate effect of concussive brain injury. Usually it begins within 2 seconds of impact associated with a phase of brief tonic stiffening followed by extension in one arm and contralateral flexion of the other limb. The pathophysiology is not well understood. It has been previously postulated that the fast acceleration of the head by the impact stimulate the lateral vestibular nucleus triggering this motor response. Our aim was to perform a biomechanical analysis of fencing response in cases sports-related traumatic brain injury. Methods: We analyzed 4 videos of people that suffered sports-related traumatic brain injuries and had the fencing response. The videos were obtained from YouTubeTM. To investigate this phenomenon we used the Blender 2.77 software to get a model from the head of the four individual subjects. Moreover, we analyze the trajectory of the impact evaluating the acceleration and the time of the impact using the Tracker 4.93 software. We used the Wayne State Tolerance Curve and the Head Injury Criterion to assess the severity of the head impact. Results: The Wayne State Tolerance Curve showed that in all of individual videos the acceleration due to an impact is lower than the scale used to represent the curve (g acceleration around 10 gs or 98 m/s2), and the duration of the impact is far above the limits of the curve (between 30 to 60 ms). Taking into consideration the Head Injury Criterion formula, with a time window of 15ms (HIC15) and a linear acceleration, we found that cases 2 and 3 are far over the limit of 700 (according to NHTSA), while case 1 is close to that limit and case 4 is far below. Conclusions: The video analysis showed that a long duration and moderate acceleration of the impact could induce fencing response in spite of the severity of the head trauma. These biomechanical characteristics of impact can produce desihinibicion reflexes trunk including the fencing response. Funding: No