What happens when kids hit their head?

Kids are constantly getting hurt while they play. It is part of growing up – skinned knees, bruises and bumps on the head.

But currently nothing is known about these head bumps and resultant concussions. What biomechanics take place when a child gets hit on the head?

A new study set out to understand the biomechanics behind a head impact in youth.

A concussion is a form of traumatic brain injury and is caused by a blow to the head which makes the brain shift its position in the skull. This causes various symptoms which range from headaches, dizziness, confusion, visual problems, concentration difficulties, irritability, depression, and more.

These symptoms can last for a short time in young patients lasting for a few weeks. This is known as transient post-concussion symptoms (TPCSs).

When three or more concussion related symptoms last for over four weeks, they are called post-concussion symptoms (PPCSs).

To determine the biomechanical characteristics of transient and post-concussion symptoms in youth, the researchers recruited a group of 233 youth aged 5 – 18 years old, who were already predisposed with concussion symptoms and had been treated at any of the nine emergency departments within the Paediatric Emergency Research Canada (PERC) network.

A concussion is a form of traumatic brain injury and is caused by a blow to the head which makes the brain shift its position in the skull.

These patients or their parents filled out a questionnaire which gave the researchers information about the type of head impact, what surface impacted the head and what area of the head was affected along with description of the event that lead to this injury.

The researchers received sufficient information from 182 TPCS patients and 51 PPCS patients. Based on the information received from these questionnaires the researchers were able to reconstruct individual head impact events in the laboratory.

The reconstruction of these concussion related scenarios was restricted to head impacts resulting from a vertical or gravity-related fall onto the grass, floor, ice or other surfaces. These falls could have occurred after a sporting event or at Home, from a height or a standing position. Youth could have been bare headed or wearing a helmet. This kind of information was used to reconstruct head impact scenarios.

To simulate head impact, the researchers used a headform which was approximately the size of the patients head. A monorail drop rig was used to drop the headform onto an anvil at an impact velocity estimated for each impact incident. The surface of the anvil where the headform impacted was covered by material which corresponded with the surface that struck the patients head such as grass, concrete, ice etc. The angle of impact was also adjusted according to the original incident by adjusting the angle of the headform when dropped. If patients were wearing helmets and /or mask during the incident then similar helmets and headgear were used for the experiments.

The researchers also used computational and finite elements model to calculate force, velocity, peak linear and rotational acceleration and maximal principle strain to determine the collective strain damage which occurs when kids experience head impact injuries.

The researchers also compared these values between TPCSs and PPCSs and found no significant difference.

Using the same techniques as in adult patients, the magnitudes of peak linear acceleration for the youth data set were determined to be above the 50% risk of injury. The data set of the youth showed a higher brain tissue strain responses for lower energy and impact velocities than adults, indicating that youth are at a higher risk of concussions even at events which have a lower level of severity.

Although this study was not able to differentiate the biomechanical processes that take place in TPCSs and PPCSs in youths, this is the first biomechanical analysis of such a large magnitude which can be used for later investigations into youth concussion.

Maybe in the future, researchers will have answers about what really goes on inside the brain when youth experience head injuries causing temporary or long term symptoms.

Source: Journal of Neurosurgery: Pediatrics