Speed, direction, and level of head protection can predict who is most at risk of brain injury following road traffic collisions, according to a new UK study.
Imperial College London and TRL (formerly the Transport Research Laboratory) also found that cyclists who wear helmets were better protected against brain injuries and skull fractures compared to those who did not wear them – regardless of the speed at which they were travelling.
The team studied more than 2000 collisions to investigate the relationship between traumatic brain injuries (TBI) and collision parameters such as speed, direction and force of vehicle impact.
For the first time, they have shown how these collision parameters relate to different types of brain injuries and have published the findings in *Brain Communications*.
The team says its data identify collisions that are most likely to cause TBI, which could provide the basis for existing crash notification systems to better predict and communicate the risk of severe injury to emergency services.
This, say the researchers, could help first responders ensure that patients quickly receive the most appropriate kind of treatment.
They analysed two UK RTC databases – Great Britain’s Road Accident In-depth Studies (RAIDS) collision database and is managed by TRL on behalf of the UK Department for Transport and STATS19, which has 1.1 million collision casualties from police reports – examining collision casualties between 2013 and 2020.
The change in speed at impact was a good predictor of brain injury, as was the impact direction and the presence of head protection worn by cyclists.
Sensors
They found that injury risk depended on road user type, changes in speed, and the direction of impact. The most severe injuries, including subarachnoid haemorrhage, were linked to side-on impacts and in crashes with the largest changes in speed at the time of collision.
Lead author Claire Baker, PhD researcher at Imperial’s Dyson School of Design Engineering, said: “Brain injury was more likely in car users involved in impacts from the side, and where the change in speed was greater, like during a head-on collision. It was also more likely in vulnerable road users, particularly where no head protection was worn.”
In the UK and European Union, most new cars are fitted with an automatic collision notification system called eCall, which relies on inbuilt crash sensors. eCall automatically alerts the emergency services after a collision. There are other similar systems across the world.
When inbuilt sensors detect a collision, they record the vehicles’ speeds immediately before, during and after impact. They also record directional movement to ascertain impact direction, which helps piece together the circumstances surrounding an RTC.
This in-vehicle data may be used to optimise the decision-making process for potential RTC care pathways by providing rapid and accurate diagnoses of head injury risks.
Ms Baker said although the research did not include sensor data specifically, these risk relationships could inform how inbuilt collision notification systems alert the emergency services to collisions with a high brain injury risk.
These algorithms would flag likelihood and severity to emergency operators who can then direct first responders to major trauma centres, she added.
Helmets
Co-author Dr Phil Martin, head of biomechanics at TRL, said: “Harnessing in-vehicle data could help first responders quickly triage the severity of an RTC and prioritise the trauma care pathway. This will enable emergency services to provide the right resources, to the right place, at the right time, saving lives and reducing the risks of long-term debilitating injuries.”
The analysis also highlighted that pedestrians and cyclists were six times more likely than car occupants to suffer moderate and severe brain injury from RTCs.
Wearing a cycle helmet protected against brain injuries and skull fractures, even after controlling for any difference in travel or impact speed between helmeted and unhelmeted cyclists.
Senior author Professor David Sharp, from Imperial’s Department of Brain Sciences, said: “The unusual combination of detailed clinical and collision data uniquely positioned us to examine the interaction between speeds in cycle collisions, helmet use and brain injury.
“Our data confirm that cycle helmets protect against brain injury in a collision. The protective effect of helmet use was not due to cyclists with and without helmets travelling at different speeds. This new evidence from real-world RTC data demonstrates the considerable protective benefits of cycle helmets during an RTC."
The research was carried out as part of the AutoTRIAGE Project, which is funded by TRL and the Engineering and Physical Sciences Research Council.
Baker CE, Martin P, Wilson MH et al. The relationship between road traffic collision dynamics and traumatic brain injury pathology. *Brain Communications* 16 February 2022
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