Brain injury: Symptoms, signs and the mechanism of injury in road traffic accidents

22 February 2011

It can take only a matter of seconds for a traffic collision to occur, but in that short time the human body can be exposed to dynamic forces in excess of 30 times that of the victim's body weight, which can expose it to potential harm.

Whilst travelling in a vehicle the occupants remain in a state of motion within the vehicle until impacted upon by another force. At that point, the human body's movement shifts towards the point of impact; for example, if the impact is a rear-end collision, the body moves towards the rear of the vehicle, and to the front if the impact is at the front of the vehicle.

If the occupant is wearing a seatbelt the lower torso from the hips down remains relatively stationary whilst the top half of the body, particularly the neck and head, are in comparison rather floppy and unrestrained, and so more likely to come into contact with interior parts of the vehicle, causing injury.

Where the occupant is not restrained by a seatbelt, more serious injuries can be caused, because the unrestrained body becomes like a rag doll within the vehicle and can be thrown from it, sustaining further injury.

The brain is encased within the skull and surrounded by cerebrospinal fluid which acts as a protective barrier helping to cushion the brain against impact .This provides good protection to the brain in normal circumstances, but in the course of a traffic collision the brain, which is subject to the same forces as the rest of the body, is still somewhat adrift in the spiny interior of the skull.

A brain injury can result from a direct blow to the head or a sudden deceleration of the head's forward motion. When the forward motion is abruptly halted, the brain's motion also dramatically shifts toward the impact causing the brain to collide with one side of the skull and can, depending on the extent of the force, ricochet towards the opposite end of the skull. The rebound motion causes the brain to forcibly rotate and batter within the skull resulting in bruising, swelling and tearing of the brain's nerve fibres and tissues. Such trauma may cause a moderate to severe head injury to occur.

The majority of brain injury compensation claims are brought as a result of injuries sustained in road traffic accidents.

Ambulance and accident and emergency medical staff are trained to recognise the signs of a possible brain injury. Specific objective signs which indicate that an injured person may have suffered a more serious head injury include the following:

  • loss of consciousness, confusion or drowsiness
  • low breathing rate or a drop in blood pressure
  • convulsions
  • fracture/s to the skull or face, facial bruising, swelling at the injury site or a scalp wound
  • fluid drainage from the nose, mouth or ears which may be clear or bloodstained
  • severe headache
  • initial improvement followed by worsening symptoms
  • irritability, personality changes or unusual behaviour
  • restlessness, clumsiness, lack of coordination
  • slurred speech or blurred vision
  • inability to move one or more limbs
  • stiff neck or vomiting
  • pupil changes
  • inability to see, hear, taste or smell

Indicators that a mild traumatic brain injury has occurred include:

  • physical symptoms such as nausea/vomiting, dizziness, headache, blurred vision, sleep disturbance, tiredness, lethargy or other sensory loss that cannot be accounted for by other injuries or causes
  • cognitive defects such as inattention, lack of concentration, perception, memory/speech or executive functions that cannot be accounted for by emotional or other causes
  • behavioural changes and/or alterations in a person's degree of emotional responsiveness such as irritability, anger or unrestrained behaviour that cannot be accounted for by a psychological reaction to physical or emotional stress or other causes.




This information is for educational purposes only and does not constitute legal advice. It is recommended that specific professional advice is sought before acting on any of the information given. © Shoosmiths LLP 2024

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