ROTATIONAL HEAD INJURY

If a head is hit it always rotates – often causing additional damage inside the skull. This sort of injury can go unnoticed as there are often no signs of damage on the outside of the head. It is also an injury which is effectively untreatable.

Rotational head injury is startlingly common, but often under-recognised as a threat.  It is the main cause of brain injury in boxing and a principal cause of brain injury from motorcycle and motor vehicle accidents. 

It happens because the head rotates around its point of articulation, which is the neck. This causes the brain to rotate within the skull tearing the veins. This causes bleeding which results in a subdural haematoma.

Because the head is not perfectly round the brain not only spins as a whole but some parts within it spin at different rates. This sets up additional shear forces inside the brain itself. This stress within the brain results in tearing of nerve fibres and tiny veins within the brain. This is called Diffuse Axonal Injury (DAI).

There are two different types of force at play whenever an impact occurs:

• A LINEAR FORCE, which is caused by a straight and direct impact (such as when a ball hits a wall without rotating); it consists firstly of blunt compression (the hit) and then a reaction (the bounce) causing direct injury to the point of impact and potential further injuries following a straight line into the brain.
• A ROTATIONAL FORCE is slightly oblique and causes the head to rotate around its point of articulation at the top of the spine as it is hit.