Diffuse Axonal Injury (DAI)

Jules Bianchi’s injury during the Russian Grand Prix highlights is an important type of head injury that is sadly more common on the streets of Bangalore than on the F1 circuit.

Diffuse Axonal Injury is a specific type of Traumatic Brain Injury (TBI) where the very structure of the brain’s neurons becomes a liability rather than the miracle of evolution that they are.

Before we delve into this type of injury, we should understand a bit about the structure of a neuron. Neurons are a contingent of cells that make up the human brain and there are approximately 86 billion neurons in a single brain. They consist of a central star shaped cell body which accepts nerve impulses from multiple short tendrils called dendrites. The cell body then channels most of its energy and cellular machinery into a long outflow tract known as the axon. If the dendrites are the ‘inbox’ of the neuron, the axon is definitely the ‘outbox’.

The axon is a miracle of evolution; it is protected by a layer of fatty insulation known as the axonal sheath and it sends electrical signals along its length to different parts of the brain and body. Imagine this; the axons that originate in your brain can be long enough to reach the end of your spinal cord.

The different compositions of the neurons, the cell body and the axon, lead to a very interesting outcome; they are two different parts of the same cell. They have different mass and density.

This brings us to what happens to a person that leads to DAI. In an accident where the person’s head is knocked about in such a way that the head rotates quite a bit, the cell bodies of the neurons are sheared away from their axons since two parts of the same cell want to move at different velocities. This shearing effect hits a huge number of cells disrupting communication throughout the brain right away. To make matters worse, the injured cells leak chemicals into the blood stream which cause massive amounts of swelling and bleeding.

The injury is devastating on all levels and affects large parts of the brain. The denser your brain is, the worse the injury gets, meaning, the younger you are the worse a DAI type injury is.

The horrific F1 injury that we are all witnesses to marks a much greater problem. In countries like India where 2 wheeler accidents are common, we see large numbers of DAI type injuries. Riding without a helmet makes thing highly preposterous.

Patients with DAI require long term intensive care and have less chances of complete recovery. Those who survive the initial injury often require months or years of intensive rehabilitation and rarely make a full recovery.

The prevalence of those types of injuries in countries, like India, where the transport system is both archaic and chaotic, points to a burgeoning problem of young healthy minds being sacrificed to senseless and preventable TBI. The governments of countries like India have to develop their public transport system on a war-footing to bring down the incidence of such family and economy shattering injuries.