Brain injury is the leading cause of death and disability in young people and affects millions of people worldwide every year. Its effects can be devastating, not just for the individual concerned, but also for families and communities.

Clinicians, academics and biomedical scientists will forever argue that their specialty is more important than any other but, from an arguably biased neuroscientist’s perspective, there is no contest: our brain is the most important and delicate organ.

Our brain is who we are; it is responsible for our interaction with our internal and external environment, our thinking, our memories, our emotions. The complexity and sophistication of the human brain is what sets us apart from other species and what makes us the unchallenged masters of the planet.

Yet the brain’s complexity is also its vulnerability. Replacing damaged cells with new cells or even a brain tissue transplant, if ever possible, would not restore the billions of intricate neuron-to-neuron interactions forged by our lifelong learning, experiences and emotions that make each one of us an individual. If these were taken away, if we were left to live as somebody else, would there be any point in surviving at all? This seemingly abstract philosophical question is what I face every day as a neurosurgeon: would a person who has suffered a devastating brain injury want to live with a substantial neurological disability?

Research shows that most survivors of acute brain injury enjoy a good quality of life even with severe disability and we know that this wonderful, complex, mysterious organ will go on to recover for many years, sometimes defying all predictions.

But what if the brain was locked in, unable to communicate and interact with other people? What if all memories where wiped out, what if that patient’s personality changed into something totally unfamiliar to them and their loved ones? Except in extreme cases, the inaccurate science of prognosticating outcome after brain injury is hard enough; predicting whether a particular outcome might be acceptable to a brain injury survivor is nigh on impossible.

Our inability to prognosticate the outcome of acute brain injury makes the decision-making weigh like a ton of bricks for the treating clinician. Deserted by science, we turn to the next of kin, often having to ask: ‘The damage has been quite severe and there is strong possibility of significant disability as an outcome: would your loved one want to live this way?’ This is when the ripple effect starts.

I guess that my family would not know how to answer on my behalf because I would not know myself. I am optimistically confident that no level of physical disability would faze them, but how would they react, if somebody else was in my body? We, humans, are highly socially organised creatures, connected to one another by our brains like an invisible web. Unlike an amputated limb that is just ours to miss, a brain injury rips away everything that we are and all that we are connected to.

This does not even touch on the ‘burden’ of caring for somebody with a brain injury: if you are lucky enough to live in an organised and well-resourced welfare system, you will hopefully get some help and may not even need to give up your job to become your loved one’s full-time carer. If you live in a developing country, however, there is a good chance that your entire family will be condemned to poverty, destitution and marginalisation.

These are the invisible scars of brain injury: people whose body survives unharmed, people who look exactly the same from the outside but do not recognise what is inside them. People who cannot control their temper or emotions, and end up alienating their family and friends. People who become gradually trapped in social isolation by post-injury anxiety and depression. People who stumble on words and unknowingly repeat themselves over and over again. People who were independent and possibly providing for their family but now need to be supervised at all times. These people wear their plasters on the inside, with invisible scars that are too difficult for strangers to see to convey understanding and empathy.

As we mark charity Headway’s Action for Brain Injury Week, now is an important time to highlight that there is so much more research needed into prevention, early intervention and functional restoration. Hard for sure, but so much easier than trying to stop ripples.