The human brain – despite being encased snugly within its protective skull – is terrifyingly vulnerable to traumatic injury. A severe blow to the head can set in train a series of events that continue to play out for months, years and even decades ahead. First, there is bleeding, clotting and bruising at the site of impact. If the blow is forceful enough, the brain is thrust against the far side of the skull, where bony ridges cause blood vessels to lacerate. Sliding of grey matter over white matter can irreparably shear nerve fibres, causing damage that has physical, cognitive and behavioural consequences. As response mechanisms activate, the brain then swells, increasing intracranial pressure, and closing down parts of the microcirculatory network, reducing the passage of oxygen from blood vessels into the tissues, and causing further tissue injury.

It is the global nature of the damage – involving many parts of the brain – that defines these types of traumatic brain injuries (TBIs), which might result from transport accidents, assaults, falls or sporting injuries. Unfortunately, both the pattern of damage and the eventual outcome are extremely variable from patient to patient.

“This variability has meant that TBI is often considered as the most complex disease in our most complex organ,” said Professor David Menon, Co-Chair of the Acute Brain Injury Programme at the University of Cambridge. “Despite advances in care, the sad truth is that we are no closer to knowing how to navigate past this variability to the point where we can link the particular characteristics of a TBI to the best treatment and outcome.”

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