Some 160,000 Britons are admitted to hospital each year with brain injuries, often caused by traffic collisions and falls. When the brain is injured, fluid can collect inside the skull, causing pressure that can restrict the blood supply. Eventually brain cells begin to die, causing memory loss, paralysis and even death. Patients are usually treated with drugs, but if these don’t work, doctors may opt for a procedure called a ventriculostomy, in which a tube is inserted through a hole made in the skull to drain excess fluid.