Great Ormond Street is Britain's leading hospital for treating children with serious diseases of the brain - from tumours to epilepsy to rare neurovascular conditions. To save lives, doctors have no option but to undertake treatments which carry grave risks - children may be left with a mental impairment or may not even survive.

Trinity is seven-years-old and has just been diagnosed with a rare tumour in a critical part of her brain. The tumour rests on her brain stem, which controls vital functions. Her parents must decide whether to go ahead with surgery and controversial proton beam therapy.

Jack is 16 and suffers from severe epileptic seizures which cannot be controlled through medication. Great Ormond Street's epilepsy team can offer radical brain surgery which could cure him but carries serious risks. For Jack and his family it's a tough choice.

Great Ormond Street is a world-leading centre for treating a rare condition affecting the blood vessels of the brain, known as a Vein of Galen malformation. We follow Dr Adam Rennie, a consultant interventional radiologist, as he takes on the treatment of two very young children - Cody is 18-months-old and Ella Mae is a newborn baby. The condition is almost always fatal if untreated but the only possible cure is risky. Using a narrow tube fed up into the brain from an artery in the leg, blood vessels must be blocked off using tiny metal coils or glue. Dr Rennie is one of only three doctors in the country capable of carrying out the procedure. One third of his patients will not survive the operation, one third will suffer a minor bleed in the brain, one third will be cured. Show less