Stephen Sackur speaks to the paediatric neurosurgeon Owase Jeelani. Brain surgery carries with it an awesome burden of responsibility. And within neurosurgery there are particular challenges that take the physical and ethical pressure to an extreme. Imagine doing complex brain surgery on small children; then imagine trying to split conjoined twin babies joined at the head. Mr Jeelani's work has made headlines around the world. How does he deal with the stress of life and death decision-making?