Trapped inside their bodies, apparently switched off to the world, but still alive: they are the undead. Or so we thought. Forty per cent of patients in a ‘vegetative state’ are misdiagnosed.

Ten years ago, Kate went into a deep coma and was on a ventilator for several weeks. She had suffered severe brain inflammation after contracting a viral infection.

When she came out of the coma, she opened her eyes and could breathe naturally, but she was unresponsive

She was still in this condition four months after falling ill, and was later diagnosed to be in a persistent vegetative state, or PVS: in other words, persistently unaware. But the diagnosis was wrong.

She had a raging thirst that was not alleviated by the ward staff. She was racked with pain. Sometimes she’d cry out, but the ward staff thought it was just a reflex action

Kate suffered so much pain and despair that she tried to take her own life by holding her breath.