A previously healthy 59-year-old woman presented five years ago with intermittent vertical double vision which soon became continuous, without any other relevant associated history. She noticed the double vision disappeared on tilting her head downwards and to the right (fig 1A). Photographs from when she was younger (fig 1B) confirmed that her head had previously been in a normal position. Neurological examination revealed a resting head tilt to the right, and eye movement examination revealed failure of depression of the adducted left eye consistent with a left superior oblique palsy. Tilting the head …