...endless grey corridor...

"The hard part comes when the adrenaline recedes and you have to set out down the endless grey corridor..." http://t.co/SKDgRb10w6

— BrainLine (@BrainLine) July 24, 2014

Specifically written about a brain tumor case and in context refers to the caregiver's experience, but I'm not sure it isn't an apt metaphor for the injured party as well.