My Dad was diagnosed with bowel cancer 6 years ago which eventually spread to his spine (fracturing a vertebrae) & to his brain. 
Last week the hospital agreed he could come home to spend his final days with his family, in his own home. 
On the day he was coming home, he was chatting & having conversations with us, pleased he was leaving the hospital. Mum went with him in the ambulance & dosed up on pain relief he dozed off on the hours journey home. He never properly regained consciousness again....it was like he was paralysed. We could tell he was trying to communicate with his eyes & trying to speak but no sound would come out. 
He died 24 hours later. 
I just can't get my head around being able to hold a proper conversation with him while he was being put into the ambulance & then..... nothing. People have said he knew he was going home & so felt relaxed enough to let go. But all he kept saying was he couldn't wait to be in front of his own telly again & look out in the garden with his family around him.. 

Is paralysis a symptom of a morphine overdose?

Or could the tumour on his spine damage the spinal cord by being bumped about in the ambulance?

I don't think we'll ever know for sure but I wondered if paralysis comes on that quickly in a cancer patients final days.

Thank you for taking the time to read this