dear Linbin,

If you google tetraplegia vs quadriplegia... you will many a webdiscussion on this very subject.
If you have some time to kill, they make a good read.
This one for example: http://sci.rutgers.edu/forum/archive...p/t-56283.html

It seems a little like the confusion around physiotherapy and physical therapy (2 words for the same)
I have noticed that the term tetraplegia is often used to describe the symptoms after trauma and the term quadriplegia is often used to describe the symptoms of Cerebral Palsy.

Esther