In the original Japanese, there are some real instances of "sent to the shadow realm", but many more of death, so the 4kidz dub changed it wherever possible to something sending you to the shadow realm instead of killing you, and left it ambiguous in most of the remaining cases.
Wait what was the Shadow Realm a euphemism form? Hell? Death?
iirc, death.
In the original Japanese, there are some real instances of "sent to the shadow realm", but many more of death, so the 4kidz dub changed it wherever possible to something sending you to the shadow realm instead of killing you, and left it ambiguous in most of the remaining cases.