used most commonly as the default term, but you will find all the above three variants with/without hyphen.
Dorland's Illustrated Medical Dictionary. Copyright 2004. WB Saunders, an Elsevier imprint:
"carpoptosis (car·pop·to·sis) (kahr”pop-to´sis) [carpus + ptosis] -> wristdrop
"drop hand -> wristdrop
(wrist·drop) (rist´drop) a condition resulting from paralysis of the extensor muscles of the hand and fingers. Called also carpoptosis and drop hand."http://www.mercksource.com/pp/us/cns/cns_hl_d...
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company.:
Paralysis of the extensor muscles of the wrist and fingers causing the hand to hang down at the wrist. Also called carpoptosis, drop hand
The Oxford Dictionary of Sports Science & Medicine. Copyright © Michael Kent 1998, 2006, 2007.:
An inability to raise the wrist resulting from damage to the radial nerve or from a tendon injury."http://www.answers.com/wrist-drop&r=67#copyright