A Force scream was a Force exertion manifested by those whose alignment was with the dark side of the Force. It was a scream, of strong frustration, rage, or grief, emitted through the Force.
While sparring with Iskat Akaris at Inquisitorius Headquarters on Coruscant, the recently broken former Jedi Tualon Yaluna unleashed a scream by using the Force that caused his opponent to collapse in a catatonic state to the ground. Akaris could still feel the physical effects sometime after she managed to stand back up.