Trauma is a 1993 film directed by Dario Argento who also co-wrote the screenplay. The film can be described as a giallo, that is a film with influences from the horror, mystery, and thriller genres.
Aura, a young woman suffering from anorexia escapes from a psychiatric hospital and meets a young man, David who offers to let her stay with him rather than go back to the hospital. However, Aura is soon caught but her return to the hospital coincides with the start of a string of murders of hospital staff members, past and present. The killer decapitates them using a home-made garrote device, the 'noose-o-matic', on rainy days. When her father is murdered along with her mother, Aura and David team up to find the killer.
In the end, it is revealed that Aura's mother (who faked her death after murdering her husband) is the killer. Years earlier, Dr. Lloyd (Brad Dourif) was given the task of delivering Aura's brother, Nicolas. However, his clumsiness combined with a power outage (caused by a thunderstorm) led to him slicing off the newborn infant's head as he was being delivered. The head nurse during the delivery convinces the doctor to forcibly subject Aura's mother to electroshock
(This is information generated from a Wikipedia article, licensed under the GNU Free Documentation License.)