What are the symptoms of post-traumatic stress disorder?

PTSD: Ptsd can develop after you've seen or experienced a traumatic event that involved the threat of injury or death. Symtpoms include reliving the event through flashbacks, repeated nightmares & memories of event, etc; avoidance or emotional numbing, feeling detached, having no interest in usual activities; and arousal -- difficulty concentrating, falling/staying asleep, startling, & hypervigilance.