The introduction of the new edition of the Diagnostic and Statistical Manual for Mental Disorders ("DSM-5") is on the horizon. With it are coming some new, evidence-based diagnoses for dissociative disorders , which include conditions such as dissociative fugue (which will now be classified as dissociative amnesia) and dissociative identity disorder.
Fugue states have always been fascinating to me, Wikipedia states that they are
a rare psychiatric disorder characterized by reversible amnesia for personal identity, including the memories, personality and other identifying characteristics of individuality...Fugues are usually precipitated by a stressful episode, and upon recovery there may be amnesia for the original stressor.
Post-traumatic stress disorder is also precipitated by a stressful (and potentially life threatening) episode, and causes anxiety and autonomic hyperexcitablity.
I've never seen anything written about the level of stressor that can induce a fugue state, but based on their common etiology, I would assume that PTSD and fugue states are related psychologically and neurologically.
To what extent is this true, are these two seemingly different end products of the same initial event? Is there an anatomical substrate that is common to both? Does changing the status of "dissociative fugue" -> "dissociative amnesia" mean they should be considered in isolation?
 Spiegel, D., Loewenstein, R. J., et al. (2011), Dissociative disorders in DSM-5. Depress. Anxiety, 28: E17–E45. doi: 10.1002/da.20923