Posttraumatic stress disorder in a patient with no left amygdala.

Existing biological models of posttraumatic stress disorder (PTSD) posit that the amygdala plays a critical role in the development and expression of this disorder. However, increasing data indicate that the amygdalae are not functionally identical, raising the possibility that the 2 amygdalae may make differential contributions to the expression of PTSD. The authors present a unique patient who developed PTSD following a traffic accident that occurred 2 years after she had undergone removal of her left amygdala to treat pharmacologically intractable epilepsy. The authors propose that the right amygdala is preferentially involved in several processes related to the expression of PTSD symptoms, such that the disorder can occur even in the absence of the left amygdala.