Influence of Type of Traumatic Stressor on rCBF Response to Auditory Experience Recall in Post Traumatic Stress Disorder. A SPET study.

Aim: Post traumatic stress disorder (PTSD) is a clinical condition that occurs in victims of major psychological trauma. Subjects reporting assaultive events (A) are more likely to be affected by PTSD as compared to those reporting not-assaultive events (NA). The aim of this study was to investigate the differences in regional cerebral blood flow (rCBF) between two groups of subjects exposed to either assaultive or not-assaultive traumas and developing or not PTSD.
Material and Methods: Fourteen A and 33 NA subjects were included in the study. Among them 20 developed PTSD (S) and 27 did not (NS). The rCBF distribution was compared between groups during an auditory evoked re-experiencing of their traumatic event. 99mTc-HMPAO SPECT, using a three-headed gamma camera, was performed and the uptake in 29 bilateral regions of the brain was assessed using a standardised brain atlas. Analysis of variance (ANOVA) was used to test the significance of the differences in flow.
Results: In the global analysis, rCBF significantly differed between groups (p<0.001), clinical status (p<0.05) and hemispheres (p<0.001). There was also a significant group x hemisphere interaction (p<0.02). The higher flow was found in the right hemisphere of the A group. The larger differences between A and NA were found in hippocampus, nc.caudatus, anterior cingulate, prefrontal and auditory cortex. When S and NS were compared the most striking differences where in nc.caudatus, anterior cingulate, prefrontal and anterior temporal cortex.
Conclusion: Higher rCBF values under recall of their traumatic experience were found in A as compared to NA. A higher rCBF response was also found in S as compared to NS. The regions that seem to be mostly involved in the emotional response to the auditory re-experiencing are nc.caudatus and some cortical regions considered to be part of the limbic system. These findings confirm the higher morbidity of assaultive traumas and the functional substrate of PTSD symptoms.