Concussive brain injury from explosive blast

• Published in: Annals of clinical and translational neurology Vol. 1; no. 9; pp. 692 - 702
• Main Authors: Lanerolle, Nihal C., Hamid, Hamada, Kulas, Joseph, Pan, Jullie W., Czlapinski, Rebecca, Rinaldi, Anthony, Ling, Geoffrey, Bandak, Faris A., Hetherington, Hoby P.
• Format: Journal Article
• Language: English
• Published: United States John Wiley & Sons, Inc 01-09-2014; BlackWell Publishing Ltd
• Subjects: Age; Brain research; Comorbidity; Consciousness; Head injuries; Memory; Mental disorders; NMR; Nuclear magnetic resonance; Post traumatic stress disorder; Studies; Traumatic brain injury; Veterans
• ISSN: 2328-9503; 2328-9503
• DOI: 10.1002/acn3.98

Objective
Explosive blast mild traumatic brain injury (mTBI) is associated with a variety of symptoms including memory impairment and posttraumatic stress disorder (PTSD). Explosive shock waves can cause hippocampal injury in a large animal model. We recently reported a method for detecting brain injury in soldiers with explosive blast mTBI using magnetic resonance spectroscopic imaging (MRSI). This method is applied in the study of veterans exposed to blast.
Methods
The hippocampus of 25 veterans with explosive blast mTBI, 20 controls, and 12 subjects with PTSD but without exposure to explosive blast were studied using MRSI at 7 Tesla. Psychiatric and cognitive assessments were administered to characterize the neuropsychiatric deficits and compare with findings from MRSI.
Results
Significant reductions in the ratio of N‐acetyl aspartate to choline (NAA/Ch) and N‐acetyl aspartate to creatine (NAA/Cr) (P < 0.05) were found in the anterior portions of the hippocampus with explosive blast mTBI in comparison to control subjects and were more pronounced in the right hippocampus, which was 15% smaller in volume (P < 0.05). Decreased NAA/Ch and NAA/Cr were not influenced by comorbidities – PTSD, depression, or anxiety. Subjects with PTSD without blast had lesser injury, which tended to be in the posterior hippocampus. Explosive blast mTBI subjects had a reduction in visual memory compared to PTSD without blast.
Interpretation
The region of the hippocampus injured differentiates explosive blast mTBI from PTSD. MRSI is quite sensitive in detecting and localizing regions of neuronal injury from explosive blast associated with memory impairment.