A Thoracic Mechanism of Mild Traumatic Brain Injury Due to Blast Pressure Waves

TL;DR

This paper explores the thoracic mechanism as a pathway for blast pressure waves to cause mild traumatic brain injury, supported by experimental evidence and implications for protective strategies.

Contribution

It introduces the hypothesis that blast waves can reach the brain via the thorax, supported by experimental data and analysis of ballistic and blast wave effects.

Findings

Ballistic pressure waves can cause cerebral effects through internal mechanisms.

Vagotomy reduces some physiological responses but not neural damage, indicating a direct thoracic effect.

Proposed experiment isolates thoracic effects from cranial mechanisms of mTBI.

Abstract

The mechanisms by which blast pressure waves cause mild to moderate traumatic brain injury (mTBI) are an open question. Possibilities include acceleration of the head, direct passage of the blast wave via the cranium, and propagation of the blast wave to the brain via a thoracic mechanism. The hypothesis that the blast pressure wave reaches the brain via a thoracic mechanism is considered in light of ballistic and blast pressure wave research. Ballistic pressure waves, caused by penetrating ballistic projectiles or ballistic impacts to body armor, can only reach the brain via an internal mechanism and have been shown to cause cerebral effects. Similar effects have been documented when a blast pressure wave has been applied to the whole body or focused on the thorax in animal models. While vagotomy reduces apnea and bradycardia due to ballistic or blast pressure waves, it does not eliminate neural damage in the brain, suggesting that the pressure wave directly affects the brain cells via a thoracic mechanism. An experiment is proposed which isolates the thoracic mechanism from cranial mechanisms of mTBI due to blast wave exposure. Results have implications for evaluating risk of mTBI due to blast exposure and for developing effective protection.