Transient vestibular balance dysfunction after primary blast injury.

Explosive munitions are used routinely in support of military operations. Moreover, service personnel are increasingly being deployed to regions where active conflict, terrorism, and land mines pose significant threats. Despite aggressive protective measures and safety practices, blast injury is an inherent risk. In contrast to secondary and tertiary blast injuries, primary blast injuries are generally limited to the air-filled organs of the respiratory, gastrointestinal, and auditory systems. We report the case of a Marine who entered the back-blast arc of a shoulder-launched multipurpose assault weapon at close range. Despite the magnitude of the blast, he sustained none of the classic findings suggestive of severe primary blast injury. However, he manifested unique vestibular balance abnormalities that precluded his return to full duty for several months. This suggests that personnel who sustain even a mild traumatic brain injury with vestibular manifestations may need prolonged observation and modified duty in certain military occupational specialties.