Traumatic brain injury (TBI)—or in this case, Iranian Ballistic missile-related traumatic brain injury—can cause a host of symptoms, from relatively mild to life-changing. Symptoms such as cognitive dysfunction, dizziness, and chronic headaches occur far more frequently among military personnel with mild traumatic brain injury than in those without such injuries. Those with traumatic brain injury are also much more likely to experience significant emotional issues and serious sleep disorders.

The Defense Health Agency’s Hearing Center of Excellence assessed a battery of neurological tests used in the diagnosis of mild traumatic brain injury. The issue was studied between 2014 and 2017 at the Naval Medical Center in San Diego, California, and the Washington Madigan Army Medical Center at Joint Base Lewis-McChord. The goal of the study was to determine Oculomotor, Vestibular, and Reaction Time Response following a traumatic brain injury event.

According to the CDC, a traumatic brain injury is any “disruption in the normal function of the brain,” causes by a bump, blow or jolt to the head or by a penetrating head injury. TBI severity ranges from mild (concussion) to severe, with mild traumatic brain injury being the most common brain injury affecting military personnel. Troops can experience symptoms of a concussion, a “sub-concussion” that causes no symptoms, and symptoms associated with IED or other explosive devices.