Because my previous blog dealt with concussion I thought I’d continue talking about traumatic brain injury (TBI). A brain stem contusion is just one more step in the continuum of TBI. As with a concussion, the kinetic forces of impact are channeled down and out the base of the skull and thus travel through the brain stem. But unlike concussions, which temporarily disrupts neurons from functioning without causing damage to the tissue itself, these forces are strong enough to rupture the small blood vessels that nourish the brain stem, and this results in small (called petechial) hemorrhages. The location of each hemorrhage determines the symptoms it produces. Because the brain stem contains so many pathways for the control of the eyes, movement and coordination, consciousness, and other senses, the damage can cause numerous combinations of neurologic problems involving coma, double vision, paralysis, loss of hearing, and others.
In addition to producing hemorrhages, the shock wave causes a massive release of brainstem synapses, flooding the area with neurotransmitters which can compound the cause of unconsciousness.
Usually these hemorrhages are too small to be seen on a routine MRI or CT scan, so the diagnosis is based on the clinical exam. Treatment is supportive, giving the brain time to recover. Often, however, some symptoms, such as double vision or lethargy may linger for years.