In The Many Faces of TRAUMATIC BRAIN INJURY, brain injury expert witness Dr. John D. Lloyd, PhD, MErgS, CPE, CBIS, writes:
The brain is the most complex thing in the world. A baby’s brain at birth, weighing about 1 pound is already one-third the size of a typical 3-pound adult brain. And if we consider that there are one million nerve cells in a section of brain the size of a grain of rice, it is impossible to comprehend the billions and billions of neuronal pathways in an average brain. In fact, there are more neural connections in each brain than there are stars in the sky. A baby’s brain is the last of the major organs to develop in utero, where neurons are born from the division of a stem cell. Unlike most cells in the body, which die and are replaced, neurons, which are formed in the fetus, are designed to last for a lifetime.
There are two primary mechanisms associated with traumatic brain injury – impact loading and impulse loading.
Impact loading is caused by a direct blow to the head, resulting in extracranial focal injuries, such as contusions, lacerations and hematomas (bruises), skull fractures with or without penetrating injuries. The shock waves from a blunt force trauma may propel through the skull and brain causing underlying focal brain injuries, such as subdural, subarachnoid, intracerebral hemorrhages. The primary traumatic effects of an impact involve neural or vascular elements of the brain, which can be affected by delayed effects, such as deafferentiation or secondary events such as ischemia, swellings, cerebral edema and increased intracranial pressure. Impact TBIs produce significant injuries in 40.4% of events, the most common example of which is a fall.