Traumatic brain injuries frequently are closed-head sequelae of high-velocity acceleration, deceleration and/or rotational force incidents, such as vehicle accidents or patient falls. Significantly, no direct impact is necessary for causation, although often it is present and intensifies injury.
Rapid external acceleration, deceleration and/or rotational forces propel the unprotected soft brain within the hard bony skull. Those forces strain, stretch and finally shear delicate minute blood vessels and nerve fibers irrepairably, and are followed by biochemical degradation.
Much traumatic brain injury consists of diffuse axonal injury. Lesions and lacerations dispersed throughout the brain are the observable tip-of-the-iceberg of such injury and ultimately result in permanent degeneration, scarring and/or cavities.
With injury occurring at the neuronal level, the damage may not be discernable using only a CT scan, particularly in cases of mild traumatic brain injury. That primary diagnostic technique may have to be supplemented with other more expensive neuroimaging, such as MRI and even PET, SPECT or EEG; so not to overlook demonstrable injury.
Despite many victims having an outwardly normal appearance, clinically-observable damages flowing from traumatic brain injury are numerous, wide-ranging, and frequently permanent, increasing and disabling, such as persistent postconcussive syndrome – hence the national Center for Disease Control refers to it as the “silent epidemic”. Classic neurobehavioral symptoms, deficits and disorders include but are not limited to: physical (headaches, neck/back pain, tinnitus, hearing loss, aural-sensitivity, blurred vision, diplopia, photo-sensitivity, diminished taste, diminished smell, fatigue, drowsiness, seizures, tremors, sleep disturbance, vertigo/dizziness, imbalance, decreased appetite, and increased risk of altzheimer’s disease and morbidity); psychological/affective (personality change, depression, anxiety, irritability, agitation, aggression, impulsivity, moodiness, disinhibition, altered sexuality, and limited self-awareness); cognitive (visual-perceptual alteration, attention/concentration impairment, memory dysfunction, decreased processing/reaction, decreased understanding/insight, decreased reasoning/judgment, language/communication difficulties and learning problems); and socioeconomic (increase risks of interpersonal disputes, regression/dependency, suicide, divorce, substance abuse, vocational problems, occupational problems, chronic unemployment/underemployment, and economic strain).