Falls are the leading cause of traumatic brain injury
As reported by the CDC, falls are the leading cause of traumatic brain injury in the United States with unintentional falls accounting for nearly half of TBI – related hospitalizations.
Falls account for two-thirds of TBIs in adults over 65. Preventing falls is therefore key to mitigating the risk of TBI. Falls can happen to anyone and can lead to tragic consequences, even where there is no visible injury. A good example is the death of actress Natasha Richardson in 2009 at Mount Tremblant ski resort. Ms. Richardson fell and struck her head while skiing with an instructor. She never lost consciousness and was able to stand and resume skiing after her fall. She initially seemed fine and declined treatment but later in the night began to complain of severe headaches. She was rushed to the hospital, lapsed into a coma, and died two days later from an epidural hematoma – an accumulation of blood between the skull and the membrane covering the brain.
Because of the prevalence of TBIs caused by falls, a lot of research has been devoted to the biomechanics of falls.
There is general consensus that the acceleration generated by a fall can be sufficient to cause a TBI when the skull hits the ground and the brain, which floats in a layer of cerebral spinal fluid, strikes the hard interior surfaces of the skull. The biomechanics research indicates that falls in the antero-posterior direction (forward or backwards) create a high risk of TBI, particularly where the victim is not able to use strategies to reduce the impact to the head.
Every fall is different. For example, a fall can be accelerated when the victim is hit from behind at high speed, falling backwards, or falls backwards from a moving treadmill, thereby increasing the risk of TBI. A backward fall to the back of the skull, the “occiput,” can cause two separate injuries– at the initial point of contact, called the “coup” injury, and to the opposite side of the brain, as the brain rebounds within the skull, called the “contra coup” injury. Needless to say, when the victim of the fall has time to reduce the acceleration by landing on a different part of the body before striking the head or is able to roll upon impact, as gymnasts or martial artists are taught, the risk of TBI is diminished. Older victims often lack the coordination to mitigate the forces in this way. Fall can also occur too suddenly to use strategies to reduce acceleration.
As frequently discussed in this blog, the harm caused by a TBI begins, but does not end with the initial insult to the brain. The insult triggers “secondary injury cascades”, ongoing cellular activity inflicting progressive damage to neural tissue over an extended period. As discussed in a recent 2024 article in World Neurosurgery, these secondary injury cascades “involve critical shifts in metabolic and mitochondrial function, neurochemical homeostasis, and inflammatory edema…”
“While the immediate damage to neuronal tissue during the transfer of mechanical energy cannot be altered once the primary injury occurs”, the authors report, “aggressive strategies and appropriate surgical interventions offer potential for preventing or beneficially modulating secondary injury.”
Prevention is therefore threefold: reduce the risk of falls, offer training to reduce accelerating forces where possible, and deliver appropriate treatment after the fall to reduce the secondary injury cascades.