Traumatic Brain Injury or Other Acquired Brain Injury
By TBI we refer to an injury resulting from a violent trauma to the brain. The most common cause (at least, in peacetime) is a road traffic accident, though of course some result from falls, sports accidents, and assault.
TBI may be distinguished from non-traumatic brain injuries, such as stroke or anoxia due to cardio-respiratory arrest (anoxic brain injury, ABI). For a given pattern of disabilities, life expectancy after stroke is generally worse than after TBI because TBI is a one-time event whereas a stroke is generally the result of a disease process that is still present.
For one-time nontraumatic brain injuries, such as those due to hypoxia or anoxia, prognosis for survival may be similar to that in TBI, other factors being equal, though there are reasons to suspect it may be somewhat worse (see Shavelle et al. 2015).
As is the case in stroke or cerebral palsy, the resulting pattern of disabilities may range from none or mild, when the life expectancy would be nearly normal, down to the vegetative state, with no voluntary motor function or awareness of the environment. In the latter case, of course, life expectancy is dramatically reduced.
Time since injury can be a significant issue in the estimation of life expectancy after TBI. It is necessary to ask whether the pattern of abilities and disabilities stabilized. If major further improvements (or, indeed, regression) in function is expected, this needs to be taken into account. The life expectancy estimates reported in our more recent California research assume that the subject's abilities and disabilities have stabilized.
An oft-cited rule of thumb is that improvement in motor and cognitive function may occur for the first two years after injury. Although this rule has some merit, in reality the situation is more complex than this; the period for potential recovery may depend on the age of the injured person, the type of injury (traumatic versus non-traumatic), the type and quantity of therapy received, and possibly other factors.
For a recent and comprehensive review of the published literature on life expectancy in TBI, see Shavelle et al. (2007). The reader interested in life expectancy after TBI is referred to this review as a good starting point. For convenience, the Table of life expectancies is reproduced below.
A survival calculator based on our recent study, Brooks et al. (2013), is available here.