Causes of Brain Injury
Traumatic Brain Injury
In the majority of studies, falls are the leading cause of injury in the older adult (65 years and over) group.36-38,40,41,45,48 Between 2002 and 2006, TBI causes for the older adult were 60.7% falls, 7.9% motor vehicle collision (MVC), 24.7% unknown, 5.7% struck by/against, 1% assault.36
As age increased, the percentage of falls increased and that of MVC decreased.38 The most common causes of falls were simple fall,49 falls on the same level, and falls on or from steps/stairs.38 In the “old old” (over 80 years) group, falls tended to occur on staircases, icy sidewalks, getting up after a meal, getting out of bed to use the washroom, and fall off ladder.44 Persons who fell were more likely to have three or more comorbid conditions compared with those who sustained a TBI from MVC.37 Intracranial hemorrhage was more likely to occur following a fall than MVC.37 Subdural hematomas (SDHs) were more common in the older adult group.46 Intracranial hemorrhage was the most common TBI-associated diagnosis in those aged 85 and older.37 The risk of pelvic fracture regardless of cause of TBI increased with age.37 Falls were a more common cause in 55-74 age groups if they had a history of alcohol abuse.50 However, the presence of alcohol in the blood was less common in older adults than younger adults.45 Falls were more common in those with visual problems.50 This raises the question whether identifying and treating alcoholism and visual dehcits in older patients may help prevent TBI.50
When injury was caused by MVC, those over 65 tended to be the driver more than passenger and the passenger more than pedestrian.37 The main secondary injuries were in the lower extremities followed by the thorax and upper limbs.51
However, pedestrian injury risk becomes higher for the 75 and older group compared to the 65-74 age group.37,52 The risk of a pedestrian receiving an intracranial injury after being hit by a car increases steadily with age, and even more for elderly (over 65 years) pedestrians. In contrast, the number of fractures remains steady.53 For the over 65 years age group, risk of intracranial injury was equal for males and females. For all age groups, men were at slightly higher risk for fractures and intracranial injury.53 The authors propose that the increased risk of intracranial injuries may be related to the reduction of size of the brain and/or weaker neck muscles.53
Comorbid conditions that were similar between elderly patients with TBI included hypertension, diabetes mellitus, cardiac arrhythmias, and fluid and electrolyte imbalances.37 Persons who fell were more likely to have chronic pulmonary disease, Alzheimer’s and other dementias, and Parkinson’s disease.37 Of those older subjects who tested positive for alcohol, the cause of TBI was more likely to be a MVC than a fall.37 In the over 85 group, MVCs were more common in those who had congestive heart failure and endocrine disorders.50
While assaults were a more common etiology of TBI in the middle-aged group, there is evidence that violent acts against the elderly are increasing, especially in urban areas.54 Suicide risk is highest in adults over 65 years.55 The most common method is by a firearm.55,56 However, in urban settings, older adults may choose to jump from a height.55,56 Risk factors for suicide attempts in this age group include being white and male, a history of depression, chronic pain or illness, and social
isolation.55,57
Elderly (65 and older) had a higher rate of SDH.58 GCS at the accident scene was higher in the elderly group.58 But after age 80, epidural hematomas were unlikely.44
In gender studies, men over 80 were more likely to have hematomas and contusions than women and were more likely to have a more severe GCS.44
Nontraumatic Brain Injury
The most common causes of nTBI were brain tumors, anoxia, and vascular insults.38 Other causes included encephalitis, meningitis, encephalopathy, infections, and toxins. With increasing age, the percentage of tumors decreased and the percentage due to anoxia and vascular insults increased.38 In the oldest age group (85 and older), the percentage of women with nTBI increased compared with that of men.38 nTBI tended to be more common in the 65-74 age group while TBI tended to be more common in the 85+ age group.38
