Mild Traumatic Brain Injury: Outcome Factors
This study examined the controversial issue of why post-concussion symptoms persist longer than the first few weeks or months after mild traumatic brain injury (MTBI) in some patients. Eighty-four adults, (sixteen years or older) with MTBI were compared to a control group of fifty-three adults with other minor injuries.
At one week and at three months after injury, both groups were examined for post-concussion symptoms, behavioral issues, and cognitive performance. The MTBI group reported more symptoms of headaches, dizziness, fatigue, visual disturbance, and memory problems at one week post-injury. Neuropsychological testing of the two groups found that the MTBI group performed at lower levels than the controls on all but one of the tests. By the three-month evaluation, differences between the groups had significantly reduced with no significant differences between the groups revealed by neuropsychological testing. The MTBI group did still report greater intensity of headaches and concentration problems, but for most of the MTBI group the other symptoms had largely resolved.
While the majority of the MTBI group appeared to have made progress in their recovery by the time of the three-month examination, twenty (24%) of the MTBI group reported ongoing problems of a significant nature. Those MTBI patients that had ongoing difficulties did not differ from the others in the MTBI group in terms of age, education, posttraumatic amnesia duration (PTA), or socioeconomic level. The still symptomatic group did differ from the other MTBI patients in marital status (those in the problem group were more likely to be unmarried). Perhaps because of the small size of the problem group no other significant differences were seen between them and the other MTBI group on the measured variables. Despite the lack of statistical significance, the data did lead the researchers to surmise that those in the problem group were more likely to be female, students, and had a history of previous head injury, psychological, or neurological problems. Injury mechanism also appeared to be an important factor, with the authors noting:
"...a higher proportion of those in the problem group had been injured in motor vehicle accidents. It is also noteworthy that there was a significant interaction between Sex X Cause of Injury. A significantly higher proportion of females were injured as a result of motor vehicle accidents, whereas a higher proportion of men were injured as a result of sporting accidents…This may explain the higher frequency of reported problems in females."
"Further examination of the case histories of the problem cases revealed that a third of the problem group were suffering from neck or back pain, which appeared to be contributing to their symptoms, especially headaches, and causing general distress."
This study was different from most other MTBI research in two ways. The researchers used a control group of patients that had recently suffered injury, and that was demographically well matched to the study group. Also, the sample consisted mostly of MTBI patients that had not been admitted to the hospital. The authors note that one significant limitation existed in this study. There was a high rate of attrition of participants between the one-week and the three-month post-injury study periods. Although those that did not return did not differ from those that did on most demographic measures, premorbid psychological, and injury severity measures, those that returned were different in that they tended to be slightly older and better educated. There is a chance that the size of the problem group was inflated because those that returned at three-months were more likely to be those with ongoing problems.
The authors conclude:
"Overall, it would appear that a broad range of factors contributed to outcome following mild TBI in the present study. Injury severity as measured by PTA duration, and age were not contributing factors. However, some other factors were associated with the presence of ongoing problems. These included a history of previous neurological or psychiatric problems or previous head injury, being a student, and the presence of concurrent life stressors. Being involved in a motor vehicle accident rendered participants more likely to have significant ongoing problems. Whether this was related to the velocity of impact causing greater mechanical forces, shear strains and consequent diffuse axonal injury, whether it resulted in a higher incidence of other trauma, such as neck or back problems, or whether it resulted simply in greater psychological trauma is unclear…The presence of other stressors, such as being a student, having other neurological or psychiatric problems, having neck or back pain, or having to cope with concurrent life stressors, may have reduced the injured person’s ability to cope with the symptoms and cognitive slowing resulting directly from the injury. Stress levels and poor psychological adjustment may contribute to the maintenance of symptoms."
Ponsford J, Wilmott C, Rothwell A, Cameron P, Kelly A, Nelms R, Curran C, and NG K. Factors influencing outcome following mild traumatic brain injury in adults. Journal of the International Neuropsychological Society 2000;6:568-579.
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