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J Head Trauma Rehabil. 1998 Dec;13(6):39-56.

The enigma of "hidden" traumatic brain injury.

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Department of Rehabilitation Medicine,The Mount Sinai Medical Center, NewYork, New York, USA.



To examine individuals with "hidden" traumatic brain injury (TBI), defined in this study as those who sustained a blow to the head, with altered mental status, and experienced a substantial number of the cognitive, behavioral, and emotional sequelae typically associated with brain injury but did not make the causal connection between the injury and its consequences.


Comparison of four groups of individuals matched for age, gender, years of education, and duration of loss of consciousness.


This study of hidden TBI followed the identification of 143 individuals who, within a larger study of people with TBI who live in the community, identified themselves as "nondisabled" (they were to be part of the comparison sample) but who had experienced a blow to the head that left them at minimum dazed and confused.


21 of these 143 individuals also reported large numbers of symptoms (eg, headaches, memory problems) associated with TBI. This group (Hidden TBI-High Symptoms group) was compared to three other matched samples: one with known TBI (Known Mild TBI group) and one with no disability (No Disability group) (both of which were drawn from the larger study), and one group of individuals who identified themselves as having no disability but who had experienced a blow to the head that resulted in a few symptoms (Head Trauma-Low Symptoms group).


All study participants were administered an interview that incorporated several existing instruments documenting levels of reported symptoms, emotional well-being/distress, and vocational/social handicaps.


The Hidden TBI-High Symptoms group was found to be similar to the Known Mild TBI group in terms of the number and types of symptoms experienced, whereas the Head Trauma-Low Symptoms group was similar in this respect to the No Disability group. The two former groups also evidenced high levels of emotional distress, whereas the two latter groups did not. However, on measures of handicap, the Hidden TBI-High Symptoms and Head Trauma-Low Symptoms groups were similar to the No Disability group and dissimilar from the Known Mild TBI group in that the last group experienced vocational handicap, in particular, whereas the other groups did not.


We conclude that hidden TBI occurs at a nontrivial level (7% of our nondisabled sample). Also, individuals with hidden TBI (with persistent symptoms), unlike those with known mild TBI, are likely to experience emotional distress but not vocational handicap following injury.

[Indexed for MEDLINE]

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