Noncredible cognitive performance in the context of severe brain injury.

In two litigating patients with histories of severe brain injury (i.e., coma > or =2 days and residual brain imaging abnormalities), noncredible cognitive symptomatology was demonstrated by: (1) "failed" performance on multiple cognitive "effort" tests, (2) noncredible performance on standard neuropsychological instruments, (3) questionable validity of personality inventory profiles, and (4) marked inconsistency in test performance across testing evaluations or marked inconsistency between test scores and activities of daily living documented through surveillance videotapes. Some patients with severe traumatic brain injury show substantial, if not full recovery, and in a litigating context, may feign cognitive symptoms. These cases indicate that tests to verify cognitive effort should be routinely administered to all patients in litigation or who have other motive to feign symptoms, not just patients with mild or questionable brain injury.