Errors in diagnosing post-traumatic stress disorder after traumatic brain injury.

Evidence to support the view that post-traumatic stress disorder (PTSD) can occur after traumatic brain injury (TBI) continues to grow. However, the reported incidence of cases with both diagnoses ranges widely, from less than 1% to more than 50%. Given that the incidence of TBI is high, a more precise incidence has to be established if screening and treatment resources are to be considered. Are cases being missed or are they over-diagnosed? The single case report presented here does not definitively answer this question, but illustrates the potential shortcomings of diagnosing PTSD using questionnaire measures alone (Impact of Events Scale, Post-traumatic Stress Diagnostic Scale and General Health Questionnaire) and indicates a need for a conjoint interview which takes into account the common effects of TBI and the symptom overlap between PTSD and TBI.