The evolution of spontaneous confabulation, delusional misidentification and a related delusion in a case of severe head injury

We describe a young woman who suffered a severe head injury, resulting in pathology to the right ventro-medial and polar frontal cortex with some involvement of the left ventro-medial and the right dorso-lateral regions as well. There was also a small infarct in the corona radiata of the right parietal lobe. The patient showed fleeting confabulations, succeeded by a more stable Fregoli (misidentification) delusion, followed in turn by the deluded belief that a nephew was inhabiting the hospital. These psychiatric features arose in the context of severe memory, perceptual and executive dysfunctions, which outlasted the abnormal beliefs by several months. The findings are interpreted in terms of changes in the executive 'specification' and 'verification' of memories through time. It is argued that neuropsychological theories of phenomena such as spontaneous confabulation and delusional misidentification need to take account not only of the presence of particular lesions associated with 'static' cognitive deficits, but also of 'dynamic' changes through time as these abnormal ideas emerge, evolve and wane.