Abstracts

Rationale: The recognition of familiar faces entails sequential cognitive processing with initial encoding of face-specific information, followed by semantic association with previously learned information, and ends with a subjective feeling of familiarity. The study of disorders of facial recognition such as prosopagnosia and the study of delusions of identity such as the Capgras syndrome have fostered understanding of cognitive networks which support recognition. Focal epilepsy has rarely been reported to produce similar syndromes which can provide insight into how focal seizures cause cognitive dysfunction. Methods: We describe a 32 year-old woman who developed frequent two-minute episodes of unresponsive staring which were interictaly accompanied by a persistent and firmly held delusion of familiarity for previously unknown people and faces. The patient was admitted to the epilepsy monitoring unit for long term video EEG evaluation. She underwent a cognitive evaluation during the delusion and following treatment with antiepileptic medication. The patient had an MR imaging and a SPECT scan during the period of symptoms and following resolution. Results: Examination reveled isolated false labeling of unknown faces as familiar in the absence of a perceptual or associative prosopagnosia, similar difficulties with places or names, or deficits in other higher order cognitive functions. Video EEG monitoring revealed frequent complex partial seizures arising independently from the right and left temporal lobes. SPECT imaging revealed a region of hyperperfusion in the right cingulate gyrus and hypoperfusion in the right temporal lobe. Following treatment with antiepileptic medication, the delusion remitted along with normalization of the cognitive changes and SPECT findings. Conclusions: We postulate that the delusion resulted from inappropriate hyper-labeling of facial percepts with emotional responses as a result of ongoing seizure activity. During this delusion, the step of semantic association was skipped and not required to generate the feeling a familiarity. In effect, seizures resulted in an aberrant connection between the posterior basal temporal cortex for facial recognition and the limbic system. Such a disturbance in cognitive processing can likely only be caused by seizure activity and never by a static lesion. This delusion is in direct opposite to the Capgras syndrome, seen in traumatic brain injury and dementia, where facial percepts are hypo-labeled by emotional responses. To the authors’ knowledge, this cognitve disturbance has not previously been reported in association with epilepsy.