Misidentification syndromes related to face specific area in the fusiform gyrus

The "delusional misidentification syndromes" are a group of uncommon and varied disorders in which, in typical form, the patient thinks that a particular familiar person is someone else or a certain familiar place is a duplicate. Although first identified and considered a memory disorder by Pick, evidence in support of this has been difficult to identify. They have been most often seen in various psychotic and organic brain diseases but lesions have been generally diffuse although the right temporal lobe has been implicated. A patient was investigated who abruptly developed a disorder wherein she misidentified her husband as her deceased sister and claimed that her home was a duplicate of her real home that were typical of Frégoli syndrome and Pick's reduplicative paramnesia, respectively. A discrete area of brain damage, probably ischaemic, in this patient was seen on MRI in the anterior part of the right fusiform gyrus and a smaller area in the nearby anterior middle and inferior temporal gyri with associated parahippocampal and hippocampal atrophy. A high order nervous system function that is devoted to the identification of faces is located in the adjacent midportion of the fusiform gyrus and a similar locus for environmental scenes, termed the parahippocampal place area, is present in the bordering parahippocampal gyrus. The misidentification phenomena in this case can be explained by disruption of the connections of these highly specialised areas with the most anterior inferior and medial part of the right temporal lobe where long term memory and mechanisms for the retrieval of information that are required for the visual recognition of faces and scenes are stored.