Pathological hyperfamiliarity for others from a left anterior cingulate lesion

[A case of encephalitis with hyperfamiliarity for faces]

A 21-year-old right-handed woman was admitted to our hospital with fever, headache, and seizures. On admission, she showed anterograde and retrograde amnesia. These features, together with mild pleocytosis in the cerebrospinal fluid, led to the diagnosis of encephalitis. Brain MRI was normal. EEG revealed small spike waves in the left temporal lobe. There were no recurrent convulsions. Five days later, she stated she had hyperfamiliarity for faces of people she had never met before. She reported that many people appeared familiar regardless of age, sex, and profession; however, feelings of likes and dislikes did not accompany these symptoms. This symptom lasted for 20 days. Her ability to recognize known faces was normal, and prosopagnosia was not present. Neuropsychological tests indicated that her verbal memory was impaired. The retrograde amnesia remained until discharge. Considering the psychological findings attributable to left temporal lobe dysfunction, as well as previous reports on similar cases, our case suggests a possible relationship between lesions of the left temporal lobe and hyperfamiliarity for faces.

A patient who misidentified all surrounding persons as her family

This report describes a patient who misidentified all surrounding persons as her family after a cerebral hemorrhage in the right temporal lobe. She had no difficulty with visual face recognition. Single-photon emission computed tomography revealed hyperperfusion in the right amygdala and hippocampus. Electroencephalography showed a bilateral fronto-temporal delta burst intermittently during the symptom. Carbamazepine suppressed the symptom completely. These results suggest that hyperexcitability in the right limbic system and bilateral fronto-temporal cortex might cause the alteration of familiarity. She felt a strong sense of familiarity to others. Perhaps because it lasted a long time, she regarded these other people as her family.

Hyperfamiliarity for faces

OBJECTIVE

To report 4 cases of hyperfamiliarity for faces (HFF) and review 5 previously reported cases.

METHODS

We identified cases of HFF from PubMed search and references in prior reports.

RESULTS

Three of our 4 cases had pathologic findings that were most extensive in the left temporal lobe. HFF occurred after a tonic-clonic seizure (cases 1 and 3), during simple partial seizures (case 2), and in the setting of an increase in simple partial seizure frequency but not during seizures (case 4). All 9 cases were adults with 1 or more seizures; symptoms first occurred after seizures in 5 cases and during seizures in 1 case. Ictal symptoms lasted from seconds to minutes and from 2 days to more than 7 years in the other 6 cases. The duration of HFF was not associated with the presence or extent of a structural lesion. While in several cases HFF appears to result from a postictal Todd paralysis, the mechanism underlying persistent cases is uncertain.

CONCLUSIONS

This modality (visual)-specific and stimulus (face)-specific syndrome is associated with diverse structural, functional imaging, and neurophysiologic findings. Lesions are more often left-sided and involve the temporal lobe. Epilepsy and seizures were present in all 9 cases, suggesting a pathophysiologic relationship, which likely varies among cases. Although only reported in 9 patients, HFF is probably much more common than it is diagnosed.