COGNITIVE AND PSYCHIATRIC IMPAIRMENT IN HERPES-SIMPLEX VIRUS ENCEPHALITIS SUGGEST INVOLVEMENT OF THE AMYGDALO-FRONTAL PATHWAYS

The long-term neuropsychological and psychiatric sequelae of herpes si mplex virus encephalitis (HSVE) and their relationship to the volume o f temporal lesions and to amygdala and hippocampus damage remain undef ined. We have conducted a prospective study of longterm sequelae in 11 patients with clinically presumed HSVE and detection of HSV DNA in th e cerebrospinal fluid by polymerase chain reaction. Six months after e ncephalitis, patients underwent neuropsychological and language assess ment. At the same stage, single photon emission computed tomography (S PECT) evaluated the occurrence of hypoperfusion with an index of asymm etry. MRI was used for the measurement of amygdala, hippocampus and ce rebral lesions by two blind neurologists. The volume of the amygdala a nd hippocampus was compared with those of five controls, matched for a ge and level of education. Longterm memory disorders were seen in 6 pa tients, associated with the larger lesions and damage of at least two structures. Long-term behavioural changes with emotionalism, irritabil ity, anxiety or depression were prominent in 7. Left prefrontal hypope rfusion appeared in 8 patients, associated with psychiatric disorders in 7 and left amygdala damage in 6. The reduction of amygdala and hipp ocampus volume was correlated with the overall volume of lesions. Diff erent patterns of mesial temporal lobe damage occurred, involving eith er amygdala alone, or amygdala and hippocampus, but never hippocampus alone. MRI volumetric measurements in HSVE could be a good indicator o f long-term progno sis. Persistant behavioural changes could be relate d to an amygdala and frontal dysfunction.