1998 Volume 29 Issue 3 Pages 337-343
Herpes simplex encephalitis is well known as an acute type of limbic encephalitis, and a paraneoplastic syndrome is also known as a subacute and progressive type of limbic encephalitis. However, we experienced a 25-yearold woman in whom the both types of limbic encephalitis were excluded, and the diagnosis of non-herpetic acute limbic encephalitis (NHALE) was established. The lesion was confined to medial parts of the temporal lobes, namely hippocampi, amygdaloid nuclei, parahippocampal gyri and fusiform gyri which showed abnormal signal intensities on MRI. In this patient, fever was the first manifestation similar to the usual encephalitis, but consciousness was clear and memory impairment was remarkable from the initial stage of the illness, which remained about one and a half years later as the typical feature of amnesia. Totally 24 cases of NHALE including our case have been reported. In all the cases, the immediate recall and the remote memory were intact, and only the recent memory was impaired, which is characteristic of the amnestic syndrome due to damage to the hippocampi. Among the 24 cases of NHALE, 46 per cent did not have fever, and 38 per cent did not show lowered levels of consciousness, which indicate that the diagnosis of encephalitis would not always easy in the initial stage of the illness.
