Case Study on Focal Retrograde Amnesia due to Limbic Encephalitis

Abstract

This case study addresses episodic memory impairment or focal retrograde amnesia related to limbic encephalitis. The patient in question was a right-handed man in his 60s who developed focal retrograde amnesia due to limbic encephalitis. An abnormal MRI signal was observed in the right medial temporal lobe. Immediately after the encephalitis onset, mental symptoms—including impaired consciousness, disorientation, hallucinations, and delusions—appeared; however, his condition improved with medical treatment. After transfer to a convalescent and rehabilitation hospital, various neuropsychological tests were conducted but no apparent functional decline was observed in intellectual function, attention, memorization, or retention. However, the patient exhibited impairments related to autobiographical memory and memory of events 4 - 5 years before the onset of limbic encephalitis. Based on these observations, the patient was considered to exhibit focal retrograde amnesia due to limbic encephalitis. Despite exhibiting retrograde amnesia, he had no difficulty in his daily life in the ward. Moreover, after discharge from hospital, smooth work reinstatement was possible. This case demonstrates that, even after exhibiting retrograde amnesia, if its duration is relatively short and physical function and other higher-order brain functions are sustained, social rehabilitation—including work reinstatement—is feasible.