過去の二重感と，過去への往復現象を示した視床下部胚細胞腫の1例

A Rare Massive Parenchymal Metastasis in Central Nervous System from Abdominal Non-Hodgkin Lymphoma :： Effectiveness of Stereotactic Radiosurgey:Case Report

要旨　過去の二重感と過去への往復現象を示した1例を報告した。症例は31歳，右利き男性。視床下部胚細胞腫の治療後に，前向性健忘と5年以内の逆向性健忘を呈した。加えて，高校卒業後から逆向性健忘の始まる時期までの記憶に対する二重感と，現在と高校時代を行き来しているかのような異常な言動がみられた。検討により，二重感のある時期の社会的出来事の著しく若年への定位，高校時代の記憶の異常な鮮明感の存在が認められた。自分の時間軸への出来事の定位障害は，二重感と往復現象の消失後も変わらず存在したが，異常な鮮明感はこれらの症状の消失と同時に消失した。Papezの回路と，基底外側回路が同時に部分的損傷を受け，記憶機能の部分的低下と親近感の異常をきたしたことが，これらの症状を引き起こした可能性を考えた。

After the successful treatment of a hypothalamic germinoma, a 31-year-old right-handed male developed a difficulty in memory and admitted to our department for detailed evaluation.

　Neuropsychologically he showed no personality change, confabulation, misidentification, delusion or disorientation to physical time. Neither aphasia, dementia or frontal lobe dysfunction was found. However, he showed a moderate degree of anterograde amnesia and a retrograde amnesia for the last 5 years judged by a public events test. Moreover, his temporal markings of a correctly remembered event in the post high school days shifted strongly toward the high school days. This temporal location abnormality was largely limited to the events from the days of his graduation from the high school to the period 5 years prior to the present incident. He felt personal events happened during this period as if they had occurred in the high school days, although he well knew that they actually happened much later. At the same time he felt that memories of the high school days were abnormally vivid and recent.

　Most interestingly, he was found to have been experiencing a funny feeling that he was living in the high school days and the present at the same time. The feeling occurred either simultaneously or alternatively. In the latter instance, he would suddenly start behaving as if he were a high school student. He would start urging his wife to go to the school together immediately. This behavior would be over in several minutes. His consciousness was clear in these instances and there was no amnesia for these periods.

　A brain MRI with gadolinium enhancement showed a lesion extending in the hypothalamus, anterior thalamus, basal forebrain and midbrain bilaterally.

　After eight months this abnormality of temporal sensation disappeared. However, tendency to make the date of a public event nearer to the high school period persisted.

　We hypothesize that impaired temporal estimation for an event recalled from the retrograde memory store and mis-arousal of familiarity evoked at the time of spontaneous recollection are responsible for double feeling of time of an experience.

　These phenomenon might be attributable to the partial destruction of the Papez' and the basolateral limbic circuits.