急激な視力低下を呈した初期のposterior cortical atrophyの1例

Sudden visual impairment in a case of posterior cortical atrophy in its early stage

要約　背景：Posterior cortical atrophyは，初期では視覚障害のみがあり，最終的に痴呆に至る予後不良な神経変性疾患である。目的：初期のposterior cortical atrophyの1症例の報告。症例：46歳男性が1年前からの視力障害で受診した。矯正視力は左右とも0.3であり，特記すべき眼科的な異常はなく，視野は左下1/4同名半盲様であった。問診から視覚失認が疑われた。磁気共鳴画像検査（MRI）で頭頂葉から後頭葉にかけて皮質萎縮があり，神経内科での認知機能検査と合わせ，posterior cortical atrophyと診断された。9か月後に矯正視力は左右とも指数弁に低下したが，Teller acuity cardsでの視力測定では左右とも0.4であった。結論：Posterior cortical atrophyの患者は最初に眼科を受診することが多いが，検眼鏡的には異常がないので注意が必要である。Teller acuity cardsによる視力測定が診断に寄与する可能性がある。

Abstract.　Background：Posterior cortical atrophy（PCA）initially manifests visual complaints. It is a neuro-degenerative disease that may finally result in dementia. Purpose：To report a case of PCA in its early stage. Case：A 46-year-old male presented with visual impairment since one year before. His corrected visual acuity was 0.3 in either eye. Routine ophthalmological examinations showed no definitive findings. Perimetry showed homonymous quadrantanopia in the lower left sector. Visual agnosia was suspected upon further interview. Magnetic resonance imaging（MRI）showed cortical atrophy ranging from frontal and posterior lobe. He was diagnosed with PCA after cognitive tests by neurologists. His visual acuity decreased to finger counting in either eye. Still, Teller acuity cards showed the visual acuity to be 0.4 in both eyes. Conclusion：Ophthalmologists ought to be aware of this clinical entity because patients may initially consult for eye problems. There is a possibility that findings by Teller acuity cards may be useful in its diagnosis.