小児の特発性動眼神経麻痺の1例

A case of idiopathic oculomotor nerve palsy in a child

要約　目的：小児の特発性動眼神経麻痺を経験したので報告する。

症例：患者は4歳，男児。起床時に複視を自覚し，近医を受診したところ外斜視を指摘され，精査目的に当院を紹介され受診した。

所見：視力は右（1.0），左（0.9）。左眼は散瞳固定で対光反射は消失しており，調節障害を認めた。右眼を固視眼とする外斜視を認めたが，明らかな眼球運動制限は確認できなかった。感冒症状などの前駆症状はなく，血液検査や画像検査では原因を特定できなかった。無治療で経過観察を行い，徐々に内転・下転障害と外・上斜視の増悪を認めたが，発症14日後より改善傾向を認めた。輻湊を除き眼球運動障害はほぼ消失したが，瞳孔径・対光反射の左右差や調節障害は残存し，羞明の後遺症を生じた。

結論：小児の特発性動眼神経麻痺は稀な疾患であり，確立した治療法はない。比較的予後が良いとの報告があるが，後遺症を残す症例もあり，治療・予後についてはさらなる検討を要する。

Abstract　Purpose：We report a case of idiopathic oculomotor nerve palsy diagnosed in a child after a visit to an ophthalmologist.

Case：A 4-year-old boy presented with diplopia which he had suddenly experienced upon awakening one day. He visited an ophthalmologist who noted exotropia. He was referred to our hospital for close examination.

Clinical findings：The patient had a vision of 20/20 and 20/22 in the right and left eye respectively. His left eye had mydriasis and loss of light reflex. We observed exotropia of his left eye without obvious oculomotor limitation. There were no prodomal symptoms, and laboratory examinations and diagnostic imaging failed to reveal the etiology. Follow-up without treatment gradually worsening of limitations of adduction and depression with exohypertropia. His findings improved 14 days later. The ocular motility disorder disappeared almost completely except for presence of convergence, but the left-right difference in pupil diameter and light reflex and dysregulation were remained, resulting in the sequelae of photophobia.

Conclusions：Idiopathic oculomotor nerve palsy in children is a rare condition with no established treatment. Although the prognosis has been reported to be relatively good, there have been cases of sequelae, and further investigation is needed regarding treatment and prognosis.