動眼神経異常連合運動に対する斜視手術の1例

A case of strabismus surgery on acquired oculomotor synkinesis

　動眼神経麻痺の回復過程で，外眼筋，上眼瞼挙筋，瞳孔括約筋などに異常連合運動が起こる現象は良く知られているが，その眼位異常や眼瞼下垂の矯正に際しては，異常な神経支配に対する配慮が必要となる。

　症例は20歳，男性。頭部外傷による右眼の動眼神経麻痺で，異常連合運動として，下転時の瞼裂開大と縮瞳，内転時の瞼裂開大を認めた。さらに上下転制限を認め，筋電図にて上，下方視時の上下直筋の同時収縮を確認した。これに対し，右下斜視の矯正目的で右眼下直筋後転4mmを施行したところ，眼位は正位となり，更に第一眼位での眼瞼下垂が消失した。第二段階として，下方視での上下偏位矯正目的で，左眼下直筋Faden 14 mmを施行したが，効果は不十分であった。

　以上より，動眼神経異常連合の症例では，上，下直筋手術の効果は，上，下直筋共同収縮の有無に左右されるため，術式の選択にあたって十分配慮すべきである。また，眼位により瞼裂幅が変化する例では，眼筋手術によって眼瞼下垂の改善の可能性があると考えた。

A 20-year-old male developed third nerve palsy in his right eye following blunt head trauma. Six months after the injury, he manifested lid-gaze and pupil-gaze synkinesis due to aberrant oculomotor nerve regeneration. Right hypotropia was also present in the primary position. Voluntary vertical eye movement was restricted due to co-contracture of the superior and inferior rectus muscles in the right eye as proven by electromyogram. Addition-ally, the right eye was ptotic in the primary posi-tion, with lid retraction in the down and left gaze.Miosis occurred in the down gaze, while the pupil remained dilated in gaze in other directions.As the initial therapeutic approach, we perform-ed recession of the right inferior rectus by 4 mm to correct the right hypotropia. This procedure result-ed in correction of the ptosis and the vertical deviation. Recession of the inferior rectus would mean that an additional innervation is required to maintain the primary position. The ptosis seemed to have thus improved with the attempted fixation with his dominant right eye.

As the second step, we performed a Faden opera-tion of 14 mm on the left inferior rectus to correct the residual vertical deviation during downward gaze. This attempt was futile. It appeared that attempts at balancing counter-paresis by means of Faden operation is useless in the presence of para-doxical innervation of both vertical rectus muscles.

Rinsho Ganka (Jpn J Clin Ophthalmol) 41(11) : 1259-1262,1987