Dell'Osso L F, Hertle R W, Williams R W, Jacobs J B
Veterans Affairs Medical Center and the Department of Neurology, Case Western Reserve University and University Hospitals of Cleveland, Ohio 44106, USA.
J AAPOS. 1999 Jun;3(3):166-82. doi: 10.1016/s1091-8531(99)70063-7.
Human eye-movement recordings have documented that surgical treatment of congenital nystagmus (CN) also produces a broadening of the null zone and changes in foveation that allow increased acuity. We used the achiasmatic Belgian sheepdog, a spontaneously occurring animal model of human CN and see-saw nystagmus (SSN), to test the hypothesis that changes induced by surgical interruption of the extraocular muscle afference without a change in muscle-length tension could damp both oscillations.
An achiasmatic dog with CN and SSN underwent videotaping and infrared oculography in a sling apparatus and head restraints before and after all extraocular muscles (stage 1: 4 horizontal rectus muscles and stage 2 [4 months later]: 4 vertical rectus muscles and 4 oblique muscles) were surgically tenotomized and immediately reattached at their original insertions.
The dog had immediate and persistent visible, behavioral, and oculographic changes after each stage of this new procedure. These included damped CN and SSN, increased ability to maintain fixation, and increased periods of maintaining the target image on the area centralis over a broad range of gaze angles.
Severing and reattaching the tendons of the extraocular muscles affect some as-yet-unknown combination of central nervous system processes producing the above results. This new procedure may prove effective in patients with CN with either no null, a null at primary position, or a time-varying null (due to asymmetric, (a)periodic, alternating nystagmus). We infer from our results in an achiasmatic dog that tenotomy is the probable cause of the damping documented in human CN after Anderson-Kestenbaum procedures and should also damp CN and SSN in achiasma in humans. It may also prove useful in acquired nystagmus to reduce oscillopsia. The success of tenotomy in damping nystagmus in this animal suggests that the proprioceptive feedback loop has a more important role in ocular-motor control than has been appreciated. Finally, we propose a modified bimedial recession procedure, on the basis of the damping effects of tenotomy.
人类眼动记录表明，先天性眼球震颤（CN）的手术治疗还会使静息区变宽，并使注视发生改变，从而提高视力。我们使用无交叉的比利时牧羊犬，这是一种人类CN和跷跷板眼球震颤（SSN）的自发动物模型，来检验以下假设：在不改变肌肉长度张力的情况下，通过手术中断眼外肌传入所引起的变化可以抑制这两种震颤。
一只患有CN和SSN的无交叉狗在吊带装置和头部固定器中进行录像和红外眼动图检查，在所有眼外肌（第1阶段：4条水平直肌；第2阶段[4个月后]：4条垂直直肌和4条斜肌）进行手术切断肌腱并立即在其原始附着点重新附着之前和之后。
在这个新手术的每个阶段后，这只狗立即出现并持续存在明显的行为和眼动图变化。这些变化包括CN和SSN受到抑制、保持注视的能力增强，以及在广泛的注视角度范围内将目标图像保持在中央凹区域的时间增加。
切断并重新附着眼外肌肌腱会影响产生上述结果的中枢神经系统过程的某种未知组合。这种新手术可能对没有静息区、在初始位置有静息区或有随时间变化的静息区（由于不对称、（非）周期性、交替性眼球震颤）的CN患者有效。我们从无交叉狗的结果推断，腱切断术可能是人类在安德森 - 凯斯滕鲍姆手术后CN中记录到的震颤抑制的原因，并且也应该能抑制人类无交叉情况下的CN和SSN。它在后天性眼球震颤中减少视振荡方面也可能证明是有用的。腱切断术在抑制这种动物的眼球震颤方面的成功表明，本体感受反馈回路在眼动控制中的作用比人们所认识到的更为重要。最后，我们基于腱切断术的抑制作用提出了一种改良的双眼内直肌后徙手术。
