先天性眼瞼下垂症の病態解析に基づいたわれわれの筋膜移植術とその長期成績

Our Aponeurotic Fascia Graft Technique for Congenital Blepharoptosis Based on a Pathophysiological Analysis, and Its Long-Term Outcome

はじめに

　先天性眼瞼下垂症に対する前頭筋を用いた再建においては，前頭筋の運動を眼瞼へ伝えることを目的として自家移植や人工物が用いられている。われわれは自家移植となる大腿筋膜移植による治療を行ってきたが，その問題となるのが移植後の筋膜組織の収縮である。移植筋膜組織の収縮に関し，われわれはラットを用いた腱移植の実験より，移植した腱の収縮量を減少させるためには十分な腱周囲組織を付着させることがその生着に有利に働き，移植後の組織収縮を減少させることを報告した 1）。また，短期観察ではあるが筋膜移植を行った臨床例における結果として，移植後6カ月時点での移植筋膜の収縮量が約15 ％であったことも報告している 2）。

　小児期に治療されることが多い同治療では，移植された生体材料の術後変化につき把握することは重要である。本論文では長期例における移植筋膜の変化率について評価を行い，新たな知見を得たので報告する。

　Dysgenesis of the levator muscle is the most common cause of congenital blepharoptosis. Based on the results of a pathophysiological analysis, this condition can be divided into two pathological types. In both types, the involuntary reflex contraction of the levator muscle via Müller's mechanoreceptors, which is essential for maintaining eyelid opening, is impaired. We thus speculated that reconstruction using the reflex contraction of the frontalis muscle with fascia grafts is necessary to achieve a more natural eye-opening function. Since this reconstruction is often performed in childhood, it is also necessary to take growth changes into consideration. We have described several key points regarding these growth changes, including the necessity of using a fascia graft with appropriate surrounding tissue to prevent the postoperative shrinkage of the grafted fascia. We evaluated the growth changes of the grafted fascia in 42 patients over a period of 10 years, and we found that the average shrinkage of the grafted fascia length was 7.5 %. However, the length of the _ _ _ _ _ was significantly increased at both downward gaze and eye-closing compared to the primary gaze. Moreover, the lengths of the patientsʼ grafts were significantly different from the values obtained during the observation period and was increased at the long-term observation point.

　These results suggest that our aponeurotic fascia graft technique for congenital blepharoptosis prevents the problematic postoperative contracture and thus enables two goals: accommodating growth changes, and dynamic kinematic reconstruction.