甲状腺相关性眼病提上睑肌的MRI表现

The MRI manifestations of the levator muscles in thyroid associated ophthalmopathy

目的利用磁共振成像(MRI)观察甲状腺相关眼病(TAO)患者不同眼位下提上睑肌的形态变化,探讨上睑退缩或下落迟缓的可能原因。设计前瞻性病例对照研究。研究对象TAO患者42例。方法将TAO眼外肌病患者42例(84眼)按有无上睑退缩分为患眼组(A组)和非患眼组(B组),并设正常对照组(C组),在原在位、上视眼位、下视眼位观察沿肌肉走行各个位点的提上睑肌的截面积变化。主要指标提上睑肌的截面积变化。结果 A、B组提上睑肌均较正常组明显增粗[A组(3.08±0.20)mm,B组(2.60±0.20)mm,正常组(1.41±0.06)mm],且提上睑肌的厚度与上直肌厚度有显著相关性(r=0.995)。提上睑肌的收缩功能(患眼组仅占正常人的40%)和舒张功能(患眼组仅占正常人的60%)均较正常降低,且收缩功能以肌腹处降低最为明显(A组收缩率为0.21,正常组为0.95)。沿提上睑肌走行各位点收缩率曲线B组与正常组更接近,而舒张率曲线A、B两组近乎重合。结论 TAO眼睑异常患者的提上睑肌本身虽明显增粗,但其舒张和收缩功能却不同程度受损,而且收缩功能的受损程度可能直接决定是否出现眼睑退缩等临床表现。

Objective To observe the levator muscles using MRI at the different functional eye positions and to expose the main cause of eyelid retraction in thyroid associated ophthamopathy （TAO）. Design Prospective case-control study. Participants Forty-two TAO patients. Methods TAO patients were divided into 2 groups： group A, with eyelid retraction; group B, without eyelid retraction. Normal controls were also included in this project, as group C. Area of each functional point along the levator muscle was measured at primary, down-gaze, up-gaze positions. Main Outcome Measures The area of each point along the levator muscle. Results Hypertrophy were presented in eyelid retraction group （group A 3.08±0.20, group B 2.60±0.20, control 1.41±0.06）, highly related to the enlargement of superior rectus muscle （r=0.995）. Both systolic rate and diastolic rate were found significantly reduced, to 40% and 60% of the controls respectively. Muscle belly was the point that contributed the most of the reduction of muscle retraction function. The systolic curve of group B was quite close to that of the controls, whereas the diastolic curve matched that of group A. Conclusion In spite of the hypertrophy of levator, both contraction and relaxation functions of levtator are reduced in TAO patients. Furthermore, the deficiency of the contraction may contribute the most to the eyelid retraction.