Bendszus Martin, Koltzenburg Martin, Wessig Carsten, Solymosi Laszlo
Department of Neuroradiology, University of Würzburg, Germany.
AJNR Am J Neuroradiol. 2002 Sep;23(8):1427-31.
MR changes in denervated muscles have been reported to occur within days up to several weeks after peripheral nerve damage. The purpose of this experimental study was to investigate the longitudinal changes in denervated muscles by using MR imaging.
In 12 Lewis rats, the left sciatic nerve was transected at the level of the proximal thigh. MR imaging of both legs was performed before and 1 hour, 24 hours, 48 hours, 7 days, 14 days, 28 days, and 2 months after the procedure. The MR protocol included T1-weighted spin-echo, T2-weighted double turbo spin-echo, and turbo inversion recovery magnitude (TIRM) sequences obtained in the axial plane. Signal intensities (T2-weighted double turbo spin-echo and TIRM sequences) and the T2 TR (T2-weighted double turbo spin-echo sequence) were recorded for the soleus, peroneal, and gracilis muscles of both sides. Moreover, the circumferences of both lower legs were determined on the basis of T1-weighted images.
Twenty-four hours after denervation, a signal intensity increase in the denervated peroneal and soleus muscles was present on TIRM images. On T2-weighted images, only the peroneal muscle exhibited slightly increased signal intensities and T2 TR. Forty-eight hours after nerve transection, the denervated soleus and peroneal muscles revealed prolonged T2 TR and marked increased signal intensities on T2-weighted and TIRM images when compared with the contralateral side, which further increased at or less than 2 months after denervation. Muscle atrophy of the denervated muscles was present as early as 7 days after denervation and was also increased at follow-up examinations.
The TIRM sequence is more sensitive than is T2-weighted imaging in the detection of signal intensity changes in denervated muscle. These changes occur as early as 24 (TIRM sequence) and 48 (T2-weighted sequence) hours, respectively, after complete transection of the sciatic nerve in rats and precede muscle atrophy. The sensitivity to early signal intensity changes in denervated muscles may support the use of MR imaging in the diagnosis of peripheral nerve lesions.
据报道，失神经支配肌肉的磁共振（MR）改变发生在外周神经损伤后的数天至数周内。本实验研究的目的是利用MR成像研究失神经支配肌肉的纵向变化。
选取12只Lewis大鼠，在大腿近端水平切断左侧坐骨神经。分别于手术前、术后1小时、24小时、48小时、7天、14天、28天和2个月对双侧下肢进行MR成像。MR检查方案包括在轴位平面获取的T1加权自旋回波、T2加权双涡轮自旋回波和涡轮反转恢复幅度（TIRM）序列。记录双侧比目鱼肌、腓骨肌和股薄肌的信号强度（T2加权双涡轮自旋回波和TIRM序列）以及T2 TR（T2加权双涡轮自旋回波序列）。此外，根据T1加权图像测定双侧小腿周长。
去神经支配24小时后，TIRM图像上失神经支配的腓骨肌和比目鱼肌信号强度增加。在T2加权图像上，只有腓骨肌的信号强度和T2 TR略有增加。神经切断术后48小时，与对侧相比，失神经支配的比目鱼肌和腓骨肌在T2加权和TIRM图像上显示T2 TR延长且信号强度明显增加，在去神经支配后2个月时或更早进一步增加。失神经支配肌肉的萎缩最早在去神经支配7天后出现，随访检查时也有所加重。
在检测失神经支配肌肉的信号强度变化方面，TIRM序列比T2加权成像更敏感。这些变化分别在大鼠坐骨神经完全切断后24小时（TIRM序列）和48小时（T2加权序列）出现，且早于肌肉萎缩。对失神经支配肌肉早期信号强度变化的敏感性可能支持MR成像在外周神经病变诊断中的应用。
