Kato Koki, Tomura Noriaki, Takahashi Satoshi, Watarai Jiro
Department of Radiology, Akita University School of Medicine, 1-1-1 Hondo, Akita 010-8543, Japan.
Magn Reson Med Sci. 2002 Nov 1;1(3):157-64. doi: 10.2463/mrms.1.157.
We reviewed the MR appearance of motor denervation of the third (mandibular) division of the trigeminal nerve (V3) and of the hypoglossal nerve.
Six cases of tumor of the head and neck with motor denervation were retrospectively evaluated. These comprised two patients with V3 denervation, three patients with hypoglossal nerve denervation, and one patient with both V3 and hypoglossal denervation. The observation was conducted for 6 to 44 months after onset. In denervated muscles, changes in signal intensity in T(1)- and T(2)-weighted images, degree of contrast enhancement, and volume of muscle were estimated during the follow-up period.
In all cases of V3 denervation, the muscles showed no change in signal intensity in the T(1)-weighted images up to three months after onset. In two cases of hypoglossal denervation, the tongues appeared ipsilaterally hyperintense in the T(1)-weighted images within the first three months. In one case with V3 denervation and two cases with hypoglossal denervation, denervated muscles appeared hyperintense in the T(2)-weighted images up to three months after onset. At three months after denervation, the signal intensities of all motor-denervated areas increased in both T(1)- and T(2)-weighted images. Postcontrast T(1)-weighted images obtained within the first three months displayed contrast enhancement of all denervated muscles. In three cases of V3 denervation, the volumes of the affected muscles were reduced after the first three months. In three cases of hypoglossal denervation, the ipsilateral volume of the tongue decreased at three months after onset.
Up to three months after onset, the denervated muscles appeared hyperintense in the T(2)-weighted images and contrast enhancement in postcontrast T(1)-weighted images before fatty infiltration and volume loss were apparent. Familiarity with the MR appearance of denervated muscles accompanying tumors of the head and neck is important to avoid confusion with inflammatory or neoplastic processes.
我们回顾了三叉神经第三支（下颌支，V3）和舌下神经运动失神经支配的磁共振成像表现。
对6例头颈部肿瘤伴运动失神经支配的病例进行回顾性评估。其中包括2例V3失神经支配患者、3例舌下神经失神经支配患者以及1例V3和舌下神经均失神经支配的患者。在发病后6至44个月进行观察。在随访期间，评估失神经支配肌肉在T1加权和T2加权图像上的信号强度变化、对比增强程度以及肌肉体积。
在所有V3失神经支配的病例中，发病后三个月内T1加权图像上肌肉信号强度无变化。在2例舌下神经失神经支配病例中，发病后前三个月内，患侧舌在T1加权图像上呈高信号。在1例V3失神经支配病例和2例舌下神经失神经支配病例中，发病后三个月内失神经支配肌肉在T2加权图像上呈高信号。失神经支配三个月后，所有运动失神经支配区域在T1加权和T2加权图像上的信号强度均增加。发病后前三个月内获得的增强后T1加权图像显示所有失神经支配肌肉均有对比增强。在3例V3失神经支配病例中，发病后三个月后受累肌肉体积减小。在3例舌下神经失神经支配病例中，发病后三个月患侧舌体积减小。
发病后三个月内，在脂肪浸润和体积减小明显之前，失神经支配肌肉在T2加权图像上呈高信号，在增强后T1加权图像上有对比增强。熟悉头颈部肿瘤伴发的失神经支配肌肉的磁共振成像表现对于避免与炎症或肿瘤性病变混淆很重要。
