A 22-year-old man was injured in a high-speed motor vehicle collision, sustaining multiple limb fractures and pneumothoraxes. Immediately following the accident, he had difficulty moving his right upper limb. A brachial plexus injury was suspected. He was referred for electrodiagnostic studies (EDX) 3 months later, without imaging studies available for review. At the time of EDX, he described minimal strength improvements since the accident. The examination revealed atrophy of the right deltoid and rotator cuff muscles, which had 0 of 5 strengths, respectively, on the Medical Research Council (MRC) scale. Right biceps brachii was atrophic with MRC 2 of 5 strengths. Sensation was reduced around the right upper shoulder and the right lateral forearm.

EDX results suggested a severe nerve injury involving both the upper trunk of the brachial plexus and the nerve roots on the right. Neuromuscular ultrasound (NMUS) was performed using a 4–12 MHz linear transducer. Ultrasound findings were most concerning for a C6 nerve root avulsion (Fig 1). This finding dramatically impacts treatment as reinnervation cannot occur in a nerve root avulsion. Ultrasound additionally demonstrated less marked right upper trunk enlargement. MRI imaging was obtained, confirming a pseudomeningocele at C6, the key finding of a traumatic nerve root avulsion. MRI also demonstrated enhancement of the upper trunk. The patient underwent multiple nerve transfer surgeries attempting to restore innervation to the right deltoid, biceps brachii, and supraspinatus muscles.

NMUS provides rapid and valuable information complementary to EDX in brachial plexus injuries. Previous case reports suggest the ultrasound finding of a large hypoechoic structure, adjacent to the nerve root at the neural foramen may indicate nerve root avulsion.¹ The ultrasonographic beam cannot penetrate bone to image into the neural foramen, an advantage of MRI imaging, the gold standard in nerve root avulsion.¹ In our case, the pseudomeningocele did not extend past the neural foramen on MRI (Fig 1). The ultrasound images obtained reflect the significant nerve root injury but likely also demonstrate additional pathology such as edema and inflammation in the nerve root. These ultrasound images demonstrate the ability of NMUS to add to patient care in cases of traumatic brachial plexus injuries.

Panel (A) T2 STIR coronal MRI image demonstrating C6 nerve root enhancement and illustrating ultrasound transducer placement for long axis (panel B) and short axis (panel D) NMUS images.

Panel (B) Long axis ultrasound image of the markedly enlarged C6 nerve root. Proximally, the root is diffusely hypoechoic. Distally, there is mixed hyper- and hypoechoic contents with nerve fascicles visualized.

Panel (C) T2 axial MRI image of pseudomeningocele at the right C5-C6 neural foramen.

Panel (D) Short axis ultrasound image of the C6 nerve root. This level is confirmed using bony anatomy; at this level, the transverse process has a large anterior tubercle (arrow).² There is a large hypoechoic structure with a hyperechoic border (arrowhead) and increased Doppler flow suggesting increased vascularity (not shown). Internally, there is a region of hyperechogenicity which may represent neural elements. The cross-sectional area measuring inside the hyperechoic border is 63 mm² (normal 5–11 mm²).³

一名22岁男子在高速机动车相撞中受伤，肢体多处骨折并出现气胸。事故发生后，他的右上肢活动困难。怀疑臂丛神经损伤。 3 个月后，他被转诊进行电诊断研究 (EDX)，但没有可供审查的影像学研究。在 EDX 期间，他描述了自事故发生以来力量的微小改善。检查发现右侧三角肌和肩袖肌肉萎缩，根据医学研究委员会 (MRC) 量表，这两项肌肉的强度分别为 0 分（满分 5 分）。右侧肱二头肌萎缩，MRC 为 5 项强度中的 2 项。右上肩和右侧前臂周围的感觉减弱。

EDX 结果表明严重的神经损伤，涉及臂丛神经上干和右侧神经根。使用 4-12 MHz 线性换能器进行神经肌肉超声 (NMUS)。超声检查结果最令人担忧的是 C6 神经根撕脱伤（图 1）。这一发现极大地影响了治疗，因为神经根撕脱不会发生神经再生。超声检查还显示右上躯干增大不太明显。获得 MRI 成像，证实 C6 处存在假性脑膜膨出，这是创伤性神经根撕脱的关键发现。 MRI 还显示上躯干增强。患者接受了多次神经转移手术，试图恢复右三角肌、肱二头肌和冈上肌的神经支配。

NMUS 提供快速且有价值的信息，作为臂丛神经损伤 EDX 的补充。先前的病例报告表明，超声发现神经根处神经孔附近有一个大的低回声结构可能表明神经根撕脱。¹超声束无法穿透骨骼对神经孔进行成像，这是 MRI 成像的优势，而 MRI 成像是神经根撕脱术的金标准。¹在我们的病例中，MRI 上显示假性脑膜膨出并未超出神经孔（图 1）。获得的超声图像反映了严重的神经根损伤，但也可能显示出其他病理，例如神经根中的水肿和炎症。这些超声图像证明了 NMUS 在创伤性臂丛神经损伤的情况下增强患者护理的能力。

图 (A) T2 STIR 冠状 MRI 图像显示 C6 神经根增强，并说明长轴（图 B）和短轴（图 D）NMUS 图像的超声换能器放置。

图 (B) 显着增大的 C6 神经根的长轴超声图像。近端，根部呈弥漫性低回声。在远端，存在混合的高回声和低回声内容，并可见神经束。

(C) 右侧 C5-C6 神经孔假性脑膜膨出的 T2 轴向 MRI 图像。

图 (D) C6 神经根的短轴超声图像。这个水平是通过骨骼解剖学确认的；在这个水平上，横突有一个大的前结节（箭头）。²有一个大的低回声结构，带有高回声边界（箭头），多普勒血流增加表明血管分布增加（未显示）。在内部，有一个高回声区域，可能代表神经元件。高回声边界内测量的横截面积为 63 mm ²（正常为 5–11 mm ²）。³