Center of Biological and Health Sciences, Department of Neurosurgery, University of the South of Santa Catarina (Unisul), Tubarão, SC, Brazil.
J Neurosurg. 2012 Feb;116(2):409-13. doi: 10.3171/2011.7.JNS11672. Epub 2011 Aug 19.
Classically, C5-7 root injuries of the brachial plexus have been associated with palsies of shoulder abduction/external rotation, elbow flexion/extension, and wrist, thumb, and finger extension. However, current myotome maps generally indicate that C-8 participates in the innervation of thumb and finger extensors. Therefore, the authors have hypothesized that, for palsies of the thumb and finger extensors, the injury should affect the C-5 through C-8 roots.
The authors tested their hypothesis in 30 patients with upper-type palsies of the brachial plexus. They traced a correlation between clinical findings and root injury, as documented by CT myelography, direct visualization during surgery, and electrophysiological studies.
In C5-8 root injuries, shoulder abduction and external rotation were paralyzed, and in all patients, wrist extensors were paralyzed. However, in 22 of the 30 patients, wrist extension was possible, because of contraction of the extensor digitorum communis and extensor pollicis longus. Wrist flexion and pronation also were preserved. The T-1 root contributed significantly to innervation of the thumb and finger flexors, ensuring 34% grasping and 40% pinch strength relative to the normal side. Hand sensation was largely preserved.
Based on the authors' observations, they suspect that the clinical scenario previously attributed to a C5-7 root injury is, in fact, a C5-8 root injury. The authors propose referring to this partial palsy of the brachial plexus as a "T-1 hand."
经典地，臂丛 C5-7 神经根损伤与肩外展/外旋、肘屈伸和腕、拇指和手指伸展无力相关。然而，当前的肌节图谱通常表明 C-8 参与拇指和手指伸肌的神经支配。因此，作者假设对于拇指和手指伸肌无力，损伤应影响 C5-8 神经根。
作者在 30 例上肢型臂丛神经损伤患者中测试了他们的假设。他们根据 CT 脊髓造影、手术中直接观察和电生理研究记录的根损伤，追踪了临床发现与根损伤之间的相关性。
在 C5-8 神经根损伤中，肩外展和外旋无力，所有患者腕伸肌无力。然而，在 30 例患者中的 22 例中，由于指总伸肌和拇长伸肌的收缩，腕伸肌仍可活动。腕屈和旋前也得以保留。T1 根对手指屈肌和拇指屈肌的神经支配有重要贡献，相对于健侧，保证了 34%的抓握力和 40%的捏力。手的感觉基本保留。
基于作者的观察，他们怀疑先前归因于 C5-7 神经根损伤的临床情况实际上是 C5-8 神经根损伤。作者建议将这种臂丛神经的部分无力称为“T1 手”。
