I: Common clinical manifestations of brachial plexus nerve root or stem injury A. Upper trunk or upper middle trunk injury: Main clinical manifestations: both shoulder abduction and flexion elbow dysfunction. How to distinguish the upper trunk injury from the upper trunk injury or C5, C6 and C5, C6, C7 injury according to clinical examination, theoretically, the muscle strength of the pectoralis major clavicularis muscle is 0 level for simple upper trunk injury, but when examined, it will be found that the muscle strength of the entire pectoralis major muscle is still close to normal, and careful examination will reveal only a small part of the upper part of its atrophy; upper and middle trunk injury at the same time, you can feel a very obvious difference between the muscle strength of the pectoralis major and normal. Only the lower 1/3 of the pectoralis major muscle strength is nearly normal, and the upper and middle parts are atrophied and have 0 muscle strength. Similarly, examination of the strength of the latissimus dorsi muscle will reveal that the strength of the upper trunk or C5 and C6 injuries is not significantly different from that of the healthy side, while the strength of the middle and lower trunk injuries, although at grade 3 or higher, will still be significantly different from that of the normal side when examined. In addition, we observed that the muscle strength of the radial carpal flexors could be distinguished from the upper trunk and upper middle trunk injuries by examining the muscle strength of the radial carpal flexors. In cases of upper trunk or C5 and C6 injuries, the muscle strength is still above grade 3, while in the latter case, the muscle strength is mostly grade 0. Based on the above examination, it can be initially determined whether the patient has an upper trunk or upper middle trunk injury. Is it possible to determine whether the nerve root is preganglionic or postganglionic based on clinical examination? Theoretically, the long thoracic nerve originates from the C5 to C7 nerve root about 25px after exiting the intervertebral foramen. In practice, however, even if an avulsion injury of the superior middle trunk occurs, the pterygoid scapula is not easily observed on clinical examination. When the anterior serratus is paralyzed and the other muscles of the scapular girdle function normally or well, the pterygoid scapula is easily manifested. After upper and middle stem avulsion, the pterygoid scapula is not exhibited even when the anterior serratus is completely paralyzed because the abduction and external rotation of the shoulder joint is completely lost and the range of motion of the scapula is significantly reduced. In contrast, through nerve displacement, when the shoulder abduction function is restored, the pterygoid scapula can be observed when performing shoulder abduction movements. Therefore, it is of little use to rely on the pterygoid scapula to determine whether the superior middle trunk is a preganglionic injury.
The supraclavicular Tinel sign (+) is instructive in determining whether there is a residual nerve root outside the foramen. If the C5 nerve root is ruptured (postganglionic injury), there may be radiating numbness on supraclavicular percussion and may reach up to the elbow along the lateral aspect of the upper arm (radiating along the sensory innervation area of C5); if there are residual C5 and C6 nerve roots outside the foramina, they may radiate to the lateral aspect of the forearm and reach the thumb; if they radiate along the lateral aspect of the upper arm and the radial aspect of the forearm to the palm, C5, C6, and C7 may all be postganglionic injuries. Since the anterior root in the spinal canal is more prone to avulsion, sometimes only the intact posterior root remains, and the above signs (false positives) can still occur on supraclavicular percussion, but the anterior root has been avulsed.
B. Complete injury of the upper middle trunk and incomplete injury of the lower trunk (C5 to C8 nerve root injury): Main clinical manifestations: loss of shoulder abduction, elbow flexion, elbow extension, wrist extension, and finger extension. Since only the T1 nerve root remains, the function of flexor and intrinsic hand muscles mostly exists, and the function of the long thumb extensor and the intrinsic extensor of the index finger and little finger sometimes partially exists. The difference with complete injury of the upper middle trunk: the former has complete loss of elbow extension, wrist extension, and total finger extension function, as well as complete paralysis of the pectoralis major and latissimus dorsi muscles.
C, total brachial plexus injury: the main clinical manifestations: complete loss of motor function of the upper limb, except for the presence of nociceptive sensation in the medial upper arm, loss of sensory function below the shoulder. Total brachial plexus injury is not the same as total brachial plexus nerve avulsion injury, about 45% of patients can still find residual nerve roots such as C5, C6, especially C5 nerve roots outside the vertebral foramen. Clinical examination reveals Horner’s sign (+) as a manifestation of inferior trunk avulsion injury. The presence of postganglionic injury to the nerve roots can be determined by the site of the supraclavicular Tinel’s sign radiation. In some patients, the radial artery pulsation is absent or significantly diminished.
Patient self-diagnosis: shoulder abduction + flexion dysfunction —- upper or upper middle trunk injury shoulder abduction + flexion dysfunction + wrist extension dysfunction (only flexion movement remains) – — complete upper middle trunk, incomplete lower trunk injury (C5 to C8 nerve root injury) Complete loss of upper extremity function —- total brachial plexus injury