Roentgen Findings in Obstetrical Injuries to the Brachial Plexus

Injury to the brachial plexus with resulting paralysis occurring at birth is caused by stretching of the nerves when the head and shoulder of the infant are forcibly separated (5). This may occur in vertex presentations when traction and lateral flexion are exerted on the neck while the shoulder is fixed in the maternal pelvis. In breech presentations, forceful manipulation with abduction and elevation of an arm and shoulder may exert excessive traction against a fixed neck. Other possible causes are difficult labor, forceps delivery, marked relaxation of the muscles of the fetus from profound anesthesia, and the use of undue force. In mild cases, there may be only hemorrhage or edema of the nerve sheaths, and spontaneous recovery usually occurs within three to six months. In more severe cases, there may be nerve-sheath rupture, hemorrhage into the nerve trunks, separation of nerve fibers, or partial or complete division of nerve trunks. Avulsion of the nerve roots from the spinal cord may also occur. The condition is not attributable to rupture of the capsule of the shoulder joint or to separation of the epiphysis of the humeral head (5). The paralysis has been classified into upper-arm, lower-arm, and whole-arm types. In the upper-arm type, or Erb's paralysis, the fifth and sixth cervical roots are involved. The arm hangs at the side with the extremity internally rotated and the forearm pronated. The elbow and wrist are flexed. The attitude of the extremity has been referred to as the “waiter's tip” position. When the paralysis persists, the limb becomes atrophic, contractures result, and external rotation is impaired. In the uncommon lower-arm type, or Klumpke's paralysis, the seventh and eighth cervical and first thoracic roots are involved. Loss of function of the intrinsic hand muscles, the flexors of the wrist, and the long flexors of the fingers results in a clawhand. Horner's syndrome may be associated with this paralysis as a result of injury to the cervical sympathetic fibers which enter the cord through the first dorsal root and, in some instances, the eighth cervical root. In the whole-arm type, roots C5 through T1 are involved. The entire arm is flaccid with wrist drop and paralysis of the small muscles of the hand. Marked atrophy of the arm is present, and its growth is delayed. Roentgen Findings In the injured newborn, the metaphysis of the humerus is farther from the glenoid than normal (Fig. 1). Development of the epiphyses of the humeral head is retarded (Fig. 2), and atrophy of the soft tissues around the shoulder joint is present (Fig. 3). The scapula is elevated and rotated outward. Later, the ossification center for the humeral head may lie lateral to that of the greater tuberosity because of internal rotation of the humerus. If the phrenic nerve is involved, the diaphragm on the affected side is elevated (Fig. 4) (2).