CHAPTER 27
Brachial Plexus Injuries
Newborn Brachial Plexus Injury
INTRODUCTION/ETIOLOGY/EPIDEMIOLOGY
• The incidence of newborn brachial plexus injury is estimated to be 0.9 per 1,000 total births.
• Most are traction injuries to the brachial plexus (Table 27-1 and Table 27-2) caused by downward positioning of the shoulder and lateral flexion or hyperextension of the neck during delivery, resulting in varying degrees of upper extremity muscle weakness, which can lead to progressive glenohumeral joint deformity and dislocation.
• Shoulder dystocia is documented in about 50% of cases.
— Although the incidence of brachial plexus injury decreased from 1997 to 2012, shoulder dystocia remains the most common risk factor.
• Risk factors are listed in Box 27-1.
• Brachial plexus injuries most commonly occur in newborns with macrosomia but without macrocephaly.
— This combination allows the head to be delivered easily but traps the shoulders against the pubic bone.
• Cesarean is the preferred delivery method for babies with macrosomia, but it does not preclude the possibility of brachial plexus injury.
• Comorbidities
— Diaphragmatic paralysis is documented in 1% to 5% of cases. C3, C4, and C5 nerve roots contribute to the phrenic nerve, which innervates the ipsilateral hemidiaphragm. Suspect this in any newborn with a brachial plexus injury and respiratory distress, including mild tachypnea.
— Horner syndrome is documented in 5% to 30% of cases. Disruption of the sympathetic nerves that arise from the nerve roots in the lower cervical and upper thoracic spinal cord results in miosis, ptosis, enophthalmos, and anhidrosis of the ipsilateral face.
• Newborn brachial plexus injury classification is based on anatomic level of injury.
— C5-C6 injuries
■Erb palsy (Erb-Duchenne paralysis)
■90% of neonatal brachial plexus injuries
■Injury of the upper trunk avulsion is rare.
— C5-C7 injuries
■Extended Erb palsy
Table 27-1. Brachial Plexus Injuries and Associated Deficits
| Injury | Sensory Deficit | Motor Deficit |
|---|---|---|
| C5 root | Lateral shoulder | Shoulder external rotation and abduction |
| C6 root | Cubital fossa Tip of thumb | Elbow flexion Extensor carpi radialis longus |
| C7 root | Thumb, index, and middle fingers Dorsal radial hand | Flexor carpi radialis Brachioradialis Pronator teres |
| C8 root | Ring and little fingers Dorsal ulnar hand | Wrist and finger flexion |
| T1 root | None or minimal | Intrinsic muscles of the hand |
| Upper trunk | Lateral shoulder Thumb, index, and middle fingers | Shoulder external rotation and abduction, elbow flexion Pronator teres Flexor carpi radialis |
| Middle trunk | Thumb, index, and middle fingers Radial forearm Radial dorsal hand | Shoulder external rotation and abduction, elbow extension Pronator teres Flexor carpi radialis |
| Lower trunk | Ring and little fingers Medial arm and forearm | Most of the wrist and finger flexors Median and ulnar intrinsics |
| Posterior cord | Lateral shoulder | Shoulder abduction |
| Lateral cord | Thumb, index, and middle fingers Cubital fossa Radial forearm | Pronator teres Flexor carpi radialis Elbow flexion |
| Medial cord | Ring and little fingers Medial arm and forearm | Most of the wrist and finger flexors Median and ulnar intrinsics |
Table 27-2. Brachial Plexus Terminal Nerve Injuries and Associated Deficits
| Injured Nerve | Sensory Deficit | Motor Deficit |
|---|---|---|
| Suprascapular | None or minimal | Supraspinatus Infraspinatus |
| Long thoracic | None or minimal | Serratus anterior |
| Axillary (ie, circumflex) | Shoulder joint Distal lateral shoulder | Deltoid Teres minor |
| Musculocutaneous | Radial forearm | Biceps brachii Brachioradialis Coracobrachialis |
| Radial | Most of the dorsal hand | Triceps brachii Brachioradialis Extensor carpi radialis longus and brevis Supinator Extrinsic extensor muscles of wrist and fingers |
| Median | Palmar aspect of the first 3½ digits and dorsal aspect from fingertip to distal interphalangeal joint | Abductor pollicis brevis Flexor pollicis brevis Opponens pollicis Flexor digitorum profundus (index and middle fingers) First and second lumbricals |
| Ulnar | Fifth digit and ulnar half of fourth digit | Flexor carpi ulnaris Flexor digitorum profundus (ring and little fingers) Third and fourth lumbricals Opponens digiti minimi Flexor digiti minimi Abductor digiti minimi interossei Adductor pollicis |
Box 27-1. Risk Factors for Newborn Brachial Plexus Injury
| Maternal • Previous child with newborn brachial plexus injury • Fibroids • Bicornate uterus • Diabetes • Primiparity • Advanced maternal age • Grand multiparity |
| Fetal • Macrosomia • Transverse lie • Low tone • Neonatal depression |
| Parturitional • Abnormal presentation • Dysfunctional labor • Prolonged second stage of labor • Assisted delivery (eg, vacuum, forceps) |
— C8-T1 injuries
■Klumpke paralysis
■About 1% of newborn brachial plexus injuries
■Injury to C8 and T1 roots; avulsion is more common
— C5-T1 injuries
■Total plexus injury (flail extremity)
■8% to 23% of newborn brachial plexus injuries
— Diaphragmatic paralysis and Horner syndrome are more frequent with a total plexus injury than with Klumpke and Erb palsies.
SIGNS AND SYMPTOMS
• C5-C6 injuries (Erb palsy [Erb-Duchenne palsy])
—
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