A 3-month-old child has motor and sensory loss in the right upper extremity in the C5–C6 distribution. Which birth injury is most likely?

A 3-month-old child has motor and sensory loss in the right upper extremity in the C5–C6 distribution. Which birth injury is most likely?

• A. Hemiplegia
• B. Erb-Duchenne paralysis
• C. Spinal Cord Injury
• D. Klumpke's paralysis

Answer: (B)

Traction or stretch injury to the upper trunk of the brachial plexus during birth, affecting the C5–C6 nerve roots, is most likely. This injury—Erb-Duchenne palsy—produces motor and sensory loss in the lateral (proximal) part of the upper extremity because the nerves that innervate the shoulder and elbow muscles (such as the deltoid, supraspinatus, infraspinatus, and biceps) arise from C5–C6. Clinically, infants may show weakness in shoulder abduction and elbow flexion with sensory loss over the lateral arm, which aligns with the C5–C6 distribution described. Other injuries involve different nerve roots or sites. Klumpke’s palsy affects the lower trunk (C8–T1) and typically impairs intrinsic hand muscles with sensory loss in the medial forearm and hand, sometimes producing a hand weakness or clawing pattern. A spinal cord injury or a central brain injury would produce a broader or different pattern of weakness and sensory loss, not confined to the C5–C6 distribution of a single upper limb in a newborn. Therefore, the presentation best fits Erb-Duchenne paralysis.

Traction or stretch injury to the upper trunk of the brachial plexus during birth, affecting the C5–C6 nerve roots, is most likely. This injury—Erb-Duchenne palsy—produces motor and sensory loss in the lateral (proximal) part of the upper extremity because the nerves that innervate the shoulder and elbow muscles (such as the deltoid, supraspinatus, infraspinatus, and biceps) arise from C5–C6. Clinically, infants may show weakness in shoulder abduction and elbow flexion with sensory loss over the lateral arm, which aligns with the C5–C6 distribution described.

Other injuries involve different nerve roots or sites. Klumpke’s palsy affects the lower trunk (C8–T1) and typically impairs intrinsic hand muscles with sensory loss in the medial forearm and hand, sometimes producing a hand weakness or clawing pattern. A spinal cord injury or a central brain injury would produce a broader or different pattern of weakness and sensory loss, not confined to the C5–C6 distribution of a single upper limb in a newborn. Therefore, the presentation best fits Erb-Duchenne paralysis.