Overview Snapshot A 1-day-old boy is noted by his parent that his arm is in an abnormal position. The boy was born to a 27-year-old woman at 38 weeks gestation via spontaneous vaginal delivery. The birth was complicated by shoulder dystocia. On physical exam, the newborn's right arm is adducted and internally rotated with forearm extension. The hand and wrist movements are preserved in the affected arm. Introduction Brachial Plexus Lesions Plexopathy Lesion Location Etiology Clinical Presentation Erb palsy C5-C6 roots negatively affects the deltoid and biceps brachii muscle C7 can occasionally be involved Trauma leading to separation of the head and neck e.g., lateral neck traction during birth delivery "Waiters tip" internal rotation, adduction, and extension of the arm if C7 is involved there will be flexion of the wrist and fingers Atrophy and weakness of the deltoid biceps brachii Klumpke palsy C8-T1 roots negatively affects the intrinsic muscles of the hand Upward force exerted on the arm when delivering a newborn grabbing a tree branch in an attempt to prevent a fall "Claw hand" extension at the metacarpophalangeal (MCP) joints and flexion at the distal interphalangeal (DIP) and PIP jointssecondary to impaired function of the lumbricals of the hand extension at the metacarpophalangeal (MCP) joints and flexion at the distal interphalangeal (DIP) and PIP joints secondary to impaired function of the lumbricals of the hand Thoracic outlet syndrome Compression of neurovascular structures in the thoracic outlet classically involved C8-T1 Pancoast tumor Cervical rib Neurogenic thoracic outlet syndrome pain, numbness, and weakness in the affected nerves worsened when elevating the arms above the head (e.g., brushing hair) Winged scapula Long thoracic nerve negatively affects the serratus anterior muscle Injury to the long thoracic nerve neuralgic amyotrophy direct trauma to the shoulder or lateral chest wall (e.g., playing football) surgery breast surgery with axillary lymph node dissection Projecting of the affected scapula while the patient presses against the wall