Brachial plexus injuries have an incidence of 2-3/1000 births. Risk factors include being a large for dates infant, prolonged labor, or breech delivery. About 45% are associated with shoulder dystocia. In the non- dystocia group, one study found an association with primagravidas, small infants, and mothers less than 20 years old. This has led some to believe that intrauterine factors play some role in the etiology. 

Brachial plexus injuries are often subjects of medicolegal cases.

Presentation

1. Usually discovered at birth or shortly after by an inequality of upper arm movement, an unequal Moro reflex, or suspicion because of the type of delivery.
2. Erb's Palsy- the most common type and involves injury to C5 and C6. There is an inability to abduct the shoulder, externally rotate the arm, and supinate the forearm. The hand and wrist are spared and there is a normal grasp. DTRs are absent. Rarely, the fibers to the diaphragm are involved and there may be paralysis on the ipsilateral side.
3. Klumpke's- involves C8-T1 and will have inability to flex wrist or grasp. If sympathetic fibers of T1 are involved, there may be an ipsilateral ptosis and miosis(Horner's syndrome). Much less common than Erb's and recovery rate less.
4. Entire plexus involved from C5-T1

Differential Diagnosis

1. Fracture or injury to the humerus
2. Fracture of the clavicle

1. Initial management includes careful examination and history taking
2. Need neurologic evaluation to recommend further workup and to establish baseline loss of function so that improvement may be monitored. Neurologist may recommend physical therapy to do passive range of motion and prevent contractures and atrophy of muscles. 
3. MRI may delineate complete avulsion of the nerve roots.
4. Usually if not better by 3-6 months, there will be permanent deficits. 
5. Muscle group transplants and nerve grafting have been done with some success. 
6. Reassure parents and make sure that you do not boldly claim that the arm will be perfect in a short period of time.

1. Sellinger, Catherine. Brachial Plexus Injuries. Pediatrics in Review. February 1992
2. Gilbert William et al. Associated Factors in 1611 Cases of Brachial Plexus Injuries. Obstetrics Gynecology April 199