Case Report:

A 32-year-old woman delivered a large (4800 g) baby vaginally after some difficulty with her labor. Her prenatal course was complicated by diabetes, which occurred during pregnancy. At delivery, the infant’s head emerged, but the shoulders were “stuck” behind the maternal symphysis pubis, requiring the obstetrician to apply some effort and maneuvers to free up the infant’s shoulders and complete the delivery. The infant was noted to have a good cry and pink color but was not moving its right arm.
Case 1 Questions:

• What is the most likely diagnosis?
• What is the most likely etiology for this condition?
• What is the likely anatomical mechanism for this disorder?
Answers / Explanation

[HIDE]
ANSWERS TO CASE 1: Brachial Plexus Injury
Summary: A large (4800 g) infant of a diabetic mother is delivered after some difficulty and cannot move its right arm. There is a shoulder dystocia (the infant’s shoulders are stuck after delivery of the head).

Most likely diagnosis: Brachial plexus injury, probably Erb’s palsy.
Most likely etiology for this condition: Stretching of the upper brachial plexus during delivery.

Likely anatomical mechanism for this disorder: Stretching of nerve roots C5 and C6 by an abnormal increase in the angle between the neck and the shoulder.
[/HIDE]