A 4-month-old boy presented for evaluation of congenital paralysis of the left arm. He had been the 2968-g product of a 38-week gestation. Pregnancy was complicated by poor prenatal care and maternal alcohol and intravenous cocaine abuse. The infant presented in double-footling breech position. He was delivered vaginally and had Apgar scores of 8 and 9 at 1 and 5 minutes, respectively. He was placed in a special care nursery because of hypothermia and respiratory distress, where suspected sepsis and substance withdrawal symptoms were treated.
On admission to the nursery, vital signs were as follows: rectal temperature, 35° C; respiratory rate, 70 breaths per minute; pulse rate, 140 beats per minute; and blood pressure, 55/35 mm Hg. His head circumference was 34 cm. Examination demonstrated a normal-appearing, alert infant with sternal retractions, nasal flaring, and clear breath sounds. He was diffusely hypotonic, with diminished spontaneous movements. A lumbar puncture produced