EXPLANATION FOR QUESTION 23

 QUESTION 23

This infant has Klumpke palsy due to shoulder dystocia. Risk factors include infant large for gestational age (birth weight >4 kg),
maternal diabetes, and maternal obesity. Excessive traction of th.e 8th cervical (C8) and 1st thoracic (T1) nerves during delivery can
result in the rare complication of left hand paralysis. Sometimes, there is associated damage to the sympathetic fibers that run along
CS and T1 that manifests as ipsilateral miosis and ptosis (Horner syndrome)
Prognosis depends on whether damage was due to nerve stretching or compression as opposed to avulsion. Horner syndrome also
portends a suboptimal outcome. Treatment is controversial but usually involves gentle massages and physical therapy to prevent
contractures. In most cases, function returns within a few months. If there is no improvement by age 3-9 months, surgical
intervention may be considered.

The differential diagnosis of abnormal arm movement includes such other potential complications of difficult shoulder delivery as

fractures of the clavicle or humerus, Erb-Duchenne palsy, and cerebral injury from perinatal asphyxia.

(Choices A and 8) Brachia! plexus injury can sometimes accompany clavicular and humerus fractures. This patient does not have

crepitus or bony irregularity over the clavicle or humerus, making fracture unlikely Although nondisplaced clavicular fractures may

initially be hard to palpate, these infants are typically asymptomatic

(Choice C) Erb-Duchenne palsy is the most common type of brachia! plexus injury and involves the 5th and 6th cervical nerves,

leading to the "waiter's tip" posture. The affected arm may have decreased or absent Moro reflexes, but grasp reflex should remain

intact

(Choice E) Perinatal asphyxia results from compromised placental or pulmonary gas exchange. Severe hypoxia leads to poor

perfusion and acidosis initially in peripheral tissues followed by the brain. This infant has neither systemic symptoms nor

encephalopathy, making perinatal asphyxia unlikely

(Choice F) Perinatal stroke can result in abnormal arm movement presenting as hyperreflexia and hypertonia This infant does not

have hyperactive reflexes or excessive tone and his symptoms are isolated to the lower brachia! plexus, making cerebral infarction

unlikely

Educational objective:

Klumpke palsy is a rare but potentially permanent complication off shoulder dystocia Injury to the 8th cervical and 1st thoracic nerves

results in hand paralysis and ipsilateral Horner syndrome.