In a term (38‑week) macrosomic infant of an uncontrolled diabetic mother delivered vaginally who has a weak right‑side Moro reflex (suggesting Erb‑Duchenne palsy), what is the most appropriate management?

Management of Neonatal Brachial Plexus Injury (Erb's Palsy)

The most appropriate management is C - Immobilization of the affected arm and support, as this macrosomic infant of an uncontrolled diabetic mother with a weak right-side Moro reflex has sustained a birth-related brachial plexus injury (Erb-Duchenne palsy) that requires conservative management with gentle immobilization, positioning, and early physical therapy. 1

Clinical Context and Diagnosis

This clinical scenario represents a classic presentation of Erb's palsy following shoulder dystocia in a high-risk delivery:

• Risk factors are maximally present: macrosomic infant (>4,500g likely), uncontrolled maternal diabetes, and vaginal delivery create an 18-to-21-fold increased risk of brachial plexus injury compared to normal birth weight infants 1, 2
• The weak Moro reflex on the right side indicates upper brachial plexus injury (C5-C6 nerve roots), producing the characteristic "waiter's tip" position with the arm hanging limply from the shoulder 1
• Shoulder dystocia risk in this scenario ranges from 19.9% to 50% given the combination of diabetes and macrosomia 1, 3

Why Immobilization is Correct (Option C)

Immediate Management Steps

• Gentle immobilization by positioning the affected arm across the abdomen in a natural position is the cornerstone of initial treatment 1
• Avoid rigid immobilization which can cause joint contractures and worsen outcomes 1
• Pain management should be provided as nerve injuries are painful 1

Evidence Supporting Conservative Management

• 80-96% complete recovery rate occurs with conservative management, especially if improvement begins within the first two weeks 4, 1
• Early physical therapy (within first 2 weeks) maintains range of motion and prevents contractures 1
• Passive and active range of motion exercises are recommended following initial immobilization, though no intervention has been proven definitively effective 4

Why Surgery is Incorrect (Option A)

• Surgery is reserved for non-recovery cases at 3-6 months, not as initial management 1
• Surgical exploration of the brachial plexus with nerve grafting or nerve transfers is only considered when there is no recovery by 3-5 months 1, 4
• Immediate surgery is never indicated for birth-related brachial plexus injury 1

Why IV Dextrose is Incorrect (Option B)

While hypoglycemia is a significant concern in infants of diabetic mothers, this question specifically addresses the management of the brachial plexus injury (weak Moro reflex), not metabolic complications:

• IV dextrose treats hypoglycemia, which is a separate complication requiring concurrent management but does not address the nerve injury 5
• The weak Moro reflex is a neurological finding from birth trauma, not a metabolic derangement 1
• Hypoglycemia screening should still be performed as part of comprehensive care for infants of diabetic mothers, but this is not the answer to managing the brachial plexus injury 5

Essential Concurrent Assessments

Rule Out Associated Injuries

• Obtain plain radiographs of chest/shoulder immediately to exclude clavicular fracture, which occurs with 10-fold increased frequency in macrosomic infants and often accompanies brachial plexus injury 1, 2
• Assess grasp reflex: preserved grasp with weak Moro suggests upper brachial plexus injury (C5-C6) rather than lower plexus involvement 1
• Examine for humeral fracture, another common associated injury 1

Screen for Other Diabetic Complications

• Thorough examination for congenital anomalies including cardiac defects, neural tube defects, and caudal regression, as infants of mothers with uncontrolled diabetes have increased risk 1
• Monitor for hypoglycemia, hypocalcemia, hyperbilirubinemia, and polycythemia which are common metabolic complications 5

Follow-Up and Prognosis

Specialist Referral Timeline

• Refer to pediatric neurology or orthopedics within 1-2 weeks if weakness persists beyond the first few days 1
• Initiate physical therapy early (within first 2 weeks) to maintain range of motion 1

Expected Outcomes

• 80-90% of cases recover fully within 3-6 months with conservative management 1
• 10-20% risk of permanent deficit exists, requiring realistic parental counseling 1
• Best prognosis occurs when improvement begins within the first two weeks 4

Critical Pitfalls to Avoid

• Do not delay radiographs - clavicular fracture must be excluded immediately as it is 10-fold more common in macrosomic infants 1, 2
• Do not provide false reassurance - while most cases resolve, parents need realistic expectations about the permanent deficit risk 1
• Do not use rigid immobilization - this causes joint contractures and worsens outcomes 1
• Do not delay physical therapy referral - early intervention within 2 weeks is critical for optimal recovery 1

Maternal Counseling for Future Pregnancies

• Postpartum diabetes screening with 75g oral glucose tolerance test at 4-12 weeks postpartum, as 50-70% lifetime risk of developing type 2 diabetes exists 1
• Preconception glycemic control (A1C <6.5%) reduces macrosomia risk from 20% to 2% in subsequent pregnancies 1