Birth brachial plexus injury
Incidence is 0.3–2.0 per 1000 live births (0.1% in infants with birthweight<4000 gm 1)). Rarely, a congenital case may be mistaken for BBPI 2). Some contend that the plexus injury may occur when uterine contractions push the shoulder against the mother’s pubic bone or with lowering of the shoulder with opposite inclination of the cervical spine 3).
Classification of BBPI injuries: Upper plexus injuries are most common, with about half having C5 & C6 injuries, and 25% involving C7 also 4). Combined upper and lower lesions occur in ≈ 20%. Pure lower lesions (C7–1) are rare, constituting only ≈ 2% and seen most commonly in breech deliveries. Lesions are bilateral in ≈ 4%.
Risk factors
1. shoulder dystocia
2. high birth weight
3. primiparous mother
4. forceps 5) or vacuum assisted delivery
5. breech presentation 6)
6. prolonged labor
7. previous birth complicated by BBPI
Management
Most surgeons observe all patients until age 3 months. Conservative surgeons may wait up to 9 months. More aggressive surgeons will explore the plexus at age 3 months if not antigravity in deltoid, biceps or triceps. In cases of proven avulsion (pseudomeningocele and EMG indicative of a preganglionic injury), nerve transfers are a valid option at 3 months 7). EMG may show signs of reinnervation, but the recovery may not be robust enough.