The prognosis for recovery from brachial plexus injury sustained at or befo
re birth is generally favorable. However, roughly 10% of these infants rema
in profoundly weak and later exhibit functional disability in the affected
arm. Early identification of these at-risk infants would be helpful in sele
cting patients for surgical management. In our prospective study, 80 infant
s with brachial plexus injury were examined on a monthly basis. Complete re
covery occurred in 53 (66%); in 9 (11%), mild weakness persisted. In each c
hild, recovery to antigravity strength in the biceps, triceps, and deltoid
was noted by 6 months of age. Moderate arm weakness persisted in 7 children
(9%); none had antigravity strength in the deltoid at age 6 months. Eleven
children (14%) had severe permanent weakness (mean follow-up: 4.4 years).
At age 6 months, these individuals exhibited at best 2/5 strength proximall
y and typically 0-1/5 strength in the wrist and finger extensors. Our resul
ts demonstrate that detailed strength testing up to 6 months of age predict
s not only complete recovery of neonatal brachial plexus injury but also th
ose children destined for long-term severe disability.