The overall incidence of BPBI is estimated to be 1.74 per 1000 live births.[15]Van der Looven R, Le Roy L, Tanghe E, et al. Risk factors for neonatal brachial plexus palsy: a systematic review and meta-analysis. Dev Med Child Neurol. 2020 Jun;62(6):673-83.
https://www.doi.org/10.1111/dmcn.14381
http://www.ncbi.nlm.nih.gov/pubmed/31670385?tool=bestpractice.com
In the US, the incidence of BPBI has declined from 1.7 to 0.9 cases per 1000 live births over the last few decades.[2]Abzug JM, Mehlman CT, Ying J. Assessment of current epidemiology and risk factors surrounding brachial plexus birth palsy. J Hand Surg Am. 2019 Jun;44(6):515.e1-515.e10.
http://www.ncbi.nlm.nih.gov/pubmed/30266479?tool=bestpractice.com
[16]DeFrancesco CJ, Shah DK, Rogers BH, et al. The epidemiology of brachial plexus birth palsy in the United States: declining incidence and evolving risk factors. J Pediatr Orthop. 2019 Feb;39(2):e134-40.
http://www.ncbi.nlm.nih.gov/pubmed/29016426?tool=bestpractice.com
[17]Chen HY, Blackwell SC, Yang LJ, et al. Neonatal brachial plexus palsy: associated birth injury outcomes, hospital length of stay and costs. J Matern Fetal Neonatal Med. 2022;35(25):5736-44.
http://www.ncbi.nlm.nih.gov/pubmed/33632043?tool=bestpractice.com
The decline is in line with the increasing incidence of caesarean deliveries in the US.[2]Abzug JM, Mehlman CT, Ying J. Assessment of current epidemiology and risk factors surrounding brachial plexus birth palsy. J Hand Surg Am. 2019 Jun;44(6):515.e1-515.e10.
http://www.ncbi.nlm.nih.gov/pubmed/30266479?tool=bestpractice.com
[16]DeFrancesco CJ, Shah DK, Rogers BH, et al. The epidemiology of brachial plexus birth palsy in the United States: declining incidence and evolving risk factors. J Pediatr Orthop. 2019 Feb;39(2):e134-40.
http://www.ncbi.nlm.nih.gov/pubmed/29016426?tool=bestpractice.com
The most common type of BPBI is Erb palsy (C5 to C6 nerve involvement), accounting for about 45% of cases of BPBI.[6]Smith NC, Rowan P, Benson LJ, et al. Neonatal brachial plexus palsy: outcome of absent biceps function at three months of age. J Bone Joint Surg Am. 2004 Oct;86-A(10):2163-70.
http://www.ncbi.nlm.nih.gov/pubmed/15466724?tool=bestpractice.com
An additional injury to C7, referred to as extended Erb's palsy, is discovered in roughly 20% to 30% of cases of BPBI.[6]Smith NC, Rowan P, Benson LJ, et al. Neonatal brachial plexus palsy: outcome of absent biceps function at three months of age. J Bone Joint Surg Am. 2004 Oct;86-A(10):2163-70.
http://www.ncbi.nlm.nih.gov/pubmed/15466724?tool=bestpractice.com
[7]Heise CO, Zaccariotto M, Martins RS, et al. Self-biting behavior in patients with neonatal brachial plexus palsy. Childs Nerv Syst. 2022 Sep;38(9):1773-6.
http://www.ncbi.nlm.nih.gov/pubmed/35723725?tool=bestpractice.com
Total plexus involvement (C5 to T1), or global plexus palsy, represents about 20% of cases of BPBI.[6]Smith NC, Rowan P, Benson LJ, et al. Neonatal brachial plexus palsy: outcome of absent biceps function at three months of age. J Bone Joint Surg Am. 2004 Oct;86-A(10):2163-70.
http://www.ncbi.nlm.nih.gov/pubmed/15466724?tool=bestpractice.com
[8]Abid A. Brachial plexus birth palsy: Management during the first year of life. Orthop Traumatol Surg Res. 2016 Feb;102(1 suppl):S125-32.
https://www.doi.org/10.1016/j.otsr.2015.05.008
http://www.ncbi.nlm.nih.gov/pubmed/26774906?tool=bestpractice.com
Klumpke's palsy (C8 to T1) is the least common, comprising less than 1% of cases of BPBI.[7]Heise CO, Zaccariotto M, Martins RS, et al. Self-biting behavior in patients with neonatal brachial plexus palsy. Childs Nerv Syst. 2022 Sep;38(9):1773-6.
http://www.ncbi.nlm.nih.gov/pubmed/35723725?tool=bestpractice.com
[9]al-Qattan MM, Clarke HM, Curtis CG. Klumpke's birth palsy: does it really exist? J Hand Surg Br. 1995 Feb;20(1):19-23.
http://www.ncbi.nlm.nih.gov/pubmed/7759926?tool=bestpractice.com