Congenital brachial plexus palsy - reply

Dear Sir,

The authors would like to thank Dr Khunda for his interest in our article. There is paucity of British literature regarding the risk factors for brachial plexus injury in presence of shoulder dystocia. Most of the published literature is from the Scandinavian and American population.

As regards the second query about the conclusion that in the presence of shoulder dystocia, brachial plexus injury is more likely to occur if labour is augmented in cases of primiparous women (Tandon and Tandon 2005), 23 out of 27 women comprise 85% of the group. Although in the other three women, shoulder dystocia did not occur, the neonatal variables were similar. The fourth baby was twin-two and the arm required manipulation for delivery. This group was too small to be sub-classed as a different group.

As regards the two rare scenarios that Dr Khunda mentions in his letter, the commoner causes are the ones we would like to cite as first possible reasons for the posterior shoulder injuries as mentioned in the literature. In a review of the causation of Erb's palsy, Sandmire and DeMott (2002) noted that landmark papers by Boyd et al. (1983) and Levine et al. (1984) reported first cases of brachial plexus injury without concurrent shoulder dystocia. The anterior arm is more likely to be involved in cases associated with shoulder dystocia, whereas the posterior shoulder is more likely to be involved in the absence of shoulder dystocia (Gherman et al. 1998). They thought that because of the distance the posterior arm traverses in the pelvis (13 cm compared with 5 cm for the anterior) even though the posterior shoulder may not be stuck at delivery, i.e. there may not be shoulder dystocia; maternal forces, rotation to an oblique diameter or both may result in injury during descent of the posterior shoulder to below the promontory of the sacrum.