To the Editor:

I read the article “Posterior shoulder dislocation in infants with neonatal brachial plexus palsy”( 2004;86A:787-793) by Moukoko et al. with keen interest and I would like to make some remarks on their findings.

First, contrary to the authors' statement, not only incidental reports of shoulder deformities in obstetric brachial plexus lesion (OBPL) infants are available, but these deformities were the subject of an MRI study of infants considered for neurosurgical treatment (van der Sluijs et al., 2001), which showed that the majority had some kind of shoulder deformity. As to the clinical findings reported by Moukoto et al, the dorsally dislocated humeral head has been described by Birch (Birch R, 1998) as the lump sign.

Second, the more subtle shoulder deformities seem absent from this study. As the authors remark, a spectrum of shoulder deformities is present in some OBPL infants. Yet in the reported study only the extreme end of this spectrum ( the dislocations) seem present while all other patients have normal shoulders.

Third, the reported prevalence of 11 out of 134 children developing an internal rotation contracture seems low compared to other studies (Waters, 1999). The prevalence of deformities is influenced by the definition used and the cohort studied. Since the majority of OBPL infants show a full recovery, studies which do not include all infants directly post partum will show higher percentages of residual symptoms. Because the referral bias in the Moukoko study is unknown, the value of the reported prevalence is unclear.

Fourth, concerning the relevance of these deformities, shoulder function depends on neuromuscular and skeletal factors. While neuromuscular injury may lead to changes in skeletal deelopment, some of these skeletal changes could be adaptive processes that optimise the residual neuromuscular function. Recent experience with operative treatment of internal rotation contractures showed mixed results (van der Sluijs et al., 2004).

Finally, I wish to compliment the authors for showing the potential of ultrasonography,a technique that may replace either CT or MRI, for imaging shoulder deformities in OBPL infants,

J.A. van der Sluijs, MD PhD,

Reference List

1.Birch R. Birth lesions of the brachial plexus. In: Birch R, Bonney G, Wynn Parry CB, eds., Surgical disorders of the peripheral nerves. London, Churchill Livingstone, 1998: 209-233 2. van der Sluijs, van Ouwerkerk WJ, de Gast A, Nollet F, Winters H, Wuisman PI. Treatment of internal rotation contracture of the shoulder in obstetric brachial plexus lesions by subscapular tendon lengthening and open reduction: early results and complications. J Pediatr.Orthop.B 2004; 13:218-224 3. van der Sluijs, van Ouwerkerk WJ, de Gast A, Wuisman PI, Nollet F, Manoliu RA. Deformities of the shoulder in infants younger than 12 months with an obstetric lesion of the brachial plexus. J Bone Joint Surg Br. 2001; 83:551-555 4. Waters. Comparison of the natural history, the outcome of microsurgical repair, and the outcome of operative reconstruction in brachial plexus birth palsy. J.Bone Joint Surg.Am. 1999; 81:649-659