Obstetric brachial plexus palsy

For the development of treatment strategies for infants with obstetric brachial plexus palsy (OBPP), knowledge of the expected degree of spontaneous recovery is fundamental. However, as logical as this may appear, one of the problems of evaluation of treatment is that methodologically sound studies of the natural history of OBPP are scarce. A large number of papers exist on the subject, but in general their scientific framework is not appropriate to provide adequate data on the natural history of OBPP.¹ A number of features of the study design may influence the outcome of a reported OBPP patient series.² (1) Retrospective series carry the risk of inclusion bias; prospective studies, therefore, are preferred. (2) The study population should be constituted on a demographic basis, as results based on referrals to specialized centers or on hospital records may be biased by selection towards more severe cases. (3) Follow-up should be sufficiently long and complete. (4) Assessment of the end-stage of recovery should be accurate and reproducible, preferably using a specialized pre-defined assessment protocol. (5) No intervention in the natural course should take place.

Lagerkvist et al.³ describe 114 infants with OBPP who were prospectively identified in a well-defined geographical area. Ninety-eight of these infants were followed-up until 18 months of age, and evaluation had taken place by means of muscle strength measurement and functional scales. This means that 16 (14%) were lost to follow-up. Additionally, in three children nerve surgery had been performed, intervening in the natural history. The importance of this study is that they present a prospective, population-based series with detailed description of the neurological end-stage. This study design is what makes their paper stand out positively from other studies of the natural history of OBPP.

These authors eventually report an incidence of 2.9 per 1000 live births, which seems reasonably in line with current obstetric literature. Eight of 98 followed-up patients showed functional impairment at 18 months, so roughly one in five of OBPP patients suffer permanent neurological deficit. This is important information that should be given to parents at the moment they are confronted with the diagnosis. Most of these incompletely recovered children succeeded in activities of daily living in an independent, but frequently asymmetrical way. Only long-term follow-up will answer the question of what percentage of these children will actually suffer from functional impairment, secondary joint deformities, increased fatigability, or pain.

A real therapeutic challenge remains to identify those children who will benefit from surgical treatment of their nerve lesion. It is well recognized that nerve ruptures (neurotmesis) and root avulsions do not recover spontaneously. It is important to identify those children with these severe lesion types – preferably as early as possible – as they may benefit from nerve reconstruction.

Also in this respect, the paper of Lagerkvist et al. adds to the existing literature. They observe that if the biceps muscle recovers by 3 months of age, a complete recovery can be expected. Additionally, the authors show that when a total lesion exists that involves nerves C5 through T1, chances of recovery are lower.

Therefore, infants with OBPP whose biceps muscle does not recover quickly, or who have a more extended lesion, should be referred to a specialized center for an evaluation at the age of 3 months if there is an indication for nerve surgery. Nerve reconstructive surgery usually does not result in a normal arm function, but even in children with an initial flail limb, our and others’ results^4–6 show that useful hand function can be gained in these otherwise severely disabled infants.