Obstetric brachial plexus palsy--risk factors and predictors

Obstetric brachial plexus palsy is a rare condition occurring in about 1 per thousand of live births. It is caused most often by traction during delivery, although in some cases clear evidence of direct injury to the nerves is not present. The aim of the study was to define risk factors for obstetric brachial plexus palsy and relate the chances of recovery to the severity of the injury.

Two prospective databases of patient information and clinical assessment data were used for the study. The first database contained information about pregnancy, labour, severity of injury, operative procedures and coexisting disorders of 162 children. The second comprised information about clinical assessment of the affected limb in 76 patients. The mean age of patients at last follow-up was 6 years and 9 months.

High birth weight, shoulder dystocia, forceps delivery and clavicle fracture were important risk factors in obstetric brachial plexus injury. Breech delivery was not associated with a higher incidence of nerve injuries despite literature data pointing to the contrary. A Caesarean incision reduced the risk of plexus palsy but did not eliminate it completely. In Narakas group 1 patients, recovery of biceps function occurred before the age of 4 months. The vast majority of the children will have complete recovery of the affected limb. In group III and IV, return to full function is very unlikely. Our results confirm that Narakas' classification, apart from being very popular for classifying severity of the pathology, is a strong predictor of outcome.