Can obstetrical brachial plexus palsy be caused by a cervical rib?
Background: The incidence of obstetric brachial plexus palsy (OBPP) is between 0.38 to 2.6 per 1000 live births. However, incidence of OBPP caused by cervical rib is unknown. Cervical ribs prevalence is 0.74–12 % and is higher in females. We describe such a case of OBPP successfully treated with early operative intervention.
Method: Patient with normal weight and uncomplicated vaginal birth suffered from brachial plexus injury (Narakas II) with no clinical improvement postpartum, after 3 months of observation. Preoperative imaging (X-ray/magnetic resonance imaging) showed no findings, but intraoperative exploration revealed that C7 root was riding on the cervical rib with a thick neuroma-incontinuity involving C5, C6, and C7 roots. After resecting the neuroma and cervical rib, nerve defects were reconstructed microsurgically with spinal-accessory nerve transfer and nerve grafts.
Results: Postoperatively, shoulder- and arm-function after 1 year were nearly fully restored (Gilbert 120 and Mallet V). Shoulder strength rated M4. Elbow and hand strength rated M4 and M5 with Gilbert and Raimondi functional scores of IV and V, respectively.
Conclusion: While OBPP caused by cervical rib is rare, this etiology should be identified during the prenatal screening sonography. Thus, extra precautions can be taken during deliveries to decrease incidence of OBPP secondary to cervical rib. Early surgical intervention for OBPP is successful in achieving functional restoration of the arm.