Abstract
Objective The effect of end-to-side neurotization of partially regenerated recipient nerves
on improving motor power in late obstetric brachial plexus lesions, so-called nerve
augmentation, was investigated.
Methods Eight cases aged 3 – 7 years were operated upon and followed up for 4 years (C5,6
rupture C7,8T1 avulsion: 5; C5,6,7,8 rupture T1 avulsion:1; C5,6,8T1 rupture C7 avulsion:1;
C5,6,7 ruptureC8 T1 compression: one 3 year presentation after former neurotization
at 3 months). Grade 1–3 muscles were neurotized. Grade0 muscles were neurotized, if
the electromyogram showed scattered motor unit action potentials on voluntary contraction
without interference pattern. Donor nerves included: the phrenic, accessory, descending
and ascending loops of the ansa cervicalis, 3rd and 4th intercostals and contralateral C7.
Results Superior proximal to distal regeneration was observed firstly. Differential regeneration
of muscles supplied by the same nerve was observed secondly (superior supraspinatus
to infraspinatus regeneration). Differential regeneration of antagonistic muscles
was observed thirdly (superior biceps to triceps and pronator teres to supinator recovery).
Differential regeneration of fibres within the same muscle was observed fourthly (superior
anterior and middle to posterior deltoid regeneration). Differential regeneration
of muscles having different preoperative motor powers was noted fifthly; improvement
to Grade 3 or more occurred more in Grade2 than in Grade0 or Grade1 muscles. Improvements
of cocontractions and of shoulder, forearm and wrist deformities were noted sixthly.
The shoulder, elbow and hand scores improved in 4 cases.
Limitations The sample size is small. Controls are necessary to rule out any natural improvement
of the lesion. There is intra- and interobserver variability in testing muscle power
and cocontractions.
Conclusion Nerve augmentation improves cocontractions and muscle power in the biceps, pectoral
muscles, supraspinatus, anterior and lateral deltoids, triceps and in Grade2 or more
forearm muscles. As it is less expected to improve infraspinatus power, it should
be associated with a humeral derotation osteotomy and tendon transfer. Function to
non improving Grade 0 or 1 forearm muscles should be restored by muscle transplantation.
Level of evidence Level IV, prospective case series.
