ABSTRACT
With or without previous early neurotization, the brachial plexus in obstetric palsy regenerates partially leading to variable degrees loss of function and deformity necessitating secondary correction. Correction after latissimus dorsi to rotator cuff transfer is not maintained. Posterior shoulder dislocation occurs after humeral rotation osteotomies. Both presuppose some degree of shoulder abduction. Further, corrective surgery will not benefit a flail wrist. Improving muscle power is the solution. End-to-side neurorrhaphy allows neurotization of partially injured recipient nerves without downgrading already regained recipient muscle power, a technique we called nerve augmentation. The aim was to investigate the effect of nerve augmentation on improving motor power in late obstetric brachial plexus lesions. 8 obstetric brachial plexus palsy cases aged 3-7 years were operated upon and followed up for 4 years. 5 patients were C5, 6 ruptures C7, 8T1 avulsions; 1 a C5,6,7,8 rupture T1 avulsion and 1 a C5,6,8T1 rupture C7 avulsion; 1 presented to us 3 years having undergone neurotization at the age of 3 months for a C5,6,7 rupture, C8 T1 compression. Patients were evaluated for deformities, muscle function, cocontractions. Root avulsions were evaluated by CT cervical myelography and confirmed intraoperatively. Shoulder, elbow and hand functions were scored using the modified Gilbert shoulder and elbow evaluation scales, and the Raimondi hand evaluation scale respectively. All nerves to Grades 1-3 muscles were selected for neurotization. Nerves to Grade 0 muscles were neurotized, if the electromyogram showed scattered motor unit action potentials on voluntary contraction without interference pattern. After exploration, the following donor nerves were selected for intertwining neurotization or closed loop grafting 25: The phrenic [7 cases], the accessory [2 cases], the descending and ascending loops of the ansa cervicalis [2 cases] and the 3[rd] and 4[th] intercostals [1 case]. Long length contact contralateral C7 neurotization [25] was performed in 5 cases. In the revision case, an external rotation humeral osteotomy and a Hoffer transfer preceded neurotization. Superior proximal to distal regeneration was observed firstly, shoulder and elbow muscles improving more than forearm, wrist and finger muscles. Differential regeneration of muscles supplied by the same nerve was observed secondly, the supraspinatus muscle regenerating superior to the infraspinatus. Differential regeneration of antagonistic muscles was observed thirdly; there was superior biceps to triceps and pronator teres to supinator recovery. Differential regeneration of fibres within the same muscle was observed fourthly, the anterior and middle fibres of the deltoid muscle regenerating better than its posterior fibres. Differential regeneration of muscles having different preoperative motor powers was noted fifthly. Functional improvement [i.e. to Grade 3 or more] in the forearm and hand occurred more in Grade 2 than in Grade 0 or Grade 1 muscles. Improvements of cocontractions and of shoulder, forearm and wrist deformities were noted sixthly. The shoulder, elbow and hand scores improved in 4 cases. First, the sample size is small [8 cases]. Second, controls are necessary to rule out any natural improvement of the lesion. Third, there is marked intra- and interobserver variability in testing muscle power and cocontractions. Nerve augmentation improves muscle power in the biceps, pectoral muscles, supraspinatus, anterior and lateral deltoids, triceps and in Grade 2 or more forearm muscles. It is also expected to improve cocontractions. 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 free muscle transplantation. Notwithstanding all of the above, end-to-side neurorrhaphy needs reconsideration. Donor and recipient nerve channel carrying capacities have to be increased by cotrophism, cotropism and cotransplantation. Cell biologic procedures for restoring recipient muscle mass should be contemplated. Level IV, prospective case series