Re: Wang J-P, Huang H-K, Tu Y-K. Double fascicular nerve transfer for deltoid and triceps paralysis in a posterior cord lesion of the brachial plexus: a case report. J Hand Surg Eur. 2020, 45: 876–8

Abstract

I read this case report by Wang et al. (2020) with interest. They describe a patient, who had sustained high energy trauma, with a scapular fracture and an infraclavicular brachial plexus injury. There was absence of deltoid and triceps function, but intact radial nerve function distally. Although the supraspinatus was said to be functioning, the degree of compromise of shoulder function suggests weakness of this muscle or rotator cuff injury. The authors interpret the findings as indicating a posterior cord injury. However, this pattern of paralysis is caused by separate injury to the axillary nerve and triceps branches of the radial nerve. It falls into the group of infraclavicular injuries characterized by axillary nerve palsy without recorded shoulder dislocation (Hems and Mahmood, 2012). In that series, five patients had deltoid paralysis accompanied by paralysis of triceps but with the distal radial nerve functioning. In all five cases with this combination of injuries, and cases I have seen more recently, good spontaneous recovery of the triceps has eventually occurred. Therefore, it is questionable if repair of the triceps nerves is required. When axillary nerve injury occurs without shoulder dislocation after high energy trauma, the axillary nerve is often ruptured after it branches from the posterior cord (Hems and Mahmood, 2012). Exploration of the zone of injury is indicated to define the severity of injury and carry out repair if spontaneous recovery looks unlikely. Nerve transfer or nerve grafting are options for repair of the axillary nerve. However, if triceps is also paralysed, the commonly used transfer of the long or medial head branches of the radial nerve is not available. The use of fascicle transfers from the ulnar and median nerves to reinnervate the axillary and triceps nerves, reported by Wang et al., is interesting and appears to have been successful in restoring shoulder abduction and elbow extension. However, the photograph in Figure 1(c) shows the patient clenching his fist while performing these movements, which is suggestive of co-contraction between finger flexors and deltoid/triceps. It is unlikely that the median and ulnar nerve fascicles transferred in the upper arm will have been exclusively innervating wrist flexors. Loss of hand movement independent of shoulder and elbow movement compromises overall upper limb function. The consequences of co-contraction between donor and recipient nerves after transfer need to be considered when choosing the method of nerve reconstruction. Reconstruction of the axillary nerve with nerve grafts avoids the problem of co-contraction, with good results previously reported (Bonnard et al., 1999; Okazaki et al., 2011).