Chapter 193 - Nerve Reconstruction in Brachial Plexus Birth Injuries

Abstract

Synopsis: The vast majority of brachial plexus birth injuries (BPBIs) are caused by traction to the brachial plexus during labor. The incidence of BPBI is about 1 to 2 per 1000 births. Typically, the C5 and C6 spinal nerves are affected. The prognosis is generally considered to be good, but the percentage of children with residual deficits may be as high as 20% to 30%. The neuropathophysiological basis in BPBI is that the damaged nerves are usually stretched and damaged and form a neuroma in continuity. Typically, the nerves are not completely ruptured. Even in the most severe BPBIs, at least some axons will pass through the neuroma in continuity and reach the tubes distal to the lesion site. These axons may be particularly prone to abnormal branching and misrouting, which may explain the typical features of co-contraction and frustration of functional regeneration. An additional factor that may reduce functional regeneration is that improper central motor programming may occur. Surgery should be restricted to severe cases in which spontaneous restoration of function will not occur, that is, in neurotmesis or root avulsions. Selection of infants for surgery, and prediction of whether function will be best after spontaneous nerve outgrowth or after nerve reconstruction, is problematic. Results achieved by surgery are claimed to be superior to outcomes in conservatively treated subjects with equally severe lesions. A prospective randomized trial to answer the question of whether surgery improves functional outcome has in fact never been performed. During early surgical exploration the intraoperative appraisal of the neuroma-in-continuity and decision whether to cut or not can be difficult. In the following sections, we present an overview of our current knowledge of BPB injury based on our understanding of the neuropathophysiology.