Variation of surgical anatomy of the thoracic portion of the long thoracic nerve.

Decompression of the long thoracic nerve (LTN) is a potentially beneficial procedure for selected patients with LTN palsy. The aim of this work is to describe the surgical anatomy of the thoracic part of the LTN and highlight its variations. A retrospective review of patients undergoing exploration of the LTN was performed. Preoperatively, all patients had serratus anterior dysfunction and underwent electromyographic (EMG) assessment. All patients had an initial trial of nonoperative management. The surgical procedures were undertaken by the senior author. The anatomy of the LTN and the associated vasculature was recorded in patient records, and with digital photography. Forty-five patients underwent LTN exploration. Two patients with iatrogenic injury were excluded, leaving 43 patients for analysis. Mean age was 36 years. Sixty-seven percent of cases involved the dominant side. Trauma was the commonest cause, followed by neuralgic amyotrophy. Four patients had typical features of serratus anterior dysfunction but with normal EMG studies. Two distinct patterns of LTN anatomy were noted. In 79% of cases, a single major nerve trunk coursing along serratus anterior was observed and classified as a type I LTN. In 21% of cases, two equal major branches of the nerve were identified, which was classified as a type II LTN. Approximately one in five patients may have two major branches of the LTN. This is of clinical relevance to those who undertake any thoracic procedures, as well as those who are considering exploration of the LTN.