Long thoracic nerve injury in breast cancer patients treated with axillary lymph node dissection.

Purpose: The objectives of this study were to electromyographically (EMG) describe and analyze factors associated with long thoracic nerve injuries in breast cancer patients after axillary lymph node dissection.

Methods: This was a prospective longitudinal observational study. Two hundred sixty-four women with primary invasive breast cancer were included between 2008 and 2011. All of them were treated by axillary lymph node dissection. Patients were evaluated at 1, 6, and 12 months following surgery. The presence of winged scapula was systematically tested at each follow-up and an EMG performed whenever it was observed. Affected and unaffected groups were compared for demographic, tumour, and treatment variables. Student t test, Mann-Whitney U test, chi-squared or Fisher test were computed as appropriate.

Results: Among the 36 (13.6%) winged scapula observed, the EMG confirmed long thoracic nerve injury in 30 (11.3%) of them, 27 were partial axonotmesis and three were severe axonotmesis. At 12 months, the EMG showed that injury persisted in six (2.27%) patients. Patients with long thoracic nerve injury had a lower body mass index than unaffected patients (26.2 vs. 28.2, p = 0.045). Age, tumour stage, type of breast surgery, nodes excised, surgical complications, previous chemotherapy and previous hormonotherapy were not factors associated with winged scapula.

Conclusions: A lower body mass index was the only factor associated to long thoracic nerve injury. In most of the patients, the EMG showed partial axonotmesis. At 12 months, 2.27% of studied patients remained with an unsolved long thoracic nerve injury.