The purpose of this study is to determine whether the implementation of existing neurosurgical techniques of intraoperative neuromonitoring (IONM) and the replacement of monopolar electrocautery with bipolar electrocautery (BE), during ALND, will improve the early identification of nerves that have been implicated in the cause of neuropathically-mediated post-surgical pain syndrome (PSPS).

The purpose of this study is to determine whether the implementation of existing neurosurgical techniques of intraoperative neuromonitoring (IONM) and the replacement of monopolar electrocautery with bipolar electrocautery (BE), during ALND, will improve the early identification of nerves that have been implicated in the cause of neuropathically-mediated post-surgical pain syndrome (PSPS). The cutaneous nerves most often injured and/or volitionally sacrificed are the ICBN and MBCN nerves which, when injured, result in neuropathic pain that can be significant and a source of chronic ipsilateral arm, chest wall, and breast pain. Some preliminary data exists regarding preservation of these nerves and suggests lower rates of PSPS when the nerves are able to be visually identified and kept intact. Being able to identify the nerves through electrical stimulation may help locate the nerves and their branches when they are not able to be visually identified. Furthermore, using BE instead of monopolar electrocautery produces less current and heat spread which may protect the nerves that are not initially visible.

This study is a first step in assessing the feasibility of using IONM and specifically, somatosensory evoked potentials (SSEP) and direct electrical stimulation (DES), to reliably and efficiently identify the ICBN, MBCN, and their branches.

The primary objective of this project is to establish the stimulating and recording parameters for reproducibly and efficiently identifying the ICBN, MBCN, and their branches during ALND

Inclusion Criteria:

1. Patients ages 18-70 years old.
2. Pathologically confirmed diagnosis of breast cancer.
3. Undergoing ALND by one of the breast surgeon Sub-Investigators on this study.

Exclusion Criteria:

1. Patients having any previous axillary surgery other than percutaneous breast biopsy and/or SLNB.
2. Prior breast radiation with neuropathy clearly developing after radiation.
3. Patients who have undergone prior chemotherapy and developed post-chemotherapy neuropathy prior to ALND.
4. Patients with any pre-existing neurological conditions affecting nerves, such as neuropathy (peripheral neuropathy, neuropathic pain or nerve injury to upper extremity).
5. Patients taking medications that are known to modify neuropathic pain (eg, gabapentin, pregabalin, duloxetine, venlafaxine, lidocaine patches, capsaicin, opioids, tramadol, NMDA receptor antagonists, clonidine, cannabis, botox).
6. Patients with prior spinal surgery or spinal pathology (cervical spinal stenosis or cervical radiculopathy).
7. Patients with limb-dysfunction.
8. Patients with demyelinating disease.
9. Patients with significant co-morbidities (clotting disorders on anticoagulation, cardiac issues, other conditions that could impact long-term follow-up).
10. Patients that present with pre-operative breast, arm or chest pain ipsilateral to anticipated ALND.
11. Patients who have had prior procedures where IONM failed intraoperatively.
12. Presence of parietal cortical lesion.