To report the incidence of clinically detectable nerve injuries when utilizing transcranial electrical motor evoked potentials (MEPs) during shoulder arthroplasty. A retrospective review of patients undergoing shoulder arthroplasty with continuous IONM was performed. The criteria for nerve alerts was an 80% amplitude reduction in MEPs. The primary outcome measure was post-operative clinically detectable nerve deficit. An additional retrospective analysis on a subset of cases using an all-or-none (100% amplitude reduction) criterion applied to the deltoid was performed. Two hundred eighty four arthroplasty cases were included. There were no permanent post-operative nerve injuries and two transient nerve injuries (0.7%). MEP alerts occurred in 102 cases (36.2%). Nineteen (6.7%) cases did not have signals return above alert threshold at closure. These cases were significantly associated with post-operative nerve injury (p = 0.03). There were no false negatives, making sensitivity 100% and specificity was 93.9%. In the subset of cases in which an all-or-none criterion was retrospectively applied to just the deltoid, MEP alerts occurred in just 17.9% of cases; specificity improved to 98.0%. We conclude that utilization of the real-time diagnostic MEP data during shoulder arthroplasty aids surgeons in decision making regarding impending peripheral nerve injuries.
- Intraoperative motor evoked potentials
- Nerve injury
- Peripheral nerve function
- Peripheral nerve monitoring
- Shoulder arthroplasty