Long Thoracic Nerve Decompression and Transfer: Single-Center Case Series of Clinical and Electromyographic Outcomes

Long thoracic nerve (LTN) decompression is considered in recalcitrant scapular winging secondary to chronic LTN palsy. Nerve transfer, typically from the thoracodorsal nerve (TDN), is suggested if, despite adequate decompression, intraoperative nerve stimulation demonstrates no improvement. Literature concerning transfer is scarce. To evaluate and compare these 2 procedures' clinical and electrical outcomes, we performed a single-center, retrospective case series of all LTN decompression patients with or without transfer for chronic LTN palsy, examining postoperative adapted Medical Research Council (MRC) grades as a primary and electromyography (EMG) stimulation thresholds as a secondary outcome.

We identified 11 decompression-only and 6 patients undergoing additional transfer over an 8-year period, confirmed with preoperative serratus anterior EMG. Decompression involved proximal and distal neurolysis, with transfer, typically the lateral branch of TDN, reserved for irresponsiveness to intraoperative stimulation following decompression. Adapted pre- and postoperative serratus anterior MRC values were evaluated using a 2-tailed Student t test.

Preoperative adapted MRC grades for all 17 patients was 0; at median 12-month follow-up, this reached 3. The decompression-only preoperative median was 0 and final grade 3; for the transfers, these were 0 and 3.5 respectively, which were insignificantly different. However, time to first recovery, the first clinical evidence of serratus anterior contraction, was significantly different between the decompression-only cohort, at 3 weeks, and transfer, 7 months. Preoperative EMG thresholds were 1.0 mA pre- and 0.1 mA postoperatively; they did not impact final adapted MRC grades.

We conclude nerve transfers achieve comparable long-term outcomes where decompression alone did not improve intraoperative nerve stimulation.