Background.

Ultrasound-guided percutaneous cryoneurolysis is an analgesic technique in which a percutaneous probe is used to reversibly ablate a peripheral nerve(s) using exceptionally low temperature, and has yet to be evaluated with randomized, controlled trials. Pain following mastectomy can be difficult to treat, and we hypothesized that the severity of surgically-related pain would be lower on postoperative day 2 with the addition of cryoanalgesia as compared with patients receiving solely standard-of-care treatment.

Methods.

Preoperatively, participants at 1 enrolling center received a single injection ropivacaine 0.5% paravertebral nerve block at T3 or T4 and a perineural was catheter inserted. Participants subsequently had an active or sham ultrasound-guided percutaneous cryoneurolysis procedure of the ipsilateral T2-T5 intercostal nerves in a randomized, patient- and observer-masked fashion. Participants all received a continuous paravertebral block with ropivacaine 0.2% until the early morning of discharge (usually postoperative day 2). The primary end point was the average pain level measured using a 0-10 numeric rating scale the afternoon of postoperative day 2. Participants were followed for 1 year.

Results.

On postoperative day 2, participants who had received active cryoneurolysis (n=31) had a median [IQR] pain score of 0 [0, 1.4] versus 3.0 [2.0, 5.0] in patients given sham (n=29): difference (97.5%CI) -2.5 (-3.5, -1.5), P<0.001. There was evidence of superior analgesia through Month 12. During the first 3 weeks, cryoneurolysis lowered cumulative opioid use by 98%, with the active group using 0.3 [0, 2.8] mg of oxycodone compared with 15.0 [4.0, 24.0] mg in the sham group (P<0.001). No oral analgesics were required by any patient between Months 1-12. After 1 year chronic pain had developed in 1 (3%) active compared with 5 (17%) sham participants (P<0.001).

Conclusions.

Percutaneous cryoneurolysis markedly improved analgesia without systemic side effects or complications following mastectomy.

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