Cryoablation for the Nuss procedure: Have we jumped the gun?
Myron Yaster MD and Lynne Maxwell MD
Original article
Vidya Chidambaran, Victor F Garcia, Rebeccah L Brown. Are We Ready for Cryoablation in Children Undergoing Nuss Procedures? Anesth Analg. 2022 Apr 1;134(4):881-884. PMID: 35299214
As discussed in last week’s PAAD, over the last several years a proliferation of anesthetic techniques have been described for the severe and frequently prolonged pain endured by patients who have undergone the Nuss procedure. Last week we discussed erector spinae blocks, today intercostal nerve cryoablation (INC). The goal of these techniques (and thoracic epidural blockade) is to “eliminate or reduce postsurgical pain and shorten the duration of perioperative opioid analgesia”.1
Fundamentally, why is the Nuss procedure so painful? We don’t know, however I’ve (MY) always thought that the Nuss bar micro-fractures the sternum. And with all fractures, movement of the fracture fragments results in pain. Since patients must breathe, each breath will cause fracture movement and be quite painful. Alternatively, or maybe in addition, when the Nuss bar is tied and secured to a rib with wire, the intercostal nerves must be caught and crushed causing acute and chronic nerve pain. In addition, stretch of intercostal muscles and nerves from the new chest wall configuration may play a role (LM). Enter INC. Cryoablation involves application of extremely low temperatures to a peripheral nerve to induce Wallerian degeneration and disruption of nerve conduction. However, is INC safe and free of adverse long-term sequelae?
The FDA approval process for INC involved a 510K device waiver. Essentially, this means that approval is based on previous approvals for the same or a similar device and therefore does not require the same rigor required for new drugs or new devices. This has led to catastrophe with some medical devices. Think about implanted medical devices like pacemakers, artificial hips, cardiac stents that have failed and wreaked havoc.2
The FDA granted approval for INC in Nuss patients based on a small, 20 adolescent to young adult patient study3 which demonstrated analgesia equivalence to thoracic epidurals and shorter hospital length of stays. Chidambaran et al. argue that this is not enough evidence to demonstrate the safety of this technique in children and that that larger studies over longer periods of time are needed and we should therefore be cautious in its application. They remind us, “while innovation can be life-changing, it is crucial to exercise appropriate caution honoring our motto of “primum non nocere.””
What could go wrong? A lot! Like neuropathic pain (allodynia) following the nerve’s Wallerian degeneration and nerve regeneration. As discussed last week, a multi-institutional registry study of perioperative analgesic interventions for Nuss procedure is the best way to compare both the efficacy and sequelae of various techniques.4-6 The last one conducted by the Society for Pediatric Anesthesia Improvement Network (SPAIN) took place before erector spinae or INC were common. A “redo” “longitudinal, long-term, randomized, comparative study with neurological testing and age-appropriate questionnaires to document neurological deficits and recovery from INC versus other regional techniques” is needed.1 The same investigators cited above1 who compared INC with epidudral reported a small study (43 patients of whom 13 were > 21 years of age) of the incidence of neuropathic pain and chest wall numbness in the year following Nuss procedure with INC analgesia.7
They found persistent chest wall numbness in both groups, with a shorter duration in the patients < 21 years if age (3.4 vs 10.8 months) and, utilizing a validated (in adults) tool for neuropathic pain (Leeds Assessment of Neuropathic Symptoms and Signs), found no neuropathic pain in the younger group and and a 25% incidence in the older group. As Chidambaran et al. point out, such a small study is insufficient from which to draw conclusions about the use of such a novel technique in the pediatric population. We spoke to the leaders of the previous studies, Joe Cravero, Ty Muhly and others. There are no current plans to do this… Chidambaran et al. emphatically illustrate our obligation to do so. What do you think? Myron Yaster MD and Lynne Maxwell MD
References
1. Chidambaran V, Garcia VF, Brown RL: Are We Ready for Cryoablation in Children Undergoing Nuss Procedures? Anesth Analg 2022; 134: 881-884
2. Lenzer J. The Danger Within Us: America's Untested, Unregulated Medical Device Industry and One Man's Battle to Survive it. 2017 Little Brown and Company
3. Graves CE, Moyer J, Zobel MJ, Mora R, Smith D, O'Day M, Padilla BE: Intraoperative intercostal nerve cryoablation During the Nuss procedure reduces length of stay and opioid requirement: A randomized clinical trial. J Pediatr Surg 2019; 54: 2250-2256
4. Uhl KM, Wilder RT, Fernandez A, Huang H, Muhly WT, Zurakowski D, Cravero JP: Postoperative pain and psychological outcomes following minimally invasive pectus excavatum repair: A report from the Society for Pediatric Anesthesia Improvement Network. Paediatr Anaesth 2020; 30: 1006-1012
5. Muhly WT, Beltran RJ, Bielsky A, Bryskin RB, Chinn C, Choudhry DK, Cucchiaro G, Fernandez A, Glover CD, Haile DT, Kost-Byerly S, Schnepper GD, Zurakowski D, Agarwal R, Bhalla T, Eisdorfer S, Huang H, Maxwell LG, Thomas JJ, Tjia I, Wilder RT, Cravero JP: Perioperative Management and In-Hospital Outcomes After Minimally Invasive Repair of Pectus Excavatum: A Multicenter Registry Report From the Society for Pediatric Anesthesia Improvement Network. Anesth Analg 2019; 128: 315-327
6. Muhly WT, Maxwell LG, Cravero JP: Pain management following the Nuss procedure: a survey of practice and review. Acta Anaesthesiol Scand 2014; 58: 1134-9
7. Zobel MJ, Ewbank C, Mora R, Idowu O, Kim S, Padilla BE. The incidence of neuropathic pain after intercostal cryoablation during the Nuss procedure. Ped Surg International 2020; 36:317-24