Electroneuromyography with bipolar stimulation probe for intercostal nerve cryoablation after thoracoabdominal aortic aneurysm and mega aorta repair

Objective. To present a novel method of intraoperative triggered electroneuromyography using a bipolar stimulation probe as a modality of intraoperative neurophysiological monitoring of intercostal nerve cryoablation for pain control after thoracoabdominal aortic aneurysm and mega aorta syndrome repair. Material and methods. A single-group prospective observational case series included 7 patients with thoracoabdominal aortic aneurysm and mega aorta syndrome. In all cases, a new technique of triggered electroneuromyography for intercostal nerve cryoablation was employed as a method for postoperative pain control. Throughout hospital-stay, patients were assessed for the presence, character and localization of pain within thoracophrenolumbotomy using the Numeric Rating Scale (NRS-11) and the Visual Analogue Scale (VAS). We assessed consumption of opioid and non-opioid analgesics, in-hospital complications and adverse events. Endpoints included safety, advantages or limitations, and parameters of triggered electroneuromyography. Results. About 5—7 intercostal nerves were subjected to cryoablation in each patient (40 nerves). Mean cryoablation temperature was −71.8±2.1 °C. Time to disappearance of compound muscle action potential (CMAP) was 29.3±6.37 s. Triggered electroneuromyography with bipolar stimulation probe (baseline current 5 mA with gradual increase to 20 mA) demonstrated effectiveness in detecting CMAPs of all intercostal nerves. Identification with bipolar stimulation probe was safe, as integrity of parietal pleura, intercostal muscle, and neurovascular bundle was preserved. The technique also optimized and shortened the procedure through faster and more convenient localization of intercostal nerves. All patients demonstrated favorable postoperative pain control. Ventilation time was 12 8.5; 16.5 hours, ICU stay — 2 1.7; 4.5 days, hospital-stay — 9 8.5; 14.5 days. No intraoperative, in-hospital, or 30-day mortality was observed. Conclusion. Intercostal nerve cryoablation is an effective and technologically advanced method of regional analgesia that can be recommended in reconstructive aortic surgery. Triggered electroneuromyography using a bipolar stimulation probe is an effective, reproducible, and safe modality of neurophysiological control for intercostal nerve cryoablation, allowing optimization and simplification of this procedure for aortic team. Further studies of cryoanalgesia will define its advantages in opioid-sparing strategies for aortic and thoracic surgery.