Popliteal Nerve Catheters for Perioperative Pain Control in Charcot-Marie-Tooth Patients
Authors: An Tonya W. , Schwartz Elliot S. , Kissen Michael S. , Pollock Gabriel A. , Pfeffer Glenn B. 
Published: January 2022

Category: Hindfoot; Other Introduction/Purpose: The underlying neuropathy of Charcot-Marie-Tooth (CMT) disease often makes postoperative pain control difficult. Previous institutional regimens for outpatient foot and ankle surgery in this population included preoperative single-shot regional nerve blocks and oral narcotic analgesics, but still resulted in unplanned visits for uncontrolled pain, especially after block effects abated. Longer duration of regional anesthesia effects were desired to manage pain and reduce opioid intake. We aimed to investigate the safety and efficacy of ultrasound-guided placement of popliteal nerve catheters in CMT patients undergoing foot deformity correction surgery. Methods: Twelve CMT patients, average 28 (range 13-53) years old, undergoing reconstructive surgery by a single foot and ankle attending surgeon were consented for preoperative ultrasound-guided popliteal catheters and single-shot adductor canal blocks. Patients were separately consented for enrollment in this study and follow-up questionnaires as per Institutional Review Board protocol. Seven patients underwent joint sparing reconstruction and 5 patients had subtalar fusion. Patients were discharged on postoperative day (POD) 0. Popliteal catheters were maintained, providing continuous infusion and patient-controlled bolus doses until POD3, and then self-discontinued. Oral oxycodone 5 mg (#60-80 pills) was prescribed as needed for breakthrough pain. Daily visual analog scale (VAS) pain scores were collected by phone. Patient satisfaction (0-10) was surveyed on POD5. A pill count for opioid consumption occurred at the surgeon's office on POD14. Five-point sensory testing using a 10g Semmes- Weinstein monofilament was performed preoperatively and on POD14. Results: All patients tolerated the catheters well. There were no complications related to infection or catheter malfunction requiring replacement. Four of the twelve patients had pre-existing sensory deficits involving at least two areas on the five-point monofilament test (Table 1). Postoperative testing showed these deficits were unchanged and there were no instances of new sensory deficits. Postoperative VAS pain scores were typically low with the median value (interquartile range IQR) 3.7 (1.5 - 5.75) on POD1, 3.2 (1.75 - 4.25) on POD2, and 2.5 (1 - 3.5) on POD3 (Figure 1). At POD14, VAS pain was 1 (0.75-1). Patients consumed an average total of 25 oxycodone pills (IQR 9-42) over 2 weeks, less than half the prescribed number. Patient satisfaction was high with the mean (standard deviation) score of 9.1 (1.6). All patients reported they would choose to have a nerve catheter again for a similar surgery. Conclusion: Regional anesthesia using ultrasound-guided popliteal catheters was effective for pain control in this series of CMT patients undergoing deformity correction. Opioid consumption was reduced from historical levels and no patients required emergency treatment for uncontrolled pain. These catheters provided three days of local anesthetic infusion. No new sensory deficits were detected and patients with underlying preoperative sensory deficits remained unchanged. Patients were highly satisfied. This small study group provides preliminary evidence supporting nerve catheter usage in CMT patients. Utilizing ultrasound guidance to minimize nerve injury, nerve catheters may allow safe and successful outpatient correction of CMT foot deformity.