Does cryoneurolysis result in persistent motor deficits? A controlled study using a rat peroneal nerve injury model

Flexible circumferential bioelectronics to enable 360-degree recording and stimulation of the spinal cord

The spinal cord is crucial for transmitting motor and sensory information between the brain and peripheral systems. Spinal cord injuries can lead to severe consequences, including paralysis and autonomic dysfunction. We introduce thin-film, flexible electronics for circumferential interfacing with the spinal cord. This method enables simultaneous recording and stimulation of dorsal, lateral, and ventral tracts with a single device. Our findings include successful motor and sensory signal capture and elicitation in anesthetized rats, a proof-of-concept closed-loop system for bridging complete spinal cord injuries, and device safety verification in freely moving rodents. Moreover, we demonstrate potential for human application through a cadaver model. This method sees a clear route to the clinic by using materials and surgical practices that mitigate risk during implantation and preserve cord integrity.

Cryoanalgesia: Review with Respect to Peripheral Nerve

BACKGROUND

 Cryoanalgesia is a tool being used by interventional radiology to treat chronic pain. Within a certain cold temperature range, peripheral nerve function is interrupted and recovers, without neuroma formation. Cryoanalgesia has most often been applied to the intercostal nerve. Cryoanalgesia has applications to peripheral nerve surgery, yet is poorly understood by reconstructive microsurgeons.

METHODS

 Histopathology of nerve injury was reviewed to understand cold applied to peripheral nerve. Literature review was performed utilizing the PubMed and MEDLINE databases to identify comparative studies of the efficacy of intraoperative cryoanalgesia versus thoracic epidural anesthesia following thoracotomy. Data were analyzed using Fisher's exact and analysis of variance tests. A similar approach was used for pudendal cryoanalgesia.

RESULTS

 Application of inclusion and exclusion criteria resulted in 16 comparative clinical studies of intercostal nerve for this review. For thoracotomy, nine studies compared cryoanalgesia with pharmaceutical analgesia, with seven demonstrating significant reduction in postoperative opioid use or postoperative acute pain scores. In these nine studies, there was no association between the number of nerves treated and the reduction in acute postoperative pain. One study compared cryoanalgesia with local anesthetic and demonstrated a significant reduction in acute pain with cryoanalgesia. Three studies compared cryoanalgesia with epidural analgesia and demonstrated no significant difference in postoperative pain or postoperative opioid use. Interventional radiology targets pudendal nerves using computed tomography imaging with positive outcomes for the patient with pain of pudendal nerve origin.

CONCLUSION

 Cryoanalgesia is a term used for the treatment of peripheral nerve problems that would benefit from a proverbial reset of peripheral nerve function. It does not ablate the nerve. Intraoperative cryoanalgesia to intercostal nerves is a safe and effective means of postoperative analgesia following thoracotomy. For pudendal nerve injury, where an intrapelvic surgical approach may be difficult, cryoanalgesia may provide sufficient clinical relief, thereby preserving pudendal nerve function.

Thermoprotection of Neural Structures During Musculoskeletal Ablation

Percutaneous thermal ablation is widely used for local control and palliation of a variety of lesions throughout the musculoskeletal system. In this setting, safe ablation is predicated on the avoidance of unintentional injury to vulnerable neural structures that are often in proximity to ablation targets. This article highlights key periprocedural considerations in musculoskeletal ablation and reviews the array of active and passive thermoprotective measures that are critical to safe and successful treatment.

Ultrasound-Guided Percutaneous Cryoanalgesia for Pectus Excavatum: When Should It be Applied?

INTRODUCTION

 The addition of ultrasound-guided percutaneous cryoanalgesia (PCr) for pain management after pectus excavatum (PE) surgery offers a new and advantageous approach. Our aim is to describe our experience with PCr applied on the same day, 24 hours, and 48 hours prior to PE surgery.

MATERIAL AND METHODS

 Prospective pilot study in patients undergoing ultrasound-guided PCr (2019-2022) was divided into three groups: PCr on the same day of surgery (PCrSD), PCr 24 hours before (PCr24), and PCr 48 hours before (PCr48). We describe the application of technique and data obtained by comparing the three groups.

RESULTS

 We present 42 patients (25 PCrSD, 11 PCr24, 6 PCr48). PCr24 had a shorter procedure duration than PCrSD (65.8 vs. 91.2 minute; p = 0.048). Related to analgesia, PCr24 and PCr48 showed lower opioid consumption than PCrSD in PCA volume (48.5 and 49.6 vs. 75.1 mL; p = 0.015) and PCA time (23.3 and 23.8 vs. 34.3 hours; p = 0.01). Degree of pain (VAS scale) on the day of surgery and on the second postoperative day was lower in PCr24 and PCr48 than in PCrSD (4 and 2 vs. 5; p = 0.012; 0 and 1 vs. 2; p = 0.01, respectively) as well as shorter hospital stay (3 and 3.5 vs. 5 days; p = 0.021). In addition, PCr24 showed lower opioid consumption and hospital stay than PCr48 (p > 0.05). The greatest savings in hospital costs were obtained in the PCr24 group.

CONCLUSION

 PCr48 and PCr24 prior to PE surgery offers lower opioid consumption, less pain and shorter hospital stay than PCrSD. PCr24 is comparable to PCr48, but seems to show advantages and simpler logistics for the patient and the hospital.

Ultrasound-Guided Percutaneous Cryoneurolysis for Post-Thoracotomy Pain Syndrome: A Case Report

Post-thoracotomy pain syndrome (PTPS) is a post-operative thoracotomy complication that is difficult to treat. We describe the first-time use of ultrasound-guided percutaneous cryoneurolysis of the intercostal nerves to successfully treat PTPS refractory to conventional medications and interventions. We report a case of a 40-year-old male with two years of severe PTPS sustained after undergoing a thoracotomy. Treatment with intercostal cryoneurolysis resulted in an immediate 75% improvement in pain for six weeks followed by sustained 50% pain relief for eight weeks. This highlights the potential of this intervention as a radiation-free, safe, and efficacious therapy for chronic PTPS.

Extending Perioperative Analgesia with Ultrasound-Guided, Percutaneous Cryoneurolysis, and Peripheral Nerve Stimulation (Neuromodulation)

The use of regional anesthesia is key to a successful approach to improving postoperative analgesia, which involves local anesthetic deposition either around peripheral nerves or within a fascial plane. Unfortunately, the realistic duration even with continuous peripheral nerve blocks usually does not match the duration of surgical pain, comprising a major limitation. Here, the use of 2 interventional modalities-ultrasound-guided percutaneous cryoneurolysis and peripheral nerve stimulation-is discussed, both of which may be used to treat acute and subacute pain and may therefore have a positive impact on the incidence and severity of chronic pain development.

Low Intensity Focused Ultrasound Increases Duration of Anti-Nociceptive Responses in Female Common Peroneal Nerve Injury Rats

OBJECTIVE

Chronic pain affects 7%-10% of Americans, occurs more frequently and severely in females, and available treatments have been shown to have less efficacy in female patients. Preclinical models addressing sex-specific treatment differences in the treatment of chronic pain have been limited. Here we examine the sex-specific effects of low intensity focused ultrasound (liFUS) in a modified sciatic nerve injury (SNI) model.

MATERIALS AND METHODS

A modified SNI performed by ligating the common peroneal nerve (CPN) was used to measure sensory, behavioral pain responses, and nerve conduction studies in female and male rats, following liFUS of the L5 dorsal root ganglion.

RESULTS

Using the same dose of liFUS in females and males of the same weight, CPN latency immediately after treatment was increased for 50 min in females compared to 25 min in males (p < 0.001). Improvements in mechanical pain thresholds after liFUS lasted significantly longer in females (seven days; p < 0.05) compared to males (three days; p < 0.05). In females, there was a significant improvement in depression-like behavior as a result of liFUS (N = 5; p < 0.01); however, because males never developed depression-like behavior there was no change after liFUS treatment.

CONCLUSIONS

Neuromodulation with liFUS has a greater effect in female rats on CPN latency, mechanical allodynia duration, and depression-like behavior. In order to customize neuromodulatory techniques for different patient phenotypes, it is essential to understand how they may alter sex-specific pathophysiologies.

Development of a common peroneal nerve injury model in domestic swine for the study of translational neuropathic pain treatments

OBJECTIVE

To date, muscular and bone pain have been studied in domestic swine models, but the only neuropathic pain model described in swine is a mixed neuritis model. Common peroneal nerve injury (CPNI) neuropathic pain models have been utilized in both mice and rats.

METHODS

The authors developed a swine surgical CPNI model of neuropathic pain. Behavioral outcomes were validated with von Frey filament testing, thermal sensitivity assessments, and social and motor scoring. Demyelination of the nerve was confirmed through standard histological assessment. The contralateral nerve served as the control.

RESULTS

CPNI induced mechanical and thermal allodynia (p < 0.001 [n = 10] and p < 0.05 [n = 4], respectively) and increased pain behavior, i.e., guarding of the painful leg (n = 12). Myelin protein zero (P0) staining revealed demyelination of the ligated nerve upstream of the ligation site.

CONCLUSIONS

In a neuropathic pain model in domestic swine, the authors demonstrated that CPNI induces demyelination of the common peroneal nerve, which the authors hypothesize is responsible for the resulting allodynic pain behavior. As the anatomical features of domestic swine resemble those of humans more closely than previously used rat and mouse models, utilizing this swine model, which is to the authors' knowledge the first of its kind, will aid in the translation of experimental treatments to clinical trials.

Percutaneous cryoneurolysis for acute pain management: current status and future prospects

Introduction: Conventional nerve blocks utilize local anesthetic drugs to provide pain relief for hours or days following surgery or trauma. However, postoperative and trauma pain can last weeks or months. Ultrasound-guided percutaneous cryoneurolysis is an anesthetic modality that offers substantially longer pain relief compared to local anesthetic-based nerve blocks.Areas covered: In this review, we discuss the history, mechanism of action, and use of ultrasound-guided percutaneous cryoneurolysis by anesthesiologists in the setting of acute pain management.Expert opinion: Ultrasound-guided percutaneous cryoneurolysis offers the potential to provide weeks or months of pain relief following surgery or trauma. Compared to continuous local anesthetic-based peripheral nerve blocks, currently the gold standard for providing long duration postoperative analgesia, cryoneurolysis has benefits that include: 1) longer duration measured in weeks or months rather than days; 2) no external reservoir of local anesthetic to be carried by the patient; 3) no risk of infection; and 4) no risk of catheter dislodgement. However, cryoneurolysis can induce a prolonged motor block in addition to the sensory block, decreasing the appropriate indications to those in which potential sensory and motor deficits are acceptable. Additionally, cryoneurolysis of multiple nerves can have a substantial time requirement relative to conventional nerve blocks.

Percutaneous cryoanalgesia for pain palliation: Current status and future trends

Cryoanalgesia, otherwise termed cryoneurolysis, refers to application of extreme cold upon peripheral nerves for palliation of pain associated to nerve lesions or biomechanical syndromes of neoplastic and non-neoplastic substrate. Application of cryoanalgesia initiates a cascade of pathophysiologic events interrupting nerve conduction of painful stimuli without irreversible nerve damage. Cryoanalgesia is considered a safe procedure with minimal risk of complications when performed with percutaneous approaches under imaging guidance. In the era of an opioid overdose crisis, cryoanalgesia can be proposed as an alternative aiming at controlling pain and improving life quality. Imaging guidance has substituted open surgical and nerve stimulation approaches in nerve identification, significantly contributing to the minimally invasive character of percutaneous approaches. Ultrasound or computed tomography can serve as low cost, ideal guiding techniques due to their abilities for precise anatomic delineation, high spatial resolution and good tissue contrast. The purpose of this review is to become familiar with the most common imaging guided percutaneous cryoanalgesia indications, to learn about different technical considerations during performance providing the current evidence. Controversies concerning products will be addressed.

Cryoneurolysis and Percutaneous Peripheral Nerve Stimulation to Treat Acute Pain

Two regional analgesic modalities currently cleared by the U.S. Food and Drug Administration hold promise to provide postoperative analgesia free of many of the limitations of both opioids and local anesthetic-based techniques. Cryoneurolysis uses exceptionally low temperature to reversibly ablate a peripheral nerve, resulting in temporary analgesia. Where applicable, it offers a unique option given its extended duration of action measured in weeks to months after a single application. Percutaneous peripheral nerve stimulation involves inserting an insulated lead through a needle to lie adjacent to a peripheral nerve. Analgesia is produced by introducing electrical current with an external pulse generator. It is a unique regional analgesic in that it does not induce sensory, motor, or proprioception deficits and is cleared for up to 60 days of use. However, both modalities have limited validation when applied to acute pain, and randomized, controlled trials are required to define both benefits and risks.

Interventional Cryoneurolysis: An Illustrative Approach

The application of advanced imaging guidance and the interventional radiology skill set has expanded the breadth of nerve and nerve plexus targets in the body for potential cryoneurolysis. Advancement of the basic science supporting cryoneurolysis has further solidified proceduralists' confidence and ability to select and manage patients clinically. As these procedures continue to evolve, a structured approach to the wide variety of indications is necessary.