The Journal of Cardiothoracic Trauma

: 2019  |  Volume : 4  |  Issue : 1  |  Page : 28--34

A multi-institution case series of intercostal nerve cryoablation for pain control when used in conjunction with surgical stabilization of rib fractures

Frank Z Zhao1, John D Vossler2, Adam J Kaye3,  
1 Department of Surgery, Division of Trauma and Acute Care Surgery, The Queen's Medical Center; Department of Surgery, John A. Burns School of Medicine, University of Hawaii, Honolulu, HI, USA
2 Department of Surgery, John A. Burns School of Medicine, University of Hawaii, Honolulu, HI, USA
3 Department of Trauma, Overland Park Regional Medical Center, Overland Park, KS, USA

Correspondence Address:
Frank Z Zhao
Department of Surgery, Division of Trauma and Acute Care Surgery, The Queen's Medical Center; Department of Surgery, John A. Burns School of Medicine, University of Hawaii, Honolulu, HI


Background: Intercostal cryoneurolysis (IC) causes axonotmesis resulting in numbness distal to the nerve lesion with eventual nerve regeneration. Reported outcomes in thoracic surgery range from the majority of patients recovering normal sensation within a few weeks to some incidences of chronic neuropathic pain. We hypothesize its use can decrease pain for rib fracture patients. Methods: Multi-institution retrospective review of 13 patients who underwent surgical stabilization of rib fractures (SSRFs) with video-assisted thoracoscopy-guided IC. Demographics included mechanism of injury, number of ribs fractured and plated, and number of intercostal nerves ablated. Outcomes include pre- and post-operative pain scores, completeness of nerve function return, and dysesthesias experienced during healing. Pre- and post-operative pain scores were compared by paired t-test. Statistical significance was attributed to P < 0.05. Results: The median age was 58 (35–77) and all injuries were caused by blunt mechanism. Median number of ribs fractured was 7 (4–11). Mean time to operation was 2.1 ± 1.2 days. Median number of ribs plated was 4 (range 3–6), and the median number of intercostal nerves ablated was 6 (3–7). Eleven patients with complete pain scores were found to have mean preoperative pain of 6.9 ± 2.3 and mean postoperative pain of 4.9 ± 2.9 (P = 0.026). The mean length of stay was 8.1 ± 2.9 days after admission and 5.9 ± 2.7 days after surgery. At an average follow-up of 21.3 ± 6.2 weeks, all patients had regained some sensation. Sensation regained ranged from 10% at 16.1 weeks to 100% as early as 15.9 weeks. One patient (7.6%) developed transient severe, lifestyle limiting, hyperesthesia present at 3 months and resolved at 6 months. 8 of 13 (61.5%) patients developed transient mild-to-moderate, nonlifestyle limiting, dysesthesias. These symptoms resolved by 6 months. Conclusion: In our patients with severe rib fractures, cryoneurolysis with SSRF resulted in significantly decreased postoperative pain and approximately 70% of patients reporting some transient dysesthesias in the recovery process. While these results are encouraging, larger, prospective studies are needed to fully characterize the indications for IC.

How to cite this article:
Zhao FZ, Vossler JD, Kaye AJ. A multi-institution case series of intercostal nerve cryoablation for pain control when used in conjunction with surgical stabilization of rib fractures.J Cardiothorac Trauma 2019;4:28-34

How to cite this URL:
Zhao FZ, Vossler JD, Kaye AJ. A multi-institution case series of intercostal nerve cryoablation for pain control when used in conjunction with surgical stabilization of rib fractures. J Cardiothorac Trauma [serial online] 2019 [cited 2022 Jan 28 ];4:28-34
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Traumatic rib fractures occur in approximately 10% of trauma patients.[1] These injuries are often associated with severe pain, which contributes to major morbidities such as atelectasis and pneumonia.[2],[3] The pathophysiology behind this process centers on pain causing the impairment of adequate pulmonary function and clearance of secretions.[4] This is thought to contribute to the mortality rates of 29%, which have been reported in patients with 7 or more rib fractures.[1] Appropriate and adequate analgesia for these injuries has been shown to decrease rates of pneumonia, ventilator days, and mortality.[4],[5] However, the treatment of traumatic chest wall pain is often prolonged endeavor. Prior studies have reported 59% of patients continue to have persistent pain at 2 months after injury.[6] When followed to 6 months, 28% of isolated rib fracture patients still experienced chest wall pain.[7]

Most modern analgesia modalities have a short duration of effect (< 72 h) and require repeated doses for effective treatment. In addition, many of these modalities have contraindications for use (i.e., epidural catheters with coagulopathy or spinal fractures and nonsteroidal anti-inflammatory drugs with renal dysfunction or gastrointestinal bleeding). Historically, the predominant form of analgesic therapy fell to opioid medications. However, the past decade has seen dramatic increases in opioid-related deaths from drug overdose. In 2017 alone, 47,600 deaths from drug overdoses were caused by the opioid class of medications. Of these deaths, 15,000 were directly attributable to commonly prescribed opioids such as oxycodone and morphine.[8] As a result, the United States declared a national emergency on August 10, 2017, and emphasis has been placed on limiting the prescriptions of all opioid medication by providers.[9]

The technique of intercostal cryoneurolysis (IC) may be a useful adjunct to provide both short- and long-term analgesia for traumatic rib fracture pain. IC for control of postthoracotomy pain was first described by Nelson et al. in 1974.[10] In terms of efficacy for thoracotomy pain, multiple trials have shown that IC has equal or improved efficacy as compared to intermittent intravenous and oral opioids. Often, the performance of IC showed significantly decreased narcotic use, improved pain control, and improved compliance with pulmonary physiotherapy as compared to controls.[11],[12],[13],[14],[15],[16],[17] Recently, the use of cryoneurolysis has also been highly effective in the pediatric population undergoing the Nuss procedure for the treatment of pectus excavatum. In these patients, IC resulted in significantly less opioid requirements and shorter hospital length of stay (LOS).[18],[19],[20],[21]

With the encouraging results seen in the fields of thoracic and pediatric surgery, the authors of this study began to incorporate IC as an adjunctive analgesic technique when performing surgical stabilization of rib fractures (SSRFs). In this article, we present the results of our multicenter case series of IC for control of pain in patients with traumatic rib fractures.


Retrospective review and data collection

After obtaining approval from our institutional review board, we performed a multi-institution retrospective review of patients who underwent SSRF with video-assisted thoracoscopy surgery (VATS)-guided IC for acute rib fractures. All procedures were performed by the principal investigators and patients were treated between January 1, 2018 and August 30, 2018. No patients were excluded from analysis. Patient characteristics and demographics included age, gender, body mass index, mechanism of injury, injury severity score (ISS), chest abbreviated injury score (chest AIS), number of ribs fractured, days to surgery, number of ribs surgically plated, and number of intercostal nerves ablated. Inpatient outcomes included pre- and post-operative pain scores and LOS. Postdischarge follow-up outcome included length of follow-up, completeness of nerve function return, and presence of any hyperesthesia, hypoesthesia, or dysesthesia during the postoperative follow-up period. To characterize the return of nerve function, each patient was asked to compare the neurolysis side versus the normal side. In order to characterize dysesthesias during nerve recovery, patients were specifically asked if they experienced tingling, burning, itching, pain, or hypersensitivity. Patients were also questioned about the degree of these symptoms categorized as mild, moderate, or severe and whether their symptoms were lifestyle limiting. Each patient's pre- and post-operative pain scores were compared by paired t-test. Statistical significance was attributed to P < 0.05. All other demographic and outcome data were analyzed using descriptive statistics.

Intercostal cryoneurolysis technique

All patients underwent SSRF of displaced or flail rib fractures at the discretion of the operating surgeon. At the time of SSRF, IC was performed using a two-port VATS technique with single-lung ventilation during the cryoneurolysis portion of the procedure. A 5-mm, 30° thoracoscope was first placed for pleural space evaluation and removal of any hemothorax. This then allowed for direct visualization and the target rib levels identified with the intercostal bundle visible inferiorly. The Atricure CryoICE© cryoneurolysis probe (Mason, OH) was then placed into the thoracic cavity through a separate 12-mm port. The cryoprobe was then directed at the membranous portion of the intercostal space, 4 cm away from the base of the spine to avoid iatrogenic injury to the sympathetic ganglia chain [Figure 1] and [Figure 2]. Cryoneurolysis was then performed on each targeted intercostal level at −60°C for a period of 120 s. Between each freeze cycles, the probe was actively warmed to ambient temperature in order to release from the surrounding tissue without traction injury. At the completion of the procedure, a chest tube was placed into the thoracic cavity through one of the port sites to provide drainage of the pleural space.{Figure 1}{Figure 2}


A total of 13 patients underwent combined SSRF and IC between January 1, 2018 and August 1, 2018, between our two trauma centers. The median age was 58 (range 35–77) with 9 of 13 (69.2%) patients being male. The mechanisms of injury were: motorcycle collision (n = 5), falls (n = 6), and crush injury (n = 2). Mean ISS was 17.8 ± 10.3 and mean chest AIS was 3.2 ± 0.4. The median number of ribs fractured was 7 (range 4–11). Mean time from admission to operation was 2.1 ± 1.2 days [Table 1]. The median number of ribs plated was 4 (range 3–6), and the median number of IC levels was 6 (range 3–7). 11 of 13 patients had complete preoperative and postoperative pain score data. The mean preoperative pain was 6.9 ± 2.3, and the mean postoperative pain was 4.9 ± 2.9 (P = 0.026). The mean LOS was 9.8 ± 6.7 days after admission and 7.7 ± 2.7 days after surgery. One outlier patient with isolated unilateral rib fractures was hospitalized for 30 days (29 days postoperative) due to sequelae of severe alcohol withdraw and delirium tremens. Excluding this patient, the mean LOS was 8.1 ± 2.9 days after admission and 5.9 ± 2.7 days after surgery [Table 2].{Table 1}{Table 2}

Follow-up rate was 100% for our patients. Mean length of follow-up was 23.1 ± 5.5 weeks. By this time period, all patients had regained at least partial sensation to the chest wall. Sensation recovered ranged from 10% at 16.1 weeks to 100% as early as 15.9 weeks. 3 of 13 patients (23%) reported complete recovery of chest wall sensation at 6 months. In patients reporting persistent hypoesthesia, none stated that the hypoesthesia was bothersome. The region of hypoesthesia consistently involved the lateral and anterior portion of the chest wall dermatome. Cryoneurolysis did not produce numbness or hypoesthesia to the posterior third of the chest wall. One patient (7.6%) developed transient severe, lifestyle limiting, hyperesthesia that was present at 3 months and resolved at 6 months. 8 of 13 (61.5%) patients developed transient mild-to-moderate, nonlifestyle limiting, dysesthesias characterized as tingling, burning, cramping, or sharp pain. These symptoms also resolved by 6 months [Table 3].{Table 3}


Cryotherapy for analgesia has roots dating to the ancient Greeks with Hippocrates (460–377 BC) who described the application of snow and ice packs for pain relief. Since that time, there have been numerous military descriptions on the efficacy of cryotherapy as the method of analgesia for field amputations and procedures.[22] In modern day, cryotherapy has demonstrated continued efficacy in orthopedic, gynecologic, hernia, and major abdominal surgery.[23]

A specific method of cryotherapy termed “cryoanalgesia” evolved in the 1960s. Together the terms cryoanalgesia, cryoneurolysis, and cryoablation, all refer to the freezing of peripheral nerves in order to produce a prolonged period of analgesia. The technique relies on the Joule–Thompson effect of rapid gas expansion to absorb heat from surrounding tissues. Using nitrous oxide, the cryoprobe is able to reach temperatures of −60°C. Direct application to a peripheral nerve results in a Sunderland Stage II nerve injury known as axonotmesis. In this circumstance, the nerve axon and myelin sheath are destroyed but the endoneural, perineural, and epineural structures remain intact [Figure 3]. This is followed by Wallerian degeneration of the distal nerve resulting in numbness distal to the lesion. Regeneration of the nerve occurs along the remaining perineural structures typically between 1 and 3 mm/day.[22],[24] There are several techniques previously described for the application of the cryoprobe. This can be done percutaneously under direct visualization, direct application during open dissection, image guided using ultrasound, or thoracoscopically guided during VATS.[25] There are no studies directly comparing these techniques of application. However, the efficacy of IC has been well studied in thoracic surgery and more recently in pediatric surgery patients undergoing the Nuss procedure for treatment of pectus excavatum with the vast majority showing encouraging results.[11],[12],[13],[14],[15],[16],[17],[18],[19],[20],[21]{Figure 3}

Our results in rib fracture patients undergoing IC and SSRF show that postoperative pain scores were significantly reduced compared to preoperative values. Some patients stated that their chest wall pain was completely resolved after IC. This highlights an important difference in our study population. Trauma patients inherently differ from those in thoracic and pediatric surgery in that they experience pain and discomfort immediately after the injury. In the fields of thoracic and pediatric surgery, the pain is usually experienced postoperatively, thus the patient lacks a basis of comparison. The experience of pain and level of pain tolerance are inherently subjective and can vary widely between individuals. Therefore, the ability to assess and compare the individual trauma patient's preoperative (conventional analgesia) and postoperative (IC + SSRF) pain levels can reduce confounding variables regarding the efficacy of treatment.

The chest wall is innervated by dermatomes from thoracic vertebral levels 1 to 9 [Figure 4], below this level, transitions to the innervation of the abdominal wall. Each thoracic level contains a main intercostal nerve consisting of three branches, anterior, lateral, and posterior. This effectively creates three overlapping zones of innervation with a transition zone between each branch [Figure 5]. The anterior branch provides sensation from the sternum to anterior axillary line. The lateral branch innervates from the anterior axillary line to the mid scapula region. The posterior branch innervates from the mid scapula to the spinous process. Due to the early, proximal takeoff of the posterior branch from the main intercostal nerve, it was not affected during our IC technique as described. The resulting numbness and hypoesthesia in our patient group were distributed exactly in this fashion. All patients had normal sensation from the spinous process to the mid scapular line. Hypoesthesia began lateral to the mid scapula and wrapped anteriorly to the sternum. Due to this anatomic effect distribution, we concluded that patients with posteriorly located rib fractures are unlikely to gain benefit from an analgesia standpoint. This result has also been previously described in patients undergoing posterolateral thoracotomy and IC who continued to have pain at the posterior aspect of their incisions.[26]{Figure 4}{Figure 5}

Prior studies have described the incidence of dysesthesias and neuralgias that could accompany IC. Rates of 20% have previously been described, occurring approximately 6 weeks postoperatively and persist for 2–4 weeks.[27] When we applied IC for rib fractures, we found that a significant proportion of patients had some form of tingling, burning, or hypersensitivity around their 6-week follow-up appointment. 8 of 13 (61.5%) patients developed transient mild-to-moderate, nonlifestyle limiting, dysesthesias which all resolved before 6 months. One patient (7.6%) developed transient severe, lifestyle limiting, hyperesthesia that was present at 3 months and resolved at 6 months. Overall, the proportion of patients with dysesthesia was three times higher than previously reported in the thoracic surgery literature. We posit several explanations for the higher incidence. First, we acknowledge that our case series is small compared to prior studies in thoracic surgery. This could increase the possibility of a type I error when our incidence is directly compared to historically reported data. Second, all of our patients experienced significant blunt traumatic force causing fractures of the chest wall. IC causes Sunderland Class 2 injury to the nerve which only affects the axon and myelin sheath. However, the traumatic force and fracture mechanism could damage the perineural structures causing nerve regeneration to occur in a less organized fashion leading to dysesthesia. For this reason, we empirically recommend treatment with gabapentin 300 mg three times per day during this nerve regeneration period. We had a 100% patient follow-up rate and averaged 23.1 weeks. The completeness of our patient follow-up is a strength of our study; however, it could also have captured more minor complaints from our patients who may otherwise have not returned for long-term follow-up. Fortunately, all patients who experienced any form of dysesthesias had complete resolution of discomfort.

In regards to sensation recovery, patients were asked to compare fine touch sensation on the IC-treated side versus the normal side and estimate a percentage of recovered sensation. They reported a range from 40% to 100%. It is important to note that only 3 of 13 (23%) patients had complete sensation recovery at their 6-month follow-up appointment with the remainder experiencing various degrees of hypoesthesia. While it is possible to recover more sensation over time, we acknowledge the possibility that the hypoesthesias could persist long term. When asked about their hypoesthesia, no patients complained that they were significantly bothered by the decrease in sensation.

There were multiple weaknesses to this study. First was the retrospective nature which limited our ability to review various data points that were not prospectively collected. One area was the lack of consistent incentive spirometry volumes and cough quality data. Despite these maneuvers being standard in our rib fracture management protocols, the qualitative and quantitative data were inconsistently recorded in the medical record and not available for review and analysis. In addition, pulmonary function testing and spirometry were not routinely performed in our patient population. Thus, we were unable to evaluate whether SSRF with IC could improve either pulmonary function mechanics or compliance with chest physiotherapy. Another area of weakness was the lack of consistent narcotic use data. During the study period, one of our institutions underwent a methodology change of recording patient-controlled analgesia delivery volumes. Therefore, the total and daily opioid usage data was not available for comparison for all of our patients. Future research for IC in rib fractures should be able to prospectively ensure the adequate collection of these data points in order to evaluate the effects of IC on both pulmonary function and narcotic use. Finally, our study was unable to distinguish between the contribution of SSRF versus IC toward patient outcomes since both were performed during the same operation. Because the procedure of SSRF has not previously been linked with chest wall numbness or hypoesthesia, the authors conclude that IC was the predominant source responsible for this outcome. In regards to pain score, few if any previous studies have directly compared preoperative versus postoperative data for SSRF. However, the performance of SSRF has been linked to decreased postoperative opioid usage.[28] Therefore, it is possible that IC was not solely responsible for the decreased pain scores of our patients.


This is the first series to describe IC outcomes in traumatic rib fractures and can serve as a basis for patient counseling and decision-making. IC, when used as an adjunct with SSRF, can result in significantly decreased postoperative pain. While some patients have complete recovery of sensation, we observed that most patients had some degree of nonbothersome hypoesthesia at 6 months. During the nerve regeneration process, approximately 60% of our patients reported transient mild-to-moderate dysesthesias. Therefore, we recommend empiric treatment during this time with gabapentin 300 mg TID to reduce possible symptoms. All dysesthesias resolved by 6 months, and there were no reports of long-term neuralgia. Despite our encouraging results, larger, prospective studies are needed to fully characterize the risk/benefit profile of IC as well as to clarify indications for its use in rib fracture management.

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Conflicts of interest

There are no conflicts of interest.


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