Is circumferential minimally invasive surgery effective in the treatment of moderate adult idiopathic scoliosis?

Surgical Approaches and Short-Term Results of Circumferential Minimally Invasive Correction Surgery for Adult Idiopathic Scoliosis

OBJECTIVE

We present the surgical approaches and short-term (2 years postoperative) results pertaining to circumferential minimally invasive spine surgery (CMIS) with lateral lumbar interbody fusion (LLIF) and percutaneous pedicle screw application for adult idiopathic scoliosis (AS).

METHODS

We enrolled eight patients with AS who underwent CMIS (2018-2020) and examined the number of fused levels, upper instrumented vertebra, lower instrumented vertebra, number of LLIF-treated segments, number of preoperative intervertebral fusions, intraoperative blood loss, operative time, various spinopelvic parameters, Oswestry Disability Index, low back pain, visual analog scale (VAS), leg VAS, bone fusion rate, and perioperative complications.

RESULTS

The upper instrumented vertebra was T4, T7, T8, and T9 in two cases, whereas lower instrumented vertebra was the pelvis in all the cases. The average numbers of fixed vertebrae and segments that underwent LLIF were 13.3 ± 2.0 and 4.6 ± 0.7, respectively. All spinopelvic parameters improved significantly after surgery (thoracic kyphosis: P < 0.05, lumbar lordosis, cobb angle, pelvic tilt, pelvic incidence-lumbar lordosis, sagittal vertical axis: P < 0.001), and good alignment was achieved. The Oswestry Disability Index and VAS scores improved significantly (P < 0.001). The bone fusion rates achieved in the lumbosacral and thoracic spine were 100% and 88%, respectively. Only 1 patient showed postoperative coronal imbalance.

CONCLUSIONS

The 2-year postoperative results of CMIS for AS were good, and spontaneous bone fusion was confirmed in the thoracic spine without bone grafting. In this procedure, sufficient intervertebral release with LLIF and a percutaneous pedicle screw device translation technique enabled adequate global alignment correction. Therefore, correcting the global imbalance of the coronal and sagittal planes is more crucial than correcting scoliosis.

Complications of adult spinal deformity surgery: A literature review

Purpose:

Adult spinal deformity incidence increases accordingly as the population ages. Even though surgery is the best option for the treatment, the complications due to surgery are pretty challenging. This study aims to review the complication rates of adult spinal deformity surgery.

Methods:

A literature review of the last decade was performed searching for the query “Adult spine deformity and complication.” This search yielded 2781 results, where 79 articles were chosen to investigate the complications of adult spinal deformity surgery. In addition, the demographic data, surgical interventions, and complications were extracted from the publications.

Results:

A total of 26,207 patients were analyzed, and 9138 complications were found (34.5%). Implant failure, including screw loosening, breakage, distal and proximal junctional kyphosis, were the most common complications. The neurologic complications were about 10.8%, and the infection rate was 3.6%. Cardiac and pulmonary complications were about 4.8%.

Discussion:

Age, body mass index, smoking, osteoporosis, and other comorbidities are the significant risk factors affecting adult spinal deformity surgery. Presurgical planning and preoperative risk factor assessment must be done to avoid complications. Furthermore, intra and postoperative complications affect the patients’ quality of life and length of stay, and hospital readmissions. Revision surgery also increases the risk of complications.

Conclusion:

Good patient evaluation before surgery and careful planning of the surgery are essential in avoiding complications of adult spinal deformity.

The prevalence of proximal junctional kyphosis (PJK) and proximal junctional failure (PJF) in patients undergoing circumferential minimally invasive surgical (cMIS) correction for adult spinal deformity: long-term 2- to 13-year follow-up

OBJECTIVES

This aim of this study is to evaluate the prevalence of PJK and PJF in patients who underwent circumferential minimally invasive surgery (cMIS) for ASD.

METHODS

A prospective database of patients who underwent cMIS correction of ASD from November 2006 to July 2018 was queried. PJK was defined as angle > 10° and at least 10° greater than the baseline when measuring UIV to UIV + 2. PJF was defined as any type of symptomatic PJK which required surgery. Pre-op, latest and delta SVA and PI-LL mismatch were compared between patients with PJK and without. Only patients instrumented at 4 or more levels with full length 36″ films and a minimum 2-year follow-up were included.

RESULTS

A total of 184 patients met inclusion criteria for this study. Mean follow-up time was 85.2 months (24-158.9 months, SD 39.1). Mean age was 66 years (22-85 years). The mean number of operated levels was 6.9 levels (4-16 levels, SD 2.8). A total of 21 patients (10.8%) met PJK criteria. Only 10 (4.9%) were symptomatic (PJF) and underwent revision surgery. The other 11 patients remained asymptomatic. Comparing PJK to non-PJK patients, there was no statistically significant difference in the post-op SVA, delta SVA, post-op PI/LL and delta PI/LL between the two groups.

CONCLUSION

Our study would suggest that in the appropriately selected and well-optimized patient, CMIS deformity correction is associated with a low prevalence of PJK and PJF.

Minimally invasive surgery versus standard posterior approach for Lenke Type 1-4 adolescent idiopathic scoliosis: a multicenter, retrospective study

PURPOSE

To compare the safety and efficacy of posterior minimally invasive surgery (MIS) to standard posterior spinal fusion (PSF) surgery for Lenke Type 1-4 adolescent idiopathic scoliosis (AIS).

METHODS

This multicenter retrospective study enrolled 112 patients with Lenke Type 1-4 AIS who treated with MIS (n = 64) or PSF (n = 48) between March 2007 and January 2015. Coronal and sagittal parameters were evaluated before surgery, immediately after surgery, and at the last follow-up. Operative time, level of fusion, intraoperative blood loss, blood transfusion, and intraoperative radiation exposure were recorded. 22-item Scoliosis Research Society questionnaire (SRS-22) was applied for assessment of life quality. The accuracy of pedicle screw placement was assessed according to postoperative computed tomography images, and the complications were collected in follow-up period.

RESULTS

The baseline characteristics of 2 groups were matched. There was no significant difference between 2 groups in terms of radiographic parameters immediately after surgery and at the last follow-up. The MIS group had significantly longer operative time, more level of fusion, less intraoperative blood loss, and lower blood transfusion rate (p < 0.001). The evaluation of pain using SRS-22 showed significantly lower score in MIS group (p < 0.05). No significant difference was found between 2 groups in terms of accuracy of pedicle screw placement and complications.

CONCLUSION

Posterior MIS is a safe and effective alternative to standard open approach for Lenke Type 1-4 AIS patients with curves < 70° and reasonable flexibility. Mid-term results showed MIS had the advantages of less blood loss and pain with more fusion segments.

The Prevalence of the Use of MIS Techniques in the Treatment of Adult Spinal Deformity (ASD) Amongst Members of the Scoliosis Research Society (SRS) in 2016

STUDY DESIGN

Electronic survey administered to Scoliosis Research Society members.

OBJECTIVE

To determine the prevalence of minimally invasive surgery (MIS) techniques for the treatment of adult spinal deformity.

SUMMARY OF BACKGROUND DATA

There is a paucity of data available on the practice pattern, prevalence of minimally invasive spine surgery, and the preferred minimally invasive techniques in the treatment of adult spine deformity.

METHODS

An electronic nine-question survey regarding individual usage pattern of minimally invasive spine surgery techniques was administered in 2016 to the members of the Scoliosis Research Society. Determinants included complexity in condition of patient population, prevalence of use of minimally invasive techniques in the surgeon's practice, prevalence of use of a particular MIS technique, strategy elected during surgery, adoption of staging of procedures and timing between staging of procedures.

RESULTS

A total of 357 surgeons responded (61.3% response rate), and 154 (43.1%) of the respondents said that they use MIS as a part of their surgical treatment of adult spinal deformity. However, of these 154 respondents, 67 (43.5%) said that their MIS usage in deformity practice was between 1% and 20%. Only 11 (7.2%) said that they used MIS 81% to 100% of the time. The top MIS approaches that surgeons chose were MIS lateral lumbar interbody fusion 109 (70.59%) and MIS percutaneous screws 91 (58.8%).

CONCLUSIONS

The low rate of adoption of these techniques among the SRS members may be due to the false perception that there is not enough data to support that MIS techniques are better. This and the fact that a practitioner needs to be facile at different MIS techniques may be the true impediment to the adoption of MIS techniques in the treatment of ASD.

LEVEL OF EVIDENCE

Level IV.

Clinical and Radiologic Fate of the Lumbosacral Junction After Anterior Lumbar Interbody Fusion Versus Axial Lumbar Interbody Fusion at the Bottom of a Long Construct in CMIS Treatment of Adult Spinal Deformity

Introduction:

Surgeons use numerous arthrodesis strategies for fusion of the lumbosacral junction including anterior lumbar interbody fusion (ALIF) and axial lumbar interbody fusion (AxiaLIF). The optimal L5-S1 fusion strategy remains inconclusive. The purpose of this study is to compare the fate of the lumbosacral junction in ALIF versus AxiaLIF patients in terms of clinical and radiographic outcomes.

Methods:

Adult spinal deformity patients, treated with CMIS techniques, with at least 2-year follow-up who underwent AxiaLIF or ALIF at the lumbosacral junction were included. Patients were separated into two groups: AxiaLIF (56 patients) and ALIF (38 patients). Outcome measures included segmental lordosis, sagittal vertical alignment, lumbar lordosis (LL), pelvic incidence–LL mismatch, and pseudarthrosis, major complication, and revision surgery rates.

Results:

The ALIF group achieved greater postoperative and delta segmental lordosis, higher delta sagittal vertical alignment, higher delta LL, and lower postoperative pelvic incidence–LL mismatch. The pseudarthrosis, major complication, and revision surgery rates were higher in the AxiaLIF group. Five cases of pseudarthrosis at L5-S1 were seen, all in the AxiaLIF group.

Discussion and Conclusion:

ALIF patients showed more favorable radiographic correction parameters and lower rates of pseudarthrosis, major complications, and revision surgeries. ALIF is the preferred strategy for L5-S1 arthrodesis at a bottom of a long construct.

Contribution of Lateral Interbody Fusion in Staged Correction of Adult Degenerative Scoliosis

Objective

Lateral interbody fusion (LIF) is attractive as a less invasive technique to address anterior spinal pathology in the treatment of adult spinal deformity. Its own uses and benefits in treatment of adult degenerative scoliosis are undefined. To investigate the radiographic and clinical outcomes of LIF, and staged LIF and posterior spinal fusion (PSF) for the treatment of adult degenerative scoliosis patients, we analyzed radiographic and clinical outcomes of adult degenerative scoliosis patients who underwent LIF and posterior spinal fusion.

Methods

Forty consecutive adult degenerative scoliosis patients who underwent LIF followed by staged PSF at a single institution were retrospectively reviewed. Long-standing 36” anterior-posterior and lateral radiographs were taken preoperatively, at inter-stage, 3 months, 1 year, and 2 years after surgery were reviewed. Outcomes were assessed through the visual analogue scale (VAS), 36-Item Short Form Health Survey (SF-36), and Oswestry Disability Index (ODI).

Results

Forty patients with a mean age of 66.3 (range, 49–79) met inclusion criteria. A mean of 3.8 levels (range, 2–5) were fused using LIF, while a mean of 9.0 levels (range, 3–16) were fused during the posterior approach. The mean time between stages was 1.4 days (range, 1–6). The mean follow-up was 19.6 months. Lumbar lordosis was significantly restored from 36.4º preoperatively up to 48.9º (71.4% of total correction) after LIF and 53.9º after PSF. Lumbar coronal Cobb was prominently improved from 38.6º preoperatively to 24.1º (55.8% of total correction) after LIF, 12.6º after PSF respectively. The mean pelvic incidence-lumbar lordosis mismatch was markedly improved from 22.2º preoperatively to 8.1º (86.5% of total correction) after LIF, 5.9º after PSF. Correction of coronal imbalance and sagittal vertebral axis did not reach significance. The rate of perioperative complication was 37.5%. Five patients underwent revision surgery due to wound infection. No major perioperative medical complications occurred. At last follow-up, there were significant improvements in VAS, SF-36 Physical Component Summary and ODI scores.

Conclusion

LIF provides significant corrections in the coronal and sagittal plane in the patients with adult degenerative scoliosis. However, LIF combined with staged PSF provides more excellent radiographic and clinical outcomes, with reduced perioperative risk in the treatment of adult degenerative scoliosis.

Recent Advances in Technique and Clinical Outcomes of Minimally Invasive Spine Surgery in Adult Scoliosis

Objective:

Conventional open spinal surgery of adult scoliosis can be performed from anterior, posterior, or combined approach. Minimally invasive spine surgery (MISS) was developed for the purpose of reducing the undesirable effects and complications. This review aimed to make a brief summary of recent studies of the approach and clinical outcomes of MISS in adult scoliosis.

Data Sources:

We conducted a systematic search from PubMed, Medline, EMBASE, and other literature databases to collect reports of surgical methods and clinical outcomes of MISS in treatment of adult scoliosis. Those reports were published up to March 2017 with the following key terms: “minimally invasive,” “spine,” “surgery,” and “scoliosis.”

Study Selection:

The inclusion criteria of the articles were as followings: diagnosed with adult degenerative scoliosis (DS) or adult idiopathic scoliosis; underwent MISS or open surgery; with follow-up data. The articles involving patients with congenital scoliosis or unknown type were excluded and those without any follow-up data were also excluded from the study. The initial search yielded 233 articles. After title and abstract extraction, 29 English articles were selected for full-text review. Of those, 20 studies with 831 patients diagnosed with adult DS or adult idiopathic scoliosis were reviewed. Seventeen were retrospective studies, and three were prospective studies.

Results:

The surgical technique reported in these articles was direct or extreme lateral interbody fusion, axial lumbar interbody fusion, and transforaminal lumbar interbody fusion. Among the clinical outcomes of these studies, the operated levels was 3–7, operative time was 2.3–8.5 h. Both the Cobb angle of coronal major curve and evaluation of Oswestry Disability Index and Visual Analog Scale decreased after surgery. There were 323 complications reported in the 831 (38.9%) patients, including 150 (18.1%) motor or sensory deficits, and 111 (13.4%) implant-related complications.

Conclusions:

MISS can provide good radiological and self-evaluation improvement in treatment of adult scoliosis. More prospective studies will be needed before it is widely used.

Minimally Invasive Spinal Surgery for Adult Spinal Deformity

The purpose of this review is to present the current techniques and outcomes of adult spine deformity (ASD) surgery using the minimally invasive spine surgery (MISS) approach. We performed a systemic search of PubMed for literature published through January 2018 with the following terms: "minimally invasive spine surgery," "adult spinal deformity," and "degenerative scoliosis." Of the 138 items that were found through this search, 57 English-language articles were selected for full-text review. According to the severity of the deformity and the symptoms, various types of MISS have been utilized, such as MISS decompression, circumferential MISS, and hybrid surgery. With proper indications, the MISS approach achieved satisfactory clinical and radiological outcomes for ASD, with reduced complication rates. Future studies should aim to define clear indications for the application of various surgical options.

Pseudarthrosis in adult and pediatric spinal deformity surgery: a systematic review of the literature and meta-analysis of incidence, characteristics, and risk factors

We conducted a systematic review with meta-analysis and qualitative synthesis. This study aims to characterize pseudarthrosis after long-segment fusion in spinal deformity by identifying incidence rates by etiology, risk factors for its development, and common features. Pseudarthrosis can be a painful and debilitating complication of spinal fusion that may require reoperation. It is poorly characterized in the setting of spinal deformity. The MEDLINE, EMBASE, and Cochrane databases were searched for clinical research including spinal deformity patients treated with long-segment fusions reporting pseudarthrosis as a complication. Meta-analysis was performed on etiologic subsets of the studies to calculate incidence rates for pseudarthrosis. Qualitative synthesis was performed to identify characteristics of and risk factors for pseudarthrosis. The review found 162 articles reporting outcomes for 16,938 patients which met inclusion criteria. In general, the included studies were of medium to low quality according to recommended reporting standards and study design. Meta-analysis calculated an incidence of 1.4% (95% CI 0.9-1.8%) for pseudarthrosis in adolescent idiopathic scoliosis, 2.2% (95% CI 1.3-3.2%) in neuromuscular scoliosis, and 6.3% (95% CI 4.3-8.2%) in adult spinal deformity. Risk factors for pseudarthrosis include age over 55, construct length greater than 12 segments, smoking, thoracolumbar kyphosis greater than 20°, and fusion to the sacrum. Choice of graft material, pre-operative coronal alignment, post-operative analgesics, and sex have no significant impact on fusion rates. Older patients with greater deformity requiring more extensive instrumentation are at higher risk for pseudarthrosis. Overall incidence of pseudarthrosis requiring reoperation is low in adult populations and very low in adolescent populations.

The Role of Minimally Invasive Techniques in Scoliosis Correction Surgery

OBJECTIVE

Recently, minimally invasive surgery (MIS) has been included among the treatment modalities for scoliosis. However, literature comparing MIS to open surgery for scoliosis correction is limited. The objective of this study was to compare outcomes for scoliosis correction patients undergoing MIS versus open approach.

METHODS

We retrospectively collected data on demographics, procedure characteristics, and outcomes for 207 consecutive scoliosis correction surgeries at our institution between 2009 and 2015.

RESULTS

MIS patients had lower number of levels fused (p < 0.0001), shorter surgeries (p = 0.0023), and shorter overall lengths of stay (p < 0.0001), were less likely to be admitted to the ICU (p < 0.0001), and had shorter ICU stays (p = 0.0015). On multivariable regression, number of levels fused predicted selection for MIS procedure (p = 0.004), and multiple other variables showed trends toward significance. Age predicted ICU admission and VTE. BMI predicted any VTE, and DVT specifically. Comorbid disease burden predicted readmission, need for transfusion, and ICU admission. Number of levels fused predicted prolonged surgery, need for transfusion, and ICU admission.

CONCLUSIONS

Patients undergoing MIS correction had shorter surgeries, shorter lengths of stay, and shorter and fewer ICU stays, but there was a significant selection effect. Accounting for other variables, MIS did not independently predict any of the outcomes.

Is There a Patient Profile That Characterizes a Patient With Adult Spinal Deformity as a Candidate for Minimally Invasive Surgery?

STUDY DESIGN

Retrospective review.

OBJECTIVES

The goal of this study was to evaluate the baseline characteristics of patients chosen to undergo traditional open versus minimally invasive surgery (MIS) for adult spinal deformity (ASD).

METHODS

A multicenter review of 2 databases including ASD patients treated with surgery. Inclusion criteria were age >45 years, Cobb angle minimum of 20°, and minimum 2-year follow-up. Preoperative radiographic parameters and disability outcome measures were reviewed.

RESULTS

A total of 350 patients were identified: 173 OPEN patients and 177 MIS. OPEN patients were significantly younger than MIS patients (61.5 years vs 63.74 years, P = .013). The OPEN group had significantly more females (87% vs 76%, P = .006), but both groups had similar body mass index. Preoperative lumbar Cobb was significantly higher for the OPEN group (34.2°) than for the MIS group (26.0°, P < .001). The mean preoperative Oswestry Disability Index was significantly higher in the MIS group (44.8 in OPEN patients and 49.8 in MIS patients, P < .011). The preoperative Numerical Rating Scale value for back pain was 7.2 in the OPEN group and 6.8 in the MIS group preoperatively, P = .100.

CONCLUSIONS

Patients chosen for MIS for ASD are slightly older and have smaller coronal deformities than those chosen for open techniques, but they did not have a substantially lesser degree of sagittal malalignment. MIS surgery was most frequently utilized for patients with an sagittal vertical axis under 6 cm and a baseline pelvic incidence and lumbar lordosis mismatch under 30°.

The Influence of Lordotic cages on creating Sagittal Balance in the CMIS treatment of Adult Spinal Deformity

BACKGROUND

CMIS techniques are heavily dependent on placement of lateral interbody cages. Cages with an increased lordotic angle are being advocated to improve segmental lordosis and SVA. We assessed the segmental lordosis achieved with the individual cages. We further studied three variables and the effect each had on segmental lordosis: the lordosis angle of the cage, the position of the cage in the intervertebral space, and the level that it has been placed.

METHODS

This is a retrospective study of 66 consecutive patients who underwent lateral interbody fusion using lordotic cages as part of CMIS correction of scoliosis from June 2012 to January 2016. Standing radiographs at pre op and 6-week follow-up were reviewed to identify the position of the cage in the intervertebral space and the amount of segmental lordosis achieved.

RESULTS

A total of 224 cages were placed. The 6°, 10°, 12°, and 20° cages achieved a mean segmental lordosis of 9.00°, 13.09°, 13.23°, and 18.32°, respectively (P < .05). Additionally, cages placed in the anterior, middle, and posterior 3rd of the disk space produced 13.02°, 11.47°, and 8.23° of lordosis, respectively (P < .05). Stratifying by level, cages placed at T12-L1, L1-2, L2-3, L3-4, and L4-5 translated to mean segmental lordotic values of 8.43°, 10.02°, 11.38°, 12.91°, and 14.58°, respectively (P < .05).

CONCLUSIONS

The angle of the cage had an impact on segmental lordosis. Achieved segmental lordosis was notably more when the cage was placed in lower lumbar levels. Additionally, cages placed in the posterior 3rd of the intervertebral space had significantly worse segmental lordosis compared to those placed in the anterior or middle 3rd. Our study shows that an average delta change of 8.03° can be achieved with 12° cages and this when done at each subsequent level results in a progressive harmonious creation of lordosis. IRB approval was obtained for this study.

Effectiveness of Operative and Nonoperative Care for Adult Spinal Deformity: Systematic Review of the Literature

STUDY DESIGN

Systematic review.

OBJECTIVE

There is a need for synthesizing data on effectiveness of treatments for patients with adult spinal deformity (ASD) due to its increasing prevalence and health care costs for these patients. The objective of this review was to estimate the effectiveness of surgery versus nonoperative care in patients with ASD.

METHODS

A systematic review of articles in published in English using PubMed between 2005 and 2015. Surgical and nonsurgical series that reported baseline and follow-up health-related quality of life measures of patients with ASD with a minimum 2 years of follow-up were selected. Independent extraction of articles by 2 authors using predefined data fields, including risk of bias assessment.

RESULTS

Surgery significantly reduces disability, pain, and improves patients' quality of life. The average postoperative improvement in Oswestry Disability Index was -19.1 (±9.0), Numerical Rating Scale back pain -4.14 (±1.38), Numerical Rating Scale leg pain -3.36 (±1.33), Short-Form Health Survey 36-SF36-Physical Component score 11.2 (±5.07), and Short-Form Health Survey 36-Mental Component score 9.93 (±4.96). The complication rate ranged from 9.52% to 81.52% (mean = 39.62%), and the need for revision surgery ranged from 1.72% to 40.0% (mean = 15.71%). The best existing evidence about nonoperative care of ASD is provided from observational studies with very high risk of bias. Quantitative analyses of nonsurgical cohorts did not demonstrate significant changes in quality of life of patients after 2 years of observation.

CONCLUSIONS

This data may assist clinicians to counsel patients, as well as to inform health care providers and policymakers about what to expect from the treatment for ASD.

Thirty-Day Reoperation and Readmission Rates After Correction of Adult Spinal Deformity via Circumferential Minimally Invasive Surgery-Analysis of a 7-Year Experience

STUDY DESIGN

Single-center retrospective analysis of consecutive patients who have undergone circumferential minimally invasive surgery (cMIS) for correction of adult spinal deformity (ASD).

OBJECTIVES

To study the rates of reoperations and readmissions within the first 30 days following cMIS for correction of ASD.

BACKGROUND

Hospital readmission and reoperation rates have been emphasized as an important measure of quality and cost-effectiveness of care. However, there is little information about the readmission rates following cMIS correction of ASD.

METHODS

This is a retrospective cohort study of 214 consecutive patients with ASD who underwent correction using cMIS involving at least 2 levels. Major complications encountered during surgery or within 30 days following the index procedure that needed reoperation or readmission were recorded. The primary outcomes measured were early readmission, and early reoperation.

RESULTS

An average of 4 levels were fused. Nineteen complications were noted in the 30-day period following the index surgery, giving an early complication rate of 8.9%. Twelve of those complications occurred during the initial hospitalization and 7 complications occurred after the patient had been discharged home. Forty-seven percent of the complications occurred within the first 3 years of our experience, 37% in the next 2 years, and only 16% in the following 3 years. The 30-day readmission rate was 3.3%, which showed no statistically significant difference based on the number of levels fused.

CONCLUSIONS

Our study delivers significant evidence that efforts to reduce hospital readmissions for ASD patients should begin by concentrating on the postoperative complications. Although minimally invasive approaches will not eliminate all complications, they may have an effect on reducing the rate of major complications, most notably the rate of postoperative infection. This in turn can lead to a substantially lower readmission and reoperation rate as is reported in our study.

LEVEL OF EVIDENCE

Level IV, case series.