The management of spinal metastases from renal cell carcinoma

Vascular Pathologic Conditions in and around the Spinal Cord

Diagnosing and differentiating spinal vascular pathologic conditions is challenging. Small structures, lengthy imaging examinations, and overlapping imaging features increase the difficulty. Yet, subtle findings and helpful protocols can narrow the differential diagnosis. The authors aim to help radiologists make accurate and timely diagnoses of spinal vascular pathologic conditions in and around the spinal cord by highlighting spinal vascular anatomy, imaging findings, and three broad categories of abnormalities: infarcts, anomalies, and tumors. ©RSNA, 2024.

Trans-Sternal Multilevel Corpectomy for Cervicothoracic Renal Cell Metastasis: 2-Dimensional Operative Video

The operative management of pathological fractures at the cervicothoracic junction is a surgical challenge. Here, we present the case of a 48-year-old male patient presenting with 2 months of progressive left upper extremity weakness as well as back and bilateral arm pain (Karnofsky Performance Status 60%) who was found to have pathological fractures from C7, T1, and T2 due to metastatic renal cell carcinoma. Renal cell carcinoma is known to metastasize to bone and cause cord compression.1 Given the extensive metastasis with this highly vascular tumor, endovascular embolization was performed preoperatively to minimize intraoperative blood loss.2 Surgical management consisted of a two-stage procedure. Posterior spinal fusion from C2-T7 with C7-T2 decompression was performed during stage 1. Stage 2 consisted of a trans-sternal approach for C7, T1, and T2 corpectomy for cord decompression and placement of a cage and plate for anterior column support.3 Although prior surgeons have suggested to access upper thoracic pathology through an interaortocaval window, in this case we demonstrate a trans-sternal approach to C6-T3 that starts superior to the innominate vein and aortic arch and angles inferiorly dorsal to these vascular structures.4 When planning for a manubriotomy/trans-sternal approach, access to T1/T2 remains the most decisive factor and is most successful with a sternotomy.5 At 12-month follow-up, the patient demonstrated improvement in his left upper extremity strength and overall functional status (3/5 strength in hand grip and interossei with 5/5 in all remaining motor groups; Karnofsky Performance Status 80%). The patient consented to participate in the surgery and surgical video.

Anatomical study of the thoracolumbar radiculomedullary arteries, including the Adamkiewicz artery and supporting radiculomedullary arteries

OBJECTIVE

The aim of this paper was to identify and characterize all the segmental radiculomedullary arteries (RMAs) that supply the thoracic and lumbar spinal cord.

METHODS

All RMAs from T4 to L5 were studied systematically in 25 cadaveric specimens. The RMA with the greatest diameter in each specimen was termed the artery of Adamkiewicz (AKA). Other supporting RMAs were also identified and characterized.

RESULTS

A total of 27 AKAs were found in 25 specimens. Twenty-two AKAs (81%) originated from a left thoracic or a left lumbar radicular branch, and 5 (19%) arose from the right. Two specimens (8%) had two AKAs each: one specimen with two AKAs on the left side and the other specimen with one AKA on each side. Eight cadaveric specimens (32%) had 10 additional RMAs; among those, a single additional RMA was found in 6 specimens (75%), and 2 additional RMAs were found in each of the remaining 2 specimens (25%). Of those specimens with a single additional RMA, the supporting RMA was ipsilateral to the AKA in 5 specimens (83%) and contralateral in only 1 specimen (17%). The specimens containing 2 additional RMAs were all (100%) ipsilateral to their respective AKAs.

CONCLUSIONS

The segmental RMAs supplying the thoracic and lumbar spinal cord can be unilateral, bilateral, or multiple. Multiple AKAs or additional RMAs supplying a single anterior spinal artery are common and should be considered when dealing with the spinal cord at the thoracolumbar level.

Metastatic Renal Cell Cancer Instigating Paraplegia in a Male Patient

Renal cell carcinoma (RCC) constitutes about 2% of all adult malignancies and is the most common malignant renal neoplasm with bony metastases occurring in up to 50% of patients with RCC. In this case, we report a 42-year-old male who presented with chronic back pain and had a sudden episode of paraplegia. The patient was initially referred to the orthopedics service. He had a lumbar X-ray done followed by a CT of the spine that showed a burst fracture of the L1 vertebra with incidental finding of a right renal mass suspicious of RCC. Upon further investigations, the patient was found to have a large heterogeneous renal cortical mass with multiple cystic changes and necrosis invading the Gerota’s fascia as well as a tumor thrombus extending into the right renal vein and inferior vena cava.

Although it has been well established that RCC metastasizes to bones and it is not uncommon for vertebral column involvement, sudden paraplegia and incontinence resulting from lumbar fracture due to metastatic RCC has not been widely published. Conclusively, RCC is a common malignancy in which a significant number of patients have metastatic disease upon presentation and this can lead to initial confusion and delay in diagnosis, hence it should be part of the differential diagnosis when investigating chronic bony pain and pathological fractures.

Interventional Therapies for Pain in Cancer Patients: a Narrative Review

PURPOSE OF REVIEW

Pain is a prevalent symptom in the lives of patients with cancer. In light of the ongoing opioid epidemic and increasing awareness of the potential for opioid abuse and addiction, clinicians are progressively turning to interventional therapies. This article reviews the interventional techniques available to mitigate the debilitating effects that untreated or poorly treated pain have in this population.

RECENT FINDINGS

A range of interventional therapies and technical approaches are available for the treatment of cancer-related pain. Many of the techniques described may offer effective analgesia with less systemic toxicity and dependency than first- and second-line oral and parenteral agents. Neuromodulatory techniques including dorsal root ganglion stimulation and peripheral nerve stimulation are increasingly finding roles in the management of oncologic pain. The goal of this pragmatic narrative review is to discuss interventional approaches to cancer-related pain and the potential of such therapies to improve the quality of life of cancer patients.

Decision Making for the Surgical Treatment of Vertebral Metastases Among Patients with Short Predicted Survival

BACKGROUND

A wide spectrum of treatment choices is proposed for poor-prognosis patients with vertebral metastases. The continuous increase of this population and the propagation of less invasive techniques necessitate further study concerning which patients could benefit from palliative surgery.

METHODS

All patients with a Tokuhashi score ≤8 who had undergone palliative surgical treatment for vertebral metastasis within 4 years were retrospectively reviewed. Demographics, clinical characteristics, and data concerning the disease and the operation were recorded. Patients were assessed on discharge and at 2 months concerning eventual benefit from surgery, based on pain measurements, motor function (Frankel grade), spinal stability assessment, and complications. Statistical analysis was performed to detect possible interrelations.

RESULTS

Eighty-eight patients were reviewed. The average age was 56.5 years. The mean Tokuhashi score was 5.9, and the mean Karnofsky score was 56.4. Thirty-six patients experienced immediate improvement, 12 were lost to follow-up, and 42 were found to have benefited from surgery 2 months later. High Karnofsky score, radicular pain, morphine use, absence of complications, and immediate improvement predicted benefit from surgery.

CONCLUSIONS

Decision making for a patient with poor prognosis concerning eventual surgery for a vertebral metastasis should be based mainly on the patient's clinical presentation; the primary cancer site is of less importance.

Application of digital volume correlation to study the efficacy of prophylactic vertebral augmentation

BACKGROUND

Prophylactic augmentation is meant to reinforce the vertebral body, but in some cases it is suspected to actually weaken it. Past studies only investigated structural failure and the surface strain distribution. To elucidate the failure mechanism of the augmented vertebra, more information is needed about the internal strain distribution. This study aims to measure, for the first time, the full-field three-dimensional strain distribution inside augmented vertebrae in the elastic regime and to failure.

METHODS

Eight porcine vertebrae were prophylactically-augmented using two augmentation materials. They were scanned with a micro-computed tomography scanner (38.8μm voxel resolution) while undeformed, and loaded at 5%, 10%, and 15% compressions. Internal strains (axial, antero-posterior and lateral-lateral components) were computed using digital volume correlation.

FINDINGS

For both augmentation materials, the highest strains were measured in the regions adjacent to the injected cement mass, whereas the cement-interdigitated-bone was less strained. While this was already visible in the elastic regime (5%), it was a predictor of the localization of failure, which became visible at higher degrees of compression (10% and 15%), when failure propagated across the trabecular bone. Localization of high strains and failure was consistent between specimens, but different between the cement types.

INTERPRETATION

This study indicated the potential of digital volume correlation in measuring the internal strain (elastic regime) and failure in augmented vertebrae. While the cement-interdigitated region becomes stiffer (less strained), the adjacent non-augmented trabecular bone is affected by the stress concentration induced by the cement mass. This approach can help establish better criteria to improve vertebroplasty.

A PRELIMINARY IN VITRO BIOMECHANICAL EVALUATION OF PROPHYLACTIC CEMENT AUGMENTATION OF THE THORACOLUMBAR VERTEBRAE

In this paper, the biomechanical effectiveness of prophylactic augmentation in preventing fracture was investigated. In vitro biomechanical tests were performed to assess which factors make prophylactic augmentation effective/ineffective in reducing fracture risk. Nondestructive and destructive in vitro tests were performed on isolated osteoporotic vertebrae. Five sets of three-adjacent-vertebrae were tested. The central vertebra of each triplet was tested in the natural condition (control) non-destructively (axial-compression, torsion) and destructively (axial-compression). The two adjacent vertebrae were first tested nondestructively (axial-compression, torsion) pre-augmentation; prophylactic augmentation (uni- or bi-pedicular access) was then performed delivering 5.04[Formula: see text]mL to 8.44[Formula: see text]mL of acrylic cement by means of a customized device; quality of augmentation was CT-assessed; the augmented vertebrae were re-tested nondestructively (axial-compression, torsion), and eventually loaded to failure (axial-compression). Vertebral stiffness was correlated with the first-failure, but not with ultimate failure. The force and work to ultimate failure in prophylactic-augmented vertebrae was consistently larger than in the controls. However, in some cases the first-failure force and work in the augmented vertebrae were lower than for the controls. To investigate the reasons for such unpredictable results, the correlation with augmentation quality was analyzed. Some augmentation parameters seemed more correlated with mechanical outcome (statistically not-significant due to the limited sample size): uni-pedicular access resulted in a single cement mass, which tended to increase the force and work to first- and ultimate failure. The specimens with the highest strength and toughness also had: at least 25% cement filling, cement mass shifted anteriorly, and cement-endplate contact. These findings seem to confirm that prophylactic augmentation may aid reducing the risk of fracture. However, inadequate augmentation may have detrimental consequences. This study suggests that, to improve the strength of the augmented vertebrae, more attention should be dedicated to the quality of augmentation in terms of amount and position of the injected cement.

Minimally Invasive Muscle Sparing Posterior-Only Approach for Lumbar Circumferential Decompression and Stabilization to Treat Spine Metastasis--Technical Report

OBJECTIVE

Palliative tumor resection and subsequent stabilization are important for maximizing function and quality of life for patients suffering from spinal metastases. However, traditional operative techniques for spinal metastases with vertebral body destruction involve extensive soft tissue dissection. In the lumbar spine, open 2-staged spine procedures are routinely required with an anterior retroperitoneal approach for corpectomy and cage insertion and posterior decompression and stabilization with pedicle screws and rods. Both stages require extensive soft tissue dissection that results in significant surgical morbidity, long recovery time, and subsequent delay in initiating postoperative chemoradiotherapy, as well as initially hampering patients' overall quality of life. A minimally invasive approach is desirable for achieving spinal stability, pain control, functional recovery, rapid initiation of adjuvant therapies, and overall patient satisfaction, especially in patients whose medical and surgical therapies are aimed at palliation rather than cure.

PRESENTATION

A 59-year-old man with renal cell carcinoma and a known L1 vertebral body metastasis presented with severe progressive low back pain and was found to have a pathologic L1 vertebral body fracture with focal kyphosis.

INTERVENTION

Here, we describe a minimally invasive muscle-sparing, posterior-only approach for L1 transpedicular hemicorpectomy and expandable cage placement, L1 laminectomy, and T11-L3 posterior instrumented stabilization. The surgical corridor was achieved through the Wiltse muscle plane between the multifidus and longissimus muscles so that minimal muscle detachment was required to achieve transpedicular access to the anterior and middle spinal columns. The L1 nerve root was completely skeletonized to allow adequate lumbar hemicorpectomy, tumor resection, and expandable titanium cage insertion. Lastly, percutaneous pedicle screws and rods were inserted from T11 to L3 for stabilization.

RESULT

The patient tolerated the procedure well with no complications and less than 200 mL estimated blood loss. Postoperative computed tomography revealed restoration of intervertebral height and adequate tumor resection with excellent placement of the expandable cage and posterior construct. The patient was discharged on postoperative day 4 and had nearly no back pain 3 weeks after surgery. Adjuvant therapies were started soon after. At the 6-month follow-up, the patient required minimal narcotic pain medication. Computed tomography scan demonstrated stable hardware with no evidence of failure.

CONCLUSION

A minimally invasive muscle-sparing, posterior-only approach is a promising surgical strategy for 360-degree decompression and stabilization for the treatment of lumbar spinal metastases with minimized blood loss, muscle detachment and postoperative pain, and fast postoperative recovery and initiation of adjuvant therapy.

C1-C2 pigmented villonodular synovitis and clear cell carcinoma: unexpected presentation of a rare disease and a review of the literature

INTRODUCTION

Pigmented Villonodular synovitis (PVNS) is a rare vertebral pathology--around 50 reports, only 3 concerning C1-C2 location.

CASE REPORT

A 64-year-old man, submitted to a right nephrectomy for a clear cell carcinoma, presented with an asymptomatic osteolytic C1-C2 lesion. Even though the diagnosis of metastatic disease was the most probable, the presence of a solitary lesion without other osseous or systemic localization and the predicted low risk of recurrence imposed a surgical biopsy. A pigmented villonodular synovitis diagnosis was made, a rare vertebral pathology--around 50 reports, only 3 concerning C1-C2 location. No further treatment was assigned precluding the iatrogenic consequences of empirical treatments based on clinical diagnosis with no histopathological support. The patient remains stable at 18 months of follow-up.

CONCLUSION

A large differential diagnosis should be made when the typical findings for metastatic disease are absent precluding the iatrogenic consequences of empirical treatments based on clinical diagnosis with no histopathological support.