Effects of Radiation on Spinal Dura Mater and Surrounding Tissue in Mice

Clinical Outcomes of Total En Bloc Spondylectomy for Previously Irradiated Spinal Metastases: A Retrospective Propensity Score-Matched Comparative Study

This study aimed to investigate the clinical outcomes of total en bloc spondylectomy (TES) for spinal metastases previously treated with radiotherapy (RT). This study enrolled 142 patients who were divided into two groups: those with and those without an RT history. Forty-two patients were selected from each group through propensity score matching, and postoperative complications, local recurrence, and overall survival rates were compared. The incidence of postoperative complications was significantly higher in the group with an RT history than in the group without an RT history (57.1% vs. 35.7%, respectively). The group with an RT history had a higher local recurrence rate than the group without an RT history (1-year rate: 17.5% vs. 0%; 2-year rate: 20.8% vs. 2.9%; 5-year rate: 24.4% vs. 6.9%). The overall postoperative survival tended to be lower in the group with an RT history; however, there was no significant difference between the two groups (2-year survival: 64.3% vs. 66.7%; 5-year survival: 47.3% vs. 57.1%). When planning a TES for irradiated spinal metastases, the risk of postoperative complications and local recurrence should be fully considered.

The Impact of Frailty on Postoperative Complications in Total En Bloc Spondylectomy for Spinal Tumors

Total en bloc spondylectomy (TES) is an effective treatment for spinal tumors. However, its complication rate is high, and the corresponding risk factors remain unclear. This study aimed to clarify the risk factors for postoperative complications after TES, including the patient's general condition, such as frailty and their levels of inflammatory biomarkers. We included 169 patients who underwent TES at our hospital from January 2011-December 2021. The complication group comprised patients who experienced postoperative complications that required additional intensive treatments. We analyzed the relationship between early complications and the following factors: age, sex, body mass index, type of tumor, location of tumor, American Society of Anesthesiologists score, physical status, frailty (categorized by the 5-factor Modified Frailty Index [mFI-5]), neutrophil-to-lymphocyte ratio, C-reactive protein/albumin ratio, preoperative chemotherapy, preoperative radiotherapy, surgical approach, and the number of resected vertebrae. Of the 169 patients, 86 (50.1%) were included in the complication group. Multivariate analysis showed that high mFI-5 scores (odds ratio [OR] = 2.99, p < 0.001) and an increased number of resected vertebrae (OR = 1.87, p = 0.018) were risk factors for postoperative complications. Frailty and the number of resected vertebrae were independent risk factors for postoperative complications after TES for spinal tumors.

A Systematic Review of Perioperative Complications in en Bloc Resection for Spinal Tumors

STUDY DESIGN

Systematic review.

OBJECTIVE

En bloc resection is a major, invasive surgical procedure designed to completely resect a vertebral tumor with a sufficient margin. It is technically demanding and potentially poses risks of perioperative complications. In this systematic review, we investigated the incidence of complications after en bloc resection for spinal tumors.

METHODS

We screened PubMed and Embase databases for relevant English publications, from 1980 to 2020, using the following terms: spine OR spinal AND en bloc AND tumor. Using a standard PRISMA template, after the initial screening, full-text articles of interest were evaluated.

RESULTS

Thirty-six studies with 961 patients were included. The overall mean age of patients was 49.6 years, and the mean follow-up time was 33.5 months. There were 560 complications, and an overall complication rate of 58.3% (560/961). The 5 most frequent complications were neurological damage (12.7%), hardware failure (12.1%), dural tear and cerebrospinal fluid leakage (10.6%), wound-related complications (7.6%) and vascular injury and bleeding (7.3%). The complication-related revision rate was 10.7% (103/961). The average incidence of complication-related death was 1.2% (12/961).

CONCLUSIONS

En bloc resection is a surgical procedure that is very invasive and technically challenging, and the possible risks of perioperative complications should not be neglected. The overall complication rate is high. However, complication-related death was rare. The advantages of surgery should be weighed against the serious perioperative morbidity associated with this technique.

Postoperative communicating hydrocephalus following glioblastoma resection: Incidence, timing and risk factors

Introduction

Glioblastoma (GBM) is the most common malignant primary brain tumor. Treatment includes maximally safe surgical resection followed by radiation and/or chemotherapy. However, resection can lead to ventricular opening, potentially increasing the risk for development of communicating hydrocephalus (CH). Complications such as rebleeding and infection may also lead to CH and, eventually, the need for cerebrospinal fluid (CSF) diversion surgery. In this study, we evaluated the incidence of different types of hydrocephalus and potential risk factors for the development of CH following glioblastoma resection.

Methods

726 GBM patients who underwent tumor resection at our department between 2006 and 2019 were analyzed retrospectively. Potential risk factors that were determined for each patient were age, sex, tumor location, the number of resection surgeries, ventricular opening during resection, postoperative CSF leak, ventriculitis, and rebleeding. Uni- as well as multivariate analyses were performed to identify associations with CH and independent risk factors.

Results

55 patients (7.6%) needed CSF diversion surgery (implantation of a ventriculoperitoneal or ventriculoatrial shunt) following resection surgery. 47 patients (6.5%) had CH, on median, 24 days after the last resection (interquartile range: 17-52 days). 3 patients had obstructive hydrocephalus (OH) and 5 patients had other CSF circulation disorders. Ventricular opening (odds ratio (OR): 7.9; p=0.000807), ventriculitis (OR 3.3; p=0.000754), and CSF leak (OR 2.3; p=0.028938) were identified as significant independent risk factors for the development of post-resection CH. Having more than one resection surgery was associated with CH as well (OR 2.1; p=0.0128), and frontal tumors were more likely to develop CH (OR 2.4; p=0.00275), while temporal tumors were less likely (OR 0.41; p=0.0158); However, none of those were independent risk factors. Age, sex, or rebleeding were not associated with postoperative CH.

Conclusion

Postoperative CH requiring CSF shunting is not infrequent following GBM resection and is influenced by surgery-related factors. It typically occurs several weeks after resection. If multiple risk factors are present, one should discuss the possibility of postoperative CH with the patient and maybe even consider pre-emptive shunt implantation to avoid interruption of adjuvant tumor therapy. The incidence of CH requiring shunting in GBM patients could rise in the future.

Effects of Radiation on the Bone Strength of Spinal Vertebrae in Rats

STUDY DESIGN

A controlled laboratory study.

OBJECTIVE

The aim of this study was to examine bone damage caused by irradiation to spinal vertebrae in rats.

SUMMARY OF BACKGROUND DATA

Radiotherapy is widely used in the treatment of malignant spine tumors. However, a few studies have reported vertebral fractures following radiotherapy as an adverse reaction. There are no reports on irradiation- induced changes in bone fragility, mechanical and structural changes focusing on the spine, and the mechanism of irradiation-induced bone osteoporosis.

METHODS

Eighty-four female Wistar rats were randomly allocated to the 20 Gy irradiated or the nonirradiated (control) group. The lumbar vertebrae were irradiated with an external focal radiation dose of 20 Gy. Biomechanical, structural, and histological analyses were performed at 0, 2, 4, 6, 8, 12, and 24 weeks after irradiation. Structural analysis and bone density measurement of vertebral trabecular bone were performed by μCT. Histopathological evaluation was performed by hematoxylin and eosin staining and immunostaining.

RESULTS

The bone strength at 2 weeks after irradiation (311 ± 23 N) was 22% lower than that before irradiation (398 ± 34 N) (P  < 0.05). The trabecular spacing increased, and trabecular connectivity and width decreased significantly in the irradiated group compared with those in the non-irradiated group. The three-dimensional structure model became coarse, and the trabecular structure continued to thin and disrupt after irradiation. There was no significant change in the bone mineral density in both groups.

CONCLUSION

A decrease in bone strength was observed 2 weeks after irradiation. Bone mineral density remained unaltered, whereas the microstructure of trabecular bone changed, suggesting bone damage by irradiation.Level of Evidence: N/A.

Iatrogenic dorsal spinal cord herniation and repair with clip-based expansile duraplasty: a case report

INTRODUCTION

Myelopathy arising due to dorsal herniation of the spinal cord is a rare phenomenon, particularly so in the thoracic region. Where cases of thoracic dorsal cord herniation have been reported, the aetiology has typically been non-iatrogenic.

CASE PRESENTATION

We report the case of a paediatric oncology patient who presented with neurological deterioration secondary to thoracic dorsal spinal cord herniation, manifesting three months after laminectomy for biopsy of a spinal medulloblastoma lesion. We repaired the dural defect using non-penetrating titanium clips to create a secure expansile duraplasty, resulting in radiologically evident reduction of the cord herniation as well as corresponding clinical improvement.

DISCUSSION

Thoracic dorsal spinal cord herniation is an extremely rare occurrence after spinal surgery. Non-penetrating titanium clips can be used to form a secure expansile duraplasty following reduction of the cord herniation. Successful repair of the dural defect re-anteriorises the cord and can confer neurological benefit.

Reducing meningo-cerebral adhesions by implanting an interpositional subdural polyesterurethane graft after high-grade glioma resection

BACKGROUND

Meningo-cerebral adhesions are frequently encountered during recurrent high-grade glioma resections. Adhesiolysis not only lengthens operation times, but can also induce focal cortical tissue injury that could affect overall survival.

METHODS

Immediately after the primary resection of a high-grade glioma, a polyesterurethane interpositional graft was implanted in the subdural space covering the entire exposed cortex as well as beneath the dural suture line. No postoperative complications were documented. All patients received adjuvant radiotherapy. Upon repeat resection for focal tumor recurrence, the graft was shown to effectively reduce meningo-cerebral adhesion development.

CONCLUSION

The implantation of a synthetic subdural graft is a safe and effective method for preventing meningo-cerebral adhesions.

A novel two-layer, intradural and extradural patch graft approach to treating dural defects and tears: illustrative case

BACKGROUND

Dural tears must be quickly addressed to avoid the development of positional headaches and pseudomeningoceles, among other complications. However, sizeable areas of friable or absent dura create unique challenges when attempting to achieve a watertight seal. We have developed a two-layer subdural and epidural fibrous patch technique to treat expansive or challenging dural tears as a result of our experience treating spinal fluid leaks.

OBSERVATIONS

The authors present the treatment of a large necrotic (5 × 1.5 cm) dural defect refractory to initial attempts at standard primary repair with dural patch grafting and requiring a revision with a dual-layer patch to manage persistent cerebrospinal fluid leakage.

LESSONS

The use of a two-layer (subdural and epidural) patch is both a safe and effective dural repair technique for creating a watertight seal in challenging large areas in which the dura may be damaged, scarred, or absent. We also propose that this technique may be able to be used for smaller challenging tears, as well as potentially for repairs of large blood vessels or other fluid-filled structures in the body.

Radiation Disrupts the Protective Function of the Spinal Meninges in a Mouse Model of Tumor-induced Spinal Cord Compression

BACKGROUND

Recent advances in multidisciplinary treatments for various cancers have extended the survival period of patients with spinal metastases. Radiotherapy has been widely used to treat spinal metastases; nevertheless, long-term survivors sometimes undergo more surgical intervention after radiotherapy because of local tumor relapse. Generally, intradural invasion of a spinal tumor seldom occurs because the dura mater serves as a tissue barrier against tumor infiltration. However, after radiation exposure, some spinal tumors invade the dura mater, resulting in leptomeningeal dissemination, intraoperative dural injury, or postoperative local recurrence. The mechanisms of how radiation might affect the dura have not been well-studied.

QUESTIONS/PURPOSES

To investigate how radiation affects the spinal meninges, we asked: (1) What is the effect of irradiation on the meningeal barrier's ability to protect against carcinoma infiltration? (2) What is the effect of irradiation on the meningeal barrier's ability to protect against sarcoma infiltration? (3) What is the effect of irradiation on dural microstructure observed by scanning electron microscopy (SEM)? (4) What is the effect of irradiation on dural microstructure observed by transmission electron microscopy (TEM)?

METHODS

Eighty-four 10-week-old female ddY mice were randomly divided into eight groups: mouse mammary tumor (MMT) implantation 6 weeks after 0-Gy irradiation (nonirradiation) (n = 11), MMT implantation 6 weeks after 20-Gy irradiation (n = 10), MMT implantation 12 weeks after nonirradiation (n = 10), MMT implantation 12 weeks after 20-Gy irradiation (n = 11), mouse osteosarcoma (LM8) implantation 6 weeks after nonirradiation (n = 11), LM8 implantation 6 weeks after 20-Gy irradiation (n = 11), LM8 implantation 12 weeks after nonirradiation (n = 10), and LM8 implantation 12 weeks after 20-Gy irradiation (n = 10); female mice were used for a mammary tumor metastasis model and ddY mice, a closed-colony mice with genetic diversity, were selected to represent interhuman diversity. Mice in each group underwent surgery to generate a tumor-induced spinal cord compression model at either 6 weeks or 12 weeks after irradiation to assess changes in the meningeal barrier's ability to protect against tumor infiltration. During surgery, the mice were implanted with MMT (representative of a carcinoma) or LM8 tumor. When the mice became paraplegic because of spinal cord compression by the growing implanted tumor, they were euthanized and evaluated histologically. Four mice died from anesthesia and 10 mice per group were euthanized (MMT-implanted groups: MMT implantation occurred 6 weeks after nonirradiation [n = 10], 6 weeks after irradiation [n = 10], 12 weeks after nonirradiation [n = 10], and 12 weeks after irradiation [n = 10]; LM8-implanted groups: LM8 implantation performed 6 weeks after nonirradiation [n = 10], 6 weeks after irradiation [n = 10], 12 weeks after nonirradiation [n = 10], and 12 weeks after irradiation [n = 10]); 80 mice were evaluated. The spines of the euthanized mice were harvested; hematoxylin and eosin staining and Masson's trichrome staining slides were prepared for histologic assessment of each specimen. In the histologic assessment, intradural invasion of the implanted tumor was graded in each group by three observers blinded to the type of tumor, presence of irradiation, and the timing of the surgery. Grade 0 was defined as no intradural invasion with intact dura mater, Grade 1 was defined as intradural invasion with linear dural continuity, and Grade 2 was defined as intradural invasion with disruption of the dural continuity. Additionally, we euthanized 12 mice for a microstructural analysis of dura mater changes by two observers blinded to the presence of irradiation. Six mice (three mice in the 12 weeks after nonirradiation group and three mice in the 12 weeks after 20-Gy irradiation group) were quantitatively analyzed for defects on the dural surface with SEM. The other six mice (three mice in the 12 weeks after nonirradiation group and three mice in the 12 weeks after 20-Gy irradiation group) were analyzed for layer structure of collagen fibers constituting dura mater by TEM. In the SEM assessment, the number and size of defects on the dural surface on images (200 μm × 300 μm) at low magnification (× 2680) were evaluated. A total of 12 images (two per mouse) were evaluated for this assessment. The days from surgery to paraplegia were compared between each of the tumor groups using the Kruskal-Wallis test. The scores of intradural tumor invasion grades and the number of defects on dural surface per SEM image were compared between irradiation group and nonirradiation group using the Mann-Whitney U test. Interobserver reliabilities of assessing intradural tumor invasion grades and the number of dural defects on the dural surface were analyzed using Fleiss'κ coefficient. P values < 0.05 were considered statistically significant.

RESULTS

There was no difference in the median (range) time to paraplegia among the MMT implantation 6 weeks after nonirradiation group, the 6 weeks after irradiation group, the 12 weeks after nonirradiation group, and the 12 weeks after irradiation group (16 days [14 to 17] versus 14 days [12 to 18] versus 16 days [14 to 17] versus 14 days [12 to 15]; χ2 = 4.7; p = 0.19). There was also no difference in the intradural invasion score between the MMT implantation 6 weeks after irradiation group and the 6 weeks after nonirradiation group (8 of 10 Grade 0 and 2 of 10 Grade 1 versus 10 of 10 Grade 0; p = 0.17). On the other hand, there was a higher intradural invasion score in the MMT implantation 12 weeks after irradiation group than the 12 weeks after nonirradiation group (5 of 10 Grade 0, 3 of 10 Grade 1 and 2 of 10 Grade 2 versus 10 of 10 Grade 0; p = 0.02). Interobserver reliability of assessing intradural tumor invasion grades in the MMT-implanted group was 0.94. There was no difference in the median (range) time to paraplegia among in the LM8 implantation 6 weeks after nonirradiation group, the 6 weeks after irradiation group, the 12 weeks after nonirradiation group, and the 12 weeks after irradiation group (12 days [9 to 13] versus 10 days [8 to 13] versus 11 days [8 to 13] versus 9 days [6 to 12]; χ2 = 2.4; p = 0.50). There was also no difference in the intradural invasion score between the LM8 implantation 6 weeks after irradiation group and the 6 weeks after nonirradiation group (7 of 10 Grade 0, 1 of 10 Grade 1 and 2 of 10 Grade 2 versus 8 of 10 Grade 0 and 2 of 10 Grade 1; p = 0.51), whereas there was a higher intradural invasion score in the LM8 implantation 12 weeks after irradiation group than the 12 weeks after nonirradiation group (3 of 10 Grade 0, 3 of 10 Grade 1 and 4 of 10 Grade 2 versus 8 of 10 Grade 0 and 2 of 10 Grade 1; p = 0.04). Interobserver reliability of assessing intradural tumor invasion grades in the LM8-implanted group was 0.93. In the microstructural analysis of the dura mater using SEM, irradiated mice had small defects on the dural surface at low magnification and degeneration of collagen fibers at high magnification. The median (range) number of defects on the dural surface per image in the irradiated mice was larger than that of nonirradiated mice (2 [1 to 3] versus 0; difference of medians, 2/image; p = 0.002) and the median size of defects was 60 μm (30 to 80). Interobserver reliability of assessing number of defects on the dural surface was 1.00. TEM revealed that nonirradiated mice demonstrated well-organized, multilayer structures, while irradiated mice demonstrated irregularly layered structures at low magnification. At high magnification, well-ordered cross-sections of collagen fibers were observed in the nonirradiated mice. However, disordered alignment of collagen fibers was observed in irradiated mice.

CONCLUSION

Intradural tumor invasion and disruptions of the dural microstructure were observed in the meninges of mice after irradiation, indicating radiation-induced disruption of the meningeal barrier.

CLINICAL RELEVANCE

We conclude that in this form of delivery, radiation is associated with disruption of the dural meningeal barrier, indicating a need to consider methods to avoid or limit Postradiation tumor relapse and spinal cord compression when treating spinal metastases so that patients do not experience intradural tumor invasion. Surgeons should be aware of the potential for intradural tumor invasion when they perform post-irradiation spinal surgery to minimize the risks for intraoperative dural injury and spinal cord injury. Further research in patients with irradiated spinal metastases is necessary to confirm that the same findings are observed in humans and to seek irradiation methods that prevent or minimize the disruption of meningeal barrier function.

Incidence of Unrecognized Incidental Durotomy during Surgery for Malignant Spinal Tumor

Introduction

Cerebral spinal fluid leak from durotomy is a well-known risk with spinal surgeries. The aim of this study is to identify the incidence of unrecognized incidental durotomy during posterior surgery for spinal metastases and its risk factors.

Methods

Participants comprised 75 patients who underwent posterior spine surgery for spinal metastases between January 2012 and December 2016. Cases with apparent durotomy noticed intraoperatively were excluded. Unrecognized durotomy was diagnosed as the presence of wide subcutaneous fluid retention on magnetic resonance imaging at least 3 months postoperatively. For comparison, 50 patients who underwent cervical laminoplasty due to cervical spondylotic myelopathy were examined using the same method. We also examined correlations between occurrence of durotomy and patient characteristics such as age, type of tumor, location of tumor (ventral or dorsal), extent of tumor, and history of radiotherapy before surgery.

Results

Unrecognized durotomy occurred in 21 cases of spinal metastasis (26.7%) and in 1 case of cervical spondylotic myelopathy (2%), representing a significant difference between groups. Age, type of tumor, location of tumor, extent of tumor, and history of radiotherapy before surgery did not correlate significantly with occurrence of durotomy. No local trouble was observed in durotomy cases, except in one case with subcutaneous local infection.

Conclusions

The incidence of unrecognized incidental durotomy is significantly higher during surgery for spinal metastases than that during surgery for degenerative disease.

Risk factors for local recurrence after total en bloc spondylectomy for metastatic spinal tumors: A retrospective study

BACKGROUND

The aim of this study was to evaluate local recurrence and survival outcomes after frozen autograft total en bloc spondylectomy for metastatic spinal tumors.

METHODS

We retrospectively analyzed data from 91 patients with metastatic spinal tumors who underwent frozen autograft total en bloc spondylectomy at our institution between May 2010 and April 2015. We assessed the incidence, primary cancer type, and sites of local recurrence. Risk factors for local recurrence were also examined through the statistical analysis of 17 items, including clinico-pathological characteristics, treatment history, and preoperative or surgical complications. Survival outcomes were evaluated with particular attention paid to the presence of local recurrence.

RESULTS

The median follow-up duration was 27.4 months (range, 4-66 months). Local recurrence was diagnosed in 10 of 91 patients (11.0%). The sites of recurrence were intradural in 4 cases, epidural in 3 cases, in a vertebral body adjacent to the resected vertebral body in 2 cases, and in the paraspinal muscle in 3 cases. None of the patients had recurrence from the liquid nitrogen-treated tumor-bearing autograft. There were no local recurrences of renal cell carcinoma, thyroid cancer, or lung cancer. Multivariate analysis indicated that radiotherapy history was the only risk factor for local recurrence (odds ratio, 6.26; 95% confidence interval, 1.21-45.62; p = 0.04). The 2-year survival rate was significantly lower for the recurrence group than for the non-recurrence group (p < 0.05).

CONCLUSIONS

A history of radiation was the only risk factor for local recurrence. Patients with recurrence had a significantly worse prognosis than those without recurrence.

Incidental durotomy during total en bloc spondylectomy

BACKGROUND CONTEXT

The incidence of incidental durotomy (ID) during total en bloc spondylectomy (TES) tends to be higher than that during other spinal surgeries because of the peculiarities of TES, including its highly invasive nature, epidural tumor extension, and use in patients who often have complicated medical backgrounds. However, there have been no detailed reports on ID associated with TES.

PURPOSE

The study aimed to investigate ID during TES in detail.

STUDY DESIGN

This is a retrospective review of prospectively collected data.

PATIENT SAMPLE

The study included 105 consecutive patients with spinal tumor who underwent TES between May 2010 and February 2015 (59 men, 46 women; mean age, 54.0 years [range, 14-75 years] at the time of surgery).

OUTCOME MEASURES

Outcome measures included the incidence, risk factors, anatomical location, intraoperative maneuvers, and postoperative course of ID associated with TES.

MATERIALS AND METHODS

Medical and operative records and imaging findings were reviewed. Univariate analysis and multivariable stepwise logistic regression models were used to identify independent risk factors for ID.

RESULTS

Incidental durotomy occurred in 18 (17.1%) of the 105 patients. The univariate and multivariate analyses demonstrated that older age (adjusted odds ratio [aOR], 6.09; 95% confidence interval [CI], 1.17-31.76; p=.03), radiotherapy (RT) history (aOR, 5.31; 95% CI, 1.46-19.49; p=.01), and revision surgery (aOR, 19.42; 95% CI, 3.46-109.14; p<.01) were independent risk factors for ID. Incidental durotomy was more likely to occur during dissection of tumor tissues in proximity to the nerve root. Although all of the ID cases were primarily sutured and covered with polyglycolic acid mesh and fibrin glue spray, eight cases required additional intervention because of intractable postoperative cerebrospinal fluid leakage. Six of these eight had a history of RT.

CONCLUSIONS

Our results may help better identify high-risk patients for ID during TES, which may aid surgeons with optimal surgical decision making and in counseling patients on perioperative complications.

Risk for surgical complications after previous stereotactic body radiotherapy of the spine

OBJECT

Stereotactic body radiotherapy (SBRT) for vertebral metastases has emerged as a promising technique, offering high rates of symptom relief and local control combined with low risk of toxicity. Nonetheless, local failure or vertebral instability may occur after spine SBRT, generating the need for subsequent surgery in the irradiated region. This study evaluated whether there is an increased incidence of surgical complications in patients previously treated with SBRT at the index level.

METHODS

Based upon a retrospective international database of 704 cases treated with SBRT for vertebral metastases, 30 patients treated at 6 different institutions were identified who underwent surgery in a region previously treated with SBRT.

RESULTS

Thirty patients, median age 59 years (range 27-84 years) underwent SBRT for 32 vertebral metastases followed by surgery at the same vertebra. Median follow-up time from SBRT was 17 months. In 17 cases, conventional radiotherapy had been delivered prior to SBRT at a median dose of 30 Gy in median 10 fractions. SBRT was administered with a median prescription dose of 19.3 Gy (range 15-65 Gy) delivered in median 1 fraction (range 1-17) (median EQD2/10 = 44 Gy). The median time interval between SBRT and surgical salvage therapy was 6 months (range 1-39 months). Reasons for subsequent surgery were pain (n = 28), neurological deterioration (n = 15) or fracture of the vertebral body (n = 13). Open surgical decompression (n = 24) and/or stabilization (n = 18) were most frequently performed; Five patients (6 vertebrae) were treated without complications with vertebroplasty only. Increased fibrosis complicating the surgical procedure was explicitly stated in one surgical report. Two durotomies occurred which were closed during the operation, associated with a neurological deficit in one patient. Median blood loss was 500 ml, but five patients had a blood loss of more than 1 l during the procedure. Delayed wound healing was reported in two cases. One patient died within 30 days of the operation.

CONCLUSION

In this series of surgical interventions following spine SBRT, the overall complication rate was 19%, which appears comparable to primary surgery without previous SBRT. Prior spine SBRT does not appear to significantly increase the risk of intra- and post-surgical complications.