Multi-modal management of aggressive vertebral hemangioma: A single center experience

Mohamed Farouk; Mohamed Ali Kassem; Ashraf Ezzeldein; Mohamed Mohsen Ameen; Ali Hassan Elmokadem; Mohamed M Elsherbini

doi:10.7461/jcen.2025.E2024.12.003

J Cerebrovasc Endovasc Neurosurg > Epub ahead of print

Farouk, Kassem, Ezzeldein, Ameen, Elmokadem, and Elsherbini: Multi-modal management of aggressive vertebral hemangioma: A single center experience

Clinical Article

Journal of Cerebrovascular and Endovascular Neurosurgery 2025;jcen.2025.E2024.12.003.

Published online: March 13, 2025

DOI: https://doi.org/10.7461/jcen.2025.E2024.12.003

Multi-modal management of aggressive vertebral hemangioma: A single center experience

Mohamed Farouk

, Mohamed Ali Kassem, Ashraf Ezzeldein, Mohamed Mohsen Ameen, Ali Hassan Elmokadem, Mohamed M Elsherbini

Department of Neurosurgery, Mansoura University, Mansoura, Egypt

Correspondence to Mohamed Farouk Department of Neurosurgery, Mansoura University, Elgomhouria St., Mansoura City, Egypt 35516 Egypt Tel +20 (50) 2383781 E-mail ns.m.farouk@gmail.com

Received December 7, 2024 Revised December 24, 2024 Accepted February 13, 2025

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Objective

This study aims at spotlighting different lines of management of aggressive vertebral hemangioma (VH) through a retrospective analysis of single center experience.

Methods

Results

The study included nine patients, comprising six females and three males, with a mean age of 29.3 years (ranging from 14 to 46). Six patients underwent Trans-arterial embolization (TAE), of whom five underwent further surgical procedures, while one patient found TAE to be sufficient as a stand-alone management technique. Eight patients underwent surgical management, five of whom were pre-operatively embolized.

Conclusions

Aggressive VHs are rare, and their management is challenging. Most cases require a multi-modal management, especially when presented with neurological deficit. Pre-operative embolization and/or vertebroplasty are safe and useful tools to decrease intra-operative bleeding of such a vascular pathology in cases undergoing open surgical procedures.

Keywords: Vertebral hemangioma, Laminectomy, Therapeutic embolization, Vertebroplasty, Sclerotherapy

INTRODUCTION

Most cases of vertebral hemangioma (VH), the most common spinal lesion, are accidentally discovered and can be managed conservatively. When patients present with constant pain, the possibility of minimally invasive approaches such as vertebroplasty should be considered, as the high vascularity of the lesion itself makes surgical intervention relatively challenging, with high risk of blood loss. Therefore, surgical interventions are typically reserved only for cases with neural compression and neurological deficit.

Aggressive hemangiomas are symptomatic due to their pathological behavior, including bone expansion, disturbance of blood flow, compression fracture, and extraosseous extension either into spinal canal or neural foramen. Aggressive hemangiomas can be presented by local, radicular, or myelopathic symptoms, due to compression by body collapse, extradural hemorrhage, or extraosseous soft tissue extension. This rare course makes it difficult to suspect clinically, its differential diagnosis includes aneurysmal bone cysts, solitary myeloma, metastatic tumors, and Paget disease [10].

Trans-arterial embolization (TAE) can be introduced as a sole line of management, or in conjunction with other lines, either as a curative line of management or as a pre-operative step to reduce intra-operative blood loss. However, despite the availability of numerous lines of management, there is no fixed algorithm for treatment options, which makes decision making more complicated and potentially inconsistent.

METHODS

Patients

Patients diagnosed with aggressive VHs in a tertiary referral center were reviewed from 2014 through 2024. Data of patients who met the inclusion criteria were analyzed. Patients of all ages, both sexes and all varieties of clinical presentation were included, only patients who underwent at least one intervention were included. Patients who were managed conservatively and patients with incomplete clinical and/or radiological reports were excluded. Diagnosis was confirmed using imaging (computed tomography (CT), digital subtraction angiography (DSA), and/or magnetic resonance imaging (MRI)), and details of full pre-operative neurological examination. Patients with follow-up over at least three months were included, while those with incomplete medical records were excluded. The enrolled patients’ medical records were reviewed, and epidemiological, clinical, radiological, operative, and follow-up data were collected. All data collection procedures were approved by the relevant Institutional Review Board.

Medical research council (MRC) motor power scaling system [20] is adopted during neurological evaluation of motor power (MP), grades are referred to as grades 0 to 5, where grade 5 represents intact motor power, while grade 0 represents total paralysis.

Diagnosis and treatment protocol

Diagnosis of aggressive VH in our center’s guidelines was based on clinical presentation, CT scans, and MRI with IV contrast. For patients with suspected pathology, digital subtraction angiography was performed, to confirm diagnosis and to study the feeders’ tree, to evaluate the feasibility of embolization. Vertebroplasty with or without TAE was indicated for patients who did not exhibit neurological deficit and/or instability, but whose intractable debilitating pain was not improving. Surgical decompression with or without fixation was indicated for patients who presented with neurological deficit and/or neural compression symptoms. In this series, the treatment option was chosen according to surgeon’s experience, course of the disease, location of the lesion, and efficiency of pre-operative embolization.

Follow-up

During follow-up, clinical neurological examination was performed, and post-operative radiological follow-up was conducted immediately, and during follow-up to observe recurrence.

RESULTS

The study included nine patients, comprising six females and three males, with a mean age of 29.3 years (ranging from 14 to 46). Most lesions (5/9) were dorsal cases, followed by lumbar (n=3) cases, and a single cervical case. Six patients underwent TAE, of whom five underwent further surgical procedures, while one patient found TAE to be sufficient as a stand-alone management technique. Eight patients underwent surgical management, five of whom were pre-operatively embolized. The surgical procedures included hemilaminectomy, laminectomy, fixation, and vertebroplasty, with various combinations of selected procedures tailored and fashioned according to patients’ presentation and radiology (Table 1).

Six patients presented with neurological motor deficit with various degrees, with or without long standing history of spinal axial pain, as shown in Table 1, while three patients presented with intractable axial spinal pain and radiculopathy. Three patients of those who presented with neurological deficit (3/6 patients, 50 %) showed early post-operative improvement of motor power, while two patients’ neurological status remained unchanged, and only one patient (17%) suffered post-operative deterioration of motor power after surgical procedures (laminectomy, vertebroplasty, and fixation without pre-operative embolization).

The follow-up period ranged from 94 to 531 days, with mean follow-up period of 234.4 days. During follow-up, seven patients showed intact motor power on various intervals, while one patient’s motor power remained stationary, and the other one suffered post-operative decline of motor power to grade 2, and subsequently returned to basal pre-operative neurological status (grade 4).

Histopathological analysis confirmed pathological entities for patients who underwent open surgical procedures, and pathology was confirmed only radiologically for patients who underwent only vertebroplasty. No patients underwent pre-operative CT guided biopsy.

ILLUSTRATIVE CASES

Case 1 (Fig. 1)

A 14-year-old female presented with progressive paraparesis for two months (LL motor power grade II to III). Post-contrast MRI revealed an aggressive D6 hemangioma with leak into the spinal canal causing cord compression. Conventional catheter angiography showed feeders from right D6, right D7, left D6, and left D7 intercostal arteries. Preoperative embolization of all feeders using particles to minimize intraoperative hemorrhage risk. Paraparesis showed mild improvement after embolization (G III to IV -ve). Surgical decompression of the hematoma through fenestration with cement vertebroplasty was performed with minimal blood loss. The patient recovered more rapidly after surgery and was discharged home on the seventh postoperative day with motor power grade IV +ve.

Case 2 (Fig. 2)

A 34-year-old female presented with mid-dorsal back pain, paraparesis, and urine incontinence. MRI dorsal spine showed D12 leaking hemangioma compressing the conus. Catheter angiography showed D12 aggressive hemangioma fed from D10-12 radicular arteries bilaterally (not shown). There was no definitive large feeder suitable for catheter maneuvering for TAE. Patient underwent surgical decompression with intra-operative cement injection through the pedicle. After vertebroplasty completion, transpedicular screws were inserted at D10-D11-L1-L2. Laminectomy and decompression were performed, with minimal blood loss observed by the effect of vertebroplasty. Favorable postoperative course was noticed, the patient recovered full motor power one week after surgery.

DISCUSSION

VH is the most common benign lesion of the spine, characterized by proliferation of blood capillary and expansion of blood sinus. Autopsies and radiographic studies indicate up to 10-12% incidence among population [15]. VH is usually discovered accidentally, as it is asymptomatic, without aggressive behavior. When symptomizing, these lesions tend to be insidious in course, causing neurological defects over long intervals, and rarely become rapidly progressive [14].

VH is basically a lesion of the vertebral body, with less common involvement of pedicle and posterior elements. It is typically located in the dorsal and lumbar lesions of the spine, with approximately 33% of multiplicity [11]. Clinically, VH’s are classified to three types, according to the Enneking staging system: stage I is latent with no symptoms (i.e., accidentally discovered); stage II is associated with active bony destruction leading to pain; and stage 3 is aggressive VH, whereby patients present with neurological deficit due to epidural hematoma and/or soft tissue involvement [13].

Although there is no evidence-based algorithm for management of aggressive VH due to rarity of this incidence, it is not indicated to perform surgical decompression unless the patient is neurologically compromised, which is the chief distinction between grade II and grade III. In this study, three patients of grade II lesions underwent only minimally invasive approach either vertebroplasty or TAE; on the other hand, grade III lesions underwent surgical decompression. Although Hekster et al. [18] described the decompressive effect of embolization, in this series any case presented with neurological manifestations underwent surgical decompression with or without embolization.

Although the vertebral body is the most affected part by VH, only posterior surgical procedures were adopted in our practice, anterior approach for corpectomy and fixation was performed in previous reports [3,27,28]. The aim of anterior approaches is to achieve spine stability rather than radical excision which is not sought in these cases due to the benign nature of the pathology, the choice of surgical procedure in this study is concomitant with previous reports [8,17,22] which confirmed the long term efficiency of vertebroplasty for anterior column augmentation in cases of VH, these results out weights the surgical risk for anterior approaches, especially for thoracic and lumbar spine; the most common sites.

Pre-operative embolization is generally safe, with very rare adverse events reported in the literature. The most serious complication is unintended release of emboli causing vascular blockage, potentially leading to spinal cord ischemia, heart attack, stroke, or occlusion of the peripheral arteries. Spinal cord ischemia is particularly concerning because it can result in paralysis, loss of bowel and bladder control, sexual dysfunction, and sensory deficits. This risk arises when emboli inadvertently enter radiculomedullary arteries not clearly visible on pre-embolization angiograms, due to contrast preferentially flowing into the tumor’s high-flow vessels. Another risk factor is embolization material refluxing through unrecognized intersegmental artery anastomosis, which can also cause spinal ischemia [1].

Pre-operative thorough analysis of the spinal angiogram is essential to identify radiculomedullary and spinal arteries, as well as potential intersegmental anastomosis, a step that is essential to minimize the mentioned complications. Embolization is generally avoided if a radiculomedullary artery is close to tumor-feeding vessels, or if these vessels supply both the Adamkiewicz artery and hemangioma [25].

Relative contraindications include identification of radiculomedullary arteries through segmental connections, arteriovenous shunting within the tumor, renal failure, or severe coagulopathy. Alternative methods, such as transpedicular n-Butyl Cyanoacrylic Acid (nBCA) embolization, can be adopted when vasculature of the hemangioma is not ideal for TAE [12]. Additional potential complications include allergic reactions to embolizing agents, and bleeding from early revascularization, due to the rapid breakdown of the embolization materials.

Currently, there is no agreement on the most effective embolic agent for treating VHs. Various agents are commonly used, including Gelfoam, liquid embolic agents like Onyx, particulate agents such as polyvinyl alcohol particles, mechanical occlusion devices like coils, NBCA, and sclerosing agents such as ethanol. Some studies suggest favorable outcomes with ethanol embolization, while others highlight higher complication rates, such as spinal cord injury, Brown-Sequard Syndrome, osteonecrosis, asystole, vertebral collapse, transient neurological deterioration, and hemodynamic instability. Transient paraparesis is a reported potential complication after Gelfoam embolization, while paralysis has been observed following polyvinyl alcohol particles [23]. Alcohol is reported to be safe, with a preference over onyx due to economic factor [27]. In this study, pre-operative embolization was performed using particles in all cases who underwent the procedure.

Combining preoperative embolization with vertebroplasty has been successfully used to reduce intraoperative bleeding. This approach is advocated because arterial embolization blocks feeding vessels without eliminating the tumor’s capillary or cavernous channels. Vertebroplasty can address the residual vascular bed post-embolization, particularly in challenging cases where embolization is technically difficult, such as when the artery of Adamkiewicz originates from an intercostal artery or in the presence of tortuous vessels. Furthermore, vertebroplasty helps strengthen the anterior column, thereby lowering the risk of vertebral collapse in vertebrae weakened by hemangiomas. Complications associated with vertebroplasty are uncommon, but can include the formation of a dense cast around the tumor’s epidural component, and cement leakage into the spinal canal [2].

Radiotherapy alone as a line of management of acute viral hepatitis (AVH) is reported in small case series and single case reports [4,5,6,7]. Although radiotherapy is usually safe and effective for aggressive VH, it has some inherent drawbacks. For instance, neurological recovery is slower for radiotherapy when compared to surgery where recovery is nearly 100%. A major multi-center study of seven German institutes reported success rate of approximately 90.5% of patients with symptomatic VH who were treated with radiotherapy solely after a median of 68 months follow-up [19]. The study also included patients with neurological deficits, but neurological recovery was only recorded among 79.2% of such patients. Another study of 137 patients reported symptoms relief within 18 months after radiotherapy, while neurological deficit was not discussed clearly in this study [21].

Stereotactic radiosurgery was studied as well by Zhang et al in a small case series of five patients, improvement was achieved for four patients over 12-month period [30].

Radiation myelitis is a feared complication of radiotherapy, especially for patients with spinal cord compression, as proven by reports on neurological deterioration after radiotherapy for patients with more than 40% spinal canal encroachment [29].

In our experience, radiotherapy was not one of the lines of management due to slow course of improvement and the availability of pre-operative embolization which reduces the risk of surgery. The choice of the appropriate line of management is decided regarding lesion location and aggressiveness. Typically, VH involves the whole body of vertebrae with or without posterior element involvement, thus jeopardizing the integrity of the stability of the spine. Surgical decompression is indicated for cases with neuronal element compression, while fixation is indicated for instability and decided for each case solely.

The high vascularity of VH’s makes surgical intervention highly susceptible to significant blood loss, as discussed previously, therefore pre-operative embolization is an important concept for management, as it decreases blood loss [16,24]. Pre-operative embolization is a means of blood loss reduction and also identification of feeder vessels, to prevent iatrogenic injury of cord blood supply [9].

Our results and adopted scheme of management are in line with a recently published meta-analysis since its conclusion confirmed that the decision to decompress the spinal canal or not, with or without adjuvant line, is strictly based on neurological status of patient at presentation, as non-surgical lines of management can be used solely only for patients who are neurologically intact at presentation [26].

CONCLUSIONS

Aggressive vertebral hemangioma is a rare pathology with no clear algorithm for management, however, surgical decompression is indicated for cases with neural canal encroachment. Management of each case is individually tailored according to clinical and radiological presentation.

Pre-operative embolization and/or vertebroplasty are useful tools to decrease intra-operative bleeding of such a vascular pathology in cases undergoing open surgical procedures. Vertebroplasty as a single line of management is useful for intractable pain cases with no neural compression.

NOTES

Disclosure

The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.

Fig. 1.

(A) (sagittal) and (B) (axial) post-contrast MRI showed aggressive D6 hemangioma with leak into the spinal canal causing cord compression. (C-F) Conventional catheter angiography showed feeders from right D6, right D7, left D6, and left D7 intercostal arteries (respectively). (G-J) After embolization of all feeders using particles, marked reduction of vasculature is noted. (K) Post-operative CT scan showing the fenestration bone window for hematoma evacuation, cement vertebroplasty is noticed as well allover vertebral body. MRI, magnetic resonance imaging; CT, computed tomography

Fig. 2.

(A) Sagittal T2FS MRI showed D12 leaking hemangioma compressing the conus. (B) intraoperative image of surgical procedure which included D12 laminectomy and long segment fixation using transpedicular screws. (C) and (D) antroposterior and lateral radiograph shows results after vertebroplasty, decompression and posterior fixation. MRI, magnetic resonance imaging

Table 1.

Clinical and epidemiological data

Patient	Age	Sex	Location	Neurological deficit	Preoperative embolization	Arteries embolized	Surgical Procedure	Surgical complications	Immediate postoperative results	Recurrence	Follow up	Follow up (Days)
1	14	F	T6	Yes	Yes	Bilateral T5, T6	Hemilaminectomy & vertebroplasty	None	Improved	No	Intact neurologically	531
2	34	F	T12	Yes	No	None	Laminectomy, vertebroplasty and fixation	None	Improved	No	Improved neurologically including bladder and bowel symptoms	422
3	35	M	T10	Yes	No	None	Laminectomy, vertebroplasty and fixation	Increased LE weakness	Postop awoke G II	No	Improved weakness to G IV	112
4	46	F	L1	Yes	Yes	Bilateral L1, L2, T12	Laminectomy and fixation	None	Unchanged	No	Improved neurologically	224
5	25	M	T2	No	Yes	Bilateral T2	Vertebroplasty	None	Unchanged	No	Intact neurologically	134
6	10	M	C4,5	No	Yes	Right vertebral feeders	None	None	Unchanged	No	Intact neurologically	95
7	33	F	L2	Yes	No	None	Laminectomy, vertebroplasty and fixation	None	Unchanged	No	Intact neurologically	322
8	27	F	T7	Yes	Yes	Bilateral T7, left T6	Laminectomy and fixation	None	Unchanged	No	Intact neurologically	99
9	40	F	L4	No	Yes	Bilateral L4	Vertebroplasty	None	Unchanged	No	Intact neurologically	171

REFERENCES

1. Acosta FL, Dowd CF, Chin C, Tihan T, Ames CP, Weinstein PR. Current treatment strategies and outcomes in the management of symptomatic vertebral hemangiomas. Neurosurgery. 2006 Feb;58(2):287-95.

2. Acosta FL, Sanai N, Chi JH, Dowd CF, Chin C, Tihan T, et al. Comprehensive management of symptomatic and aggressive vertebral hemangiomas. Neurosurgery Clinics of North America. 2008 Jan;19(1):17-29.

3. Adeolu AA, Balogun JA, Adeleye AO, Adeoye PO, Okolo CA, Ogbole GI. Management of symptomatic vertebral haemangioma in a resource challenged environment. Child’s Nervous System. 2010 Jul;26(7):979-82.

4. Aich RK, Deb AR, Banerjee A, Karim R, Gupta P. Symptomatic vertebral hemangioma: Treatment with radiotherapy. Journal of Cancer Research and Therapeutics. 2010 Apr-Jun;6(2):199-203.

5. Aksu G, Fayda M, Saynak M, Karadeniz A. Spinal cord compression due to vertebral hemangioma. Orthopedics. 2008 Feb;31(2):169.

6. Asthana AK, Tandon SC, Pant GC, Srivastava A, Pradhan S. Radiation therapy for symptomatic vertebral haemangioma. Clinical Oncology. 1990 May;2(3):159-62.

7. Beyzadeoglu M, Dirican B, Oysul K, Surenkok S, Pak Y. Evaluation of radiation carcinogenesis risk in vertebral hemangioma treated by radiotherapy. Neoplasma. 2002 49(5):338-41.

8. Boschi V, Pogorelić Z, Gulan G, Perko Z, Grandić L, Radonić V. Management of cement vertebroplasty in the treatment of vertebral hemangioma. Scandinavian Journal of Surgery. 2011 100(2):120-4.

9. Chen YL, Hu XD, Xu NJ, Jiang WY, Ma WH. Surgical treatment of compressive spinal hemangioma : A case series of three patients and literature review. Orthopade. 2018 Mar;47(3):221-7.

10. Cloran FJ, Pukenas BA, Loevner LA, Aquino C, Schuster J, Mohan S. Aggressive spinal haemangiomas: Imaging correlates to clinical presentation with analysis of treatment algorithm and clinical outcomes. British Journal of Radiology. 2015 88(1055):20140771.

11. Cross JJ, Antoun NM, Laing RJC, Xuereb J. Imaging of compressive vertebral haemangiomas. European Radiology. 2000 10(6):997-1002.

12. Eichberg DG, Starke RM, Levi AD. Combined surgical and endovascular approach for treatment of aggressive vertebral haemangiomas. British Journal of Neurosurgery. 2018 Aug;32(4):381-8.

13. Enneking WF. A system of staging musculoskeletal neoplasms. Clinical Orthopaedics and Related Research. 1986 Mar:(204):9-24.

14. Ergun T, Lakadamyali H, Lakadamyali H, Mukaddem A. acute spinal cord compression from an extraosseous vertebral hemangioma with hemorrhagic components: a case report. Journal of Manipulative and Physiological Therapeutics. 2007 Oct;30(8):602-6.

15. Fox MW, Onofrio BM. The natural history and management of symptomatic and asymptomatic vertebral hemangiomas. Journal of Neurosurgery. 1993 Jan;78(1):36-45.

16. Goldstein CL, Varga PP, Gokaslan ZL, Boriani S, Luzzati A, Rhines L, et al. Spinal hemangiomas: Results of surgical management for local recurrence and mortality in a multicenter study. Spine. 2015 May;40(9):656-64.

17. Gupta AK, Phukan P, Bodhey N. Percutaneous vertebroplasty for the treatment of symptomatic vertebral hemangioma with long-term follow-up. Interdisciplinary Neurosurgery: Advanced Techniques and Case Management. 2021 Mar;23:100968.

18. Hekster REM, Luyendijk W, Tan TI. Spinal-cord compression caused by vertebral haemangioma relieved by percutaneous catheter embolisation. Neuroradiology. 1972 Mar;3(3):160-4.

19. Heyd R, Seegenschmiedt MH, Rades D, Winkler C, Eich HT, Bruns F, et al. Radiotherapy for symptomatic vertebral hemangiomas: Results of a multicenter study and literature review. International Journal of Radiation Oncology Biology Physics. 2010 May;77(1):217-25.

20. Medical Research Council. Aids to the Examination of the Peripheral Nervous System. Memorandum no. 45. Her Majesty’s Stationery Office, London.

21. Miszczyk L, Tukiendorf A. Radiotherapy of painful vertebral hemangiomas: The single center retrospective analysis of 137 cases. International Journal of Radiation Oncology Biology Physics. 2012 Feb;82(2):e173-80.

22. Nambiar M, Maingard JT, Onggo JR, Phan K, Asadi H, Brooks DM, et al. Single level percutaneous vertebroplasty for vertebral hemangiomata - a review of outcomes. Pain Physician. 2020 Nov;23(6):E637-42.

23. Ozkan E. Embolization of spinal tumors: Vascular anatomy, indications, and technique. Techniques in Vascular and Interventional Radiology. 2011 Sep;14(3):129-40.

24. Robinson Y, Sheta R, Salci K, Willander J. Blood loss in surgery for aggressive vertebral haemangioma with and without embolisation. Asian Spine. 2015 Jun;9(3):483-91.

25. Combined treatment of hypervascular spinal tumors. Our experience. Endovascular Neuroradiology. 2020 Jan;29(3):24-45.

26. Subramaniam MH, Moirangthem V, Venkatesan M. Management of aggressive vertebral haemangioma and assessment of differentiating pointers between aggressive vertebral haemangioma and metastases-a systematic review. Global Spine. 2023 May;13(4):1120-33.

27. Sultan AE, Hassan T, Abdelbary M, Elwany A. Multidisciplinary management of invasive vertebral hemangioma: the role of different neurointervention modalities-a retrospective study. Egyptian Journal of Neurosurgery. 2023 Sep;38(39.

28. Swaminathan G, Jonathan GE, Mani SA, Keshava SN, Moses V, Prabhu K. Surgical strategies in the management of aggressive spinal haemangiomas: Retrospective case series with literature review and a practical treatment algorithm. Brain and Spine. 2018 4:102736.

29. Wang B, Meng N, Zhuang H, Han S, Yang S, Jiang L, et al. The role of radiotherapy and surgery in the management of aggressive vertebral hemangioma: A retrospective study of 20 patients. Medical Science Monitor. 2018 Sep;24:6840-50.

30. Zhang M, Chen YR, Chang SD, Veeravagu A. CyberKnife stereotactic radiosurgery for the treatment of symptomatic vertebral hemangiomas: A single-institution experience. Neurosurgical Focus. 2017 Jan;42(1):E13.