Stereotactic radiosurgery for intramedullary spinal arteriovenous malformations

CyberKnife Radiosurgery for Spinal Intramedullary Arteriovenous Malformations: A Single-Center Experience

BACKGROUND

Intramedullary spinal arteriovenous malformation (ISAVM, glomus type) is a type of spinal cord arteriovenous malformation, which is a rare disease known often to have a complex vascular supply interfering with that of the spinal cord, and is in complex anatomical relations with cord structures and nerve roots. Though microsurgical and endovascular treatment has mainly been the standard options, in high-risk cases with these treatments, stereotactic radiotherapy (SRT) might be the option of choice.

METHODS

We retrospectively reviewed 10 consecutive patients with ISAVM who received SRT using CyberKnife at the Japanese Red Cross Medical Center (Tokyo, Japan) from January 2011 to March 2022.

RESULTS

No case in this series suffered from hemorrhage after applying SRT. One case experienced neurological impairment 10 years after SRT, which we attributed to venous congestion due to the remaining lesion. No case of radiation myelopathy was observed in this series. In one case, the nidus volume reduction and loss of flow voids were obvious, though improvement in the neurological outcome was not apparent. No radiological changes were observed in the other 9 patients.

CONCLUSIONS

Even in lesions without radiological changes, no hemorrhagic events were observed for an average period of 4 years. SRT may be a feasible option in treating ISAVM, especially for lesions in which microsurgical resection and endovascular treatment are inapplicable. To ascertain the safety and efficacy of this approach, further studies with more patients and longer follow-up is required.

Recurrence Rates Following Treatment of Spinal Vascular Malformations: A Systematic Review and Meta-Analysis

BACKGROUND

Spinal vascular malformations (SVMs), including arteriovenous malformations (AVMs) and arteriovenous fistulas (AVFs), are a varied group of vascular lesions that can be subclassified according to localization, vascular structure, and hemodynamics. Early intervention is necessary to halt progression of disease and minimize irreversible dysfunction. We sought to characterize initial treatment success and recurrence rates following interventional treatment of various types of SVMs.

METHODS

A systematic review and meta-analysis were performed following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. SVMs were categorized into 4 groups: dural AVFs, perimedullary AVFs, intramedullary AVMs, and extradural-intradural AVMs (e.g., epidural, paraspinal). Initial occlusion, recurrence, and complication rates were compared using random-effects analysis.

RESULTS

There were 112 manuscripts included, with a total of 5626 patients with SVM. For treatment, 2735 patients underwent endovascular embolization, 2854 underwent surgical resection, and 37 underwent stereotactic radiosurgery. The initial treatment success and overall recurrence rates following surgical resection of all SVMs were 89.5% (95% CI: 80.5%-98.5%) and 2.3% (95% CI: 0.9%-3.7%), respectively. Those rates following endovascular embolization were 55.9% (95% CI: 30.3%-81.5%) and 27.7% (95% CI: 11.2%-44.2%), respectively. Higher rates of initial treatment success and lower rates of recurrence with surgery were observed in all subtypes compared to embolization. Overall complication rates were higher after embolization for each of the SVM categories.

CONCLUSIONS

Surgical resection of SVMs provided higher rates of initial complete occlusion and lower rates of recurrence than endovascular techniques. Attaining technical success through obliteration must still be weighed against clinical impact and natural history of the specific vascular malformation.

Vascular Malformations of the Spinal Cord in Children

Vascular malformation of the spinal cord in children is a rare and complicated disease spectrum. We will start from the basic spinal cord vascular anatomy and the controversial classification of this kind of disease. Then, we will elaborate the clinical manifestations, diagnostic imaging and treatment of pediatric spinal vascular malformations based on the practical experience of our center and from literature.

Applications of Frameless Image-Guided Robotic Stereotactic Radiotherapy and Radiosurgery in Pediatric Neuro-Oncology: A Systematic Review

BACKGROUND

CyberKnife-based robotic radiosurgery (RRS) is a widely used treatment modality for various benign and malignant tumors of the central nervous system (CNS) in adults due to its high precision, favorable safety profile, and efficacy. Although RRS is emerging in pediatric neuro-oncology, scientific evidence for treatment indications, treatment parameters, and patient outcomes is scarce. This systematic review summarizes the current experience and evidence for RRS and robotic stereotactic radiotherapy (RSRT) in pediatric neuro-oncology.

METHODS

We performed a systematic review based on the databases Ovid Medline, Embase, Cochrane Library, and PubMed to identify studies and published articles reporting on RRS and RSRT treatments in pediatric neuro-oncology. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were applied herein. Articles were included if they described the application of RRS and RSRT in pediatric neuro-oncological patients. The quality of the articles was assessed based on their evidence level and their risk for bias using the original as well as an adapted version of the Newcastle Ottawa Quality Assessment Scale (NOS). Only articles published until 1 August 2021, were included.

RESULTS

A total of 23 articles were included after final review and removal of duplicates. Articles reported on a broad variety of CNS entities with various treatment indications. A majority of publications lacked substantial sample sizes and a prospective study design. Several reports included adult patients, thereby limiting the possibility of data extraction and analysis of pediatric patients. RRS and RSRT were mostly used in the setting of adjuvant, palliative, and salvage treatments with decent local control rates and acceptable short-to-intermediate-term toxicity. However, follow-up durations were limited. The evidence level was IV for all studies; the NOS score ranged between four and six, while the overall risk of bias was moderate to low.

CONCLUSION

Publications on RRS and RSRT and their application in pediatric neuro-oncology are rare and lack high-quality evidence with respect to entity-related treatment standards and long-term outcomes. The limited data suggest that RRS and RSRT could be efficient treatment modalities, especially for children who are unsuitable for surgical interventions, suffer from tumor recurrences, or require palliative treatments. Nevertheless, the potential short-term and long-term adverse events must be kept in mind when choosing such a treatment. Prospective studies are necessary to determine the actual utility of RRS and RSRT in pediatric neuro-oncology.

The Stanford stereotactic radiosurgery experience on 7000 patients over 2 decades (1999-2018): looking far beyond the scalpel

OBJECTIVE

The CyberKnife (CK) has emerged as an effective frameless and noninvasive method for treating a myriad of neurosurgical conditions. Here, the authors conducted an extensive retrospective analysis and review of the literature to elucidate the trend for CK use in the management paradigm for common neurosurgical diseases at their institution.

METHODS

A literature review (January 1990-June 2019) and clinical review (January 1999-December 2018) were performed using, respectively, online research databases and the Stanford Research Repository of patients with intracranial and spinal lesions treated with CK at Stanford. For each disease considered, the coefficient of determination (r2) was estimated as a measure of CK utilization over time. A change in treatment modality was assessed using a t-test, with statistical significance assessed at the 0.05 alpha level.

RESULTS

In over 7000 patients treated with CK for various brain and spinal lesions over the past 20 years, a positive linear trend (r2 = 0.80) in the system's use was observed. CK gained prominence in the management of intracranial and spinal arteriovenous malformations (AVMs; r2 = 0.89 and 0.95, respectively); brain and spine metastases (r2 = 0.97 and 0.79, respectively); benign tumors such as meningioma (r2 = 0.85), vestibular schwannoma (r2 = 0.76), and glomus jugulare tumor (r2 = 0.89); glioblastoma (r2 = 0.54); and trigeminal neuralgia (r2 = 0.81). A statistically significant difference in the change in treatment modality to CK was observed in the management of intracranial and spinal AVMs (p < 0.05), and while the treatment of brain and spine metastases, meningioma, and glioblastoma trended toward the use of CK, the change in treatment modality for these lesions was not statistically significant.

CONCLUSIONS

Evidence suggests the robust use of CK for treating a wide range of neurological conditions.

Spinal Vascular Shunts: A Patterned Approach

Spinal vascular shunts, including fistulas and malformations, are rare and complex vascular lesions for which multiple classification schemes have been proposed. The most widely adopted scheme consists of 4 types: type I, dural AVFs; type II, intramedullary glomus AVMs; type III, juvenile/metameric AVMs; and type IV, intradural perimedullary AVFs. MR imaging and angiography techniques permit detailed assessment of spinal arteriovenous shunts, though DSA is the criterion standard for delineating vascular anatomy and treatment planning. Diagnosis is almost exclusively based on imaging, and features often mimic more common pathologies. The radiologist's recognition of spinal vascular shunts may improve outcomes because patients may benefit from early intervention.

Stereotactic Body Radiotherapy (SBRT) for an Extracranial Arteriovenous Malformation of the Pelvis

Extracranial arteriovenous malformations (AVMs) are rare pathological, benign conditions that are characterized by aberrantly connected arteries and veins without normal intervening capillary vasculature. Although stereotactic radiosurgery is an established, efficacious, safe treatment for intracranial AVMs, there is no known published data on the use of stereotactic body radiotherapy (SBRT) for the treatment of abdominopelvic AVMs. One patient with an extracranial AVM in the pelvis that was only partially responsive to embolization was treated with SBRT to a dose of 21 Gy, delivered in three fractions over six calendar days. At presentation, the patient was non-ambulatory due to neuropathic pain from a sciatic impingement of the AVM. The patient underwent two prior catheter-based embolization procedures that had achieved partial obliteration, but with the persistence of neuropathic pain and symptoms. After SBRT to the pelvic AVM, the patient had marked improvement in pain over 10 months and was able to ambulate again. Follow-up angiography and CT demonstrated the obliteration of previously visualized AVM. We describe the first known report of pelvic AVM successfully treated with a combination of embolization and SBRT. Three-fraction SBRT to a total dose of 21 Gy appears to be safe and effective for extracranial AVMs arising in the pelvis. This strategy may be considered for patients with pelvic AVMs that are refractory to standard interventional therapies. However, these findings should be validated in larger cohorts.

Vascular Spinal Cord Disorders

Vascular disorders of the spinal cord are uncommon yet under-recognized causes of myelopathy. Etiologies can be predominantly categorized into clinical and radiographic presentations of arterial ischemia, venous congestion/ischemia, hematomyelia, and extraparenchymal hemorrhage. While vascular myelopathies often produce significant morbidity, recent advances in the understanding and recognition of these disorders should continue to expedite diagnosis and proper management, and ideally improve patient outcomes. This article comprehensively reviews relevant spinal cord vascular anatomy, clinical features, radiographic findings, treatment, and prognosis of vascular disorders of the spinal cord.

Vascular Myelopathies

PURPOSE OF REVIEW

Neurologists should be able to identify clinical and neuroimaging features that distinguish vascular disorders from other causes of myelopathy.

RECENT FINDINGS

Although certain clinical features suggest a vascular etiology in acute and chronic myelopathy settings, accurate MRI interpretation within the clinical context is key. Recent studies have shown vascular myelopathies are frequently misdiagnosed as transverse myelitis, and recognition of this diagnostic pitfall is important. Many different vascular mechanisms can cause myelopathy; this article provides a comprehensive review that simplifies disease categories into arterial ischemia, venous congestion/ischemia, hematomyelia, and extraparenchymal hemorrhage.

SUMMARY

It is important to recognize and manage vascular disorders of the spinal cord as significant causes of acute, subacute, and progressive myelopathy.

Spinal vascular malformations: Angiographic evaluation and endovascular management

Spinal vascular malformations (SVM) are classified based on their location (intramedullary, perimedullary, radicular, extradural) and flow pattern (high-flow, low-flow, no arteriovenous shunt). High-flow SVMs are generally congenital lesions diagnosed in children and young patients without gender predominance. They present with hemodynamic disturbances, mass effect, or hemorrhages, but may also be discovered incidentally. Low-flow SVMs tend to be acquired lesions presenting in older men with progressive myelopathy caused by spinal venous hypertension. They are rarely associated with vascular syndromes but may accompany prothrombotic conditions. The sensitivity and specificity of conventional MRI are excellent for high-flow SVMs but poor for low-flow lesions, which are frequently diagnosed with extensive delays reducing the potential for favorable outcomes. The sensitivity of advanced MRI techniques remains unclear, notably for the detection of low-flow shunts without flow voids on conventional MRI. Catheter angiography remains the gold standard modality for the evaluation of the spinal vasculature and its disorders. SVMs can be treated by surgical or endovascular means. Initially plagued by high recurrence rates due to inadequate embolization material, endovascular techniques represent nowadays a valid alternative to surgery, thanks notably to the introduction of liquid embolic agents.

Adult Spinal Arteriovenous Malformations: Natural History and a Multicenter Study of Short-Term Surgical Outcomes

OBJECTIVE

Spinal arteriovenous malformations (SAVMs) are a very rare and complex spinal cord pathology that require high clinical acumen to diagnose and treat. Management includes both nonoperative and operative paradigms. A review of the literature yields a paucity of data regarding the surgical outcomes of SAVMs, with the majority of data limited to single-center outcomes and/or small sample sizes. The purpose of this study was to use a multi-institutional international database to study the natural history of SAVMs.

METHODS

We used the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database to select patients that underwent laminectomy for surgical excision of a SAVM between 2008 and 2017.

RESULTS

The data from 196 patients were studied (65.8% male, 34.2% female). A majority of cases were in the thoracic region (53.6%), followed by thoracolumbar (31.6%) and cervical (14.8%) regions. The mean age was 57.4 years and 52.5% patients were graded ASA class 3-5 before the operation. The mean operation time was 215 minutes, with a significantly lower operative time for thoracic arteriovenous malformations (195.6 minutes) when compared with cervical (266.6 minutes) and thoracolumbar (223.7 minutes). The mean length of hospital stay was 6.4 days. Patients had a 6.6% readmission rate and a 4.6% reoperation rate within 30 days.

CONCLUSIONS

This study presents the largest analysis of patients undergoing surgery for SAVMs and 30-day postoperative outcomes. Operative time differed based on SAVM location. The three most frequent complications (deep vein thrombosis, wound infection, and UTI) occurred at rates of 3.6% or less.

Vascular Disorders of the Spinal Cord

PURPOSE OF REVIEW

Prompt recognition and timely management of vascular disorders of the spinal cord can improve patient outcomes. This article provides contemporary and practical knowledge about the most common vascular myelopathies.

RECENT FINDINGS

New studies have provided additional information on the risk factors and impact of neurologic monitoring on perioperative spinal cord infarction. Additionally, recent publications have provided information on the impact of misdiagnosis, corticosteroid treatment, and postoperative prognosis in the treatment of spinal dural arteriovenous fistulas and have discussed the outcome of patients with spinal arteriovenous malformations treated with embolization, surgery, and stereotactic radiosurgery. Finally, recent studies have provided information on the natural history and postoperative prognosis of spinal cavernous malformations and on the risk factors and surgical outcome of patients with spinal epidural hematomas.

SUMMARY

Diagnostic and therapeutic challenges are inherent in managing patients with vascular disorders of the spinal cord, and clinicians should have a thorough understanding of these disorders to facilitate optimal outcomes for patients with these potentially devastating illnesses. This article begins by reviewing functional vascular anatomy and subsequently describes the fundamental characteristics of both ischemic and hemorrhagic vascular myelopathies to equip clinicians with the knowledge to avoid common pitfalls.

Surgical Treatment of Vascular Intramedullary Spinal Cord Lesions

Background Vascular lesions represent a rare subset of intramedullary spinal cord pathology and consist of cavernous malformations (CM), hemangioblastomas, and arteriovenous malformations (AVM). These lesions are each unique and the literature pertaining to their surgical management is largely limited to retrospective case series and case reports. Objectives To evaluate the surgical management of each of these lesions with special attention to postoperative functional status. Methods A single-institution case series of intramedullary vascular lesions treated with surgery was retrospectively evaluated. The primary variables of interest included preoperative and postoperative McCormick grades. Other variables of interest included frequency and indication for conventional spinal angiography, rates of preoperative embolization, postprocedural complications, operative time, intraoperative blood loss, and length of hospital stay. Results Thirty-six patients were identified over the 17-year study period, including 20 with hemangioblastomas, 13 with CMs, and three with AVMs. The median preoperative McCormick grades were 2, 2, and 3 for hemangioblastomas, CMs, and AVMs, respectively. The median postoperative McCormick grades were 2, 2, and 2 for hemangioblastomas, CMs, and AVMs, respectively at the most recent follow-up. Preoperative angiography was performed in all AVM cases and 29% of hemangioblastomas. Preoperative embolization was performed in 40% of hemangioblastoma cases undergoing preoperative angiography. Operative times were similar between the three lesion groups. In three cases of hemangioblastoma resection and one case of CM resection, McCormick grade improved by one point following surgery. At a mean follow-up of 30.9 months for hemangioblastomas, 7.95 months for CMs, and 24 months for AVMs, all patients were at least at their discharge baseline, with no new neurologic complaints. Conclusion Intramedullary vascular lesions are rare and represent a complex surgical patient population. Surgical resection with or without preoperative angiography and embolization appears to be safe and to halt neurologic decline.

[Technical aspects and indications of extracranial stereotactic radiotherapy]

Extracranial stereotactic radiotherapy has developed considerably in recent years and is now an important part of the therapeutic alternatives to be offered to patients with cancer. It offers opportunities that have progressively led physicians to reconsider the therapeutic strategy, for example in the case of local recurrence in irradiated territory or oligometastatic disease. The literature on the subject is rich but, yet, there is no real consensus on therapeutic indications. This is largely due to the lack of prospective, randomized studies that have evaluated this technique with sufficient recoil. We propose a review of the literature on the technical aspects and indications of extracranial stereotactic radiotherapy.

Stereotactic Radiotherapy for Intramedullary Spinal Arteriovenous Malformations

Introduction Preliminary results of stereotactic radiotherapy (SRT) for spinal arteriovenous malformation (AVM) in five cases are presented.  Methods Two cases were male and three were female. Their median age was 32 years (range: 23 to 54 years). The spinal intramedullary AVMs were located in the cervical spine in three and in the thoracic spine in two. SRT with 20 Gy in four fractions was delivered to the nidus in every case. Results At the end of the median follow-up period of 5.5 years (range: 3 to 8.5 years), the neurological symptoms and signs were improved or unchanged as compared with before treatment, although a temporary adverse effect developed between a half year and one year after SRT in one case. The nidi were obliterated five and a half years after SRT in one case and three years after SRT in one. In the other three cases, the nidi were unchanged. Conclusion SRT with 20 Gy in four fractions was thought to be a safe treatment, though this study dealt with only a small number of patients with a short-term follow-up period.

A Review of Vascular Abnormalities of the Spine

Patients with spinal vascular lesions present with unique symptoms and have important anatomical and physiologic changes that must be considered prior to treatment. In this mini-review, we provide an overview of normal spinal vascular anatomy and discuss several key spinal vascular lesions. We provide an overview of cavernous malformations, intradural arteriovenous malformations, perimedullary arteriovenous fistulas, and dural arteriovenous fistulas. Important considerations are addressed in terms of pathologic characterization, specific imaging findings, and treatment approaches.

Spinal Glomus Arteriovenous Malformation Manifesting with a Subarachnoid Hemorrhage

BACKGROUND

Spinal arteriovenous malformations (AVMs) are rare lesions that may cause serious neurologic morbidity. With developments in endovascular technology and embolic materials, endovascular management of spinal AVMs has gained popularity.

CASE DESCRIPTION

A 61-year-old woman presented with the worst headache of her life and an acute onset of nausea and vomiting and was shown to have a grade 2 subarachnoid hemorrhage (SAH) on computed tomography scan. A 6-vessel cerebral angiogram was negative for any vascular abnormalities. Magnetic resonance imaging and magnetic resonance angiography of the neck showed a flow-related enhancement compatible with a vascular abnormality at the level of C2. Cervical spinal angiography showed a cervical spinal cord glomus (type II) AVM at the level of C2 draining into perimedullary venous plexus. Transarterial Onyx embolization was performed and resulted in complete occlusion of the AVM. The patient made a complete neurologic recovery.

CONCLUSIONS

Spinal AVMs manifesting as intracranial SAH are uncommon. These lesions are frequently overlooked on cerebral angiography and account for a small proportion of angiogram-negative SAHs. A negative angiogram in the setting of SAH should prompt a comprehensive evaluation of the cervical segmental arterial supply to exclude a cervical spinal AVM. Endovascular embolization may be effective in treating spinal glomus AVMs with good clinical outcomes and with complete angiographic obliteration. Onyx embolic agent should be considered as the agent of choice to manage spinal glomus AVMs.