Cranial Arteriovenous Malformations Research Articles

Multicenter US clinical experience with the Scepter Mini balloon catheter.

Distal navigability and imprecise delivery of embolic agents are two limitations encountered during liquid embolization of cerebrospinal lesions. The dual-lumen Scepter Mini balloon (SMB) microcatheter was introduced to overcome these conventional microcatheters' limitations with few small single-center reports suggesting favorable results. A series of consecutive patients undergoing SMB-assisted endovascular embolization were extracted from prospectively maintained registries in seven North-American centers (November 2019 to September 2022). Fifty-four patients undergoing 55 embolization procedures utilizing SMB were included (median age 58.5; 48.1% females). Cranial dural arteriovenous fistula embolization was the most common indication (54.5%) followed by cranial arteriovenous malformation (27.3%). Staged/pre-operative embolization was done in 36.4% of cases; and 83.6% of procedures using Onyx-18. Most procedures utilized a transarterial approach (89.1%), and SMB-induced arterial-flow arrest concurrently with transvenous embolization was used in 10.9% of procedures. Femoral access/triaxial setups were utilized in the majority of procedures (65.5% and 60%, respectively). The median vessel diameter where the balloon was inflated of 1.8 mm, with a median of 1.5 cc of injected embolic material per procedure. Technical failures occurred in 5.5% of cases requiring aborting/replacement with other devices without clinical sequelae in any of the patients, with SMB-related procedural complications of 3.6% without clinical sequelae. Radiographic imaging follow-up was available in 76.9% of the patients (median follow-up 3.8 months), with complete occlusion (100%) or >50% occlusion in 92.5% of the cases, and unplanned retreatments in 1.8%. The SMB microcatheter is a useful new adjunctive device for balloon-assisted embolization of cerebrospinal lesions with a high technical success rate, favorable outcomes, and a reasonable safety profile.

Our Experience in the Surgical Management of Arterio-Venous Malformations of the head and neck

Vascular anomalies comprise a diverse group of abnormalities in blood vessel morphogenesis that usually occur prenatally. Arterio-venous malformations (AVMs) are rare congenital vascular lesions accounting for 1.5% of all vascular anomalies, with 50% of them occur in the oral and maxillo-facial regions. Treatment of large, complex vascular lesions is a serious challenge for patients and surgeons because it can cause disfigurement and massive haemorrhage, which may be spontaneous or the result of surgical intervention. Our study aimed to demonstrate surgical management of massive AVMs of the head and neck. This retrospective study shows the treatment outcomes of 28 patients with massive maxillo-facial vascular malformations, who presented to our department for treatment from 1 January 2015 to 31 July 2022. Twenty-eight patients with a mean age of 17.32 ± 12.21 years (women: 15, men: 13) were enrolled in the study. Diagnosis included extra cranial AVMs of the head and neck region. Treatment modalities, in isolation or combination, included angioembolisation procedure, sclerotherapy, and surgery. Management of AVMs is challenging owing to the replacement of normal tissue by the diseased ones and the high rate of recurrence. Hence, multi-modal approaches are needed for the effective restoration of tissues.

Elective intervention for unruptured cranial arteriovenous malformations in relation to ARUBA trial: a National Inpatient Sample study.

In 2014, A Randomized Trial of Unruptured Brain Arteriovenous Malformations (ARUBA) concluded that medical management alone for cranial arteriovenous malformations (AVMs) had better clinical outcomes than interventional treatment. The impact of the ARUBA study on changes in the rates of intervention and outcomes is unknown. Thus, we investigated whether the conclusions from ARUBA may have influenced treatment modalities and outcomes of unruptured AVMs. The National Inpatient Sample (NIS) was queried between 2006 and 2018, for adult patients with an AVM who were admitted on an elective basis. Interventions included open, endovascular, and stereotactic surgeries. Join-point regression was used to assess differences in slopes of treatment rate for each modality before and after the time-point. Logistic regression was used to assess the odds of non-routine discharge and hemorrhage between the two time-points for each treatment modality. Linear regression was used to assess the mean length of stay (LOS) for each treatment modality between the two time-points. A total of 40,285 elective admissions for AVMs were identified between 2006 and 2018. The rate of intervention was higher pre-ARUBA (n = 15,848; 63.8%) compared to post-ARUBA (n = 6985; 45.2%; difference in slope - 8.24%, p < 0.001). The rate of open surgery decreased, while endovascular and stereotactic surgeries remained the same, after the ARUBA trial time-point (difference in slopes - 8.24%, p < 0.001; - 1.74%, p = 0.055; 0.20%, p = 0.22, respectively). For admissions involving interventions, the odds of non-routine discharge were higher post-ARUBA (OR 1.24; p = 0.043); the odds of hemorrhage were lower post-ARUBA (OR 0.69; p = 0.025). There was no statistical difference in length of stay between the two time-points (p = 0.22). The rate of intervention decreased, the rate of non-routine discharge increased, and rate of hemorrhage decreased post-ARUBA, suggesting that it may have influenced treatment practices for unruptured AVMs.

Left Parietal Craniotomy for Resection of Grade IV Arteriovenous Malformation: 2-Dimensional Operative Video.

Parieto-occipital arteriovenous malformations (AVMs) are the second most common site for cranial AVMs. These lesions are defined as eloquent when the nidus involves either the postcentral gyrus or the occipital pole. If located on the dominant hemisphere, these lesions can also involve the arcuate fasciculus ventrally. This patient had a large unruptured Spetzler-Martin grade IV AVM within the parieto-occipital region extending deeply to the ventricle, following presentation with a seizure. The digital subtraction angiography demonstrated feeding vessels from both the middle cerebral artery and posterior cerebral artery distributions. Despite the high Spetzler-Martin grade, the lesion demonstrated favorable features such as a compact nidus, convexity presence, and lack of involvement of the precentral and postcentral gyrus. Preoperative embolization was utilized. The AVM was successfully resected both superficially and deeply to the level of the atrium of the lateral ventricle. Postoperative angiography demonstrated complete removal of the AVM, and the patient made a complete recovery from the procedure. The patient gave informed consent for surgery and video recording. Institutional review board approval was deemed unnecessary. Used with permission from Barrow Neurological Institute, Phoenix, Arizona.

Dosimetric comparison of iPlanⓇ Pencil Beam (PB) and Monte Carlo (MC) algorithms in stereotactic radiosurgery/radiotherapy (SRS/SRT) plans of intracranial arteriovenous malformations

Stereotactic radiosurgery/radiotherapy (SRS/SRT) is a hypofractionated treatment where accurate dose calculation is of prime importance. The accuracy of the dose calculation depends on the treatment planning algorithm. This study is a retrospective dosimetric comparison of iPlanⓇ Monte Carlo (MC) and Pencil Beam (PB) algorithms in SRS/SRT plans of cranial arteriovenous malformations (AVMs). PB plans of 60 AVM patients who were already treated using 6 MV photons from a linear accelerator were selected and divided into 2 groups. Group-I consists of 30 patients who have undergone embolization procedure with high density OnyxⓇ prior to radiosurgery whereas Group-II had 30 patients who did not have embolization. These plans were recalculated with MC algorithm while keeping parameters like beam orientation, multileaf collimator (MLC) positions, MLC margin, prescription dose, and monitor units constant. Several treatment coverage parameters, isodose volumes, plan quality metrics, dose to organs at risk, and integral dose were used for comparing the 2 algorithms. The isodose distribution generated by the 2 algorithms was also compared with gamma analysis using 1%/1 mm criterion. The difference between the 2 groups as well as the differences in dose calculation by PB and MC algorithms were tested for significance using independent t-test and paired t-test respectively at 5% level of significance. The results of the independent t-test showed that there is no significant difference between the Group-I and Group-II patients for PB as well as MC algorithm due to the presence of high density embolization material. However, results of the paired t-test showed that the differences between the PB and MC algorithms were significant for several parameters analyzed in both groups of patients. The gamma analysis results also showed differences in the dose calculated by the 2 algorithms especially in the low dose regions. The significant differences between the 2 algorithms are probably due to the incorrect representation of the loss of lateral charged particle equilibrium and lateral broadening of small photon beams by PB algorithm. MC algorithms are generally considered not essential for dose calculations for target volumes located in the brain. This study demonstrates PB algorithm may not be sufficiently accurate to predict dose distributions for small fields where there is loss of LCPE. The lateral broadening due to the loss of LCPE as predicted by the MC algorithm could be the main reason for significant differences in the parameters compared. Hence, an accurate MC algorithm if available may prove valuable for intracranial SRS treatment planning of such benign lesions where the long life expectancy of patients makes accurate dosimetry critical.

BMP10-mediated ALK1 signaling is continuously required for vascular development and maintenance.

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal-dominant vascular disorder characterized by development of high-flow arteriovenous malformations (AVMs) that can lead to stroke or high-output heart failure. HHT2 is caused by heterozygous mutations in ACVRL1, which encodes an endothelial cell bone morphogenetic protein (BMP) receptor, ALK1. BMP9 and BMP10 are established ALK1 ligands. However, the unique and overlapping roles of these ligands remain poorly understood. To define the physiologically relevant ALK1 ligand(s) required for vascular development and maintenance, we generated zebrafish harboring mutations in bmp9 and duplicate BMP10 paralogs, bmp10 and bmp10-like. bmp9 mutants survive to adulthood with no overt phenotype. In contrast, combined loss of bmp10 and bmp10-like results in embryonic lethal cranial AVMs indistinguishable from acvrl1 mutants. However, despite embryonic functional redundancy of bmp10 and bmp10-like, bmp10 encodes the only required Alk1 ligand in the juvenile-to-adult period. bmp10 mutants exhibit blood vessel abnormalities in anterior skin and liver, heart dysmorphology, and premature death, and vascular defects correlate with increased cardiac output. Together, our findings support a unique role for Bmp10 as a non-redundant Alk1 ligand required to maintain the post-embryonic vasculature and establish zebrafish bmp10 mutants as a model for AVM-associated high-output heart failure, which is an increasingly recognized complication of severe liver involvement in HHT2.

Steal Phenomenon with Tonsillar Arteriovenous Malformation

Cranial vascular malformations can cause symptoms of headache, stroke, transient ischemic attack, or other cerebrovascular disorders due to steal phenomenon. Subclavian steal phenomenon is a localized change in cerebral perfusion from a cranial arteriovenous malformation (AVM). We present the only recorded case of a tonsillar AVM causing a transient ischemic attack due to steal phenomenon.

Synchronous cerebral arteriovenous malformation and lung adenocarcinoma carcinoma brain metastases: A case study and literature review

IntroductionWhile there are numerous published cases of arteriovenous malformations (AVMs) developing in the setting of malignancy, it is extremely rare to find them concurrently associated in the brain. Clinical caseThis is the case of a 55-year-old male who presented to the emergency department complaining of headaches, memory and visual changes. Neuro-imaging revealed a right temporal parietal AVM and an adjoining hyperenhancing occipitotemporal lobe lesion with concern for a possible evolving stroke. The patient was treated with radiosurgery for the AVM. His symptoms progressed one month later, and repeat imaging suggested interval enlargement of the previously presumed stroke that was intricately associated with the AVM, in addition to two new small enhancing lesions of the left temporal lobe. Microsurgical resection of the temporal lobe mass revealed adenocarcinoma of the lung. ConclusionThis case represents a previously undocumented confluence of cranial AVM that initially masked a non-small cell lung cancer brain metastasis.

The rare case of a large complex intraosseous cranial arteriovenous malformation with successful multidisciplinary management

Intraosseous cranial arteriovenous malformations (AVMs) are very rare, challenging entities. The authors report the case of an extracranial parietooccipital vascular lesion. A 12-year-old boy presented with accelerated growth of a right scalp lesion over a few months. Digital subtraction angiography showed a large, right parietooccipital intraosseous AVM with multiple complex arterial feeders. Treatment of these lesions is difficult and can necessitate a multidisciplinary approach. In the featured case, 6 embolization procedures were performed over 1 year, including both transarterial and transvenous approaches, followed by total resection. The authors describe what is thought to be the second case of an AVM originating in the cranial bones and the first case with successful multidisciplinary management.

Time resolved computed tomography angiography in the evaluation of brain arteriovenous malformation: a feasibility study.

Background and purpose Digital subtraction angiography is the current gold standard for diagnosing as well as the follow-up of cerebral arteriovenous malformations. However, as it is invasive, relatively expensive and time-consuming, a non-invasive alternative is of interest. We aimed to evaluate the feasibility of time resolved computed tomography angiography (TR-CTA) in a series of five diagnosed cranial arteriovenous malformation patients, demonstrated by conventional digital subtraction angiography with respect to acquisition, depiction of angiographic phases and radiation exposure. Materials and methods Five patients demonstrating a cranial arteriovenous malformation on digital subtraction angiography were studied with TR-CTA. The TR-CTA imaging was done by using a 128-detector computed tomography scanner. Digital subtraction angiography and TR-CTA studies were independently read by two blinded observers, by using a standardised scoring sheet. TR-CTA results were analysed with digital subtraction angiography as the criterion standard. Results TR-CTA generated comparable angiographic phases. In all five cases, there was complete agreement between digital subtraction angiography and TR-CTA regarding the size, arterial feeders, nidal morphology and venous drainage of the arteriovenous malformation. Conclusions TR-CTA imaging as a technique is feasible, providing images with good temporal and spatial resolution at an acceptable radiation dose. It appears to be a promising non-invasive adjunct to digital subtraction angiography.

Alk1 controls arterial endothelial cell migration in lumenized vessels

Heterozygous loss of the arterial-specific TGFβ type I receptor, activin receptor-like kinase 1 (ALK1; ACVRL1), causes hereditary hemorrhagic telangiectasia (HHT). HHT is characterized by development of fragile, direct connections between arteries and veins, or arteriovenous malformations (AVMs). However, how decreased ALK1 signaling leads to AVMs is unknown. To understand the cellular mis-steps that cause AVMs, we assessed endothelial cell behavior in alk1-deficient zebrafish embryos, which develop cranial AVMs. Our data demonstrate that alk1 loss has no effect on arterial endothelial cell proliferation but alters arterial endothelial cell migration within lumenized vessels. In wild-type embryos, alk1-positive cranial arterial endothelial cells generally migrate towards the heart, against the direction of blood flow, with some cells incorporating into endocardium. In alk1-deficient embryos, migration against flow is dampened and migration in the direction of flow is enhanced. Altered migration results in decreased endothelial cell number in arterial segments proximal to the heart and increased endothelial cell number in arterial segments distal to the heart. We speculate that the consequent increase in distal arterial caliber and hemodynamic load precipitates the flow-dependent development of downstream AVMs.

Cranial Arteriovenous Malformations During Pregnancy: A Multidisciplinary Algorithm for Safe Management. Case Series and Review of the Literature

Background:Cerebral arteriovenous malformations (AVMs) are relatively uncommon lesions in general population and rare among pregnant females, meanwhile they carry a relatively higher morbidity and mortality. In view of limited data for optimal management, we try to address dilemmas commonly encountered in pregnant females with cranial AVM and propose multidisciplinary algorithms for safe management. Methods:Five cases of cerebral AVM pregnant females (ruptured during pregnancy) were followed up for 2 years after diagnosis. Endovascular embolization was performed in 3 cases and the other cases underwent expectant management. Natural history regarding rebleeding, time at bleeding, pregnancy and obstetric management as well as the endovascular management and teratogenicity issues were the primary outcome measures. Besides, we conducted a review of literature (Pubmed, Sciencedirect and other databases) during the years 1972 to 2013. Results: We categorized the obtained data into key issues. The effect of pregnancy as a risk for AVM rupture appeared to be ill defined. The best time for AVM intervention during pregnancy and puerperium as well as the best mode for AVM management were decided based upon maternal counselling and multidisciplinary opinion. The myths of embolization teratogenicity and vaginal delivery risk during pregnancy appeared true due to lack of congenital anomalies over 2 years follow up. Although our cases underwent caesarean section, there is no apparent risk in normal vaginal delivery. Conclusion: Cranial AVM during pregnancy is an uncommon, yet a challenging topic. Small sample size and relatively limited period of follow-up were our major obstacles. Further prospective studies are needed to elucidate the safety of endovascular versus microsurgical management during pregnancy over a longer follow up periods, especially in context of embolization with non-adhesive embolic agents, such as Onyx.

Alk1 controls arterial endothelial cell migration in lumenized vessels.

Heterozygous loss of the arterial-specific TGFβ type I receptor, activin receptor-like kinase 1 (ALK1; ACVRL1), causes hereditary hemorrhagic telangiectasia (HHT). HHT is characterized by development of fragile, direct connections between arteries and veins, or arteriovenous malformations (AVMs). However, how decreased ALK1 signaling leads to AVMs is unknown. To understand the cellular mis-steps that cause AVMs, we assessed endothelial cell behavior in alk1-deficient zebrafish embryos, which develop cranial AVMs. Our data demonstrate that alk1 loss has no effect on arterial endothelial cell proliferation but alters arterial endothelial cell migration within lumenized vessels. In wild-type embryos, alk1-positive cranial arterial endothelial cells generally migrate towards the heart, against the direction of blood flow, with some cells incorporating into endocardium. In alk1-deficient embryos, migration against flow is dampened and migration in the direction of flow is enhanced. Altered migration results in decreased endothelial cell number in arterial segments proximal to the heart and increased endothelial cell number in arterial segments distal to the heart. We speculate that the consequent increase in distal arterial caliber and hemodynamic load precipitates the flow-dependent development of downstream AVMs.

Dosimetric measurements of an n-butyl cyanoacrylate embolization material for arteriovenous malformations.

The therapeutic regimen for cranial arteriovenous malformations often involves both stereotactic radiosurgery and endovascular embolization. Embolization agents may contain tantalum or other contrast agents to assist the neurointerventionalists, leading to concerns regarding the dosimetric effects of these agents. This study investigated dosimetric properties of n-butyl cyanoacrylate (n-BCA) plus lipiodol with and without tantalum powder. The embolization agents were provided cured from the manufacturer with and without added tantalum. Attenuation measurements were made for the samples and compared to the attenuation of a solid water substitute using a 6 MV photon beam. Effective linear attenuation coefficients (ELAC) were derived from attenuation measurements made using a portal imager and derived sample thickness maps projected in an identical geometry. Probable dosimetric errors for calculations in which the embolized regions are overridden with the properties of water were calculated using the ELAC values. Interface effects were investigated using a parallel plate ion chamber placed at set distances below fixed samples. Finally, Hounsfield units (HU) were measured using a stereotactic radiosurgery CT protocol, and more appropriate HU values were derived from the ELAC results and the CT scanner's HU calibration curve. The ELAC was 0.0516 ± 0.0063 cm(-1) and 0.0580 ± 0.0091 cm(-1) for n-BCA without and with tantalum, respectively, compared to 0.0487 ± 0.0009 cm(-1) for the water substitute. Dose calculations with the embolized region set to be water equivalent in the treatment planning system would result in errors of -0.29% and -0.93% per cm thickness of n-BCA without and with tantalum, respectively. Interface effects compared to water were small in magnitude and limited in distance for both embolization materials. CT values at 120 kVp were 2082 and 2358 HU for n-BCA without and with tantalum, respectively; dosimetrically appropriate HU values were estimated to be 79 and 199 HU, respectively. The dosimetric properties of the embolization agents are very close to those of water for a 6 MV beam. Therefore, treating the entire intracranial space as uniform in composition will result in less than 1% dosimetric error for n-BCA emboli smaller than 3.4 cm without added tantalum and n-BCA emboli smaller than 1.1 cm with added tantalum. Furthermore, when effective embolization can be achieved by the neurointerventionalist using n-BCA without tantalum, the dosimetric impact of overriding material properties will be lessened. However, due to the high attenuation of embolization agents with and without added tantalum for diagnostic energies, artifacts may occur that necessitate additional imaging to accurately identify the spatial extent of the region to be treated.

Onyx® in the management of cranial arteriovenous malformations

The ethylene vinyl alcohol copolymer, Onyx® (ev3, Inc., MN, USA), is an embolic agent used in the management of arteriovenous malformations (AVMs) and was approved by the US FDA in 2005. Use of Onyx has resulted in higher curative rates compared with previous embolic agents such as N-butyl-2-cyanoacrylate. Onyx has several advantages over previous embolic agents. For instance, Onyx is a copolymer and does not adhere to catheters but solidifies slowly owing to the diffusion of its solvent dimethyl sulfoxide. This review focuses on different results obtained from the experience of different neurointerventionalists with an emphasis on the aim to cure. The studies presented are compared in terms of curative rates, morbidity and mortality. Ideas are presented for future treatment options for AVM rupture using nanotargeted therapy with the guide of specific markers highly expressed on the surface of cells or tissues of interest. Such nanotargeted therapy might transform AVM treatment with new embolic agents.

SU‐E‐T‐415: Dosimetric Measurements of An N‐Butyl Cyanoacrylate Embolization Material for Arteriovenous Malformations

Purpose: The therapeutic regimen for cranial arteriovenous malformations (AVMs) often involves both stereotactic radiosurgery and adjunct endovascular embolization. Embolization agents often contain radiopaque contrast to assist the neurointerventionalists, leading to concerns regarding the dosimetric effects of these contrast agents. This study investigated dosimetric properties of n‐butyl cyanoacrylate (n‐BCA) plus lipiodol (NPL) with and without tantalum powder. Methods: The NPL was provided cured from the manufacturer (Codman Trufill; Codman &amp; Shurtleff, Inc., Raynham, MA) with and without tantalum. Attenuation measurements were made for the samples with and without tantalum powder and compared to the attenuation of a water substitute using a 6MV photon beam. Effective linear attenuation coefficients (ELAC) were derived from the attenuation measurements and measured sample thicknesses. Interface effects were investigated using a parallel plate ion chamber placed at set distances below fixed samples. Finally, Hounsfield units were measured using our department's standard stereotactic radiosurgery CT protocol. Results: For a 3cm square field, the ELAC was 0.0428 1/cm and 0.0474 1/cm for NPL without and with tantalum respectively, compared to 0.0461 1/cm for the water substitute. Non‐density corrected dose calculations would Result in errors of −0.33% and 0.13% per cm thickness of NPL without and with tantalum, respectively. Interface effects compared to water were less than 1.3% for both embolization materials. CT values at 120 kVp were 2082 HU and 2358 HU for NPL without and with tantalum, respectively. Conclusion: The dosimetric properties of NPL are very close to those of water for therapeutic energies. Therefore, treating the entire intracranial space as uniform in composition will Result in typically less than 1% dosimetric errors. However, due to the high attenuation of both embolization agents for diagnostic energies, artifacts may occur that necessitate MR imaging to accurately identify the spatial extent of the region to be treated.

REAL-TIME IMAGE GUIDANCE FOR OPEN VASCULAR NEUROSURGERY USING DIGITAL ANGIOGRAPHIC ROADMAPPING

Angiographic roadmapping, commonly used for catheter navigation in endovascular procedures, is the superimposition of a live fluoroscopic image on a previously stored digitally subtracted angiogram. We evaluated this technique for the first time as a method for image-guided navigation during surgical resection of intracranial and spinal vascular lesions. After obtaining Institutional Review Board approval, we retrospectively reviewed 38 procedures in 35 patients at two centers performed by one neurosurgeon in which intraoperative roadmapping was used as an image-guided navigation tool for surgical resection of cranial and spinal arteriovenous malformations or fistulae. This technique requires femoral or radial artery access and a portable vascular C-arm capable of digitally subtracted angiogram and roadmap angiography in the operating room suite. Once a roadmap identifying the vascular lesion is obtained, a sterile radiopaque instrument is placed over the skin/wound to precisely localize the lesion in multiple dimensions. Angiographic roadmapping was used for resection of seven spinal arteriovenous malformations or fistulae, 23 cranial arteriovenous malformations or fistulae, one aneurysm, two carotid-cavernous fistulae, and transtorcular embolization of five vein of Galen malformations. In all cases, the technique helped us to make precisely localized incisions, avoid unnecessary bone removal, and readily directed us to the vascular lesion. In several cases, it allowed localization of small fistulae not visible on magnetic resonance imaging or computed tomographic angiography scans. Finally, this approach facilitated immediate angiographic confirmation of complete resection at the end of each case. Angiographic roadmapping is an effective intraoperative navigation tool for resection of vascular lesions that has not been previously described and offers several advantages to frameless stereotaxy.

Measurement of repositioning accuracy during fractionated stereotactic radiotherapy for intracranial tumors using noninvasive fixation of BrainLAB radiotherapy equipment

Purpose: A noninvasive fixation mask device is used for stereotactic radiotherapy (SRT) in our hospital. Fractionated SRT is useful because it results in less damage to normal tissues, for which the positioning accuracy of the removable noninvasive fixation device is important. We examined the repositioning accuracy of a BrainLAB removable noninvasive fixation device on the coordinates of computed tomography (CT) for treatment planning. Methods and Materials: The subjects were 13 patients who had undergone head SRT. The removable noninvasive fixation mask device used was a noninvasive fixation device for the BrainLAB system. The accuracy of the irradiation apparatus was evaluated using Winston-Lutz test film, and the repositioning accuracy of the fixation device was examined using differences in the distance on the X, Y, and Z coordinates between the treatment planning and repositioning times determined by comparing the relative coordinates. The evaluation was performed using the relative coordinates of the standard and test points. Results: The accuracy of the irradiation center with the apparatus was within 0.5 mm. In the 13 patients, the difference in the distance between the treatment planning and repositioning procedures ranged from 0.1 to 2.080 mm, and an accuracy of within 2 mm was obtained in 84.6% of the patients using the fixation device. Conclusion: The BrainLAB noninvasive SRT fixation device was considered useful for routine treatment with high accuracy.

Embolization of cranial/spinal tumours and vascular malformations with hydrogel microspheres. An experience of 69 cases

Objective: To evaluate polymethyl methacrylate hydrogel microspheres (HMs) as an embolization material in the management of hypervascular craniofacial and spinal lesions. Material and Methods: Sixty-nine patients with vascular lesions of the craniofacial and spinal regions underwent embolization with HM. The pathologies included craniofacial tumours (n=38), cranial arteriovenous malformations (AVMs) (n=7), dural AVM (n=1), cavernous carotid fistula (n=1), spinal tumours (n=7), spinal AVMs (n=6), orbital lesions (n=4) and scalp AVMs (n=5). Surgery was done in 56 patients. The blood loss at surgery, tumour shrinkage, surgical cleavage and ease of removal of tumour was noted from the records. Histopathology was available in 39 patients. A follow-up of 3 months to 6 years was available in 13 patients in whom embolization was the sole treatment. Surgical and histopathological findings were correlated with angio-embolization findings. Results: HMs were easy to inject through the microcatheter with good control. Good devascularization was obtained in 61 patients and partial in 8 patients. Two patients developed complications due to presence of anastomoses between intra- and extracranial circulation and 1 patient due to tumor swelling. Histopathology showed presence of HMs in all the lesions, with minimal inflammatory reaction in 2 patients. Patients with spinal lesions treated with embolization only stabilised in neurologic deficits. Conclusion: HMs are highly suitable as embolization agents in the management of craniofacial and spinal hypervascular lesions.

Embolization of cranial/spinal tumours and vascular malformations with hydrogel microspheres. An experience of 69 cases.

To evaluate polymethyl methacrylate hydrogel microspheres (HMs) as an embolization material in the management of hypervascular craniofacial and spinal lesions. Sixty-nine patients with vascular lesions of the craniofacial and spinal regions underwent embolization with HM. The pathologies included craniofacial tumours (n=38), cranial arteriovenous malformations (AVMs) (n=7), dural AVM (n=1), cavernous carotid fistula (n=1), spinal tumours (n=7), spinal AVMs (n=6), orbital lesions (n=4) and scalp AVMs (n=5). Surgery was done in 56 patients. The blood loss at surgery, tumour shrinkage, surgical cleavage and ease of removal of tumour was noted from the records. Histopathology was available in 39 patients. A follow-up of 3 months to 6 years was available in 13 patients in whom embolization was the sole treatment. Surgical and histopathological findings were correlated with angio-embolization findings. HMs were easy to inject through the microcatheter with good control. Good devascularization was obtained in 61 patients and partial in 8 patients. Two patients developed complications due to presence of anastomoses between intra- and extracranial circulation and 1 patient due to tumor swelling. Histopathology showed presence of HMs in all the lesions, with minimal inflammatory reaction in 2 patients. Patients with spinal lesions treated with embolization only stabilised in neurologic deficits. HMs are highly suitable as embolization agents in the management of craniofacial and spinal hypervascular lesions.