Conventional radiation therapy of intracranial arteriovenous malformations: long-term results

Efficacy of radiosurgery with and without angioembolization: A subgroup analysis of effectiveness in ruptured versus unruptured arteriovenous malformations - An updated systematic review and meta-analysis

Background

Congenital arterial defects such as cerebral arteriovenous malformations (AVMs) increase brain bleeding risk. Conservative therapy, microsurgical removal, percutaneous embolization, stereotactic radiosurgery (SRS), or a combination may treat this serious disease. This study compares angioembolization with SRS to SRS alone in ruptured or unruptured brain ateriovenous malformations (BAVM) patients.

Methods

We followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses recommendations for this study. Until September 2023, PubMed/Medline, Cochrane, and Clinicaltrials.gov were searched for literature. English-language studies comparing SRS alone to embolization with SRS on ruptured or non-ruptured AVMs that could not be operated on were considered. The Newcastle-Ottawa Scale assessed research study quality.

Results

Results included 46 studies with a total of 7077 participants. There was a greater obliteration rate in the SRS-only group (60.4%) than in the embolization plus SRS group (49.73%). Particularly in the SRS-only group, ruptured AVMs showed a noticeably greater obliteration rate than unruptured AVMs (P = 0.002). However, no notable differences were found in hemorrhagic events or radiation-induced changes between the two groups; however, the SRS-only group had a slightly greater, yet not statistically significant, mortality rate.

Conclusion

Our data showed that ruptured brain AVMs had a much greater obliteration rate than unruptured ones, mostly due to SRS alone, without embolization. The aggregated data showed no significant changes, whereas SRS alone decreased radiation-induced alterations and hemorrhagic rates but with increased mortality. SRS alone may have a higher risk-to-reward ratio for nidus obliteration in ruptured brain AVM patients, so it should be used without embolization, although more research is needed to determine the effects of immediate and late complications.

Unruptured cerebral arteriovenous malformation in children: Outcome in treated and untreated patients

BACKGROUND

The management of unruptured cerebral arteriovenous malformation (URCAVM) is highly controversial; however, data regarding URCAVM in children are scarce.

MATERIAL AND METHODS

We retrospectively reviewed consecutive children followed for URCAVM in our department between 2001 and 2021.

RESULTS

Out of 36 patients, 12 were initially managed by observation, and 24 underwent first-line treatment: 8 by microsurgery, 10 by radiosurgery, 2 by embolization, and 4 by combined treatment. Mean follow-up of the whole group was 63months. Complete cure of the malformation was obtained in 14 patients (58%) in the treatment group: 8/8 in the microsurgery group, 5/10 in the radiosurgery group, 1/4 in the combined treatment group, and none in the embolization group. Two of the initially non-treated patients presented cerebral hemorrhage, with significant neurological consequences. In the treatment group, 5 patients presented new neurological deficits, only 1 of which, however, was functionally significant. Headache improved in 11 cases, mostly in the treatment group. Overall, 6 patients in the treatment group became asymptomatic, versus none in the observation group.

CONCLUSIONS

The treatment of URCAVM is a reasonable option in many pediatric cases, considering the cumulative risk of cerebral hemorrhage during the child's lifetime, as well as the symptoms specific to URCAVM. Microsurgery, when feasible, offers the best functional results and control of the AVM; however, the risk-benefit ratio should be weighed on a case-by-case basis. More studies will be needed to inform treatment decisions in pediatric URCAVM.

The impact of embolization on radiosurgery obliteration rates for brain arteriovenous malformations: a systematic review and meta-analysis

There exists no consensus in the literature regarding the impact of pre-stereotactic radiosurgery (SRS) embolization on obliteration rates and clinical outcome after radiosurgery treatment of intracranial arteriovenous malformations (AVM). We performed a systematic review of four databases and included studies with at least 10 patients evaluating obliteration rates of intracranial AVMs treated with SRS alone (SRS cohort) and combined pre-SRS embolization followed by SRS (E + SRS cohort). Meta-analytic results were pooled together via random-effects models. A total of 43 studies, with 7103 patients, were included in our analysis. Among our included patients, complete obliteration was achieved in 51.5% (964/1871) of patients in the E + SRS cohort as compared to 61.5% (3217/5231) of patients in the SRS cohort. Meta-analysis of the pooled data revealed that obliteration was significantly lower in the E + SRS cohort (pooled OR = 0.64, 95% CI = 0.54-0.75, p < 0.0001). The use of pre-SRS embolization was significantly associated with lower AVM obliteration rates when compared to treatment with SRS alone. Our analysis seeks to provide a macroscopic insight into the complex interaction between pre-SRS embolization and brain AVM obliteration rates and prognosis. Pre-SRS embolization may still be beneficial in select patients, and further studies are needed to identify patients who benefit from neoadjuvant AVM embolization.

How to improve obliteration rates during volume-staged stereotactic radiosurgery for large arteriovenous malformations

OBJECTIVE

The management of large-volume arteriovenous malformations (AVMs) with stereotactic radiosurgery (SRS) remains challenging. The authors retrospectively tested the hypothesis that AVM obliteration rates can be improved by increasing the percentage volume of an AVM that receives a minimal threshold dose of radiation.

METHODS

In 1992, the authors prospectively began to stage anatomical components in order to deliver higher single doses to AVMs > 15 cm3 in volume. Since that time 60 patients with large AVMs have undergone volume-staged SRS (VS-SRS). The median interval between the first stage and the second stage was 4.5 months (2.8-13.8 months). The median target volume was 11.6 cm3 (range 4.3-26 cm3) in the first-stage SRS and 10.6 cm3 (range 2.8-33.7 cm3) in the second-stage SRS. The median margin dose was 16 Gy (range 13-18 Gy) for both SRS stages.

RESULTS

AVM obliteration after the initial two staged volumetric SRS treatments was confirmed by MRI alone in 4 patients and by angiography in 11 patients at a median follow-up of 82 months (range 0.4-206 months) after VS-SRS. The post-VS-SRS obliteration rates on angiography were 4% at 3 years, 13% at 4 years, 23% at 5 years, and 27% at 10 years. In multivariate analysis, only ≥ 20-Gy volume coverage was significantly associated with higher total obliteration rates confirmed by angiography. When the margin dose is ≥ 17 Gy and the 20-Gy SRS volume included ≥ 63% of the total target volume, the angiographically confirmed obliteration rates increased to 61% at 5 years and 70% at 10 years.

CONCLUSIONS

The outcomes of prospective VS-SRS for large AVMs can be improved by prescribing an AVM margin dose of ≥ 17 Gy and adding additional isocenters so that ≥ 63% of the internal AVM dose receives more than 20 Gy.

Distinctive distribution of lymphocytes in unruptured and previously untreated brain arteriovenous malformation

AIM

To test the hypothesis that lymphocyte infiltration in brain arteriovenous malformation (bAVM) is not associated with iron deposition (indicator of microhemorrhage).

METHODS

Sections of unruptured, previously untreated bAVM specimens (n=19) were stained immunohistochemically for T-lymphocytes (CD3⁺), B-lymphocytes (CD20⁺), plasma cells (CD138⁺) and macrophages (CD68⁺). Iron deposition was assessed by hematoxylin and eosin and Prussian blue stains. Superficial temporal arteries (STA) were used as control.

RESULTS

Both T lymphocytes and macrophages were present in unruptured, previously untreated bAVM specimens, whereas few B cells and plasma cells were detected. Iron deposition was detected in 8 specimens (42%; 95% confidence interval =20-67%). The samples with iron deposition tended to have more macrophages than those without (666±313 vs 478±174 cells/mm²; P=0.11). T-cells were clustered on the luminal side of the endothelial surface, on the vessel-wall, and in the perivascular regions. There was no correlation between T lymphocyte load and iron deposition (P=0.88). No macrophages and lymphocytes were detected in STA controls.

CONCLUSIONS

T-lymphocytes were present in bAVM specimens. Unlike macrophages, the load and location of T-lymphocytes were not associated with iron deposition, suggesting the possibility of an independent cell-mediated immunological mechanism in bAVM pathogenesis.

Long-term Outcomes After Staged-Volume Stereotactic Radiosurgery for Large Arteriovenous Malformations

BACKGROUND:

Stereotactic radiosurgery is an effective treatment modality for small arteriovenous malformations (AVMs) of the brain. For larger AVMs, the treatment dose is often lowered to reduce potential complications, but this decreases the likelihood of cure. One strategy is to divide large AVMs into smaller anatomic volumes and treat each volume separately.

OBJECTIVE:

To prospectively assess the long-term efficacy and complications associated with staged-volume radiosurgical treatment of large, symptomatic AVMs.

METHODS:

Eighteen patients with AVMs larger than 15 mL underwent prospective staged-volume radiosurgery over a 13-year period. The median AVM volume was 22.9 mL (range, 15.7-50 mL). Separate anatomic volumes were irradiated at 3- to 9-month intervals (median volume, 10.9 mL; range, 5.3-13.4 mL; median marginal dose, 15 Gy; range, 15-17 Gy). The AVM was divided into 2 volumes in 10 patients, 3 volumes in 5 patients, and 4 volumes in 3 patients. Seven patients underwent retreatment for residual disease.

RESULTS:

Actuarial rates of complete angiographic occlusion were 29% and 89% at 5 and 10 years. Five patients (27.8%) had a hemorrhage after radiosurgery. Kaplan-Meier analysis of cumulative hemorrhage rates after treatment were 12%, 18%, 31%, and 31% at 2, 3, 5, and 10 years, respectively. One patient died after a hemorrhage (5.6%).

CONCLUSION:

Staged-volume radiosurgery for AVMs larger than 15 mL is a viable treatment strategy. The long-term occlusion rate is high, whereas the radiation-related complication rate is low. Hemorrhage during the lag period remains the greatest source of morbidity and mortality.

Stereotactic radiosurgery for arteriovenous malformations, Part 6: multistaged volumetric management of large arteriovenous malformations

Object

The object of this study was to define the long-term outcomes and risks of arteriovenous malformation (AVM) management using 2 or more stages of stereotactic radiosurgery (SRS) for symptomatic large-volume lesions unsuitable for surgery.

Methods

In 1992, the authors prospectively began to stage the treatment of anatomical components to deliver higher single doses to AVMs with a volume of more than 10 cm3. Forty-seven patients with such AVMs underwent volume-staged SRS. In this series, 18 patients (38%) had a prior hemorrhage and 21 patients (45%) underwent prior embolization. The median interval between the first-stage SRS and the second-stage SRS was 4.9 months (range 2.8–13.8 months). The median target volume was 11.5 cm3 (range 4.0–26 cm3) in the first-stage SRS and 9.5 cm3 in the second-stage SRS. The median margin dose was 16 Gy (range 13–18 Gy) for both stages.

Results

In 17 patients, AVM obliteration was confirmed after 2–4 SRS procedures at a median follow-up of 87 months (range 0.4–209 months). Five patients had near-total obliteration (volume reduction > 75% but residual AVM). The actuarial rates of total obliteration after 2-stage SRS were 7%, 20%, 28%, and 36% at 3, 4, 5, and 10 years, respectively. The 5-year total obliteration rate after the initial staged volumetric SRS with a margin dose of 17 Gy or more was 62% (p = 0.001). Sixteen patients underwent additional SRS at a median interval of 61 months (range 33–113 months) after the initial 2-stage SRS. The overall rates of total obliteration after staged and repeat SRS were 18%, 45%, and 56% at 5, 7, and 10 years, respectively. Ten patients sustained hemorrhage after staged SRS, and 5 of these patients died. Three of 16 patients who underwent repeat SRS sustained hemorrhage after the procedure and died. Based on Kaplan-Meier analysis (excluding the second hemorrhage in the patient who had 2 hemorrhages), the cumulative rates of AVM hemorrhage after SRS were 4.3%, 8.6%, 13.5%, and 36.0% at 1, 2, 5, and 10 years, respectively. This corresponded to annual hemorrhage risks of 4.3%, 2.3%, and 5.6% for Years 0–1, 1–5, and 5–10 after SRS. Multiple hemorrhages before SRS correlated with a significantly higher risk of hemorrhage after SRS. Symptomatic adverse radiation effects were detected in 13% of patients, but no patient died as a result of an adverse radiation effect. Delayed cyst formation did not occur in any patient after SRS.

Conclusions

Prospective volume-staged SRS for large AVMs unsuitable for surgery has potential benefit but often requires more than 2 procedures to complete the obliteration process. To have a reasonable chance of benefit, the minimum margin dose should be 17 Gy or greater, depending on the AVM location. In the future, prospective volume-staged SRS followed by embolization (to reduce flow, obliterate fistulas, and occlude associated aneurysms) may improve obliteration results and further reduce the risk of hemorrhage after SRS.

ARTERIOVENOUS MALFORMATIONS AFTER LEKSELL GAMMA KNIFE RADIOSURGERY

OBJECTIVE

Although relevant information exists regarding the chance of obliterating arteriovenous malformations (AVMs) using radiosurgery, the overall chance of cure after gamma knife radiosurgery is usually only extrapolated from a portion of all monitored patients. This chance and the risks involved in radiosurgery, including repeat treatment when necessary in a defined population of treated patients, were analyzed in our study.

METHODS

Between October 1992 and June 2000, gamma knife radiosurgery was performed on 330 patients with AVMs. The volume of the AVM nidus ranged from 0.15 to 28.6 cm3 (median, 3.9 cm3). When complete obliteration was not achieved within 3 years, repeat radiosurgery was performed on 76 patients. The volume of the nidus for the second treatment ranged from 0.09 to 16.8 cm3 (median 2.9 cm3). The result was reviewed in 300 (91%) patients after the first round of treatment and in 68 (89.5%) after the second round of treatment.

RESULTS

AVM obliteration was achieved in 222 (74%) patients after the first round of radiosurgery and in 47 (69%) after the second. The overall chance of cure was 92% (269 patients). Final angiography verified complete obliteration by 12 to 96 months (median, 25 mo) after initial radiosurgery. Smaller volume AVMs and the application of a higher radiation dose resulted in a higher chance of obliteration. The risk of rebleeding after radiosurgery was 2.1% annually until full obliteration, and the overall mortality from rebleeding was 1%. The risk of permanent morbidity after the first and second radiosurgery treatments were 2.7 and 2.9%, respectively. The cumulative risk of morbidity in both groups of patients was 3.4%.

CONCLUSION

Although one-quarter of the patients required that the treatment be repeated, gamma knife radiosurgery can offer a high cure rate for patients treated for AVMs with a low risk of morbidity and mortality from rebleeding during the latent period.

Calculation of isoeffective doses and the α /β value by comparing results following radiosurgery and radiotherapy for arteriovenous malformations of the brain

Object

The authors sought to assess the relationship between obliteration rate and different dose parameters following fractionated radiotherapy for arteriovenous malformations (AVMs). A comparison of the results of radiosurgery and radiotherapy for AVMs was made to calculate the best fit α/β value, which would then be used as a model for predicting the treatment outcome, independent of the number of fractions applied.

Methods

Data from 1453 patients were analyzed: 1154 treated with radiosurgery and 300 with fractionated radiotherapy. The relationships between dose and obliteration rate after 3 years were calculated, and the best fit curve to the empirical results was defined. The higher the dose per fraction, biologically effective dose, and the lower the total dose, the higher the obliteration rate. The isoeffective doses when comparing radiotherapy and radiosurgery independent of the α/β value could not be defined. The dose per fraction had the best predictive value, independent of the number of fractions.

Conclusions

Dose per fraction seems to be the decisive parameter for the treatment response following both radiotherapy and radiosurgery. A larger number of fractions did not increase the obliteration rate. The data indicate that higher doses per fraction should be used when irradiating AVMs.

Linac-based radiosurgery or hypofractionated stereotactic radiotherapy in the treatment of large cerebral arteriovenous malformations

PURPOSE

We investigate retrospectively clinical outcome after radiosurgery (RS) or hypofractionated stereotactic radiotherapy (HSRT) in patients with large cerebral arteriovenous malformations (AVMs).

METHODS AND MATERIALS

This analysis is based on 48 patients with cerebral AVM greater than 4 cm treated with HSRT or RS at our institution. Fifteen patients received HSRT, with 26 Gy median total dose in 4 to 5 fractions, and 33 patients received RS with 17 Gy median total dose in 4 to 5 fractions. Median target volume was 27 cc in HSRT and 7 cc in RS; median maximum diameter was 6 cm and 5 cm, respectively. Seventeen patients experienced intracranial hemorrhage before treatment. Median follow-up was 2.6 years.

RESULTS

The 3-year and 4-year actuarial complete obliteration (CO) after HSRT was 17% and 33% and after RS was 47% and 60%, respectively. Actuarial CO was higher in AVMs less than 5 cm (66% vs. 37% after 4 years). Intracranial hemorrhage after HSRT occurred in 3 of 15 patients after 18 months median, and after RS in 7 of 33 patients after 17 months median. Bleeding risk was significantly higher in patients with prior hemorrhage (p < 0.04). Preexisting neurologic dysfunction improved/dissolved in 50% and remained stable in 45%.

CONCLUSIONS

Large AVMs need a long time period to obliterate and show a high bleeding risk. Multimodal treatment strategies are required to reduce treatment volume before radiotherapy.

Hypofractionated Conformal Stereotactic Radiotherapy for Arteriovenous Malformations

OBJECTIVE

Arteriovenous malformations (AVMs) are congenital vascular lesions that are associated with high morbidity and mortality if left untreated. There are several options for treatment, including radiotherapy. Safe and effective single-fraction radiotherapy for patients with large AVMs has been considered difficult.

METHODS

Between December 1986 and June 2001, 36 patients with cerebral AVMs were treated with hypofractionated conformal stereotactic radiotherapy at Umeå University Hospital. Twenty-nine patients have been followed angiographically to date and are reported in this study.

RESULTS

Twenty-four (83%) of 29 patients (mean AVM volume, 11.5 cm3) underwent complete obliteration of their AVMs. The rates of angiographically verified total obliteration at 2 years after treatment were 56% for AVMs 4 to 10 cm3 and 50% for AVMs larger than 10 cm3. The obliteration rate increased considerably with extended follow-up. Five years after treatment, the obliteration rates were 81% for AVMs 4 to 10 cm3 and 70% for AVMs larger than 10 cm3.

CONCLUSION

Hypofractionated conformal stereotactic radiotherapy may be an important alternative to single-fraction radiotherapy in patients with large AVMs or AVMs located in eloquent areas, because it allows the administration of a higher radiation dose than is possible to deliver in single-fraction radiosurgery. With our technique of hypofractionated conformal stereotactic radiotherapy, the rate of obliterating AVMs was comparable to that of single-dose radiosurgery, although the volumes of the irradiated AVMs in our study were larger than those reported previously.

Focal fractionated radiotherapy for intramedullary spinal arteriovenous malformations: 10-year experience

OBJECT

Radiosurgical treatment of spinal arteriovenous malformations (AVMs) is becoming a practical therapeutic option as methodology improves, but no comparative study has yet been published on focal fractionated radiotherapy. The authors report their experience with conventional and hypofractionated radiotherapy for spinal AVM.

METHODS

Candidates for this study were patients who experienced symptoms due to an intramedullary AVM but were ineligible for embolization or surgery. Of 21 patients with spinal AVMs, 10 cases in a 10-year period met this criterion. Angiography and contrast-enhanced computerized tomography scanning were used for treatment planning in all cases. Fractionated radiotherapy was performed using a linear accelerator, extracranial immobilization system, and frequent orthogonal linacographic verification. The starting radiation dose was 32 Gy in two, 36 Gy in three, and 40 Gy in two patients, in a regimen involving 1.8 to 2-Gy daily fractions; this was recently changed to a hypofractionation schedule of 30 Gy (in eight sessions) in one and 20 Gy (in four sessions) in two patients.

RESULTS

The follow-up period ranged from 26 to 124 months (median of 49 months). There were no hemorrhages nor any adverse reactions attributable to irradiation. Of the seven patients who consented to undergo follow-up angiography, the nidus size decreased in five, but complete obliteration did not occur in any patient.

CONCLUSIONS

Because no patient experienced adverse effects, the maximum tolerable radiation dose for the spinal cord associated with an AVM could not be identified, although it presumably is higher than those administered. The lack of rebleeding in patients in whom complete angiographic occlusion was absent suggests that the natural history of spinal AVMs may be less aggressive than previously reported.

Combined embolization and microsurgery for cerebral arteriovenous malformation

Thirty-seven of 396 patients with arteriovenous malformations (AVMs) were treated by preoperative embolization and surgical excision in our medical center between 1991 and 1997. The AVMs were Spetzler-Martin grade I in six, grade II in 11, grade III in 12, grade IV in four, and Grade V in four. A total of 69 embolization procedures were performed using estrogen alcohol and polyvinyl acetate as liquid embolization materials. AVM grades improved following embolization in 10 patients. Three hemorrhages occurred several days after the final embolization, probably due to hemodynamic stress on the unoccluded perforating feeders or drainer occlusion. Surgical resection was performed under guidance of intraoperative digital subtraction angiography. Although the AVMs were excised totally in one stage with no major neurological deficits, normal perfusion pressure breakthrough occurred in a patient with prominent collateral circulation of the AVM which developed after the main feeder embolization. Preoperative staged embolization with estrogen alcohol and polyvinyl acetate is effective to expand the surgical indication and to achieve complete resection of difficult AVMs. Direct surgery should be performed as soon as possible if hemodynamic changes are observed following embolization.

Treatment outcome of single or hypofractionated single-isocentric stereotactic irradiation (STI) using a linear accelerator for intracranial arteriovenous malformation

BACKGROUND AND PURPOSE

We investigated the use of hypofractionated stereotactic radiotherapy (HFSR) to reduce adverse radiation effects in comparison to single-fraction stereotactic radiosurgery (SRS) for intracranial arteriovenous malformations (AVMs).

MATERIALS AND METHODS

This study includes 53 intracranial AVMs treated between 1991-1998. HFSR was selected for 26 AVMs with a maximum diameter > or 2.5 cm or at eloquent area. Twenty-seven patients were treated with SRS (18 AVMs < 2.5 cm at non-eloquent area, nine patients who were unfit for prolonged ring-wearing). The most frequent minimum dose (Dmin) was 20 Gy for SRS and 28 Gy for HFSR in four fractions. The mean follow-up duration was 34.6 months for SRS and 35.4 months for HFSR.

RESULTS

As a whole, the 3 and 5-year actuarial obliteration rates were 64 and 92%. Age <20 years old (P=0.02) and a maximum diameter <2 cm were favorable factors (P=0.05). A difference in the distribution of patients was observed in size (> or =2.5 cm or not) (P<0.001) and location (eloquent or not) (P<0.001) between SRS and HFSR due to the treatment selection. However, no significant differences were observed in the actuarial rates of obliteration and transient increased signals with T2-weighted MR images between SRS and HFSR. Radiation necrosis occurred in two patients treated with SRS and in none with HFSR. Intracranial hemorrhage after treatment happened in two treated with SRS and three with HFSR.

CONCLUSIONS

HFSR appears to be at least as effective as SRS in achieving complete obliteration of intracranial AVM, although its definitive role remains to be investigated.

The rationale and technique of staged-volume arteriovenous malformation radiosurgery

PURPOSE

Stereotactic radiosurgery is an effective management strategy for properly selected arteriovenous malformation (AVM) patients. However, the risk of postradiosurgical radiation-related injury generally limits this procedure to patients with AVMs of an average diameter of 3 cm or less. Radiosurgery of large AVMs in a planned staged fashion was undertaken to limit the radiation exposure to the surrounding normal brain.

METHODS AND MATERIALS

Between April 1997 and December 1999, 10 patients with a median AVM volume of 17.4 cm(3) (range, 7.4-53.3 cm(3)) underwent staged-volume radiosurgery (23 procedures). At the first radiosurgical procedure, the total volume of the AVM is estimated and a dose plan calculated that covers 10 cm(3)-15 cm(3), or one-half the nidus volume if the AVM is critically located (brainstem, thalamus, or basal ganglia). At 6-month intervals thereafter, radiosurgery was repeated to different portions of the AVM with the previous dose plan(s) being re-created utilizing intracranial landmarks to minimize radiation overlap. Radiosurgical procedures were continued until the entire malformation has been irradiated.

RESULTS

The radiation dosimetry of staged-volume AVM radiosurgery was compared to hypothetical single-session procedures for the 10 patients. Staged-volume radiosurgery decreased the 12-Gy volume by an average of 11.1% (range, 4.9-21%) (p < 0.001). The non-AVM 12-Gy volume was reduced by an average of 27.2% (range, 12.5-51.3%) (p < 0.001).

DISCUSSION

Staged-volume radiosurgery of large AVMs results in less radiation exposure to the adjacent brain. Further follow-up is needed to determine whether this technique provides a high rate of AVM obliteration while maintaining an acceptable rate of radiation-related complications.

Radiation therapy for benign central nervous system disease

The most common indication for the use of radiation therapy in the treatment of benign central nervous system disease is for the treatment of benign brain tumors, such as meningioma, pituitary adenoma, acoustic neuroma, arteriovenous malformation, and craniopharyngioma. Other less common benign intracranial tumors treated with radiation include chordoma, pilocytic astrocytoma, pineocytoma, choroid-plexus papilloma, hemangioblastoma, and temporal bone chemodectomas. Benign conditions, such as histiocytosis X, trigeminal neuralgia, and epilepsy, are also amenable to radiation treatment. There have also been reports of radiosurgery being used for the treatment of movement disorders and psychiatric disturbances, such as obsessive-compulsive and anxiety disorders. For benign brain tumors, radiation therapy as either primary or adjuvant therapy plays an integral role in improving local control. In the treatment of trigeminal neuralgia, epilepsy, tremor, and some psychiatric disturbances, radiosurgery may help ameliorate or eliminate some symptoms. Patients with benign central nervous system disease are expected to live a long time. As such, treatment should be highly conformal and based on three-dimensional planning using magnetic resonance imaging, computed tomography, or both. It is critical that damage to normal brain be minimized.

Staged volume radiosurgery followed by microsurgical resection: a novel treatment for giant cerebral arteriovenous malformations: technical case report

OBJECTIVE AND IMPORTANCE

We describe the successful treatment of symptomatic giant arteriovenous malformations (AVMs) using staged volume radiosurgery followed by microsurgical resection.

CLINICAL PRESENTATION

A 57-year-old man presented with Spetzler-Martin Grade 5 AVMs, with persistent headaches and seizures. He had previously undergone eight attempts at AVM embolization and a craniotomy for attempted AVM resection; he had suffered four episodes of brain hemorrhaging but had made a good neurological recovery.

INTERVENTION

Because of the persistent symptoms of the patient and his history of hemorrhaging, a treatment plan based on staged radiosurgical treatments of different portions of the AVMs (three sessions, spaced 6 mo apart), followed by delayed microsurgical removal of the much-reduced residual AVMs (3 years later), was undertaken. The patient did not suffer any additional hemorrhaging episodes, his AVMs were completely removed, and he has made a good recovery.

CONCLUSION

Staged volume radiosurgery followed by microsurgical resection of the residual AVMs represents a novel treatment strategy for the management of Grade 5 AVMs that might be untreatable by any single treatment method used alone.

Gamma knife surgery for previously irradiated arteriovenous malformations

OBJECTIVE

The goal was to report the treatment results after a second gamma knife treatment and to compare them with the results obtained after a first gamma knife treatment, as well as to investigate whether the models to predict the results after a first treatment are also applicable after gamma knife treatment of previously irradiated arteriovenous malformations.

METHODS

The number of complications and the posttreatment hemorrhage rate were recorded for 112 patients in the study, and the number of obliterations was recorded for the 101 patients for whom conclusive angiograms were obtained. The results were compared with the expected results after a first gamma knife treatment.

RESULTS

The observed number of obliterations was 62, which is not significantly different from the predicted number of 65. There were 14 observed and 5 predicted complications. When the risk from the preceding radiation treatment was added, the observed number of complications was similar to the predicted number. Six hemorrhages were observed after the second treatment. Of the 5 patients with unchanged arteriovenous malformation size after both the first and second treatments, 2 experienced hemorrhages after the second treatment, compared with none among the 81 patients for whom the malformation was obliterated or significantly decreased in size after the second treatment.

CONCLUSIONS

The obliteration rate after gamma knife surgery for previously irradiated arteriovenous malformations is similar to that after primary gamma knife treatment. The complication rate increases with the amount of radiation previously given. The incidence of posttreatment hemorrhages is lower in the latency period if the malformation is affected by the radiation.

Microsurgical results for small arteriovenous malformations accessible for radiosurgical or embolization treatment

OBJECTIVE

A consecutive series of microsurgically treated small arteriovenous malformations (AVMs), up to 3 cm in diameter, which are theoretically ideal candidates for radiosurgery or embolization, is described. We intended to elucidate the safety and efficacy of the microsurgical removal of AVMs, as compared with the results for radiosurgery and embolization reported in the literature.

METHODS

Sixty-two patients (32 female and 30 male patients) ranging in age from 7 to 72 years (mean age, 33.3 yr) were included in the series. Of these, 46.8% presented with intracerebral hemorrhage and 24.2% presented with seizures. The 62 patients underwent microsurgical removal of their small (<3 cm) cerebral AVMs by the same surgeon. Twenty-six AVMs (41.9%) were assigned Spetzler-Martin Grade I, 24 (38.7%) were assigned Grade II, and 12 (19.4%) were assigned Grade III. Thirty-three AVMs (53.2%) were located in eloquent brain regions. All patients underwent postoperative control angiography and clinical follow-up after 3 and 6 months.

RESULTS

The AVMs were extirpated, as confirmed by angiography, in all except one patient, thereby accounting for a 98.4% success rate per angiographic findings. The rate of immediate new postoperative neurological deficits or worsening of preexisting neurological deficits was 27.4%, and the rate of permanent significant neurological deficits was 3.2% at late follow-up. The rate of permanent significant deficits occurring after the microsurgical removal of small AVMs in eloquent regions was 6.1%. The mortality rate in the reported series was 0%. The surgical morbidity rate was 9.7%.

CONCLUSION

Microsurgery for small AVMs is superior to radiosurgery or interventional neuroradiology because of its high rate of efficacy and low rate of permanent morbidity and because immediate cure of the AVMs can be achieved in the vast majority of patients. The place for radiosurgery in the treatment of small AVMs needs to be more sharply defined after careful assessment of relevant cases by an experienced vascular neurosurgeon.

The surgical treatment of small deep intracranial ateriovenous malformations: a report of 85 cases

A series of 85 patients having what are defined as small, deep intracranial arteriovenous malformations (AVMs) is analysed in terms of presentation, investigation, treatment and outcome. This group of patients is taken from a consecutive series of 306 patients with AVM treated over a 20 year period. The anatomical distribution was as follows: cerebral hemisphere 54 patients, basal ganglia and thalamus 6 patients, brain stem and cerebellum 19 patients and deep dural 6 patients. Haemorrhage, both subarachnoid and intraparenchymal, was the predominant mode of presentation (71 of 85 cases). Other presentations were with epilepsy (5 cases), headache only (4 cases), progressive focal deficit (1 case) and mixed (4 cases). The vast majority of patients (71 of 85, 83.5%) were treated surgically: 67 by surgery only, 3 by surgery following partial embolisation and one with focussed irradiation after subtotal excision. The overall outcome in this group at 1 month was 27 (38.0%) improved (largely due to haematoma removal), 42 (59.2%) unchanged and 2 (2.8%) worse. One of the unchanged group died during the second month with pulmonary complications following prolonged impairment of consciousness. The two patients worse at 1 month (Gd I -> Gd II) returned to Gd I within 3 months. There were 3 patients treated non-surgically (2 by focussed irradiation and 1 by embolisation) while 11 patients were not treated because they declined treatment (3 cases), they died before treatment could be carried out (3 cases), or treatment was deemed inadvisable (5 cases). The results of surgical treatment in small deep AVMs are compared with those of other treatment modalities, in particular focussed irradiation. It is argued on the basis of these figures that surgery remains the best treatment for these lesions.

The safety and effectiveness of brain arteriovenous malformation embolization using acrylic and particles: the experiences of a single institution

The purpose of this article is to report on the safety and effectiveness of brain arteriovenous malformation (AVM) embolization for two series of patients, of which one was treated with particulate embolization and the other with acrylic embolization. Sixty-five consecutive patients from embolization logs and patient records from 1988 to 1993 were reviewed. AVMs were routinely treated with particulate embolization early in the review (1988-1991), and after a transition period, the technique was changed to acrylic embolization for the remainder of the study period (1992-1993). All patients were treated with the ultimate goal of complete AVM obliteration. AVMs were embolized and resected, if possible, and if unresectable, they were reduced in size with embolization and radiated. The course of treatment for each patient was reviewed. The effectiveness at the end of treatment was analyzed for the ability to resect the AVM and, if unresectable, the ability to reduce the AVM to radiation size. Additionally, the safety of each embolization technique was evaluated in the context of comprehensive care, in terms of the safety of the procedure itself, the surgical resection after embolization, and the outcome at the end of comprehensive treatment. This article outlines the safety and effectiveness of acrylic and particulate embolization at a single institution. The ability to surgically resect an AVM after embolization and to reduce nidus size with acrylic was at least comparable with that with particulate embolization. Comprehensive complication rates were lower after acrylic embolization and were heavily influenced by a decreased number of surgical complications in the acrylic series. These data support the need to conduct a randomized prospective clinical trial to compare the relative safety and effectiveness of the two methods of embolization.

'Steal' is an unestablished mechanism for the clinical presentation of cerebral arteriovenous malformations

BACKGROUND AND PURPOSE

Focal neurological deficits (FNDs) in patients with arteriovenous malformations (AVMs) have been widely attributed to the phenomenon of "cerebral steal." The incidence of focal deficits was investigated in a large prospective sample.

METHODS

Using data from patient history and examination, CT or MRI, and transcranial Doppler sonography, we studied 152 consecutive, prospective AVM patients for evidence of FNDs unrelated to a hemorrhagic event. Feeding mean arterial pressure was measured during superselective angiography.

RESULTS

Two (1.3%) of 152 patients met the criteria for a progressive FND. Nonprogressive FNDs were seen in 11 (7.2%) patients (stable in 4.6%, reversible in 2.6%). The median observation time period was 17 months (range, 1 to 60 months). There were no differences in transcranial Doppler mean velocities in feeding arteries in FND versus non-FND groups (118 +/- 44 versus 112 +/- 37 cm/s, P > .05) or pulsatility indexes (0.53 +/- 0.20 versus 0.55 +/- 0.15, P > .05). Feeding artery pressure was similar in FND (n = 10) and non-FND (n = 96) groups (39 +/- 16 versus 39 +/- 16 mm Hg at a systemic pressure of 82 +/- 18 versus 75 +/- 14 mm Hg, NS).

CONCLUSIONS

Nonhemorrhagic focal neurological syndromes in AVM patients are infrequent. Progressive deficits are especially rare. There was no relation between feeding artery pressure or flow velocities and FND. There does not appear to be sufficient evidence to assign steal as an operative pathophysiological mechanism in the vast majority of AVM patients.

Transcranial Doppler ultrasonography in cerebral arteriovenous malformations. Diagnostic sensitivity and association of flow velocity with spontaneous hemorrhage and focal neurological deficit

BACKGROUND AND PURPOSE

We sought to investigate (1) the sensitivity of transcranial Doppler ultrasonography (TCD) for diagnosis of cerebral arteriovenous malformations (AVMs) and (2) the association of feeding artery flow velocity profiles with spontaneous hemorrhage and focal neurological deficit in AVM patients.

METHODS

We examined 114 consecutive AVM patients prospectively by TCD; 22 non-AVM patients with acute cerebral hemorrhage and 52 normal subjects served as controls. To estimate the association of blood flow velocity patterns in feeding arteries with spontaneous hemorrhage and focal neurological deficit, the total group of AVM subjects was divided into patients with and without a history of bleeding and also into those with and without clinical signs of "steal" (focal deficit unrelated to hemorrhage).

RESULTS

Sensitivity for large and medium-sized AVMs was high (> 80%), whereas 62% of small AVMs were missed. TCD was also highly sensitive (80%) in a group of five AVM patients with acute hemorrhage. Flow velocity profiles were not related to spontaneous hemorrhage (mean velocity, 111 cm/s in patients with hemorrhage versus 114 cm/s in patients without hemorrhage; P = .65) or clinical signs of steal (mean velocity, 111 cm/s versus 113 cm/s in patients with and without steal, respectively; P = .89).

CONCLUSIONS

We concluded that (1) TCD is highly sensitive for large and medium-sized AVMs; (2) in acute cerebral hemorrhage TCD may help to differentiate AVM from non-AVM bleeds; (3) the predictive value of TCD findings for clinical sequelae of AVMs remains undetermined; and (4) the concept of hemodynamic steal in AVMs is not supported by TCD data.

Intra- and paraventricular arteriovenous malformations: symptomatology, neuroradiological diagnosis, surgical approach and postoperative results

A series of 8 patients with para- and intraventricular arteriovenous malformations (AVM) is presented. Confirmed by histopathological examination or based upon their history all of them sustained recurrent intraventricular or intracerebral haemorrhages. Our results strongly recommend a surgical removal of these AVMs as a feasible and mandatory form of treatment. Conservative methods, e.g., embolisation or gamma beam irradiation leave the patient susceptible to rebleeding which often results in devastating neurological deficits. Total removal of the AVM with minimal surgical trauma was achieved in 7 patients under controlled hypotension and was facilitated by stereotactic guidance in two patients. Post surgical re-bleeding was not observed in any of our patients even though in one case only a subtotal resection of the angiomatous malformation was achieved. Based on our experience, we advocate an inspection of the lateral ventricle in order to avoid leaving any intraventricular portion of the vascular malformation behind. MRI investigation is recommended because the multiplanar images clarify the topographic-anatomic location and its relation to important surgical landmarks.