arteriovenous malformations and associated aneurysms

2
Perspectives Robert F. Spetzler, M.D. Director, Barrow Neurological Institute (BNI) J. N. Harber Chair of Neurological Surgery at BNI Chairman and President, Barrow Neurosurgical Associates, Professor of Surgery Section of Neurosurgery, University of Arizona College of Medicine Arteriovenous Malformations and Associated Aneurysms Kaith Almefty and Robert F. Spetzler A rteriovenous malformations (AVMs) of the brain often present complex management decisions for the treating surgeon. The surgical treatment of these lesions is intended to eliminate the risks of intracranial hemorrhage; how- ever, eliminating this risk must be balanced by the risks and morbidity and mortality associated with treating the lesion. Natural history studies have provided the basis for assessing the risk of hemorrhage and associated morbidity of untreated AVMs. The annual risk of intracranial hemorrhage associated with an untreated AVM is 2%-3% per year; the risk of recurrent hemor- rhage is even greater. The risk of death in the event of hemor- rhage is approximately 10%, and the risk of a neurologic deficit is approximately 50% (8). In 1986, the Spetzler-Martin grading scale was introduced to help surgeons make the complex decisions on how to manage these lesions (8). Recently, the scale was simplified into a 3-tier grading scale (9). At the Barrow Neurological Institute, the management of AVMs follows a treatment paradigm whereby Class A (previ- ously grades I and II) lesions are managed with surgical resection. Class C (grades IV and V) AVMs are treated conservatively. Other authors, such as de Oliveira et al. (2) and Lawton (4) have suggested that Class B (Grade III) lesions be further subclassified and proposed management strategies for their subclasses. de Oliveira et al. (2) reclassified Grade III AVMs into Grade IIIA (large) and IIIB (small, in eloquent areas) lesions and proposed emboli- zation plus surgery for the IIIA and radiosurgery for IIIB AVMs. Lawton (4) recommended surgery for small, eloquent AVMs with deep drainage (size [S1], eloquence [E1], deep venous drainage [V1]), conservative treatment for larger lesions without deep drainage (S2, E1, V0), and “judicious” selection for his interme- diate group (S2, E0, V1). We also have found this class of lesions to be complex and heterogeneous, typically requiring a multimo- dality approach with the use of microsurgical, endovascular, and radiosurgical techniques. Although the grading scales offer surgeons guidance for making these complex treatment decisions, each AVM is unique and should be considered individually. Features such as the number and distribution of feeding arteries, previous hemorrhages, the patient’s neurologic status, the amount of flow through the lesion, the degree of vascular steal from surrounding brain, and the number and location of associated aneurysms should be considered. A grading scheme that encompassed all of these features would be cumbersome and impractical. Many of the factors, however, are interrelated and thus are often captured indirectly in the grading schemes. The association of aneurysms in patients with AVMs is well documented with a reported incidence between 10% and 58%. It is also well demonstrated that an additional risk of intracranial hemorrhage is present in AVM patients with aneurysms. Re- dekop et al. (7) classified these aneurysms as either intranidal, flow-related, or unrelated to the AVM nidus. In patients with intranidal aneurysms, this group found a 10% risk of hemorrhage per year, which is considerably greater than the 2%-4% annual hemorrhage rate usually attributed to AVMs. Given the increased risk associated with AVM-associated aneurysms, some authors have suggested aggressive man- agement strategies. The belief that hemodynamic changes associated with the abrupt elimination of AVMs may place the associated aneurysm at a greater risk of rupture led Batjer et al. (1) to recommend treatment of the aneurysm before pursuing resection of the AVM. Thompson et al. (10) also recommended a management protocol designed to treat the aneurysms by surgical or endovascular means before admin- istering definitive therapy for the AVM. Key words Arteriovenous malformation Cerebral aneurysm Abbreviations and Acronyms AVM: Arteriovenous malformations Division of Neurological Surgery, Barrow Neurological Institute, St. Joseph’s Hospital and Medical Center, Phoenix, Arizona, USA To whom corresponding should be addressed: Robert F. Spetzler, M.D. [E-mail: [email protected]] Citation: World Neurosurg. (2011) 76, 5:396-397. DOI: 10.1016/j.wneu.2011.06.051 Commentary on: Cerebral Arteriovenous Malformations Associated with Flow-Related and Circle of Willis Aneurysms by Lv et al. pp. 455-458. 396 www.SCIENCEDIRECT.com WORLD NEUROSURGERY, DOI:10.1016/j.wneu.2011.06.051

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Page 1: Arteriovenous Malformations and Associated Aneurysms

iemNrTurra

IslsooCasaOazLd[ddt

Perspectives

Robert F. Spetzler, M.D.

Director, Barrow Neurological Institute (BNI)J. N. Harber Chair of Neurological Surgery at BNI

Chairman and President, Barrow Neurosurgical Associates, Professor of SurgerySection of Neurosurgery, University of Arizona College of Medicine

Arteriovenous Malformations and Associated Aneurysms

Commentary on:Cerebral Arteriovenous MalformationsAssociated with Flow-Related and Circle ofWillis Aneurysmsby Lv et al. pp. 455-458.

Kaith Almefty and Robert F. Spetzler

A rteriovenous malformations (AVMs) of the brain oftenpresent complex management decisions for the treatingsurgeon. The surgical treatment of these lesions is

ntended to eliminate the risks of intracranial hemorrhage; how-ver, eliminating this risk must be balanced by the risks andorbidity and mortality associated with treating the lesion.atural history studies have provided the basis for assessing the

isk of hemorrhage and associated morbidity of untreated AVMs.he annual risk of intracranial hemorrhage associated with anntreated AVM is 2%-3% per year; the risk of recurrent hemor-hage is even greater. The risk of death in the event of hemor-hage is approximately 10%, and the risk of a neurologic deficit ispproximately 50% (8).

n 1986, the Spetzler-Martin grading scale was introduced to helpurgeons make the complex decisions on how to manage theseesions (8). Recently, the scale was simplified into a 3-tier gradingcale (9). At the Barrow Neurological Institute, the managementf AVMs follows a treatment paradigm whereby Class A (previ-usly grades I and II) lesions are managed with surgical resection.lass C (grades IV and V) AVMs are treated conservatively. Otheruthors, such as de Oliveira et al. (2) and Lawton (4) haveuggested that Class B (Grade III) lesions be further subclassifiednd proposed management strategies for their subclasses. deliveira et al. (2) reclassified Grade III AVMs into Grade IIIA (large)nd IIIB (small, in eloquent areas) lesions and proposed emboli-ation plus surgery for the IIIA and radiosurgery for IIIB AVMs.awton (4) recommended surgery for small, eloquent AVMs witheep drainage (size [S1], eloquence [E1], deep venous drainageV1]), conservative treatment for larger lesions without deeprainage (S2, E1, V0), and “judicious” selection for his interme-iate group (S2, E0, V1). We also have found this class of lesionso be complex and heterogeneous, typically requiring a multimo-

Key words� Arteriovenous malformation� Cerebral aneurysm

Abbreviations and AcronymsAVM: Arteriovenous malformations

396 www.SCIENCEDIRECT.com WO

dality approach with the use of microsurgical, endovascular, andradiosurgical techniques.

Although the grading scales offer surgeons guidance for makingthese complex treatment decisions, each AVM is unique andshould be considered individually. Features such as the numberand distribution of feeding arteries, previous hemorrhages, thepatient’s neurologic status, the amount of flow through thelesion, the degree of vascular steal from surrounding brain, andthe number and location of associated aneurysms should beconsidered. A grading scheme that encompassed all of thesefeatures would be cumbersome and impractical. Many of thefactors, however, are interrelated and thus are often capturedindirectly in the grading schemes.

The association of aneurysms in patients with AVMs is welldocumented with a reported incidence between 10% and 58%.It is also well demonstrated that an additional risk of intracranialhemorrhage is present in AVM patients with aneurysms. Re-dekop et al. (7) classified these aneurysms as either intranidal,flow-related, or unrelated to the AVM nidus. In patients withintranidal aneurysms, this group found a 10% risk of hemorrhageper year, which is considerably greater than the 2%-4% annualhemorrhage rate usually attributed to AVMs.

Given the increased risk associated with AVM-associatedaneurysms, some authors have suggested aggressive man-agement strategies. The belief that hemodynamic changesassociated with the abrupt elimination of AVMs may place theassociated aneurysm at a greater risk of rupture led Batjer etal. (1) to recommend treatment of the aneurysm beforepursuing resection of the AVM. Thompson et al. (10) alsorecommended a management protocol designed to treat theaneurysms by surgical or endovascular means before admin-istering definitive therapy for the AVM.

Division of Neurological Surgery, Barrow Neurological Institute, St. Joseph’sHospital and Medical Center, Phoenix, Arizona, USA

To whom corresponding should be addressed: Robert F. Spetzler, M.D.[E-mail: [email protected]]

Citation: World Neurosurg. (2011) 76, 5:396-397.DOI: 10.1016/j.wneu.2011.06.051

RLD NEUROSURGERY, DOI:10.1016/j.wneu.2011.06.051

Page 2: Arteriovenous Malformations and Associated Aneurysms

afi

PERSPECTIVES

However, Redekop et al. (7) noted regression of 80% of distalnd of 17% of proximal aneurysms after treatment of the AVMrst. Meisel et al. (6) reported on 305 AVMs with associated

aneurysms and suggested that intranidal aneurysms should beprimary treatment targets whereas proximal aneurysms shouldnot. Their rationale was based on evidence that the latter oftenregress after definitive AVM treatment and on their finding thatproximal aneurysms were not associated with the same increasein hemorrhage rate as intranidal aneurysms. Redekop et al. (6)and Meisel et al. (7) presented good evidence for the treatmentof intranidal aneurysms and observation of proximal aneurysms.

It is our paradigm that the symptomatic lesion be treated. Inthe event of intracranial hemorrhage, an attempt to identifythe causative lesion and treatment should be directed at thatlesion. We have traditionally regarded associated aneurysmsas independent risk factors and treated them aggressively. Forproximal aneurysms the decision is based on size, as withgeneral aneurysm treatment, and small proximal aneurysmsare followed while larger proximal aneurysms treated directly.We have advocated that Grade IV and V AVMs be managedconservatively (3). However, in the presence of associatedaneurysms, we believe that the aneurysm should be treateddirectly without intervention to the AVM, given the highmorbidity associated with treating the AVM primarily. Further-more, we do not recommend partial treatment of high-gradeAVMs except in the case of a progressive neurologic deficit

related to vascular steal (3).

ification of the grading scale. Neurosurgery 52:740-748, 2003.

for arteriovenous malform476-483, 1986.

WORLD NEUROSURGERY 76 [5]: 396-397, NOVEMBER 2011

In the present paper, Lv et al. (5) retrospectively reviewed 302patients treated with AVMs at their institution. Their large seriescovers the important topic of risk of rupture in AVMs that havehigh-risk features such as associated aneurysms. In this series,an intranidal-associated aneurysm was present in 13.6% of theircases, and extranidal aneurysms were present in 10.9%. Theauthors suggested that AVM-associated aneurysms be classifiedas either circle of Willis or flow related. They further suggestedthat circle of Willis aneurysms be managed in a fashion similar tothe general treatment of aneurysms. They found that aneurysmswere more often associated with AVMs that became symptom-atic with hemorrhage, older patients, and infratentorial lesions. Intheir series, flow-related aneurysms were not associated withsignificantly more intracranial hemorrhages than circle of Willisaneurysms. However, circle of Willis aneurysms had a greaterincidence of subarachnoid hemorrhage. This finding suggeststhat circle of Willis aneurysms should be treated primarily.

The appropriate management of AVMs remains complex, andthis study is an additional resource to the growing literature onthe incidence and risks of AVM-associated aneurysms. Specifi-cally, Class B AVMs continue to challenge surgeons with difficulttreatment decisions. Indeed, four questions await clear andconclusive answers. First, what is the extent of risk attributableto “high-risk” features such as associated aneurysms? Second,which subtypes of these aneurysms are associated with thegreatest risk of hemorrhage? Third, what is the true pathogenesisof these aneurysms? And finally, which modality is most effec-

tive for their treatment?

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REFERENCES

1. Batjer H, Suss RA, Samson D: Intracranial arterio-venous malformations associated with aneurysms.Neurosurgery 18:29-35, 1986.

2. de Oliveira E, Tedeschi H, Raso J: Comprehensivemanagement of arteriovenous malformations. Neu-rol Res 20:673-683, 1998.

3. Han PP, Ponce FA, Spetzler RF: Intention-to-treatanalysis of Spetzler-Martin grades IV and V arterio-venous malformations: natural history and treat-ment paradigm. J Neurosurg 98:3-7, 2003.

4. Lawton MT: Spetzler-Martin Grade III arterio-venous malformations: surgical results and a mod-

5. Lv X, Wu Z, Li Y, Jiang C, Yang X, Zhang J: Cerebralarteriovenous malformations associated with flow-related and circle of Willis aneurysms. World Neu-rosurg 76:455-458, 2011.

6. Meisel HJ, Mansmann U, Alvarez H, Rodesch G,Brock M, Lasjaunias P: Cerebral arteriovenous mal-formations and associated aneurysms: analysis of305 cases from a series of 662 patients. Neurosur-gery 46:793-800, 2000.

7. Redekop G, TerBrugge K, Montanera W, WillinskyR: Arterial aneurysms associated with cerebral arte-riovenous malformations: classification, incidence,and risk of hemorrhage. J Neurosurg 89:539-546,1998.

8. Spetzler RF, Martin NA: A proposed grading system

ations. J Neurosurg 65:

ww

9. Spetzler RF, Ponce FA: A 3-tier classification of ce-rebral arteriovenous malformations. Clinical arti-cle. J Neurosurg 114:842-849, 2011.

0. Thompson RC, Steinberg GK, Levy RP, Marks MP:The management of patients with arteriovenousmalformations and associated intracranial aneu-rysms. Neurosurgery 43:202-211, 1998.

itation: World Neurosurg. (2011) 76, 5:396-397.OI: 10.1016/j.wneu.2011.06.051

ournal homepage: www.WORLDNEUROSURGERY.org

vailable online: www.sciencedirect.com

878-8750/$ - see front matter © 2011 Elsevier Inc.ll rights reserved.

w.WORLDNEUROSURGERY.org 397