Arteriovenous Malformation Management via Arteriovenous Malformation Management via Endovascular Embolization: Onyx versus n-Endovascular Embolization: Onyx versus n-butyl cyanoacrylate (nBCA)butyl cyanoacrylate (nBCA)

Ahmed El-Gengaihy, MDAhmed El-Gengaihy, MD11, Alveena Dawood BS, Charles , Alveena Dawood BS, Charles Prestigiacomo, MD Prestigiacomo, MD 1,2,1,2, Oriana Cornet, Oriana Cornet, 11 Chirag Gandhi, Chirag Gandhi, MDMD1,21,2

11Department of Neurological Surgery and Department of Neurological Surgery and 22Department of Radiology,Department of Radiology, New Jersey New Jersey Medical School, University of Medicine and Dentistry of New Jersey, Newark, NJMedical School, University of Medicine and Dentistry of New Jersey, Newark, NJ

Introduction The prevalence of brain arteriovenous malformations

(BAVMs) is estimated to be less than 1 in 100,000 in the population

The annual cumulative risk of bleeding due to rupture is 2-4%, increasing up to 6% in the first year after hemorrhage

The annual risk of mortality is less than 1%

Treatment of BAVMs is achieved by embolization, surgery, radio-surgery, or a combinations of these modalities

Introduction, cont.

The aim of endovascular management of BAVMs before surgical resection is to minimize intra-operative blood loss, occlude the entire BAVM, or at least minimize the size of the nidus

Endovascular treatment is achieved by using n-butyl cyanoacrylate (nBCA; Cordis Microvascular, Inc., New Brunswick, NJ) or Onyx (ev3, Inc., Irvine, CA). embolic agents

Purpose of the Study

Report our experience in using onyx vs nBCA and highlight the anatomical and clinical

results accomplished using these two forms of treatment

Methods

Patients treated endovascularly using Onyx or nBCA from 2003 to 2009 were retrospectively analyzed

A total of 325 procedures involving BAVMs were performed at UMDNJ University Hospital

Out of these procedures onyx was used as the sole embolic agent in 29 procedures; nBCA, on the other hand, was used in the larger population. This may be due the fact that Onyx was introduced to our facility in 2007

For the sake of comparison; we only analyzed 35 consecutively selected nBCA cases embolized within the same time period

Methods, cont.

All patient underwent digital subtraction angiography prior to any staged embolization

All embolization procedures were performed by fellowship trained endovascular neurosurgeons

Patients’ data; including demographics, complication rates and pre-operative Spetzler-Martin grading scale, were collected

Contrast load, fluoroscopy time, as well as the number of arteries feeding the nidus were obtained

Methods, cont.

Pre- and post-embolization volumes were assessed by two independent raters

We used Pasqualin* method in calculating the volume of the BAVM

Pasqualin A, Barone G, Cioffi F, Rosta L, Scienza R, Da Pian R. The relevance of anatomic and hemodynamic factors to a classification of cerebral arteriovenous malformations. Neurosurgery. 1991 Mar;28(3):370-9 Department of Neurosurgery, Verona City Hospital, Italy.

Methods, cont.

BAVM is considered to take an ellipsoid shape and its volume is measured by multiplying the products of 3 diameter of the BAVM (width, height, length) by 0.52 or more practically divide the products of the three diameters by half as shown in the following equation..

V= (wxhxl)/2

The horizontal and the vertical diameters were calculated from the antero-posterior projection and the longitudinal diameter from the lateral projection

Methods, cont.

Figure 1 .. showing the method of AVM calculation V= (wxhxl)/2

W L

H

Methods, cont.

Figure 2, A & B: Showing a 47 year old female with a left frontal BAVM;

A .. shows pre-embolization lateral view angiogram, andB .. shows post-embolization lateral angiogram after 3 staged embolizations with Onyx as the sole embolic agent

Methods, cont.

Figure 3, C & D: Showing a 49 year old male with right parietal BAVM;

C .. shows pre-embolization lateral view angiogram, andD .. shows post-embolization lateral view angiogram after 5 staged embolizations with nBCA as the sole embolic agent

Results Table 1: AVM Locations

Location ONYX

nBCA

Frontal 25%

37.5%

Frontoparietal 50%

0%

Cerebellar 12.5%

12.5%

Occipital 0%

12.5%

Parietal occipital 12.5%

0%

Temporal 0%

25%

Parietal 0%

12.5%

Results, cont. Table 2: Pre-embolization Nidus Volume

Volume (cm3) ONYX

nBCA

<3 23.5%

60%

3-7 35.3%

13.3%

>7 41.2%

26.7%

Mean±SD* 5.59±4.8 4.11±4.3

*p=0.06

Results, cont.

Comparison between Fluoroscopy time Mean and Standard Deviation

A B

Column

0.00

8.00

16.00

24.00

32.00

40.00

48.00

56.00

64.00

72.00

80.00

88.00

96.00

104.00

112.00

120.00

128.00

Flu

oro

sco

py

Tim

e

Po

st-

Em

bo

liza

tio

n P

erc

en

t R

ed

uct

ion

Onyx

OnyxnBCA nBCA

p=0.0009

p=0.2

Results, cont.

Discussion

In this retrospective study, we report our clinical and anatomical results after using Onyx and nBCA in treatment of BAVM

There was no significant difference among the cohorts regarding sex, age and Spetzler-Martin grading scale

Both modalities of treatment are comparable in regards to percentage of obliteration of the BAVM and procedural complication

Discussion, cont.

Onyx requires fewer number of staged embolizations (2.6+/-9) to achieve the same degree of obliteration as nBCA(3.4+/-1.1)p=0.07

Onyx fluoroscopy time was significantly higher when compared to nBCA (p=0.009)

BAVM in the Onyx cohort had pre-embolization larger volume when compared with nBCA, however regression analysis did not show linear correlation between fluoroscopy time and BAVM volume

Contrast load in the nBCA cohort was slightly higher when compared to Onyx (p=0.8)

Discussion, cont.

The Trend towards lesser embolization procedures and higher obliteration rate in the Onyx cohort most likely represent the slower and more controlled injection technique characteristic of Onyx

It may be argued that this trend may reach statistical significance if more patients were studied

It is possible that fewer embolization procedures and higher obliteration rates may negate the increased fluoroscopy time associated with Onyx treatment

Discussion, cont.

However, longer fluoroscopic times certainly increase the risk of procedural complications and subject the patient and the operator to higher radiation doses that may lead to delayed complications such as, development of benign and malignant brain tumors

Nonetheless, onyx my penetrate deeply into the nidus of the AVM and occlude more pedicles of the AVMs through one catheterization

Fewer embolization procedures, on the other hand may decrease the overall risks of catheter angiography including; thrombo-embolic complications, micro-catheter complications, vessels perforation .. etc

Discussion, cont.

Literature comparing Onyx and nBCA is limited

Valet et al.* reported similar findings when comparing both modalities of treatment

They reported statistically significant increase in fluoroscopy time in the onyx treated cohort (p=000.1) and a trend towards nidus volume reduction per embolization in the onyx cohort(50%) relative to nBCA cohort (45%)

Velat G etal. Comparison of N-butyl cyanoacrylate and onyx for the embolization of intracranial arteriovenous malformations: analysis of fluoroscopy and procedure times. Neurosurgery. 2008 Jul;63

Discussion, cont.

They also reported about 6.6% overall complication with a trend towards increased complication in the Onyx cohort (30%) compared to nBCA (10%). Most of Onyx complications occurred within the first few months of using the agent

In our study, complications in the Onyx cohort were comparable to the nBCA group; there was no major complications in both cohorts. Minor complications that include catheter retention, asymptomatic stroke, wire perforation were slightly higher in the Onyx cohort when compared to nBCA cohort .

Limitation of the study Being retrospective in nature

Relatively small groups of patients analyzed

Lack of long term follow up

Operative dependent and learning curve; the operators were more experienced with the use of nBCA rather than onyx, which was FDA approved in 2005 and introduced to our hospital in 2007

Additional volume assessment by using Radionics fusion software which will be able to align the images volumetrically, may provide better measurement of brain lesions

Thank you