However, some of us propagate a more liberal use of intracranial stents because the stent should attribute to a more durable aneurysm occlusion on the long-term by diverting the flow and by creating a mesh at the level of the neck to be colonized and covered by endothelial cells. In view of these perceived advantages, some even place a stent after successful aneurysm occlusion by simple coiling. The key question in this issue is: Does the potential better long-term result with use of stents negate the higher expected rate of complications?

One answer to this question is provided by the recently published study by Piotin. Clinical and imaging results of 216 patients with aneurysms (181unruptured and 35 ruptured) that were treated with stent assistance were compared to results of 1109 aneurysms (549 ruptured and 560 unruptured) that were treated without stent. Permanent neurological procedure-related complications occurred in 7.4% (16 of 216) of the procedures with stents versus 3.8% (42 of 1109) in the procedures without stents. Procedure-induced mortality occurred in 4.6% (10 of 216) of the procedures with stents versus 1.2% (13 of 1109) in the procedures without stents. In other words, with stent assisted treatment, 12% of patients either died or had permanent neurological deficit as a direct consequence of the treatment. How about the angiographic results, are these better with stent than without stent? Aneurysms treated with a stent had a higher rate of initial incomplete occlusion (35% versus 18%). Only about half of the stented aneurysms had angiographic follow-up and there were less recurrences 15% (17 of 114) versus 34% (259 of 774).

Unfortunately, the authors did not further analyse the high rate of complications with stent assisted coiling (vessel perforations, aneurysm perforations, thrombo-embolic complications). They also did not provide a definition of a recurrence and more important, the rate of retreatment in both groups was not reported. Although there were fewer recurrences after stenting, the recurrence rate of 15% with stent assistance is within the normal range of 10-20% reported for coiling in general.

The results of the study by Piotin give a clear answer to our previous question: the complication rate of stent assisted coiling is alarmingly high in a population harboring mostly unruptured aneurysms located on sites that are easily accessible for surgery while the follow-up results are comparable to results of coiling in general.

In my opinion, the use of this dangerous stent-assisted coiling should be discouraged and restricted to those cases where a stent is absolutely necessary and no alternative treatment is available. For sure, placement of a stent after successful coiling should be deterred since by placing the stent the procedure is converted from low-risk to high-risk.

Finally, we should not blame the bad handling of the device for the increased complication rate; it is always the operator who decides what materials to use. The introduction of newer stents with safer handling is not an excuse for denying disappointing results.

1. How many people regularly do cervical nerve root blocks?
2. Are you using CT or conventional fluoro?
3. If you are using CT, do you use contrast to confirm needle position?

It would be great for people to comment on the blog, but you can also email me directly.

Thanks!
jenny.hoang@duke.edu

The authors analyzed the long-term stability of treatment of cerebral aneurysms treated exclusively with GDC, focusing in re-treatments and re-bleeding rates during follow up.

The authors have been meticulous in data recollection, once, these patients have been followed since 1998. Additionally, the fact to be a multicentric trial, demands a greater author commitment for the patients follow up, according to strict designed protocol.

The experience presented here, is the continuum of the data reported by the authors previously in 2005 and 2008 in this journal. Now, nevertheless, the totality of the series including unruptured and ruptured intracranial aneurysms. The authors describe the radiological findings in a considerable sample of 1036 aneurysms treated in 929 patients, with a mean of follow up of 66 months and, a very significant number over than 400 aneurysms followed more than five years.

The results of this multicentric trial must be analyzed cautiously, before to be extrapolated as part of the standard treatment of “aneurysms”. In this experience near 90% of lesions were smaller of 10 mm, and, only 2% of the lesions were giant and therefore, similar to reports of ISAT, these results could be validated just for a sub-type of patients with small aneurysms of the anterior circulation, in a good clinical status, that after a multidisciplinary evaluation were defined as good candidates to endovascular treatment , thus, there was an important selection bias and, unfortunately, exclude those lesions that have an elevated risk of treatment failure.

In this report, as well as previous publications, the authors unfortunately did not describe the characteristics of the parent vessel and his relation with the neck of the aneurysm; the dome: neck ratio was not considered and presumably, due to high rate of effectiveness reported, one would suppose that the majority of lesions had small neck or at least a favorable dome: neck ratio; although 10% required balloon remodeling assisted technique.

Regarding re-treatment group, there is lack of morphological data (i.e. size, neck diameter, Location) to analyze if, with the current endovascular technology available, these numbers could dramatically be reduced. Hence, special consideration is necessary to evaluate the 731 aneurysms that initially showed a complete occlusion, given that, it is in this group of lesions in where, really it is reflected the treatment stability over-time. Once removed the patients who died and those that were lost during the follow up, a total of 611 aneurysms was finally followed and of these, 109 (17,8%) showed a negative variation during follow up (Subtotal or incomplete) according to illustrated in table 4. Although, this result it’s in agreement with published data regarding recanalization/regrowth rates, it’s remarkably that the majority of aneurysms were small lesions , with apparent favorable dome: neck ratio and, would be expected a better result. However, these results refer to think that a greater volumetric filling and/or, the use of biological materials that promotes a more stable intra-aneurysmal thrombosis may perhaps reduce these numbers even more.

The re-bleeding rate did not surpass 1% , this demonstrates once again that the endovascular treatment of cerebral aneurysms with GDC is effective and clinically protective. But, at the same time it generates the question about the necessity of re-treatment and what are the criteria for the decision making. Currently, there is not an objective, validate and, reproducible methodology to evaluate the immediate initial occlusion and, comparatively help us to interpret the morphologic changes over the time. The work of the authors with this cohort of patients will continue generating valuable information to the world of Neurointerventionism and bring answers to this nascent specialty.

Pedro Lylyk MD.

I’m an interventional neuroradiologist in South Korea. Korea’s health insurance service inquired of the Korean Society of Interventional Neuroradiology what is the qualification of neurointerventionist for payment of interventional procedure.

I want to know certification requirements for neurointervention in America.

Does the insurance company require the other certification as well as ABR or institutional certification of fellowship?

Does anyone know what this mass could be? It was biopsied 2 years ago and pathology reported it as  “normal brain tissue”.

As you can see, the lesion is hyperintense on T2, hypointense on T1 and does not enhance.  No calcifications are present and no there is no restricted diffusion .

The patient is 25  year old and has loss of short term memory and seizures.

Any input into the nature of the mass is welcome.

Cerebral Aneurysm Calculator

This recently revised website is dedicated to providing quality resources for the management of cerebral aneurysms and features an online calculator for calculating cerebral aneurysm volume and percent packing volume after coil embolization. The site now includes product information from five major coil manufacturers including newly released coils. There is also an Imaging Library featuring multiple high resolution Netter neurovascular anatomical drawings. The site is designed to aid in both daily practice and as a research tool.

Home Page

Gary Duckwiler, MD, Director of Clinical Affairs and Fellowship Director, Division of Interventional Neuroradiology, Ronald Reagan UCLA Medical Center

Flow diversion stents and endoluminal flow-disrupting devices are new therapeutic approaches to treat challenging intracranial aneurysms [1,2]. The first generation Pipeline Embolization Device (PED) has already been used in clinical practice. The reported results of PED treatment of intracranial aneurysms appear to be promising and very encouraging for the neuro-endovascular field [1,2]. However, there has always been a lingering concern associated with any intracranial stent that they may compromise the blood flow in small side branches coming from the stented segment of artery. After the introduction of low profile, self-expandable intracranial stents such as Neuroform, Wingspan, and Enterprise, we started to realize that eloquent perforators could sustain their patency with an approximately 10% area-coverage stent [3]. Unfortunately, with a low coverage stent, the likelihood of aneurysm occlusion without adjunctive treatment is very low. Finding the “sweet spot” of neck coverage versus side branch occlusion is the ultimate target to prevent aneurysm recurrence. The introduction of PED has expanded this envelope in that we may be able to put a stent that has 30% area coverage while maintaining the patency of perforating arteries, although the long-term patency of stented artery including perforating arteries still needs to be evaluated carefully.

Masuo et al introduced a very unique experimental method to access the patency of perforating arteries coming off a major intracranial artery after the stent placement [4,5]. They used a rabbit abdominal aorta and lumbar artery to simulate the relationship between a major intracranial artery and its perforating arteries. Their studies published in AJRN 2002 (healthy aorta) and 2005 (atherosclerotic aorta) suggest that risks of perforator occlusion may increase when a stent is placed in an atherosclerotic artery [4,5]. The safety and biocompatibility of PED and PED2 were tested utilizing the same methodology except that the abdominal aortae were as healthy as a human pediatric case. Thus, the indication of PED placement for a challenging intracranial aneurysm associated with atherosclerotic change must be planned with extra caution.

Another open question is the interim effect of flow diversion on the stability of cerebral aneurysms.  Intra-aneurysmal flow and its relationship to growth and rupture of aneurysms is a highly debated topic [6].  From the landmark ISAT trial, it was proven that intra-aneurysmal coiling reduced the rerupture rate compared to historical rates [7].  Whether or not high-coverage stents will provide the same benefits predictably, without causing a negative impact of intra-aneurysmal flow dynamics remains to be seen, especially given the need for coagulation management in the acute phase.  In this study, both side branch preservation and aneurysm occlusion were obtained, which is a great first step.

The PED seems to be a promising potential solution in wide neck and possibly fusiform aneurysms that are not treatable by conventional surgery or endovascular embolization. Certainly, any efforts to further delineate the safety profile and outcome predictability of high coverage stents is valuable and necessary.

References
1. Fiorella D, Woo HH, Albuquerque FC, Nelson PK. Definitive reconstruction of circumferential, fusiform intracranial aneurysms with the pipeline embolization device. Neurosurgery 62: 1115-1121: 2008

2. Lylyk P, Miranda C, Ceratto R, Ferrario A, Scrivano E, Luna HR, Berez AL, Tran Q, Nelson PK, Fiorella D. Curative endovascular reconstruction of cerebral aneurysms with the pipeline embolization device: the Buenos Aires experience. Neurosurgery 64: 632-643: 2009

3. Biondi A, Janardhan V, Katz JM, Salvaggio K, Riina HA, Gobin YP. Neuroform stent-assisted coil embolization of wide-neck intracranial aneurysms: strategies in stent deployment and midterm follow-up. Neurosurgery 61: 460-469: 2007.

4. Masuo O, Terada T, Walker G, Tsuura M, Matsumoto H, Tohya K, Kimura M, Nakai K, Itakura T.  Study of the patency of small arterial branches after stent placement with an experimental in vivo model. AJNR Am J Neuroradiol 23: 706-710: 2002

5. Masuo O, Terada T, Walker G, Tsuura M, Nakai K, Itakura T. Patency of perforating arteries after stent placement? A study using an in vivo experimental atherosclerosis-induced model. AJNR Am J Neuroradiol 26:543-548: 2005

6. Tateshima S, Tanishita K, Omura H, Villablanca JP, Vinuela F. Intra-aneurysmal hemodynamics during the growth of an unruptured aneurysm: in vitro study using longitudinal CT angiogram database. AJNR Am J Neuroradiol. 28: 622-627: 2007

7. Molyneux AJ, Kerr RS, Yu LM, Clarke M, Sneade M, Yarnold JA, Sandercock P; International Subarachnoid Aneurysm Trial (ISAT) Collaborative Group. International subarachnoid aneurysm trial (ISAT) of neurosurgical clipping versus endovascular coiling in 2143 patients with ruptured intracranial aneurysms: a randomised comparison of effects on survival, dependency, seizures, rebleeding, subgroups, and aneurysm occlusion. Lancet. 366: 809-817: 2005

In an original research article published April 15, 2009, Yousem and Gujar set out to determine the current neruradiologic practices and opinions on the performance of C1-2 punctures for routine cervical myelography. The impetus behind this investigation was a medicolegal case where the plaintiffs attorney argued that the performance of a C1-2 puncture for cervical myelography was below the standard of care.

The authors used a survey instrument sent to neuroradiology program directors. Eleven questions were used and designed to gain an understanding of whether C1-2 punctures are performed, under what conditions they are performed, how often they are performed and whether the fellows or residents were trained to perform these procedures. 12 of 85 respondents or 14.1 % reported that their program performed less than one C1-2 puncture per year for cervical myelography, 66 of 84 or 78.6% averaged between one and twentyfive C1-2 punctures per year and 40 or 47.6% of respondents said that they averaged between one and five C1-2 punctures per year. C1-2 puncture to obtain CSF was performed by 52 of 83 programs or 62.7%. 83 of 84 respondents or 98.8% of respondents stated that there was a person trained to perform C1-2 punctures and 59 of 81 or 72.8% of programs train their fellows and/or residents to perform C1-2 punctures. Only 4 of 80 or 5% of respondents felt that performing a C1-2 puncture as the primary approach for cervical myelography in a patient with a contraindication for MR imaging was below the standard of care.

Based on the survey, we have no way to determine the frequency of the performance of C1-2 punctures per individual. In addition, myelography in the United States is performed by many physicians and other radiologists, neurologists, and neurosurgeons perform myelography and this research does not address this. The number of myelograms performed (as with other interventional procedures) has declined because of improved non-invasive imaging techniques. The real question to address, then, is whether the “standard of care” (Do others in the local physician community or throughout the country perform the procedure?) is an appropriate measure? Does performing one C1-2 puncture per year, every other year, (chose a number) or having been trained during residency qualify an individual for the performance of this procedure?

The authors make reference to the use of simulation for those that perform below a certain number of C1-2 punctures per year. What is the number? Even if an individual performs 50 per year, does that mean this individual is competent? While the authors ask a valid and interesting question, the heart of the issue is procedural competency. As a medical community, we must move toward improved documentation of procedural competency. Our traditional system of medical education has outlived its usefulness1. Consider that today we still pursue the same medical education model that worked so well when the most advanced technology in America was the Model T¹.

The effect of the dwindling availability of highly experienced physicians will become apparent first in those countries where the most severe restrictions on patient contact hours have been enforced, in Europe before America, and in those systems that have rewarded efficient care by holding hospital stays as short¹. We must decide now how to train the next generation of specialists so that a gap in expertise does not produce an unintended and unfortunate consequence of modern medical education: increased medical errors and decreased patient safety¹.

Medical simulation can be segmented into 5 categories as proposed by David Gaba.² It is important to understand these different simulation methods because each has a unique characteristic and play different roles in education. As outlined by Rosen³, verbal simulation is simply role playing. Standardized patients (SP’s) are actors used to educate and evaluate history taking and physical examination skills, communication, and professionalism. Part-task trainers may be simple anatomical models of body parts in their normal state or representing disease. The more complex modern surgical task trainers are also included in this category. Computer patients are interactive and may be software-based or part of an Internet-based virtual world. These patients serve the same functions as SPs in many areas at a reduced cost. The most comprehensive form of simulation is the electronic patient. Electronic patients can be either mannequin or VR-based, and replication of the clinical environment is integral. This method can be the most costly and might be the best along with part-task simulation for learning spinal punctures.

Bradley⁴ has pointed out that the cost of equipment, personnel, and programs only recently have been overcome by the expansion of large collaborative simulation centers. These partnerships support the projection of increases in multidisciplinary, interprofessional, and multimodal simulation training. Rosen points out that despite obstacles of implementing medical simulation: surgical specialties are moving rapidly forward with incorporating simulation into competency requirements during residency and licensure; The American College of Surgeons has begun to offer a process of certification for multidisciplinary simulation centers; and in November 2007, the American Society of Anesthesiologists posted applications to offer a similar credential on its Web site.

Another obstacle that exists and antedate’s medical simulation is the lack of medical faculty who are well trained evaluators. As pointed out by Patel et al.⁵ many instructors in medicine are not trained to be evaluators, and this may limit the reproducibility, reliability, and objectivity of their assessment of the trainee’s proficiency. This will have to be addressed as we move forward in these forms of medical education. Potential roles of simulation include aptitude testing, early skills acquisition, advanced skills training, career long training, board examination, credentialing, pre-procedural rehearsal, procedural prototyping, and replacements for animal laboratories.1

In a systematic review of 109 published studies Issenberg⁶ looked at whether medical simulation facilitates learning and found that although the overall quality of the research was considered weak, the best available evidence did show a benefit for simulation when the following conditions are met: (a) educational feedback is provided, (b) learners are given the opportunity for repetitive practice, (c) tasks range in difficulty, and (d) the exercises based on the simulation are integrated into the curriculum. When criteria of functionality such as these are met, and in particular if the simulation and its content are appropriate, simulators could seemingly provide training and assessment of IR skills. The level of fidelity (accuracy) could then be chosen to suit the training objectives of the curriculum. Training would become learner-centered, performed at the learner’s pace and remotely from patients, with a new opportunity to learn safely from mistakes. There is a need for some proof of the effectiveness, or validity, of simulated training tasks or test items and of any complete procedures and their assessment methodologies. For training purposes alone, however, it is necessary to validate only that part of the simulation being used for training.

There are a multitude of reasons why simulation may be the best method for the determination of procedural competency, and whether more stringent documentation of procedural competency will be a key question in some medical legal cases, rather than whether the standard of care was practiced and whether the individual “trained” (in the more traditional sense) to perform the procedure. Medical simulation enables students and providers to learn, practice, and repeat procedures as often as necessary in order to correct mistakes and fine tune their skills without compromising the safety of real patients. Fidelity and validity issues still justify the skeptic’s delay in implementation7, but these issues will eventually be overcome.

References:

1. Dawson S. Procedural Simulation: A Primer. J Vasc Interv Radiol 2006; 17:205–213.
2. Cooper JB, Taqueti VR. A brief history of the development of mannequin simulators for clinical education and training. Qual Saf Health Care 2004;13:11-8.
3. Rosen KR. The history of medical simulation. Journal of Critical Care 2008; 23: 157–166.
4. Bradley P. The history of simulation in medical education and possible future directions. Med Educ 2006;40:254-62.
5. Patel AA, Glaiberman C , Gould DA. Anesthesiology Clin 2007; 25: 349–359.
6. Issenberg SB, McGaghie WC, Petrusa ER, et al. Features and uses of high fidelity medical simulations that lead to effective learning: a BEME systematic review. Med Teach 2005; 27:10 –28.
7. Day RS. Challenges of biological realism and validation in simulation-based medical education. Artif Intell Med 2006; 38:47-66.