And the last but not least speaker, certainly not the shortest anyway, Mika Nymala from Helsinki, who's going to talk to us about dural fistulae, characteristic treatment and long-term outcomes. That's another very interesting topic between endovascular, open, and so forth. Thank you very much for the kind invitation, and until the slides come up, I will say that Finland is perfect for follow-up studies because of our small 5.5 million stable population. We have a lot of registries and statistics. Patients are willing to participate in follow-up studies, and we perform autopsies with the highest frequency in the world, so we actually know what's going on with these patients. Well, I take the opportunity to welcome you all to Helsinki. I have no disclosures. This work is based on one of my Ph.D. students, Anna Pieper's, thesis about dural fistulae's characteristics, treatment, and long-term outcome. You can find dural AV fistulae anywhere. You can find dura and adjoining veins and arteries. The most common locations are behind the ear in sigmoid and transverse sinuses and in the carotid cavernous fistula area, and the symptoms depend, of course, on the location. Sometimes you have a situation like this that numerous dural AV fistulae appear, and there's almost nothing you can do about it. Maybe anti-angiogenic therapy may resolve the problem in some cases. Symptoms depend on the location. Sometimes the bruise is intolerable. Patients may be suicidal, or they have problems with the eyes, so these lesions, even if not always fatal, they cause a lot of discomfort. Bleedings may be small often, but they also may be large and cause mortality. Typically not. There's a Borden classification that we use in this series. It can be criticized. Christophe Cognard from Toulouse has created another scale which sometimes is preferred, but we use the Borden classification. Borden 1 drains directly into major venous sinuses. Borden 2 drains into venous sinus with retrograde drainage into veins. And then Borden 3 drains directly with cortical venous drainage. The history of the surgery of dural AV fistula started a long time ago. There were some external clamps that were used to occlude the proximal arteries. Also, some extensive surgical approaches were described, which had often morbidity and mortality in themselves. Later on, also less invasive surgical approaches were described that occluded only the feeder. Later on, of course, embolization, stereotactic radiotherapy came available, and I will come back into those. However, there were questions, what to treat when, how, questions and answers. Aims of this particular study was to analyze the characteristics and results of treatment in a large series, excess mortality. That can be done almost exclusively in Finland. So you compare the survival of these patients to age, gender, and time-matched population. So people in the 60s lived shorter than they live nowadays. So this takes into account that as well. And also to describe the techniques and results of microneurosurgical treatment and maybe give some recommendations. So there were 261 duralevi fistulas in this first paper that was published in Journal of Neurosurgery 2013. Patients were admitted to two of the five departments in Finland between 1944 and 2006. There was a slight female predominance in this series, and the median age was about 56 years in this series. The most common symptom was a BRUID. Some patients had headache, chemosis, hemiparesis, seizures were less common, and cardiac symptoms were almost non-existent. BRUID was the most common symptom, and that really can be disturbing for the patients. Most of the cases, we couldn't tell why this duralevi fistula came in two-thirds of the cases. It was difficult to say. Only in 20% there was a trauma behind it that could be linked to the duralevi fistula. The most common locations were transfers and sigmoid sinuses. In all of the patients, it was the most common locations. Others were less common. Cortical venous drainage was detected in 34% of the duralevi fistulas, more often for unknown reasons in men than in women. We didn't really know why that was. Hemorrhage was detected in altogether 13% of these patients, more common in men than in women for unknown reasons as well. Treatment. This was a historical series studied from 1944, so there were all kinds of treatment modalities, starting from conservative to ligation of ICA or ECA, craniotomy resection, embolization, stereotactic radiosurgery, or a combination of all of these. To talk about the results, the incidence was 0.51 per 100,000 per year, and it comprised 32% of all intracranial AVMs at our department. And the catchment area of Helsinki neurosurgery in 2001 and 2005 was 1.8 million. If you want to achieve the best results, you should operate these patients, but then you have the highest complication risk, so that is not the recommendation. Craniotomy had the best results concerning total occlusion of these. Putting all together, the outcome was very good in 87% of the patients. During the median follow-up of 1.5 years, mean was 3.1, and range was up to 40 years. The second paper was focusing on excess mortality of these patients, and in this series we had 227 consecutive patients with 234 duralevy fistulas treated at these two departments. Out of the five departments, survival was compared with matched Finnish population, meaning age, gender, and calendar time were matched, and we calculated the relative survival ratio. And this is how it looks like. The annual relative survival ratio was lowest during the first year after admission, and during the first year, deaths were mainly due to treatment complications. However, if you have a duralevy fistula with a cortical venous drainage, which presented often with hemorrhage, there was excess mortality up to seven years after treatment. There was no difference between men and women. There was long-term excess mortality in duralevy fistulas in other locations than transverse sigmoid sinuses. Causes of death, there were more cardiovascular deaths than expected in the matched general population among these patients for unknown reasons. And the last part of this talk is to give the results of microsurgery of duralevy fistulas. This is a historical series studied a long time ago, and these patients were operated. This is a single surgeon series operated by my predecessor, Juha, between 1980 and 2010. Most common locations were in transverse sigmoid sinuses. In almost 60 percent of the cases, less common. You can, the second most common was cavernous sinus. Occlusion rates, you can achieve high occlusion rates with surgery. The problem is that major complications could be detected in 14 patients comprising 12 percent of the series. There were hemorrhages and severe brain swelling during and after surgery. So the incidence of duralevy fistulas in our series in this geographical area, this is a consecutive series, patients treated in two catchment areas, is twice as high as in previous reports. Occlusion rates of duralevy fistulas have improved, especially after onyx. Complication rates are rather high, and they are higher in microsurgery than embolization. And there is treatment-related excess mortality during first year after admission and long-term excess mortality in one-year survivors in those duralevy fistulas that have cortical venous drainage and those in other locations and transverse sigmoid sinuses and those presented with hemorrhage up to seven years. And more cardiovascular deaths were detected than expected. So recommendations, if patients have tolerable symptoms or no symptoms observed. Intolerable symptoms, BRUID can be suicidal almost, occlusion is recommended. Embolization is the gold treatment and or radiosurgery. Microsurgery only if embolization or radiosurgery fail. Duralevy fistulas with cortical venous drainage, occlusion of the fistula, or at least cortical venous drainage, is recommended by embolization. Microsurgery only in selected cases or if embolization fails. Radiosurgery is rarely an option. Thank you very much. Thank you, Mika. Any questions from the audience to Dr. Niemanna? Greg? Can you just describe what the surgical approach goals were? Was it complete obliteration of the fistula or was there a time where selective disconnection of the cortical venous drainage was utilized in that impact outcome? In the early series, it was just complete eradication. And later on, the occlusion of just the draining. But nowadays, I think embolization really has changed everything. There's a nice paper out from Chris Wallace in Toronto where they compared, historically at Toronto, where they went for complete obliteration microsurgically compared to a later era where they did selective disconnection. And morbidity goes down a lot if you just do selective disconnection. And the follow-up on that in terms of hemorrhage protection rates were the same between the two groups. So it's just a way to reduce morbidity. Yeah, we had the same feeling, yeah. Mika, just a brief word about indications for treatment. Let's say a burden, too. Do you make a difference whether they're symptomatic, asymptomatic? Greg Zipfel has done beautiful work on this topic. Well, Greg can speak for himself, but challenged a little bit the concept that, well, you know, higher grade means necessarily treatment. Not necessarily depends on the symptoms, the patient's age, and what he or she wishes. But if the patient is young, has intolerable symptoms, then we would go for treatment. Greg, can you summarize for the audience what you came up with? Yeah, so the early series with type 2 and 3 duralabe fistulas were almost all patients presenting with hemorrhage. And then, you know, in more current times, a lot of these patients are coming in incidentally with MRIs and so forth. So we have looked at it, Rose Du and Brigham has looked at it, and Soderman has looked at it in three separate populations. And what you see in all three of those series is that if you present with hemorrhage or non-hemorrhagic neurologic deficits, what we would categorize as aggressive symptoms from cortical venous hypertension, that patient population does very badly with 10%, 15% neurologic event rates per year with a 3% or 4% mortality rate per year. But if you take those who present completely incidental or with just symptoms of increased sinus drainage like tinnitus, those patients have an event rate of about 1.5% per year and 0% mortality. So it's significant, but it's much less than those presenting with aggressive symptoms. And so I think our conclusion on that is that you can be certainly more elective with the treatment, and I think you can be more selective with the treatment. If someone has advanced age, if someone has a lot of comorbidities, you may not treat at all. Or if the surgical or endovascular looks difficult or more complex, you could use radiosurgery because the annual event rate is only 1.5% per year, and so radiosurgery over two or three years seems reasonable. If they have aggressive symptoms with 10% or 15% event rate, radiosurgery is not an option. So I think you can tailor your approach, in my opinion, with using mode of presentation as part of your rule or your protocol. Doctor, this is a question. How do you follow that asymptomatic group that has a low event rate, and so you decide I'm going to follow this patient over the course of many years, given that with noninvasive imaging you might not appreciate a change? Well, if it's a type 2 or 3 fistula, they have cortical venous drainage, and because of advanced age or medical comorbidities are substantial and we're just going to conservatively treat them, I would just follow them along clinically, because we've determined from that initial assessment that their life expectancy is going to be short and it's not worth it to undergo risk. The other population that that follow-up comes into play is type 1 duralated fistulas without cortical venous drainage. How do you follow those? There is an upconversion rate, so about a half percent per year, a type 1 fistula will upconvert to a type 2 or 3 with cortical venous drainage, a more aggressive type. But every upconversion that's been reported in the literature has been associated with a change in symptoms. Either they develop new symptoms, new tinnitus, recurrent tinnitus, if it's been partially treated, or spontaneous resolution of their symptoms, loss of tinnitus or change in their ophthalmologic examination. So a change in symptoms, positive or negative, in the type 1 duralated fistula group we think mandates catheter angiography because with that spontaneous change there could have been a change in the fistula leading to an upconversion. If you found then it's a type 2, for example, then you want to treat it. So we follow them along clinically. The type 1s we follow along clinically. If there's any change, positive or negative, with symptoms, reangiogram, but we don't routinely do a follow-up angiogram. Type 2 and 3 fistulas where you think you're going to treat conservatively because of age or medical comorbidities, we follow them along clinically. We have the same policy.

dural fistulae

treatment

long-term outcomes

Borden classification system

surgical approaches