Doctors at The National Brain Aneurysm Center in St. Paul, MN, use intraoperative angiography (IA) now in all of its surgical procedures as re-examination of the vascular anatomy may disclose a fundamental misinterpretation of the local anatomy on the part of the surgeon that could lead to an error without the use of IA.
Increases in the number of magnetic resonance images being performed in the state of Minnesota have caused an increase in the number of discovered brain aneurysms in the last 10 years. Many of the unruptured aneurysms were of the severe and complex variety treated via intracranial aneurysm surgery rather than with less invasive coiling procedures.
To ensure best possible results for patients undergoing microsurgery for intracranial aneurysms, the medical team at The National Brain Aneurysm Center in St. Paul, Minn., performed intraoperative angiography (IA) in each case over a 10-year period.
Eric Nussbaum, M.D., chair of the National Brain Aneurysm Center presented the results from the study, IA During Intracranial Aneurysm Surgery. Experience with 1,025 Cases, at the American Association of Neurological Surgeons annual meeting on Tuesday, April 29, 2008. Co-authors are Michael Madison, M.D., Michael Myers, M.D., and James Goddard, M.D..
The primary team of neurovascular surgeon Nussbaum and interventional neuroradiologist Madison focused the findings on cases in which IA altered surgical treatment. They began using IA as a means to ensure the titanium clip used to treat the aneurysm was correctly positioned and did not affect any other vessels, nerves or arteries during the procedure. Dr. Madison performs IA during every intracranial procedure by Dr. Nussbaum.
In 1997, IA added a mean 28.5 minutes to the surgical procedure; by 2006, this was reduced to 10.5 minutes. There were no major complications from any of the IA procedures.
Overall, IA resulted in clip repositioning or the placement of additional clips in 96 cases. Intraoperative angiography demonstrated unexpected aneurysm obliteration in 42 cases when the surgeon suspected additional clip placement would be needed. Those cases most impacted by IA included large/giant aneurysms, lesions with very wide necks necessitating multi-clip reconstruction and those cases in which confirmation of a patient bypass represented a necessary precursor to vascular sacrifice.
Drs. Nussbaum and Madison also found that in a small subset of 30 patients, IA demonstrated completely unexpected residual aneurysm or vascular stenosis. Careful re-examination of the vascular anatomy by Dr. Nussbaum disclosed a fundamental misinterpretation of the local anatomy on the part of the surgeon that would have led to an error without the use of IA.
In an exclusive interview with Imaging Technology News, Dr. Nussbaum describes the logic behind forming the neurosurgeon-neuroradiogist team, how the team operates together in surgery and why he believes intraoperative imaging will eventually become the standard of care for invasive neurological procedures.
Even as early as the 1970’s, Dr. Drake realized that if you could do an angiogram in the operating room, before the head was even closed, that would be the best opportunity to correct the problem. You be able to appreciate residual aneurysm.
Back then they didn’t have the equipment to do a good quality angiogram in the operating room or the image was so degraded that it was that helpful. Then people started to do intraoperative angiography, but not in a widespread fashion.
When I started my practice, I started up front with Mike Madison, who is an interventional radiologist. We said, there are all of those surgeons out there who are worried that coiling is going to take away their business, and there are all of these neuroradiologists starting to coil aneurysms, and take away the business for the neurosurgeon. We decided, why don’t we work together and decide what is best for the patient every time. One of the things that we thought was very important was to have Dr. Madison come into the operating room and do angiogram to minimize complications and maximize the benefit for the patient. I think it has worked out very well.
It would be difficult, but not impossible, for a surgeon had endovascular training to leave the head, do the angiogram, look at the images and then go back up. But you couldn’t have someone who is not very facile with surgical angiography because it is not the most optimal circumstances. You are working under the drape working with a C-Arm and there is a time limit when getting the catheter up to the carotid. So you need somebody who is get interpretable diagnostic images in a quick fashion. If it takes 25 minutes to get the image after putting the clip on, it may be too late to correct the problem.
The use of IA in all of our intracranial aneurysm surgeries gives us a deeper sense of assurance that we have completely corrected the problem, and that we have taken every step possible to ensure our patients' safety.
The main reason is formal angiography remains the gold standard for imaging aneurysms. The problem is that to some degree the titanium clip somehow creates artifact and causes difficulty with image interpretation, particularly with CT. There is a lot of scatter artifact with CT and MR as well. Plus, MR takes time compared to an angiogram, and although CT can be very fast, the images can be very degraded. With an average time being 10 minutes, in many cases we’ll have diagnostic images in a minute or two. If we are very worried about blocking something, we will have them stop the surgery, have them put a microcatheter up in the carotid or in the vertebral, put the clip on and then take the picture so we can have an image in 20 or 30 seconds from the time that we have applied the clip.
As a team, we have gotten better at it. I included that in my presentation because one of the biggest objections to do intraoperative angiography is that it is going to take a long time. But if you do it all the time, it doesn’t add hardly any time to the operation.
We published a year ago our experience on unruptured aneurysm and the risk of serious stroke was less than 1 percent. It would have been higher without the use of intraoperative angiography.
One of the criticisms has been the radiologist could cause a stroke during the angiogram. But we have not seen that at all.
I think intraoperative angiography will become more widespread and potentially standard.