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Colorado Neurological Institute (CNI)
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CNI Interventional Neuroradiology Service
Here is a brief summary of some of these technologies which are available at the CNI: Advanced Diagnostic TestingIntra-operative Angiography: In the past fifteen years, in some centers, radiologists have been called to the operating room to perform intra-operative angiography. Greater refinement in mobile imaging technology have made this possible. Often, it is helpful to radiographically confirm that a lesion has been completely obliterated prior to terminating the surgery. Occasionally, it is not entirely clear whether or not this has occurred. Intra-operative angiography can help confirm that the goals of the operation have been met, thereby enabling the patient to avoid possible second surgery. In certain circumstances, it is also helpful to confirm the status of the normal anatomy to avoid the potential for complications. Balloon Test Occlusion: In some circumstances, it is helpful to ascertain in advance of any therapeutic intervention, whether or not intentional sacrifice of one of the carotid arteries will result in a low flow state which could lead to a stroke This is especially true in the case of some giant aneurysms, where such intentional blockage of the carotid artery may be the best treatment. One can get a general idea from the standard angiography whether or not the patient would tolerate intentional carotid artery sacrifice. Nevertheless, the balloon test occlusion is a better test for predicting how a patient may respond. In this test, a balloon is inflated in the carotid artery to temporarily block flow while the patient is awake in the angiography suite. The patient is monitored for a minimum of thirty minutes to insure that there are no clinically apparent problems. This test can therefore be helpful in cases in which carotid sacrifice may be the only option of treatment available for certain lesions. Interventional Therapies Available at CNIBrain Tumor Embolization: On occasion, it is helpful to reduce the blood supply to a brain tumor prior to surgery in order to facilitate the safety of its removal. In such instances, a catheter may be navigated up to the in-flow source to the brain tumor. Small particulate material, such as polyvinyl alcohol foam may be injected into the tumor blood supply, thereby, making the surgery easier and reducing the amount of blood loss at the time of surgery. This technology can greatly improve the safety profile of some surgical procedures. Occlusive Cerebrovascular DiseaseExtracranial Carotid Atherosclerotic Disease: The gold standard for the treatment of stroke and stroke-like symptoms due to atherosclerotic disease involving the carotid arteries is carotid endarterectomy. However, it may be desirable to employ an alternative treatment method depending upon the patient's medical condition, and other factors. In the past eight years, balloon angioplasty and, subsequently, the placement of stenting devices has arisen as a possible treatment alternative for this disease. Stenting has evolved as the preferred interventional radiological treatment alternative. In such cases, a radiological catheter is advanced to the region of the narrowing of the artery. The stent is subsequently deployed which compresses the atherosclerotic plaque and thereby enlarges the space available for blood flow. Radiographic results of these procedures can often by spectacular, although in contrast to carotid endarterectomy, this procedure has not yet been conclusively proven to reduce the incidence of stroke as has been carotid endarterectomy. This procedure should only be attempted by an experienced cerebral vascular team with the input of a neurologist or neurosurgeon specializing in this area being greatly helpful. Nevertheless, in certain selective patients, this appears to be an ideal alternative to surgery and this is a procedure which is available at CNI. Patients who are not symptomatic probably should not be considered for this type of treatment. Intra-arterial Thrombolysis: Although a proven front line therapy for strokes that present within three hours, intravenous thrombolysis, using the "clot busting" drug TPA, some patients fall outside the three hour window or fail to respond to the drug. In such instances, another treatment alternative that is available is intra-arterial thrombolysis. A catheter can be advanced into the cerebral arteries, and an angiogram performed to reveal the exact sight of blockage of the artery. The catheter may be advanced into the clot to mechanically disrupt the clot as well as used for infusion of local TPA. This can be a very effective means of reversing a low blood flow state which also allows for monitoring the results of your treatment. This is another contemporary technology available at CNI. The photos below show a case of a right middle cerebral artery embolus that was treated with intra-arterial thrombolysis. The first slide is with the right middle cerebral artery occluded. The second is recanalization after IA TPA. Cerebral Aneurysms: In the early 1990's, the Guglielmi detachable coil (GDC) was first introduced. Initially, attempts were made to try to exclude aneurysms from the circulation by placing balloons within their origin. The GDC coil became preferable. In this technique, a platinum coil is advanced into the aneurysm and it is subsequently detached by electrolysis. The coils fill the aneurysm sac and thereby exclude it from the circulation. This procedure can only be employed under certain circumstances and the joint input of a neurovascular surgical team is imperative. This appears to be a good method of preventing aneurysms from re-rupturing, at least in the short term. The ability of these to prevent hemorrhage over many years, as has been demonstrated with aneurysm clipping, is still being determined. Fortunately, this technology is available at CNI so that each patient with an intracranial aneurysm can be considered on an individual basis as to whether or not GDC coiling or surgery is the most optimum treatment. Learn more about aneurysms. Intracranial Angioplasty: Patients suffering subarachnoid hemorrhage due to an aneurysm in many cases will undergo a process called cerebral vasospasm. Blood that has leaked out at the time of the hemorrhage can be irritating to the large vessels at the base of the brain. Although the exact mechanisms by which this occurs in not known, the vessels may undergo progressive narrowing which can lead to a reduced blood flow state to the involved area of brain which may go on to a complete stroke. Traditionally, this has been managed by fluid resuscitation and enhancement of the heart's contractility and output. It appears at this point in time that the best means for reversing this, which also has a durable and lasting effect, is cerebral angioplasty. A catheter is navigated to the area of spasm, and a balloon is inflated which stretches the artery back to its original configuration.
Arteriovenous Malformations: Arterial venous malformations are congenital lesions which consist of an arterial input and a venous outflow. Arteries carry oxygenated blood which is under considerably higher pressure than that which is seen in veins, which carry deoxygenated blood back to the heart. In an AVM, the normal intervening capillary bed which would otherwise be present is replaced by a tangled mass of abnormal vessels. The normal transition of pressurized oxygenated blood toward the veins does not occur. The veins, thereby, carry a pressurized and oxygenated blood away from the center, or nidus, of the AVM. These AVM's will often present with seizures or hemorrhage. A hemorrhage from an AVM may be life threatening. Hence, under appropriate circumstances, it is necessary to remove the arterial venous malformation either with surgery or with a combination of surgery and embolization. Another alternative available for the treatment of vascular malformation is also available at the CNI, stereotactic radiosurgery. Historically, beginning in the late 1980's, the surgery on AVM's was facilitated by embolization using substances such as polyvinyl alcohol. As with brain tumors, this decreased the amount of bleeding seen at the time of surgery. Since AVM's carry a large amount of high pressure blood flow, the risk of blood loss can be prohibitive. Hence, many large lesions were never operated upon since the risk out weighed the risks of the natural history of the lesion. Although the combination of embolization and surgery advanced the treatment of this disease, some large lesions still remained untreated. Dr. Yakes, at CNI, has been the pioneer and torch bearer of a new type of treatment which was developed at CNI. In this method, he has infused the AVM with absolute ethyl alcohol. This has resulted in immediate sclerosis of the embolized vessels. In lesions in which he has been able to obtain a complete radiographic obliteration of the lesion, he has experienced at 69% cure rate. This type of treatment has not been duplicated elsewhere. Dr. Yakes has been invited to many destinations around the globe to educate others about this technique. Thus, a large number of patients have been spared the need to have open surgery. Vein of Galen Malformations: A special type of arterial venous malformation is called a Vein of Galen malformation. This is essentially an AVM or a fistula which drains into the Vein of Galen. The Vein of Galen drains the deep structures of the brain. This type of lesion is seen in children. Dr. Yakes has treated many patients using a combination of transarterial and transvenous embolization, often with alcohol. He receives referrals from all over the United States for the treatment of this disease. Arteriovenous Fistulas: A fistula is a direct connection between an artery and a vein. These can be very dangerous, in a similar fashion to arterial venous malformations. Here, the vein carries an even higher pressurized flow of blood than does an AVM. Symptoms can result from a variety of means. Carotid Cavernous Fistulas: This type of fistula often occur as a result of trauma. Here, the carotid artery develops a direct connection with the cavernous sinus, a network of veins which surround the carotid artery and runs adjacent to the optic nerve. Patients who have carotid cavernous fistulas often go blind in the involved eye. CNI interventional team has used a variety of techniques to treat carotid cavernous fistulas using only radiological means, thereby sparing patients the need for surgery. Dural Arteriovenous Fistulas: A dural arterial venous fistula is an abnormal connection between an artery supplying the scalp and skull, usually with a specialized type of vein in the lining of the skull called a sinus. These often present later in life and usually have symptoms such as a whooshing sound in one ear. These lesions become particularly dangerous when this high pressure flow enters a vein which normally drains an area of the brain. Since these veins are not accustomed to this type of pressure, they may rupture. Therefore, treatment is indicated to prevent recurrent hemorrhages. Embolization using either alcohol or polyvinyl alcohol is often performed in conjunction with surgical interruption of the involved vein. There have been an increasing number of cases, however, that are being cured at CNI using purely endovascular means. Thus, many of these patients are being spared the need to have surgery. Team MembersDonald F. Frei, Jr., MD, Interventional Neuroradiologist,
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Dr.
Frei attended medical school at the University of Cincinnati. He completed
his Diagnostic Radiology Residency at Tulane University Medical Center.
He then completed both Diagnostic Neuroradiology and Interventional Neuroradiology
fellowships at the Mallinckrodt Institute of Radiology in St. Louis, Missouri.
Currently, as a member of Radiology Imaging Associates, Dr. Frei performs
minimally invasive Interventional Neuroradiology procedures, including
acute catheter directed stroke intervention, angioplasty/stent revascularization
of cerebrovascular stenosis and minimally invasive treatment of cerebral
aneurysms and arteriovenous malformations. Dr. Frei, as a member of the
CNI Stroke Council, is working towards establishing state-of-the-art diagnosis
and management strategies in treating patients with acute stroke. Dr.
Frei is a senior member of the American Society of Interventional and
Therapeutic Neuroradiology and the American Society of Neuroradiology.
Dr.
Huddle completed medical school and radiology residency at Michigan
State University. Subsequent training included a fellowship in Diagnostic
Neuroradiology at University of Chicago School of Medicine and a fellowship
in Interventional Neuroradiology at Yale University and Harvard School
of Medicine/Massachusetts General Hospital. Following his faculty position
at the University of Colorado Health Sciences Center, he joined Radiology
Imaging Associates and Colorado Neurological Institute. His focus is minimally
invasive treatment of aneurysms, AVMs, dural fistula and acute stroke.
Dr. Huddle is a senior member of the American Society of Interventional
and Therapeutic Neuroradiology and American Society of Neuroradiology.
Dr.
Yakes, attended Rice University for undergraduate studies and graduated
from medical school at Creighton University. He served 12 years in the
US Army, including service in Desert Storm. Dr. Yakes was board certified
in 1983. He has subspecialty training in Interventional Radiology and
Interventional Neuroradiology. He established the Vascular Malformation
Center at Swedish Medical Center in 1991 to specialize in the diagnosis
and management of vascular anomalies in all anatomic locations. It is
the only center in the world that is totally dedicated to the management
of vascular malformations and is referred patients from virtually every
country in the world. 
