The subspecialty of Endovascular Surgical Neuroradiology has evolved rapidly over a relatively short period of time. Originally developed by neuroradiologists and neurosurgeons, these less invasive approaches to treatment (within the blood vessels / percutaneous route) were developed to treat patients for whom no good open surgical option existed, or when conventional surgery had failed.
As a result of rapid advancement in computer technology and the development of new devices, the scope of this specialty has broadened from treating only those who could not be treated and helped otherwise, to become a mainstream of everyday practice, replacing certain forms of conventional surgery. Throughout this progression, the name of the specialty has evolved as well: interventional neuroradiology, surgical neuroradiology, endovascular neurosurgery, endovascular surgery, and endovascular therapy.
Major milestones of this specialty are exemplified through the evolution of treatment of brain aneurysm.
1979 – Fedor Serbinenko, a Russian neurosurgeon reported his experience with endovascular techniques using embolization of aneurysm. He created balloons on his own kitchen table.
1980s – Balloon embolization became the procedure of choice for otherwise untreatable brain aneurysms; results however were poor.
Late 1988 – Dr. Guido Guglielmi arrived at the University of California in Los Angeles to join Dr. Fernando Vinuela, and together they began research on what was to become the Guglielmi Detachable Coil (GDC).
March 1990 – The world’s first patient is treated with GDC coils at UCLA Medical Center.
1991-1995 – Early series in the United States using only high risk surgical patients.
1995 – FDA approval for the GDC coils; wider use begins.
1998-1999 – During this two-year period at UCLA, 200 aneurysms were treated with coils and led this change in the United States and around the world with this cutting-edge technology.
2001 – Results of a European study ISAT lay to rest the dispute between coiling vs. conventional surgery. More than 1000 patients with ruptured aneurysm were treated and randomized. Results: Coiled patients did better when compared to open surgical patients. Following this discovery, the trial ended. And today, more than 90% of aneurysms are being coiled all over the world and open surgery remains the second option that carries major risk.
Technological advancement did not stop, however, with the emergence of advanced coiling. Since 2001, 3D imaging, balloon assisted coiling techniques and stent assisted coiling has emerged.
Simultaneously, all the other types of vascular malformations of brain and spine (brain AVM, DAVF, CCF etc) are now treated with endovascular technique and became the treatment of choice.
History of Interventional Radiology.
It wasn't long after x-rays were discovered that scientists began experimenting with interventional procedures. Early in the last century, a dedicated scientist injected contrast into one of his own arteries, and the field of angiography was born. Within a few decades, radiologists were looking at the arteries that supply the legs, the aorta and its branches in the chest and abdomen, the arteries in the head and other areas of the body.
The preferred means of access became the femoral artery in the groin, which connects to just about every artery in the body. Different catheters were developed to allow access to small arteries. During the 1960s, the use of angiograms reached its first peak. There were few options back then, and angiograms became an important, although invasive, way of looking at many organs. Radiologists could, for example, inject dye right into the renal arteries and view exquisite renal vascular anatomy and tumors quite clearly.
It became possible to see arteries that were bleeding internally for any number of reasons. The dye is seen to "extravasate" or lie outside the artery in which it was supposed to have been confined. Now what? Suppose we could get a catheter into the artery that was bleeding and inject something through it that would stop the bleeding. We could inject vasopressin (substance that causes the artery to constrict), a porous, gauze material (ultimately absorbed by the body), or coils to clog the artery and stop the bleeding.
Radiologists were now able to map the vascular supply of the entire body and perhaps even stop internal bleeding. Back then, the radiologists would simply tell the surgeons what was going on, and the surgeons would decide what to do next. That was old-fashioned radiology.
Today, when an area in an artery is severely narrowed, instead of calling the surgeon and scheduling the patient for the operating room, in many cases an interventional radiologist can insert a catheter that has a balloon at its tip. When the section of the catheter that holds the deflated balloon is positioned right across the narrowed area, the radiologist inflates the balloon to "crack the plaque" and dilate the vessel. He may do this two or three times. Most of the time the vessel will stay open. If not, the radiologist can insert a small, reinforced tube (stent) to keep the artery open. This can be done to arteries in the heart (coronary angioplasty), to vessels in the belly (renal artery angioplasty), and to vessels supplying the legs and elsewhere.
What about the carotid arteries in the neck, the ones that supply the brain and have a tendency to get narrowed by plaque? Why not dilate them with balloons?
This would be a dangerous undertaking. First of all, when the balloon is dilated and kept dilated for 10 seconds or so, the artery is completely occluded and there is no flow of blood through that artery at all. Also, when the plaque is cracked, small fragments of the plaque, or small blood clots, may flake off and cause damage. The damage inflicted by the balloon is generally tolerated in the legs and even in the coronary arteries, but the brain is not so forgiving. Investigators continued to work on the problem and carotid artery angioplasty and stenting became a standard recognized, safe procedure.
During the period in which angiography was being developed, special procedures took on an additional role. Interventional radiologists are able to locate masses (e.g., cysts, tumors) in the body and insert a needle to aspirate cells or the core of the mass. For example, before ultrasound, CT scan, and MRI scan, all sorts of masses in kidneys that were nothing more than benign renal cysts that had almost no clinical significance. The problem was that we did not know which of these masses malignant tumors were. So what we did was place needles into these masses, under fluoroscopy; drain some of the material; and send it to the lab for analysis.
It was the advent of the ultrasound and CT that really made the difference here. We could see much more and could even sample tiny lymph nodes in the abdomen because we could guide our needles to it by CT. Or we could biopsy small lesions in the breast because we could see them on ultrasound and could actually watch on the screen as our needle was approaching the cyst or tumor. Biopsy of hidden body parts through the skin (percutaneous) became a specialty unto itself.
If you can take the fluid out of a renal cyst, why not drain other fluid collections in the body, for example, abscesses in the abdomen? Since radiologists can put needles into these abscesses for diagnostic purposes, why not just drain them and make surgery unnecessary? Not many abscesses can be drained with the same thin needles used for diagnostic purposes, so something a bit bigger, like a tube, is needed. Of course, inserting tubes increases complications and reduces patient comfort level. Complications, however, can usually be avoided with a good technique and experience. If surgery can be avoided, it is certainly worth a try.
Institute of Neurosciences, Kolkata offers all of these cutting edge technologies to our patients. We are proud to have the dedicated flat panel neuroangiography cathlab (Department of Interventional Neuroradiology & Endovascular Therapy) with 3D rotational ability for performing these high end procedures which can save life and can avert riskier open surgical procedures. Dr. Purkayastha, who is the Head of this department, is vastly experienced with more than 12 years of experience in treating these patients and is routinely performing all neuro and peripheral interventional procedures such as coiling, embolization, angioplasty and stenting etc since 2006 in Kolkata (CV of Dr. Purkayastha).
DIAGNOSTIC ANGIOGRAPHY – Cerebral & spinal
Diagnostic angiography is a procedure which physicians use to investigate abnormalities of the blood vessels. For the procedure a catheter is placed in the selected blood vessel and contrast is administered while a rapid set of x-rays is obtained analogous to time lapsed photography. It is the most accurate method to identify and define aneurysms, arteriovenous malformations, carotid stenosis and many other disease processes of vessels supplying the central nervous system. It is a relatively safe procedure, but the procedure is discussed in detail with each patient and their relatives before the test.
Conscious sedation and local anesthesia is given before catheters are placed. For most angiography access to the arterial or venous system is safely via the femoral artery or vein in the groin area. The catheter is navigated into the aorta and then up into the cervical vessels under fluoroscopy in flat panel neuroangiography machine. Contrast is administered and xrays are taken to examine the arteries and veins in the brain, head or spine. Typically, the two carotid arteries in front and the two vertebral arteries in the back of the head are studied, so the brain angiogram may last from 15 to 45 minutes. In spinal angiogram, in addition to these arteries, bilateral all intercostal, lumbar arteries angiogram are also done. As part of this, we may obtain a 3-D Rotational Angiogram. Here the x-ray tube rotates around the patient collecting images. The tube then moves in reverse while contrast is given. The images are subtracted and reconstructed into a 3 dimensional model. Afterwards, the puncture site must be compressed manually after taking out the femoral sheath and the leg held straight for up to 3-6 hours to allow the artery to heal sufficiently before discharge. Most patients undergoing diagnostic angiography need to stay in the hospital for 12 hours depending on the type of catheter used and the type of closure used. This may include hemostatic patch with manual compression. Patients are always seen by a physician prior to discharge. After angiography, patients are instructed to avoid heavy lifting or exercise for 10 days and avoid swimming for 5 days. If bleeding should occur patients are instructed to go to have someone apply direct pressure to the site and go to the nearest emergency room.
CT ANGIOGRAPHY / PERFUSION
We routinely perform, CTA for the diagnosis and treatment planning of neurovascular diseases. This includes aneurysm detection, acute stroke and venous occlusive disease. CT angiography is performed with a series of thin slice axial images during a bolus of IV contrast. Data is manipulated by our technologists to show the blood vessels in the head or cervical region. Detection of aneurysms 3 mm or greater is excellent. It is possible to distinguish berry or saccular aneurysms, which occur at bifurcations in the Circle of Willis from other types. These include fusiform (spindle shaped) aneurysms and dissecting aneurysms due to a tear in the artery wall. Distal vessel aneurysms may have infectious, traumatic or neoplastic etiologies. We also use CTA to define carotid or vertebral artery diseases such as stenosis or dissection. It is invaluable for evaluating patients in the Emergency Room who present with acute stroke. We obtain a CTA of the entire cerebrovascular system from the aortic arch to the top of the head to determine the cause of the stroke. We also perform a CT perfusion scan to look for blood flow abnormalities in regions of the brain before taking the patient for acute stroke treatment. We perform all forms of endovascular stroke treatment such as IA thrombolysis and thromboaspiration.
MRI DIFFUSION & PERFUSION
MRI and MR angiography provide another method of examining the brain, spine and vasculature. MR imaging of the brain yields a more detailed examination of the tissues than CT, but it is a more involved procedure. MR angiography is used as a screening method for cerebrovascular diseases such as aneurysms, vascular malformations or stenoses. It is the study of choice for patients with suspected carotid or vertebral artery dissection. With gadolinium enhanced MRA, the data provided is similar to CTA for carotid stenosis. Diffusion and perfusion weighted MR imaging is a good method of evaluating ischemia (lack of oxygen supply due to arterial blood clot) and blood flow to the brain. Diffusion weighted MR imaging (DWI) examines the passive movement of water molecules, which tend to be restricted in areas of acute infarction. It can identify an acute stroke within an hour of onset in 95% of cases. Perfusion weighted MR imaging is used to identify areas of ischemia. In combination with DWI, one can look for areas of tissue at risk for infarct. Many times these areas can be saved by interventions with the care of the Neurology and Interventional Neuroradiology services.
ANEURYSM TRERATMENT – COILING / STENT & COILING
An aneurysm is an abnormal bulge in the wall of an artery due to weakness or injury to one or more of the three layers of arterial wall. Most are likely the result of a genetic alteration, although infection, trauma, or atherosclerosis can cause aneurysms. Many patients are asymptomatic or present with mild headaches. 40% of patients may have warning signs such as localized headache, cranial nerve paralysis, nausea or vomiting. They may have severe headache, photophobia, neck stiffness or even loss of consciousness resulting from the intracranial hemorrhage called subarachnoid hemorrhage (SAH). 30% die before reaching hospital resulting from SAH. Cigarette smoking may play a role in aneurysm development.
Brain aneurysms are usually acquired with age, but frequently a baby is born with a weakness in the arterial wall. A few medical syndromes, such as Polycystic Kidney Disease are associated with brain aneurysms, and these patients require screening.
The most significant risk factors for brain aneurysm are cigarette smoking and having a close relative who has an aneurysm. Most aneurysms are incidental, meaning that if you have one; it is unlikely that anyone else in your family has one. However, a small percentage of aneurysms run in families, and if you have two or more close relatives with a history of brain aneurysm, it is strongly recommended that all next-of-kin be screened.
Brain aneurysms affect more females than males (3:2), and 15-20% of patients have multiple (two or more) aneurysms. The average age at presentation is usually between 40-60 years of age, but I’ve treated small children, teenagers, and adults into their 80’s.
Aneurysms are classified by their size and shape:
- A berry shape is the most common. It is a small saccular shaped aneurysm resembling a berry.
- The fusiform shape is an elongated, spindle-shaped dilation.
- The dissecting aneurysm splits an artery wall through a small tear.
- Small – less than 10 mm (most commonly aneurysms are 4-7 mm in size)
- Large – 10-25 mm (a dime is 18 mm)
- Giant – Greater than 25 mm
Approximately 85% of aneurysms develop in the anterior (front) portion/circulation of the brain; 15% are found in the posterior (back) portion/circulation of the brain.
The most common locations are: Anterior Communicating (A-com) aneurysm, Posterior Communicating (P-com) aneurysm, Middle Cerebral Artery (MCA) aneurysm, Carotid Bifurcation aneurysm, Basilar tip aneurysm, and PICA aneurysm.
The risk of an aneurysm rupture is estimated at 1% per year and may vary with aneurysm type, size, location, and history of previous aneurysm rupture. When a brain aneurysm does rupture, the blood usually goes into the subarachnoid space (a space that closely surrounds the brain), or less commonly directly into the brain substance. A higher incidence of aneurysm rupture occurs during Spring and Fall; however, the reason for this has not been fully explained.
Patients with ruptured aneurysm often complain of a severe headache, and describe it as “the worst headache of my life!” A subarachnoid bleed (hemorrhage) is considered a medical emergency with potential major complications to the patient. Up to 30% of these patients die before arriving at the hospital. Another 30% are at major risk for stroke, since bleeding from the aneurysm will often cause the major blood vessels of the brain to become severly narrowed. This condition is called vasospasm. Many patients after surviving aneurysm rupture and vasospasm are permanently disabled and are unable to return to their previous activities.
Most patients have no symptoms or complaints until the aneurysm ruptures. In 40% of cases, there are some warning signs that an aneurysm is present, such as pain above and behind the eye, nerve paralysis, localized headache, neck pain, nausea and vomiting.
Catheter angiography remains the gold standard for detection of aneurysms. Diagnosis of aneurysms can be accomplished by MRI or CT angiography, although lesions less than 2-3 mm can be missed by these methods. Patients with unruptured aneurysms are usually referred to the Interventional Neuroradiology or Neurosurgery departments. When a patient with an appropriate clinical history suggesting subarachnoid hemorrhage presents to INK, he or she is examined, stabilized and brought to the Neuroradiology department for CT scan and CT angiogram of the brain. The data is analyzed by Neurointerventionalist. Patients are given the treatment choices, which address their particular aneurysm and clinical situation with consideration given to the potential risks.
Options for treatment of an aneurysm include coil embolization, which is done through a catheter inside the artery. The Neurointerventionalist places a guide catheter in the femoral artery in the groin, which is brought up to the neck using fluoroscopic x-ray guidance. A microcatheter is then brought through this guide catheter and navigated into the aneurysm. Small platinum coils are then passed through this system to fill the aneurysm and prevent arterial pressure from causing a bleed. In complicated aneurysms a temporary balloon or a stent may be placed to hold the coils in place. The catheters are removed, and the access site in the femoral artery is sealed using a closure device or manual compression. The neurosurgical alternative is to cut open the skull and place a clip across the neck of the aneurysm excluding it from the circulation. The recent International Subarachnoid Aneurysm Trial (ISAT) data suggests that patients, who can be treated by either method, have a better outcome with coiling than those treated surgically. The relative and absolute risk reductions in dependency or death after allocation to an endovascular versus neurosurgical treatment were 22.6% (95% CI 8.9-34.2) and 6.9% (2.5-11.3), respectively. In some cases occlusion of the artery with reliance on collateral circulation or bypass may be the treatment of choice. These procedures are done under general anesthesia. Patients with unruptured aneurysms usually stay in the hospital for three days, the first of which is spent in the Neuro-intensive care unit for close monitoring. Patients with ruptured aneurysms need to stay in the hospital for at least 14 days to be watched for several important medical reasons including the grade of the initial bleed, hydrocephalus and vasospasm which may need treatment after the initial coiling of the aneurysm.
For elective cases patients and their families are seen in the department before the procedure to discuss the procedure and the potential risks and benefits. Attention is given to each individual’s medical history, and all questions are discussed. Cases are reviewed by a multidisciplinary team including Neurosurgery and Neurology members in our daily morning Cerebrovascular meeting. A member of the neuroanesthesia department screens patients prior to the procedure. After a patient goes home, it is important to avoid heavy lifting/exercise for at least 10 days. Follow up after aneurysm treatment is done by angiograms at intervals of 1, 3 and 5 years to insure the best care. In a small percentage of cases, patients may need additional treatment for aneurysm regrowth.
Balloon assisted coiling
This procedure involves coiling (as above) in combination with a tiny balloon catheter to aid in holding the coil in place.
Combination of stent and coiling
This procedure involves coiling, as above, in combination with a stent (a small flexible cylindrical mesh tube) that provides a scaffold for the coil mass. This technique is very important for the management of wide neck and fusiform aneurysms.
Open surgery – Aneurysm Clipping
A surgical procedure requiring creation of an opening in the skull through which the surgeon’s instruments can enter. The surgeon can then place a clip across the neck of the aneurysm, preventing arterial blood from entering it. If there is a clot in the aneurysm, the clip also prevents the clot from entering the artery and possibly causing a stroke.