With important medical advances throughout the neurosurgical/neurological and endovascular fields, treatment for brain aneurysms is more promising than it was several years ago. There are more effective and less invasive treatment options for patients, who in years past, would have been told they had inoperable aneurysms. Decisions regarding management of an unruptured brain aneurysm are based on the careful comparison of the short- and long-term risks of aneurysmal rupture, compared to the risk of intervention whether that is surgical clipping or endovascular management.
If an aneurysm is detected but has not ruptured, there are more options: either treatment or observation. Once an aneurysm has already ruptured, the options are either open surgery or an endovascular approach. Either is recommended to be performed as early as possible after hemorrhage, to prevent rebleed of the aneurysm. The goal of either treatment is to prevent rebleeding by sealing off the aneurysm so that the aneurysm is totally obliterated with either a clip or coil.
Doctors consider several factors when deciding which treatment option is best for a particular patient. These include:
Patient age
Size of aneurysm
Location of aneurysm
Shape of aneurysm
Neurological condition of patient
Other medical conditions
Previous history of SAH or familial aneurysm
Treatment options: Clipping
Clipping is a common surgical treatment for brain aneurysms.
It is an effective, well-researched surgical procedure with excellent results. The goal of clipping is to place a small metallic clip or clips along the neck of the aneurysm. This prevents blood from entering into the aneurysm sac so that it can no longer pose a risk for bleeding. Once an aneurysm is clipped, the clip remains in place for life. The aneurysm will shrink and scar down permanently after clipping.
Unruptured Aneurysm
For the aneurysm clipping procedure, the patient is put under general anesthesia, and then prepped for surgery. The head is stabilized to make sure it does not move during the surgical procedure. Depending upon the location of the aneurysm, an incision is typically made behind the hairline or on the back of the head. A small portion of the hair is usually shaved along the line of the incision. Next, a section of the skull bone is removed from the skull using a specialized bone drill. This gives access to the lining over the brain called the Dura. The Dura is then opened to expose the brain surface. The surgeon approaches the aneurysm in the cleft between the skull and the brain and not through brain tissue. Under a microscope, the aneurysm is then carefully separated from the normal blood vessels and brain.
Clipped Aneurysm
Once it has been fully exposed, the aneurysm is then completely obliterated with a tiny metal clip, something like a tiny clothespin. This keeps blood from entering the aneurysm. As a result, future bleeding is prevented and nearby brain tissue is protected from further damage. The bone plate is then put securely into place, using thin metal plates and screws, and the wound is closed. These bone plates are MR compatible and remain in place permanently, although the skull bone will heal together over 6 – 12 months. The great majority of aneurysm clips are also MR
compatible but you should check with your surgeon prior to having an MRI.
Occlusion and Bypass
In some cases, it may be best to stop blood flow through the artery leading to the brain aneurysm. This is known as an occlusion. Sometimes the aneurysm has caused severe damage to the artery, so the doctors go in and completely shut down that part of the artery and reroute the blood. This procedure is usually done as an open surgery, which requires similar surgical preparation as in a clipping procedure such as having your head shaved, and a section of the skull bone removed.
Sometimes an occlusion is combined with a Bypass. A bypass reroutes blood flow around the occluded artery. Doctors take a small blood vessel from another part of your body, usually the leg, and graft it to a section of the brain artery where it makes most sense. This new artery (bypass) brings blood to the part of the brain that had been fed by the damaged artery.
Endovascular Embolization or Coiling
Endovascular (meaning within the blood vessel) embolization, or coiling, uses the natural access 
to the brain through the bloodstream via arteries to diagnosis and treat brain aneurysms. The goal of the treatment is to safely seal off the aneurysm and stop further blood from entering into the aneurysm and increasing the risk of rupture or possibly rebleeding.
Endovascular treatment of aneurysms is a treatment that became available in the 1980's. With the advent of this treatment, some patients who previously may have been told they had inoperable aneurysms are now given an alternative and a chance for treatment. Currently many aneurysms that are amenable to surgery for clipping can also be considered for coiling and the risk and benefits of each treatment must be discussed with the treating physicians. In some patients, because of advanced age, serious medical problems or other factors that increase the risk of brain surgery for clipping, coiling is the preferred treatment.
A small incision is made over the artery and a needle is used to puncture the blood vessel. A sheath (hollow thin tube) is then placed in the artery, which provides constant access to the artery. This catheter sheath can remain in the artery for 24 to 48 hours after the procedure, so that further interventions can be performed, if necessary. Using a catheter (hollow plastic tube) over a guiding wire, the artery leading to the aneurysm is selected. The wire is removed and the catheter is used to inject a contrast dye into the blood stream in order to visualize the normal blood vessels as well as delineate the aneurysm.
The entire process is done using continual x-ray visualization and high-speed radiographic filming techniques. The doctor takes measurements and views of the aneurysm. Once the angiogram has detected the presence, size, and location of the aneurysm, a smaller "micro catheter" is then placed inside the initial catheter. Once the micro catheter is successfully navigated into the aneurysm opening, the coil system is introduced.
Platinum coils are deposited into the aneurysm, reducing or blocking the flow of blood into the aneurysm. Once placed inside the aneurysm, a small electrical current is passed through the wire. As a result of this electrolysis, the coil detaches from the wire and remains inside the aneurysm. The wire is removed. It may take several coils to obliterate the aneurysm. In some cases the opening into the aneurysm may be wide, and a balloon or a small stent can be placed inside the blood vessel along the neck of the aneurysm to assist in the coiling procedure. If a balloon is used, it is deflated and removed at the end of the procedure. If a stent is used, it is implanted permanently into the artery, sometimes in a separate procedure, prior to coiling. The stent acts as a scaffold inside the artery to help keep the coils in place inside the aneurysm. After aneurysm packing with coils, the catheter systems are removed and the patient is transferred to the Intensive Care Unit for monitoring and further care.
Adjuncts to Endovascular Embolization/Coiling
Recent technological advances have led to the development of adjunctive devices and techniques to improve the results with endovascular embolization/coiling. These are devices that help coils stay inside the aneurysm sac, which can be particularly helpful for aneurysms with wide necks, or large aneurysms that in the past were difficult to treat with embolization/coiling.
One such adjunctive device is an intracranial stent. A stent is a metal mesh device in the shape of a pipe or tube that is placed inside the parent artery at the site of the aneurysm to cover the neck of the aneurysm. This helps to keep coils placed in the aneurysm sac to stay inside the sac.
The stents are usually made of nitinol, a high-grade metal alloy of nickel and titanium. If you have a stent placed, you will need to be on one or more antiplatelet medicines such as aspirin, clopidogrel, ticlodipine, or others.
Treatment Description
At the time of the embolization/coiling procedure, or sometimes as a separate treatment, a micro catheter and wire are navigated from the access site (usually the femoral artery in the groin) using x-ray visualization up to the site of the aneurysm in the brain. The stent can either be pushed through the microcatheter or deployed at the intended target, or with certain types of stents, the microcatheter is exchanged for a new microcatheter carrying the stent inside of it ready to deploy at its tip.
Then coils are placed in the aneurysm sac as would be performed as described in the coiling description. Once the procedure is completed, the patient is transferred to the intensive care unit or the recovery room for monitoring and care.
Liquid Embolics
Coils have been the mainstay of endovascular embolization of cerebral aneurysms. Recently there has been the technological development of liquid agents, surgical glue, for embolization of cerebral aneurysms. Currently, the liquid agent that is available in the United States is Onyx HD 500 (ethylene vinyl alcohol copolymer dissolved in dimethyl sulfoxide). Onyx HD 500 is a liquid that solidifies when in contact with blood, thus, in the treatment of cerebral aneurysms, Onyx HD 500 is injected via a microcatheter inside of the aneurysm sac, and it solidifies inside the aneurysm sac. A balloon is placed across the neck of the aneurysm and is inflated temporarily to prevent the Onyx HD 500 from leaking outside of the aneurysm sac.
Treatment Description
A microcatheter and wire are navigated from the access site (usually the femoral artery in the groin) using x-ray visualization up to the aneurysm in the brain and placed inside the aneurysm sac. A balloon is navigated from the access site up to the parent artery and placed so that it covers the neck of the aneurysm. The balloon is then inflated to block the aneurysm neck. Then dimethyl sulfoxide is injected to fill up the inside of the microcatheter, followed by the Onyx HD 500 that pushes the mixture out into the aneurysm sac. Once in contact with blood, this mixture solidifies and fills up the aneurysm sac. The balloon is deflated periodically to allow restoration of blood flow in the parent artery. Once the aneurysm is filled up with Onyx HD 500, the procedure is completed. The patient is transferred to the intensive care unit or recovery room for monitoring and care.
Pipeline Embolization Device
Approved by the FDA in April 2011, the Pipeline Embolization Device (PED) is a flexible mesh tube made of platinum and nickel-cobalt chromium alloy that can be used to block off large, giant, or wide-necked aneurysms in the internal carotid artery, a major blood vessel supplying blood to the front of the brain. The device can also reduce the likelihood that an aneurysm will rupture.
To implant the device, the Pipeline is attached to the end of a
catheter, which is inserted into an artery in the leg. The catheter is threaded into the carotid artery and into position at the aneurysm where the Pipeline is expanded against the walls of the artery and across the neck of the aneurysm, cutting off blood flow to the aneurysm. The blood remaining in the blocked-off aneurysm forms a clot that reduces the likelihood the aneurysm will grow bigger or rupture. Aneurysms successfully treated with the Pipeline will often shrink over time.
Risks and Complications
A patient's condition, the type, location, and size of the aneurysm, as well as other factors determine the potential risks and complications associated with these surgical procedures. The current combined morbidity and mortality rate related to the neurosurgical clipping of an incidental cerebral aneurysm is between 5% and 10%. The risk may be somewhat higher with large aneurysms, particularly the deepest ones. Surgery poses the lowest risk when it is performed before an aneurysm ruptures. However, there are certain risks and complications associated with these treatment options. They include:
Rebleeding
Of the 18,000 persons who survive the initial rupture of an aneurysm annually, 3,000 either die or are disabled from rebleeding.
Some believe the incidence of rebleeding is as high as 30%.
The highest incidence occurs in the first 2 weeks after initial hemorrhage.
Peaks in the incidence of rebleeding occur in the first 24 to 28 hours and at 7 to 10 days.
Rebleeding within the first 24 to 48 hours is the leading cause of death in persons surviving the initial bleed.
Approximately 70% of patients who rebleed will die.
The onset of rebleeding is usually accompanied by sudden severe headache, often associated with severe nausea and vomiting; a decrease in or loss of consciousness; and new neurological deficits. Death may occur. A CT scan can confirm rebleeding or a sudden spike in ICP with new blood seen in the bag if a ventricular drain is in place. Early treatment, with either surgical or endovascular methods, of the aneurysm is the most effective means of preventing rebleeding.
Cerebral Vasospasm
Of the 18,000 persons annually who survive initial aneurysmal rupture, 3,000 either die or are disabled from cerebral vasospasm.
Vasospasm occurs in approximately 30% of patients.
By definition, cerebral vasospasm is narrowing of a cerebral blood vessel and causes reduced blood flow distally, which may lead to delayed ischemic deficit and cerebral infarction if left untreated.
Besides the damage done by the initial SAH, brain damage produced by vasospasm is an important cause of morbidity and mortality after hemorrhage, with 14% to 36% of patients suffering disability and death.
Since improved treatment of aneurysmal subarachnoid hemorrhage has occurred with early and improved microsurgery, new endovascular techniques and better postoperative care and monitoring, vasospasm has significantly decreased as the cause of death over the last ten years (from 35% in the seventies to less than 10% at this time).
The present rescue therapies, which include ‘triple H therapy’ HHH, (hypertension/hypervolemia/ hemodilution), interventional procedures such as balloon angioplasty, intra-arterial nicardipine and other vasodilators, are associated with significant morbidity, and are labor intensive and expensive.120 A drug that would prevent delayed ischemic effects and minimize the amount of rescue therapy and optimize late outcome is desirable. When the patient’s condition deteriorates 3 to 14 days after SAH, vasospasm should be considered as the possible cause. A CT scan should be performed immediately to rule out hydrocephalus, infarction, or rebleeding.
Vasospasm can decrease cerebral perfusion to an area, causing ischemia and perhaps infarction, and can lead to further deterioration of neurological function.
Vasospasm may be differentiated as either angiographic or symptomatic.
Angiographic vasospasm refers to narrowing of a cerebral arterial territory, as noted on angiography, without clinical symptoms.
Symptomatic vasospasm is the clinical syndrome of delayed cerebral ischemia associated with angiographically documented narrowing of a major cerebral arterial territory and TCD elevation of a specific arterial territory.
Vasospasm develops 3 to 14 days after SAH (peaking at 7 to 10 days), although the onset may be delayed up to 21 days.
Post Treatment and Outcome
The recovery following treatment of an intracranial aneurysm is dependent on many factors, including whether the aneurysm has bled and the type of treatment for the aneurysm.
If an aneurysm presents with a subarachnoid hemorrhage, the length of hospitalization and recovery are dictated by the severity of the hemorrhage and not by the treatment modality. Following a subarachnoid hemorrhage, most patients will remain hospitalized for a minimum of two weeks during which time they will be monitored for the development of cerebral Vasospasm and other complications of the hemorrhage including Hydrocephalus. If the patient develops any of these complications or has a neurological deficit from the initial hemorrhage, variable periods of rehabilitation on an inpatient or outpatient basis may be necessary. Under the best of circumstances many patients may resume all of their previous activities within a period of several weeks without any specific limitations on their activities.
For patients with unruptured aneurysms, the hospitalization and recovery is typically much smoother and more predictable. In this case, the modality of treatment does influence the hospitalization and recovery. Endovascular therapy, being less invasive, is associated with a shorter hospitalization and more rapid return to previous activities. Following a successful endovascular procedure, most patients are observed in the intensive care unit overnight and discharged from the hospital the following day if there are no complications. These patients may resume all of their prior activities without any specific restrictions within a matter of days. This includes going back to work, driving and flying in airplanes.
Following a craniotomy for clip ligation of an aneurysm, most patients will spend a night in the intensive care unit and be moved out to a private room the following day. Typically, patients are discharged from the hospital a couple of days after discharge from the intensive care unit able to perform all the activities of daily living. It generally takes 4 to 6 weeks to recover from any major operation including a craniotomy for aneurysm. During this time the patients is able to care for themselves, but typically does not engage in aggressive physical activity. Patients are usually able to a care for themselves and stay alone with gradually increasing activity including walking, household chores and work that do not involve significant physical exertion. After approximately 4 to 6 weeks these activities are liberalized and patients are encouraged to resume all of their previous activities without any specific restrictions. It is by increasing activity at this time that patients more quickly resume their strength and endurance.
Because of the higher risk of recurrence of aneurysms following endovascular therapy, some routine maintenance is required and patients will typically return to their physician for follow-up angiography at variable periods of time to monitor for any evidence of recurrence. Following surgical clip ligation of the aneurysm, there typically is no routine maintenance of the aneurysm, particularly if intraoperative imaging documented complete obliteration of the aneurysm. For younger patients or those with a strong family history of aneurysms who may be at higher risk of the development of de novo aneurysms some routine monitoring may be recommended.