Abstract

            This paper gives a brief overview of the newer technology surrounding the approaches to treatment of intracranial cerebral aneurysms; the Guglielmi Detachable Coil embolization system.  The traditional method is a technique known as clipping; the surgeon performs a partial craniotomy and uses a metal device to clip the aneurysm.  With the GDC, a patient can undergo this endovascular treatment and have a posterior aneurysm coiled; one which due to its location would be deemed inoperable with the clipping method.  The goal of this paper is to help inform individuals of the other options for treatment of intracranial aneurysms regardless of their location, and the benefits of coiling versus clipping. 

Patients with posterior cerebral aneurysms, those once deemed inoperable, are now given a second chance at a fuller life with the GDC device. The Guglielmi Detachable Coil System (GDC) was developed during the 1980’s by Dr. Guido Guglielmi and was approved by the Food and Drug Administration in September of 1996. The device is a soft platinum coil that is detached into the aneurysm sac via electrolysis, and after 5-30 coils are placed (depending on the size of the aneurysm) the goal is to block off the aneurysm and keep the parent artery patent. The dependent variable in this situation is the location of the aneurysm; typically this treatment is reserved for those patients with aneurysms located in the posterior region of the brain (inaccessible by the clipping method). The independent variable being the skill of the interventional radiologist; simple because this is a new treatment and the amount of highly qualified and experienced radiologist are not readily available.  With time, more and more doctors are looking at the GDC device as an option thus requiring the training of radiologist on this new procedure. Guglielmi’s new technology is now giving hope to patients who are unable to undergo surgery for their cerebral aneurysm either due to its location, size or patient’s age. 

“Approximately 10 to 15 million Americans harbor an intracranial aneurysm and the most common clinical symptom is a headache” (Qurehsi, 2003).  A cerebral aneurysm, according to the National Institute of Neurological Disorders and Stroke is a weak or thin spot on a blood vessel in the brain that balloons out and fills with blood.  This bulging can place pressure on nerve endings or in extreme cases the aneurysm can rupture and the most important complication is the chance of it bleeding even more and not re-sealing itself and this is more apt to occur within the first 24 hours and even then one out of eight patients will die before receiving any medical attention. According to a study performed by Higashida (1997), patients with an acutely ruptured intracranial aneurysm have a greater than 50% associated rate of morbidity and mortality”. 

There are two ways an aneurysm can be treated: one is via surgery and the other is via endovascular therapy. Surgery, commonly referred to as clipping, requires that the patient be placed under sedation and undergoes a craniotomy.  Then the surgeon, using a microscope to navigate, places a metal clip around the neck of the aneurysm. Endovascular treatment is the utilization of an embolization device administrated through the blood vessel; what is referred to as coiling. According to Barker (2004), clipping had twice as many neurological complications than coiled patients, the length of stay at the hospital was 3 days longer and it cost $21,800 which was $8,600 more than the coiling method (which in 2000 averaged $13,200).

The Guglielmi Detachable Coil System (GDC) was developed during the 1980’s by Dr. Guido Guglielmi and was approved by the Food and Drug Administration in September of 1996. Guglielmi’s goal for his new device is the preservation of the parent artery.  This new technology is now giving hope to patients who are unable to undergo surgery for their cerebral aneurysm (location, size, age etc.).  The helical coil is made of a soft platinum alloy and is housed within a stainless steel wire which it is guided through until it is in place: within the aneurysm at the edge of the aneurysm neck. Once in place, the coil is then detached by electrolysis and since the coil is made of a soft alloy, it in a sense contorts to the shape of each individual’s aneurysm filling the sac. “The objective is to induce endosaccular thrombosis and occlusion thus preventing arterial inflow” (Phatouros, 1998), and according to Morrison (1997), the average number of coils used is 5, but depending on the size of the aneurysm as many as 20 have been used.

The procedure for mounting a GCD is very much the same as that of a cerebral arteriogram; usually done in specials, enters via the femoral artery and is done while using fluoroscopy.  Like the diagnostic angiography, the GDC is a less invasive procedure than surgery.  According to Phatouros (1998), the highest optimum results are achieved with aneurysms that are smaller than 12-mm in diameter and with a narrow neck. The GDC proves to be less effective in aneurysms measuring greater than 2.5-cm in diameter. The coils are considered thrombogenic so some of the risks include: perforation or rupture of the aneurysm, damage to femoral artery, contrast reaction, cerebral infarct, death or the major (highly probable) risk – stroke.  Patients that the GDC would be contraindicated would be those who are unable to anticoagulate due to an intracerebral hematoma or those with an aneurysm that has a neck that is too broad to hold the coils in place. According to Kimchi (2007), Thromboembolic events are a common complication during endovascular treatment with coils. This holds true because the GD coils “do not achieve an instantaneous occlusion an there is therefore the possibility that a transient period of slow flow in the occluded vessel may create an embolic source” (Coley, 1999).

After the coils are placed, follow-up of the placement of the coils is done 1 month later with the use of digital subtraction angiography (DSA) or magnetic resonance angiography (MRA).  “Digital subtraction angiography (DSA) is usually performed and is considered the method of reference for aneurysm evaluation because of its inherent high spatial resolution” (Gauvrit).  The purpose of these follow-up examinations is to check for coil compaction and parent artery patency.  According to Phatouros (1998), the endosaccular coil could compact creating a partial recanalization of the aneurysm. “Factors shown to be associated with higher recanalization rates include: presentation with SAH, size, location in the posterior fossa or terminus type, and the width of the aneurysm neck” (Kimchi, 2007).

Even with all of the possible negative outcomes from endovascular therapy, the benefits to date seem to outweigh those of the surgery route.  Even if the aneurysm has no neck, the GDC device is still able to be utilized with today’s technology.  According to Higashida (1997), the most difficult type of aneurysm to treat is one without a well-defined neck.  New technologies have allowed for intravascular stents to be placed at the base of an unruptured aneurysm that due to its morphology has no neck.  This stent would act as a bridge for the GDC device to anchor to allowing the coils to be detached filling the aneurysm sac.

“Endovascular treatment of intracranial aneurysms is widely used in routine clinical practice and constitutes an excellent alternative to surgery” (Gauvrit, 2006).  This statement is backed by the results of the International Subarachnoid Aneurysm Trail (ISAT).  According to Marcus, the ISAT proved that the endovascular coil procedure drastically reduced the risk of death and dependency compared to those that received surgical clipping, and those patients also had a drastically lower risk of seizures than the patients receiving surgical clipping.

Method

The purpose of this research is to view all options to treating intracranial aneurysms and to show that posterior aneurysms that once went untreated due to their location can now be accessed by newer technology with results comparable to those undergoing surgery for more common aneurysms (location). This study will validate that the Guglielmi Detachable Coil embolization device is an alternative to surgery.  Upon approval with the Institutional Review Board and insuring that all patient information will be held to HIPPA guidelines, a retrospective cohort study will be performed.  Utilizing a sampling of patients; those who have been excluded from aneurysm surgery because of the location of the aneurysm or other factors leading to poor medical condition and compare those outcomes to those who underwent surgery (with more favorable locations of the aneurysm) will prove that the GDC embolization treatment is a viable treatment for intracranial aneurysms.  Using the sample date from these cases I will use an ordinal level of measurement and with the two groups I will use the Wilcoxon ranks test. A logistic regression analyses will be used to adjust for the age and sex of the patients, and the size of the aneurysms.  The goal is for the results to prove that the GDC embolization treatment is a valid course of treatment for intracranial aneurysms and can be equal to if not superior to the surgery method for those with posterior aneurysms who without the GDC embolization treatment would not have a treatment option.

Discussion

            Through my research I have learned that the differences between surgical correction of an intracranial aneurysm (clipping) vs. the endovascular treatment (coiling, via the GDC devise) have many benefits such as shorter hospital stay and quicker recovery time. The primary benefit of the GDC device is that it allows for treatment of aneurysms deemed inaccessible by the common method of clipping. The facts on morbidity and mortality between the two options lead toward the endovascular treatment becoming the choice for treatment of intracranial aneurysms. Though this is still a relatively new technology more research will have to be done.

Conclusion

The GDC devise has been used for a little over ten years which in medical technology is still considered to a new technology. As time continues and more solid research can be done using post surgery results, like the quality of life past ten years of patients opting for the endovascular treatment, the facts will show that this new technology should not be ignored. With more radiologist being trained in this procedure and with the benefits of newer designs of the coils and the increasing number of patients that have been helped (if not saved) by this new treatment, the GDC may soon become the primary choice of treatment for all aneurysms.

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