Introduction

Stroke is the leading cause of disability and the second most common cause of death in South Korea according to the Korean Statistical Information Service23). The mortality from stroke was reported to be as 64.3 per 100.000 deaths in 2005, which was considerably higher than that reported in the Western countries6). By virtue of Korea's economic growth, Koreans are rapidly adopting a Western lifestyle and dietary habits, including increased energy intake, alcohol consumption, and cigarette smoking, whereas decreasing physical activity. These changes have subsequently resulted in the emergence of various degrees of metabolic syndrome and Koreans now have many risk factors such as obesity, hypertension, diabetes, and hypercholesterolemia.

In addition to the drastic changes in life style, ischemic cerebrovascular disease (CVD) and unruptured vasculopathies are being increasingly identified prior to drawing clinical attention, as compared to hemorrhagic CVDs. The increasing incidence of CVDs has been attributed to some crucial factors, such as good accessibility to a nearby hospital, the information from mass media and internet, and the subsequent increasing awareness of own health care by medical checkups. With the evolution of technology and the accumulation of clinical experiences, minimal invasive endovascular intervention and radiosurgery have become excellent choices for management of such disease. Because of these reasons, patients tend to visit the "ltimate available management" hospitals, the so-called "Big-Four" instead of the traditionally accepted regional institute close to home.

The main concern is which medical department that is responsible for such treatment. The dichotomized disease categories of infarction vs. hemorrhage have forced neurosurgeons to stand half way in between surgery and medicine. Furthermore, the popularization of endovascular intervention has caused tough competition among the interventionists and specifically between neurosurgeons and radiologists,  in certain institutes. Thus, we conducted a retrospective study on the practical trends of CVD management in our department with special reference to the changing patterns of CVDs and the management paradigms.

Materials and methods

Between Jan. 2004 and Dec. 2008, all the CVD patients who had been admitted to our department were enrolled in the present study. These patients were either directly admitted to the Department of Neurosurgery or they were referred from another department for close observation or operative treatment. All of them had I60 to I69 of the ICD 10 as the main disease code in the discharge notes. The following diseases were excluded: major brain trauma, neoplasm, coma attributable to metabolic disorders, vasculitis involving the brain, peripheral neuropathy, hematologic abnormalities, and central nervous system infection. After excluding these diseases, we only included pure vascular lesions such as hemorrhagic stroke and ischemic stroke, as well as unruptured aneurysm, arteriovenous malformation (AVM) and moyamoya disease.

The diagnosis and classification of stroke were performed according to a slightly revised version of the one used in the Atherosclerosis Risk in Communities (ARIC) Study. The stroke subtypes were defined according to the following criteria:ischemic stroke (thrombotic brain infarction, cardioembolic stroke, and lacuna infarctions), hypertensive hemorrhagic stroke (intraparenchymal hemorrhage; IPH and intraventricular hemorrhage; IVH), and subarachnoid hemorrhage (SAH)19).

Our hospital has traditionally divided stroke patients into two main categories of hemorrhage and infarction, according to managing Departments of Neurosurgery and Neurology, respectively. So, there were few ischemic or infarct patients in the Department of Neurosurgery, except for the cases referred for surgical treatment. Endovascular intervention had been started relatively late, at second half-year of 2005, and it became normalized at the middle of 2007 with the arrival of new participating interventional radiologist. Until then, complex vascular lesions were sometimes referred to another major hospital for intervention. Moreover, a lack of radiosurgical equipment caused some patients with unruptured vasculopathies to be referred to other hospitals where radiosurgery was available.

We reviewed our data regarding each disease entity (the numbers of patients), the main treatment modality such as surgical treatment and endovascular intervention, and non-surgical management.

Results

1. Total numbers of CVD

The total numbers of CVD patients showed slight increase from 2004 to 2006, but the growth rate became stationary after 2006. The number of surgical treatments, including open craniotomy, ventriculostomy, steretactic surgery and endovascular management, showed the same tendency for the total  CVD cases (Fig.1).

The numbers of cases of spontaneous, non-angiomatous IPH and IVH were not significantly changed throughout the entire five years (Fig. 2). In the recent years from 2007, drug-induced hemorrhage (anti-coagulants, anti-platelets, aspirin) tended to increase, but statistical significance was not obtained due to the relatively small number of cases. The reduced numbers of operated cases were attributable to the increased number of cases of this dangerous hemorrhage.

2. Intracranial Aneurysm

While the total number of intracranial aneurysm operations is increased from 2007, there was no rapid increase of ruptured aneurysm. In other words, the cause of this result was due to the increasing awareness of unruptured aneurysms (Fig. 3A). The total number of operated cases was still below 100  cases / year. However, if these are divided according to the treatment modalities, increasing number of cases was mainly treated by endovascular embolization (Fig. 3B). Since 2007, the volume of cases was slightly increased as a whole, but the number of cases of microsurgical clipping remained unchanged. The 50:50 rule of the Korean Neurosurgical Society for aneurysm treatment for the Resident training code could explain such results.

3. AVM and ischemic stroke

The number of hemorrhagic strokes from AVM rupture was quite a few in the recent years. Because our institute does not have a radiosurgery suite, most patients with unruptured AVMs were referred to another institute, except for only when emergency hematoma evacuation was required. The volume of cases of ischemic stroke appeared somewhat increased since 2006, although it was still quite low(Fig. 4). However, the main cause of such an increment was due to endovascular management of vasospasm, rather than acute ischemic stroke and cerebral infarction. The latter diseases were handled by the Neurology Department with an increasing incidence (not shown in this paper). The case numbers of these cases was simultaneously increased when endovascular procedures were started, and at the same time, the referred cases of impending massive cerebral infarction were decreased.

Discussion

1. Incidence of stroke

According to the previous reports, it was believed that in the past, hemorrhagic stroke occurred with a relative higher incidence in South Korea as compared to that of Western societies19). Of these strokes, primary IPH was the most frequently reported because a relatively low level of blood cholesterol might lead to hemorrhagic stroke than  ischemia11,15). However, as the Asian dietary habits and lifestyle became westernized, so the incidence of ischemic stroke has gradually increased in Asians5). Similar findings of stationary numbers of hemorrhagic stroke and increasing numbers of ischemic stroke were described in this present study.

Park et al.23) demonstrated this trend by comparing between the 1990's and the 2000's as follows: from 1994 to 1996, the prevalence of ischemic stroke, IPH, and SAH was 32.1%, 41%, and 26.9%, respectively. However, from 2003 to 2005, this composition was reversed as 59.6%, 25.6%, and 14.7%, respectively. There are several explanations for the changing trend of stroke, such as awareness for obtaining health care, the westernized lifestyle and dietary habits, and the development of accurate diagnostic tools. Neau et al.20) highlighted that the population at risk had becoame alert and they paid close attention to the early signs and symptoms of stroke, but the number of cases was paradoxically increased. The development of neuro-imaging techniques has made it easier to identify mild cases of stroke and to more accurately classify stroke subtype. For these reasons, the ischemic stroke and unruptured angiomatous lesions being increasingly detected23).

2. Endovascular intervention for CVD

Two representative modalities of stroke management are now being widely used (microsurgical treatment and endovascular intervention). A recent report by Byun3) showed the changing pattern of treatment methods for aneurysm in Korea. The rate of performing  microsurgical clipping and endovascular coiling has been increased by 40.2% (5248 cases in 2003 and 7357 in 2007). The noticeable finding was that the increment rate of endovascular coiling was 229%, but that for clipping was only 5.6%. In other words, endovascular techniques have rapidly replaced clipping as a strong alternative modality.

The selection of a treating modality for aneurysm can be decided according to several factors. Among them, aneurysms located at the posterior circulation and the internal carotid artery below or around the anterior clinoid process have been successfully treated with endovascular embolization. To achieve a better outcome and minimal complications, fully equipped biplane fluoroscopy with high spatial resolution, and steady maintenance of anesthesia are needed during endovascular surgery.

With development of endovascular technique and materials, including coils, liquid embolic materials, stents, and balloons, the indications for endovascular surgery for the management of brain lesion have been diversified.12) In recent years, the indications for endovascular treatment have been encompassed various disease entities as follows; 1) for obliterating aneurysms, AVMs and, arteriovenous fistulas (AVFs), and for preoperative embolization of head and neck tumors; 2) for opening up an atherosclerotic stenosis, for treating acute thromboembolic occlusive diseases and for performing, angioplasty for vasospasm;3) for delivery of chemical vasodilators, anticancer drugs, and stem cells.8)

The development of materials and techniques has provided a better outcome and a lower mortality rate for various CVDs. Higashida et al.10) presented that endovascular surgery for cerebral aneurysms had several advantages, including a shorter hospital stay, lower costs and, lower mortality and morbidity rates as compared with that of clipping cases. The same result was reported by Pandey et al.22) Although AVMs are not totally curable, the mortality and morbidity rates for embolizing AVMs are decreasing with the development of materials like n-Butyl-Cyanoacrylate (nBCA) as compared with the data of the previous reports on using a non-adhesive liquid embolic system.8)9)14)16-18)24)25)

3. Recent trends for ischemic stroke and unruptured vasculopathies

Medical treatment that including aspirin, warfarin, and clopidogrel, has played a traditional role for the management of ischemic stroke. Among these drugs, aspirin has been widely used because of its effectiveness and superiority as compared with using another single drug or combining aspirin with other drugs.1)4) Therefore, more effective treatment is required in medically intractable patients, and the recent development of endovascular salvaging techniques has resolved these problems. Moreover, endovascular management has become successfully used as the first-line treatment  with the growing evidence of the reliability of stents.2)7)13) However, as stated above, major stent procedures and occluding fistulas have been performed at the Neurology Department in our institute. To widen the scope of managing CVD, we suggest that a stenting procedure for occlusive CVD and endovascular occlusion of fistulous lesion should be included in the count of major operations, when considering the Korean residency program.

Early detection of unruptured vasculopathies before a hemorrhagic presentation, including aneurysm and AVM, has increased due to the above reasons. According to the report of the International Study of Unruptured Aneurysms (ISUIA), the rupture risk is independently increased with size (> 7mm), and even for the small size intracranial aneurysm. Although a definite standard for determining the treatment modality has not been recommended by the ISUIA, the factors related with high mortality and morbidity rates for surgical clipping are a large aneurysm more than 12mm in size, an aneurysm at the posterior circulation, and an age more than 50 years.26) The patients who harbor an unruptured aneurysm prefer endovascular management due to vague fears about brain surgery and the false notion that endovascular embolization is not surgery, but rather, it is only a procedure conducted in an angiographic suite. This situation of preferring non-craniotomy is same for patients with AVM. Although the hemorrhagic risk from AVM is generally assumed to be 2 to 4 % per year even after radiosurgery,21) radiosurgery is considered the best choice for treating an unruptured AVM in selected cases. The annual reports of a certain university hospital with a Gamma Knife suite presented only one nidus removal with open craniotomy and 48 radiosurgeries in 2008.

4. Flocking tendency to a higher grade hospital

The increasing awareness of unruptured vasculopathy and the various available treatment modalities simultaneously act on a patient's own will to choose higher grade hospitals. This tendency might accelerate the phenomenon of "the rich-get-richer and the poor-get-poorer" If such specific patients were all gathered in some institutes, the remaining hospitals will barely experienced similar diseases or hardly accumulate precious clinical experiences, and this will subsequently result in a significant imbalance between institutes. According to the annual reports of a certain university hospital, the number of clipping and coiling was 72 and 251 in 2004, and 122 and 498 in 2008, respectively. These numbers far exceed ours and performing that many clipping and coiling procedures is far beyond our reach.

5. The role of the neurosurgeon in stroke manage -ment, and the future directions

In recent years, the grey zone between pure surgical and genuine medical management has become tremendously enlarged. This gap is being rapidly filled with the emerging techniques of minimal invasive procedures, including neuro-intervention, mini-craniotomy, key-hole surgery and several types of endoscopic surgeries. In traditional point of view, neurosurgeons have played a major and prompt role in diagnosing and managing hemorrhagic CVD patients. With the diversity of tools for diagnosis and treatment, neurovascular specialists from other departments, such as neurologists and neuroradiologists, now participate in such clinical activities.

When managing stroke patients, neurosurgeons should be more involved in making the treatment plans for various diseases, including acute and chronic ischemia, and infarction. To achieve this, we should have appropriate knowledge of the physiology, patient monitoring and all the available treatments, including the medical, endovascular, and surgical techniques. Cooperation among different medical specialists is prerequisite for adequately treating such patients, instead of being competitive or uncooperative. We suggest that vascular neurosurgeons are ready to perform breakthrough surgery, such as cerebral revascularization and flow-modification procedures.

Conclusion

During the 5 years of this study, we experienced a steady rate of hemorrhagic stroke patients, while ischemic stroke and unruptured vasculopathies were increased. Although every patient can's be treated by the emerging endovascular intervention techniques, these techniques should be seriously considered for treating more stroke patients. Neurosurgeons need to be equipped with several revolutionary surgical options to adapt to the current status of management and for collaborating with other specialties for treating patients with stroke.

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