Clinical Departments

Neurosurgery

What is Neuroendovascular Therapy?

This is a treatment that can be performed “without cutting the head.” By using a thin tube called a catheter inserted through the blood vessels, doctors can widen narrowed vessels in the head and neck or block vessels to prevent bleeding.

History of Neuroendovascular Therapy

Efforts to treat cerebrovascular diseases using catheters began in the 1970s. Because cerebral blood vessels are extremely thin and follow complex paths, catheter treatment was initially thought to be unsuitable. However, with the development of more user-friendly catheters and technological advancements, the number of procedures has been increasing since the late 1990s. At our hospital, physicians who have been involved in neuroendovascular therapy since that era perform these treatments.

Procedure Method

Generally, a catheter (guiding catheter) with a diameter of about 2–3 mm is guided from an artery in the groin (femoral artery) to the neck. Under X-ray fluoroscopy, a contrast agent is injected to confirm the shape and path of the vessels. A microcatheter is then guided through the guiding catheter to the target site to perform the treatment.

Benefits and Current Status in Japan

Unlike conventional surgery, this treatment can be performed without making incisions in the head or neck or removing bone. Consequently, it is physically less stressful for patients and allows for shorter hospital stays. In Western countries, 60% to 80% of cerebral aneurysm treatments are already performed via neuroendovascular therapy.

In Japan, while the number of procedures is increasing, the ratio hasn’t reached Western levels yet, partly because Japan is known for high success rates in conventional craniotomy (clipping). We provide the best possible outcomes by carefully considering whether a craniotomy or endovascular therapy is better suited for each individual case.

Introduction to Various Neuroendovascular Treatments

1. Endovascular Therapy for Cerebral Aneurysms

a. Unruptured Cerebral Aneurysms:
Very thin, soft platinum coils are placed inside the aneurysm to fill it and prevent rupture. Patients can typically walk and eat the day after surgery, with a hospital stay of about one week.

b. Ruptured Cerebral Aneurysms (Subarachnoid Hemorrhage) (Graph 3)

The vast majority of subarachnoid hemorrhages are caused by the rupture of a cerebral aneurysm. Even after a rupture occurs, a blood clot often forms over the site like a scab, temporarily halting the bleeding. However, this “scab” is easily dislodged; if it falls off, it leads to a re-rupture (re-bleeding), which significantly worsens the patient’s condition.

Since a re-rupture carries a 30% to 50% mortality rate, it is essential to perform preventative treatment as early as possible.

In 2002, a major study based in the UK compared outcomes for patients with ruptured cerebral aneurysms who underwent either traditional craniotomy (clipping) or neuroendovascular treatment (coil embolization). The results indicated that patients who received endovascular treatment had better survival rates and a higher quality of life. Consequently, endovascular therapy has increasingly become the preferred initial treatment for ruptured aneurysms worldwide. While the adoption of coil embolization is also rising in Japan, surgical clipping is known for its excellent local results. Therefore, we believe we can provide the best outcomes for our patients by carefully evaluating each individual case to determine whether craniotomy or endovascular therapy is the more suitable approach.

2. Carotid Artery Stenosis

Arterial sclerosis caused by lifestyle diseases (high blood pressure, diabetes, etc.) or smoking can narrow the carotid artery. This can lead to blood clots or plaque causing strokes (paralysis or speech disorders). Carotid Artery Stenting (CAS), which has been covered by insurance since 2007, is an effective endovascular solution to widen these vessels. (Graph 4)

3. Recanalization Therapy for Acute Ischemic Stroke
Local Fibrinolysis, Angioplasty, and Mechanical Thrombectomy

This treatment is available only to a specific group of patients where a major cerebral artery is blocked, but the brain tissue has not yet progressed to a complete infarction (permanent damage).

Since the late 1980s, treatments such as injecting thrombolytic (clot-dissolving) agents directly through a catheter or using balloon-tipped catheters to fragment clots have been performed. In 2010, mechanical thrombectomy catheters were approved for insurance coverage for acute ischemic stroke, followed by the approval of aspiration catheters in 2011. In 2015, several landmark papers demonstrating the effectiveness of these treatments were published, further increasing the clinical necessity of these procedures in stroke management.

When a major vessel in the brain is blocked and stroke symptoms appear, a favorable outcome is unlikely unless recanalization (restoration of blood flow) is achieved within a specific timeframe. Therefore, we consider these treatments in the early stages—within a few hours of the onset of the stroke. (Graph 5)

4. Embolization of Arteriovenous Malformations (AVM)

An arteriovenous malformation (AVM) is a condition where abnormal arteries and veins in the brain are directly connected without the intervening capillary bed. This often leads to symptoms such as brain hemorrhage or seizures. It is estimated that an AVM carries an annual risk of hemorrhage of approximately 2% to 3%.

Treatment options for AVM include surgical resection via craniotomy, neuroendovascular therapy (embolization), and stereotactic radiosurgery. Endovascular therapy is often introduced prior to surgery or radiation therapy. By placing coils or administering liquid embolic agents, we can reduce the volume of blood flow or shrink the size of the malformation itself. This makes subsequent surgical resection or radiation therapy both safer and more effective. (Graph 6)

5. Embolization of Dural Arteriovenous Fistulas (dAVF)

This is a condition where abnormal connections form between arteries and veins within the dura mater, the protective lining of the brain. These abnormalities can lead to cerebral hemorrhage, neurological symptoms, or seizures.

Depending on the location of the lesion, patients may experience bloodshot or protruding eyes, or a “whooshing” tinnitus synchronized with their heartbeat. Because of these specific symptoms, some patients are referred to us after initially visiting an ophthalmologist or an otolaryngologist (ENT). Neuroendovascular therapy is used to occlude the lesion via the affected arteries or veins, effectively neutralizing the abnormal blood flow. (Graph 7)

6. Embolization for Brain Tumors

For brain tumors that are highly vascular and prone to significant bleeding, embolization is a valuable preoperative step. By occluding the feeder vessels that supply the tumor with blood, we can substantially reduce blood loss during a subsequent craniotomy. (Graph 8)