Cerebral arteriovenous malformations (AVM) have long been considered to be congenital lesions, which implies that AVMs exist at birth, and become symptomatic in young adulthood. This suggests that an AVM is a static vascular anomaly. In this paper, the author tries to revise this classic concept by showing a variety of AVM's dynamic in nature, which includes de novo AVM, growing AVM, developmental venous anomaly with AV shunts, and cerebral proliferative angiopathy. The latter two overlap with classic AVMs clinically and anatomically. In addition, metameric AVMs and syndromic systemic AVMs (hereditary hemorrhagic telangiectasia and capillary malformation-AVM) are introduced. This knowledge is useful not only in the diagnosis and management of AVMs, but provides insights in the pathogenesis of AVMs. Apparently the same structural AVMs might have their own different genesis, natural history and appropriate treatment.

View full abstract

We conducted the nationwide surgery on the present status of the treatment of dural arteriovenous fistulas (dAVF) in Japan. The questionnaires were sent to all of the 388 neurointerventionalists (268 clinics) certified by the Japanese Society of Neuroendovascular Therapy to ask the patients demography and details of treatment between 05 January and 06 December. The clinical data of 863 patients were reported by 92 clinics. 45% of the patients were men and 55% were women. Patients' mean age was 64.0±13.2 years. The cavernous sinus (CS) was involved in 396 patients (45.9%), the transverse-sigmoid sinus (TSS) in 230 (26.7%), the spinal cord in 51 (5.9%), the anterior condylar confluence (ACC) in 43 (5.0%), the tentorium in 41 (4.8%), the superior sagittal sinus in 28 (3.2%), the craniocervical junction (CCJ) in 21 (2.4%), the cranial vault in 21 (2.4%), the anterior cranial base (ACB) in 18 (2.1%), and the confluence of the sinus in 12 (1.4%). A total of 719 (83%) patients were treated endovascularly, 61 (7%) surgically, and 37 (4%) radiosurgically. The radiological results were complete obliteration in 66% of the patients, subtotal in 17%, and partial in 11%. Treatment complications were reported in 4.1% of the patients. The mean modified Rankin Scale was 1.4 before, and 0.6 after treatment. The results of the treatment of the CS and TSS lesions were acceptable and satisfactory. The analysis of the complications reported suggested that endovascular treatment sometimes tended to be selected inappropriately in the ACB and CCJ lesions.

View full abstract

We classified spinal AVMs into four types depending on the location of their AV shunt; namely dural AVFs, epidural AVFs, perimedullary AVFs, and intramedullary AVMs. These classifications can contribute to a real treatment protocol. The goal of treatment is to interrupt the AV shunt by either surgery or embolization. Dural and epidural AVFs are primarily treated by endovascular surgery using NBCA (n-butyl-cyanoacrylate) except for dural AVFs of the cranio-vertebral junction which require open surgery. Perimedullary AVFs can be treated with surgery, embolization, or both. Intramedullary AVMs have been treated by embolization only before. However, several authors have reported using stereotaxic irradiation for treating them. During the surgery, a multidisciplinary approach using intraoperative DSA, intraarterial injection of indigocarmine and ICG (indocyanine green), and MEP monitoring is highly efficient.

View full abstract

Multimodality treatment is essential for the management of particularly high-grade intracranial AVMs. The recent introduction of the Onyx system provides deeper and more profound embolization of the AVM nidus compared with NBCA (N-butyl cyanoacrylate). Successful embolization with Onyx makes the following resection safer and easier, based on our initial experience of 13 patients. Preoperative embolization with Onyx seems very useful in the surgical management of AVMs.

View full abstract

OBJECTIVE: The main goal of the treatment of cerebral arteriovenous malformations (AVM) is to eliminate the risk of hemorrhage. At present, microsurgical resection (MSR), endovascular embolization (EVT), and stereotactic radiosurgery (STR) are selected as the therapeutic options. In this study, the role of STR in a multidisciplinary strategy for AVM is discussed. MATERIALS: The data in this study are all based on the experience of STR with 714 AVMs in our hospital (78 were treated after MSR, 100 after EVT). RESULTS: The associated factors for nidus obliteration were nidus volume, delivered radiation dose, and past history of hemorrhage from AVM. The major benefit of MSR is the immediate elimination of hemorrhagic risks, but the procedure can be invasive in the eloquent area or the deep cerebral regions. EVT is less invasive than MSR, but revascularization of the AVM can take place. However, after MSR or EVT, a marked shrinkage of nidus volume is expected, and STR is successfully applicable for the residual AVM. It is very difficult to selectively resect the nidus component in the non-eloquent area without affecting the nidus in the eloquent area during MSR. On the other hand, the AVM becomes much less vascularized a few years after STR, and safe MSR is feasible in most cases. CONCLUSIONS: For AVM with large nidus involving the eloquent area or the deep cerebral region, the strategy using STR for the surgically intractable regions followed by MSR a few years later may be effective and simultaneously can eliminate the uncertain risks of radiation-induced complications, such as chronic encapsulated hematoma, growing cyst formation, and bleeding from obliterated nidus, taking place even years after AVM obliteration by STR.

View full abstract

The important aim of treatment for cerebral AVMs is prevention of hemorrhage. However, there seems to be no definite treatment strategy for them. According to the AHA Scientific Statement 2001 and Japanese guidelines for the management of stroke 2009, single surgical extirpation is not recommended for Spetzler-Martin grade IV and V. Although the natural history of high grade cerebral AVMs still remains to be clarified, there is considerable risk for their complete cure even with multimodality treatment, and incomplete treatment may raise bleeding risks. Appropriate and prudent treatment strategies should be planned for high grade cerebral AVMs considering several factors including each patient's symptoms and condition, bleeding and re-bleeding risks, location of nidi, treatment risks.

View full abstract

The surgery for a brainstem lesion is hazardous and challenging, but that for a brainstem cavernous angioma is not necessary difficult in most cases, because the boundary between the angioma and normal brain tissue is generally well demarcated by preceding hemorrhages. However, the angioma tissues have been often destructed by hemorrhage, and we should be careful not to leave any pieces of the angioma tissue. Surgical results and pathological findings of 7 cases of symptomatic brainstem cavernous angiomas are analyzed, and the various surgical strategies based on the pathological nature of this lesion are discussed.

View full abstract

In April 2010, the medical fee scheme was revised, which led to the approval of additional fees for the first time in 10 years. While drug prices were lowered, medical fees, especially inpatient hospital fees, surgical fees and other doctor-related fees, were increased substantially. In response to this new development, we compared and examined our treatment options for stroke by form of disease with a view to identifying the areas of improvement in Diagnosis Procedure Combination (DPC)-based payment system introduced in 2010 as part of the revision. A substantial increase in surgical fees for subarachnoid hemorrhage (SAH) has enabled us to perform appropriate treatment procedures. Surgical fees for the treatment of intracerebral hemorrhage, including the stereotactic surgery and craniotomy procedure, have also been increased. In case of cerebral infarction, although a high fee is set for t-PA treatment, fees for other treatment options still remain low. In fact, though some improvements have been made, there are still some restrictions on the examinations performed according to the specific conditions of the patient. The current revision of the medical fee scheme differs greatly from previous revisions in that technical fees and other doctor-related fees granted to medical practitioners have been increased, including the surgical fees for the treatment of SAH and intracerebral hemorrhage. However, fees granted for treating diseases that require conservative therapy are still insufficient and require further improvement in the future.

View full abstract