How is cerebral arteriovenous malformation treated?

  There are currently four treatment options for cerebral arteriovenous malformations (AVMs), including conservative treatment, microsurgical resection, interventional embolization, and stereotactic radiation therapy.  Conservative treatment is appropriate for patients who: have an AVM that is not bleeding and has no structural risk factors for bleeding, are located in an important functional area, and have a high likelihood of dysfunction with other treatments; have conditions that do not tolerate surgery and do not have a long life expectancy; or have concerns about surgical treatment and can be treated conservatively with close follow-up, but should be aware that AVMs in the brain have a lifelong risk, with an annual bleeding rate of approximately 4%. Preliminary results from an international multicenter randomized controlled study of long-term follow-up of unbleeding AVMs suggest that for unbleeding AVMs, the conservative treatment group had better clinical outcomes compared with other patients treated aggressively over a limited 33-month follow-up period. However, the study is highly controversial, including ethics, patient selection, follow-up time, and statistical analysis, with the expectation that long-term follow-up may provide a better opinion.  Microsurgery is the traditional treatment for cerebral AVM, eliminating the risk of hemorrhage almost immediately and allowing for improved epilepsy control. However, for most cerebral AVMs, surgical resection will be associated with relatively high surgical risks. Doctors will grade cerebral AVMs according to the internationally accepted grading criteria based on angiography to guide the choice of surgical approach. It is generally accepted that the risk of surgical resection, mainly neurological deficits, is low in patients with grade 1-2, while the risk of surgical resection alone is significantly increased in patients with grade 3-4, and direct surgical resection is generally not recommended for patients with grade 5.  Interventional embolization is the fastest growing treatment for cerebral AVM in recent years. This method involves inserting a thin catheter through the femoral artery, delivering its tip to the arterioles supplying the arteriovenous malformation and approaching the malformed mass, injecting embolic material to occlude the malformed mass and the arterioles supplying the arterioles, reducing the blood flow in the malformed mass, and eliminating the risk of bleeding. This method alone or in combination with microsurgery or stereotactic radiation therapy has transformed many high-grade AVMs from untreatable to treatable, and has made the treatment of low-grade AVMs significantly less risky or relatively simple. Previously, most AVMs could not be completely and permanently occluded by this method alone and usually required a combination of radiation therapy and, in a few patients, surgical resection for complete cure. In recent years, methodological improvements have allowed more cerebral AVMs to be cured by interventional embolization alone. However, for large AVMs, staged treatment is usually required to reduce the risk of surgery.  Stereotactic radiosurgery has also made great progress in recent years. It locates the location of the malformation mass by MRI or CT and focuses radiation such as X-rays and gamma rays on the lesion area to slowly occlude the vessel, and this treatment allows certain suitable patients to avoid invasive surgical resection or interventional treatment. However, this method takes 1 to 3 years to take effect, during which time there is still a risk of bleeding; therefore, it is only indicated for certain small unbleeding AVMs or as an adjunctive treatment after surgical and interventional embolization.  At present, different clinical centers may prefer surgical resection or interventional embolization with stereotactic radiotherapy for the comprehensive treatment of cerebral AVM according to the staging of cerebral AVM, their own advantages and patients’ wishes, and for most cerebral AVMs, less invasive interventional embolization therapy combined with stereotactic radiotherapy has become the trend.