Registry of Multimodality Treatment for Brain Arteriovenous Malformation in Mainland China

This study is a multi-center, prospective registry study led by Beijing Tiantan Hospital, and a number of comprehensive hospitals in mainland China, aiming to uncover the long-term outcomes of AVM in Real-World in China and to discover a standardized diagnosis and treatment process for the comprehensive treatment of brain AVMs. This study is an observational study that will last for 20 years. All patients were enrolled prospectively, and the study will not influence the choice of treatment modalities.

The study cohort of this study was AVM patients aged 1-80 years. The inclusion criteria were as follows: 1. The diagnosis of AVM was confirmed with digital subtraction angiography (DSA) and/or magnetic resonance imaging(MRI); 2.Patients with complete clinical and imaging data; 3. Patient or patient's legal representative agreed to collection of information for this study and signed informed consent. The exclusion criteria were as follows: 1. Received other treatment (surgery, embolization or SRS)before inclusion; 2. Expected survival time is less than 6 months; 3. Spinal AVMs; 4. Patients missing critical baseline and imaging data.

Patients will be divided into two groups: experimental group and control group. Experimental group: Patients who had received a multidisciplinary assessment to develop a treatment plan were included in the experimental group. The details were as follows: Ruptured AVMs: 1. AVMs not involved vital eloquent areas, or more than 5 mm away from functional fiber bundles, microsurgery or hybrid surgery can be performed; 2. Targeted embolization for hemorrhagic predictors could be considered as a monotherapy; embolization can be used as an adjunctive strategy to reduce flow or volume before microsurgery or stereotactic radiosurgery (SRS); 3. SRS for patients with a volume less than 10ml and not in the acute phase(< 3months) of hemorrhage. Volume-stage or dose-stage can be used for giant AVMs involving important eloquent areas; 4.Conservation can be used for AVMs that are prone to severe disability due to intervention. Unruptured AVMs: Interventions are recommended if unruptured AVMs are assessed as being at high rupture risk, or have refractory epilepsy or acceptable postoperative neurological deficits, otherwise conservative treatment is recommended. The choice of intervention strategy was the same as for ruptured AVM. Control group: Patients who had not received a multidisciplinary assessment to develop a treatment plan were included in the control group. It should be noted that the multidisciplinary team for AVM was formed in June 2018, so the prospective AVM cohort from August 2011 to June 2018 and the AVM cohort after June 2018 without comprehensive evaluation of treatment regimens by the multidisciplinary team served as the control group.

An electronic data capture system (EDC) was developed and used for data collection. All the clinical baseline data and imaging data were stored through a cloud server to facilitate the input work at different locations and at different times. Follow-up was conducted at the first 3-6 months and annually after surgery by clinical visit and telephone interview. The evaluation of mRS score was conducted by neurosurgeons who have at least 5 years' experience of clinical practice and all the images were interpreted by at least 2 radiologists independently who are with at least 5 years of clinical experience in radiology center of our institute. Researchers who performed follow-up assessments were blinded to treatment modalities.

The primary outcomes were as follows: modified Rankin Scale, obliteration rate, subsequent hemorrhage, complication rate (such as morbidity rate, new-onset neurological dysfunction, and radiation-related complications) at 3 months, 12 months, and 3 years after treatment. The secondary outcomes were as follows: improvement of clinical symptoms (epilepsy, headache, neurological dysfunction) at 3 months, 12 months, and 3 years after treatment.