Long-term Outcomes After Different Management Strategies for High-level Cerebral Arteriovenous Malformation
Long-term Outcomes After Different Management Strategies for High-level Cerebral Arteriovenous Malformation
Arteriovenous malformations (AVMs) are complex and rare cerebral vascular dysplasia. The main
 purpose of treatment is to avoid the neurological impairment caused by hemorrhagic stroke.
 The Spetzler-Martin (SM) grading system is widely used to estimate the risk of postoperative
 complication based on maximum AVM nidus diameter, pattern of venous drainage, and eloquence
 of location. Generally, grade I and II are amenable to surgical resection alone. Grade III is
 typically treated via a multimodal approach, including microsurgical resection, embolization,
 and radiosurgery (SRS). Grade IV and V are generally observed unless ruptured. However, some
 previous studies indicated that despite the high rate of poor outcomes for high-level
 unruptured AVMs, the mortality for high-level unruptured AVMs are likely lower than untreated
 patients. With the development of new embolic materials and new intervention strategies,
 patients with high-level AVMs may have more opportunities to underwent more aggressive
 interventions. The OHAVM study aims to clarify the clinical outcomes for patients with SM
 grade IV and V AVMs after different management strategies.
Follow-up: In our neurosurgical center, follow-up was conducted for all patients at the first
 3-6 months and annually after discharge by clinical visit and telephone interview.

 Study overview: The population in the OHAVM study will be divided into two parts. Clinical
 and imaging data of high-level AVM patients from 2012/04 to 2019/09 were retrospectively
 collected. And the high-level AVM patients from 2019/09 to 2019/12 were prospectively
 collected. The intervention strategies in our institution for high-level AVMs are of four
 categories: microsurgical resection, embolization, embolization+radiosurgery, and
 single-stage hybrid surgery (embolization-resection). Each participants will be followed at
 least for 5 year since enrollment. Finally, we will clarify the clinical outcomes and
 prognostic predictors for patients with SM grade IV and V AVMs after different management
 strategies.

 Sample size: About 1000 patients will be enrolled in this study, and half of them were
 unruptured. The population distribution of different management strategies is expected as
 follows: conservative:100 cases, microsurgical resection: 300 cases, embolization:250 cases,
 embolization+radiosurgery: 250 cases, single-stage hybrid surgery: 100 cases.

 Study endpoints: The neurological function prognosis, occlusion rate and complications were
 evaluated at 2 weeks, 1 year, 3 years, 5 years after the treatment and the last follow-up,
 respectively.
Inclusion Criteria:

 1. The diagnosis of AVM was confirmed with digital subtraction angiography (DSA) and/or
 magnetic resonance imaging(MRI).

 2. The SM grade was IV and V.

 Exclusion Criteria:

 1. Patients with multiple AVMs.

 2. Patients with hereditary hemorrhagic telangiectasia (HHT).

 3. Patients with missing clinical and imaging data.