This nationwide multicenter prospective cohort study will collect the treatment information and outcomes of the patients with previously untreated cavernous malformations (U-CMs) in China (at least 2000 patients from 20 centers). The investigators aim to determine the effect of different treatments on long-term outcomes in patients with untreated cerebral cavernous malformations.

Despite the availability of microsurgical excision and stereotactic radiosurgery for cavernoma treatment and known genetic causes of most familial forms of cavernoma, uncertainties remain about cause, diagnosis, prognosis, treatment, and care. According to the recently published CM treatment guideline, surgical and conservative treatments are both first-line therapeutic options in previously untreated CMs (U-CMs). However, given current data, neurosurgeons are still unable to counsel patients on which would be the best option. To address the absence of high level evidence to support cerebral CM treatment decisions, there is a need for a large sample size study of cerebral CM treatment with a prospective concurrent group. China has the largest population in the world and may have the most extensive and valuable clinical resources of U-CMs. But, till now, the current treatment and outcome situation of the disease in China is not well known. Thus, the investigators are conducting a nationwide multicenter prospective registry study in China to determine the effect of different treatments on long-term outcomes in patients with untreated cerebral cavernous malformations.At least 2000 patients with untreated cerebral cavernous malformation will be enrolled from 20 Grade Ⅲ A level hospitals distributed all over China. Clinical data and laboratory data are prospectively collected by electric case report form (CRF) and uploaded online by each neurosurgery center to form the prospective clinical database in First Affiliated Hospital of Fujian Medical University. This is a cohort follow-up study across a 5-year period with a 2 years interval of enrollment and 3 years follow up for each patient.

Inclusion Criteria:

• Definite diagnosis of cerebral CM on the basis of brain MRI or pathologic examination;
• Patients without any surgical intervention (microsurgery, radiosurgery, or multimodality treatment) before enrolment;
• Informed consent, and willing to accept long-term follow-up.

Exclusion Criteria:

• Patients receiving emergency surgery due to acute intracranial hematoma and resultant brain hernia;
• Patients with other never system diseases, such as aneurysms, tumors or other vascular malformations except venous development anomaly;
• Patients with severe underlying disease, which affects the patient's functional status and life expectancy;
• Patients with severe mental or psychologic disease.

Consecutive patients with untreated cerebral cavernous malformation are enrolled from 20 Grade Ⅲ A level hospitals distributed all over China. At the time of the participants entered the study, lesions should not have been treated by surgery or radiosurgery previously. This is a cohort follow-up study across a 5-year period. All patients in this study should meet the inclusion and exclusion criteria. Informed written consent should be obtained from eligible adult patients or from the guardians of eligible pediatric patients. All patients in the prospective part of this study can withdraw at any time.

We will share individual participant data after the primary results have been published.