Natural History of Sporadic Cerebral Cavernous Malformations by Zabramski Classification: Hemorrhage Risk and Functional Outcomes Over 5 Years

BACKGROUND AND OBJECTIVES: This study aimed to investigate the clinical presentation, natural history, and long-term outcome of sporadic cerebral cavernous malformations (CCMs) based on initial Zabramski classification. METHODS: A prospective cohort of 285 patients with sporadic CCMs was analyzed. Patients were classified into Zabramski Types I-IV based on diagnostic MRI. Clinical presentation, lesion size, location, and developmental venous anomaly presence were recorded. Prospective symptomatic hemorrhage (SH) (censored at first hemorrhage, surgery, or last follow-up) and functional outcomes were assessed using Kaplan-Meier and Cox regression analyses. Functional outcomes were measured with the modified Rankin Scale (mRS) at baseline, annually, and at the last follow-up. RESULTS: The cohort included 58.9% women and 41.1% men, with a mean age at diagnosis of 44.5 years. Zabramski Types I-IV (n = 113, 125, 40, and 7, respectively) differed significantly in clinical presentation ( P < .001). Type I lesions were symptomatic in 97.3%, Types II and III in 34.4% and 22.5%, respectively, while all Type IV lesions were asymptomatic. Type I lesions had the highest annual hemorrhage rate (13.9% per year) and a 5-year cumulative risk of 50.6%. Types II and III had lower rates (2.9% and 1.8%), whereas no hemorrhages occurred in Type IV lesions. At baseline, 70.8% of Type I patients had mRS ≥2, which decreased to 35.4% at the last follow-up. Type III lesions had favorable outcomes, with 7.5% of patients having mRS ≥2 at the last follow-up. Type IV lesions remained asymptomatic throughout. Severe SH significantly increased the odds of poor outcomes (mRS ≥3; P < .001), whereas Zabramski type was not predictive of outcomes after adjustment. CONCLUSION: Zabramski classification aids in stratifying hemorrhage risk and guiding management in CCMs. Severe SH is a critical determinant of functional outcomes, underscoring the need for comprehensive risk assessments and individualized patient care strategies.