Impact of Embolization on Clinical Outcomes After Treatment of Metameric and Sporadic Spinal Cord Arteriovenous Malformations: An Analysis of 216 Patients.

BACKGROUND AND

OBJECTIVES

Spinal arteriovenous metameric syndrome (SAMS) is a rare, complex vascular disorder characterized by multifocal spinal cord arteriovenous malformations (SCAVMs) affecting structures derived from the same metameric segment. The long-term clinical outcome of SAMS, particularly after embolization, remains poorly understood. This study evaluated the clinical outcomes of embolization for SAMS compared with nonmetameric SCAVMs.

METHODS

This retrospective study included 216 patients with intradural SCAVMs who underwent embolization (62 patients with SAMS and 154 patients without metameric background [non-SAMS group]). Clinical and imaging data were reviewed to assess clinical worsening, hemorrhagic events, and angiographic worsening during the observation period after initial embolization.

RESULTS

The overall median observation period was 44 months (IQR, 1-307). The SAMS group was associated with a higher risk of clinical and angiographic worsening compared with the non-SAMS group (hazard ratio [HR] 2.90; 95% CI 1.37-6.12; P = .0003, and HR 5.04; 95% CI 2.03-12.50; P = .0001). Regarding hemorrhagic events, the SAMS group demonstrated a risk equivalent to the non-SAMS group (HR 1.93; 95% CI 0.65-5.78; P = .234). In subgroup analysis based on final occlusion rate (≥75% or <75%) of intradural SCAVMs, failure to achieve ≥75% occlusion in the SAMS group resulted in significantly worse clinical and angiographic outcomes (HR 5.28; 95% CI 1.90-14.66; P = .001, and HR 9.41; 95% CI 3.02-29.34; P = .0001). Achieving ≥75% occlusion resulted in a risk comparable with that of the non-SAMS group.

CONCLUSION

Embolization reduced the risk of hemorrhagic events in SAMS to a level comparable with the non-SAMS group. However, SAMS carries a higher risk of clinical and angiographic worsening than non-SAMS, even after embolization. Achieving sufficient occlusion (≥75% occlusion) of intradural SCAVMs mitigates these clinical risks in SAMS.