Role Of Embolisation In Intranidal Arterio-Venous Fistula Within Cerebral Arterio-Venous Malformations

Abstract

Cerebral arteriovenous malformations (AVMs) represent complex congenital vascular anomalies characterized by aberrant connections between arteries and veins, bypassing capillary networks and leading to high-flow shunting. Within these malformations, intranidal arteriovenous fistulas (AVFs) constitute distinct high-velocity channels that intensify hemodynamic stress, elevating risks of intracranial haemorrhage, seizures, and neurological impairments. This study explores the pivotal role of endovascular embolization in managing intranidal AVFs within cerebral AVMs, emphasizing its efficacy, safety, and integration into multimodal therapeutic strategies.

Conducted as a systematic review and meta-analysis adhering to PRISMA guidelines, the investigation synthesized data from PubMed, Embase, Scopus, and Cochrane Library spanning January 2021 to January 2022. Search terms encompassed "cerebral AVM," "nidal AVF," "embolization," and related variants. Inclusion criteria targeted cohort studies and case series (>10 patients) detailing embolization outcomes specifically for nidal AVFs, excluding case reports, non-English publications, and studies lacking fistula-specific analyses. Data extraction by two independent reviewers covered patient demographics, AVM characteristics (e.g., Spetzler-Martin grades), procedural details (agents like NBCA or Onyx), occlusion rates, complications, and long-term outcomes (e.g., modified Rankin Scale scores). Quality assessment employed the Newcastle-Ottawa Scale and MINORS criteria, with meta-analysis utilizing random-effects models in Review Manager 5.4 to compute pooled proportions and heterogeneity via I² statistics.

Analysis of key studies revealed embolization's effectiveness in achieving high occlusion rates (pooled 75-90% for targeted AVFs) while mitigating hemorrhage risks (hazard ratio reduction to 0.45 in combined therapies). Complications, primarily ischemic events, occurred in 5-10% of cases, often unrelated to AVF-specific interventions. Subgroup analyses by AVM grade and embolic agent highlighted superior outcomes for Grades III-V with Onyx, facilitating adjunctive microsurgery or radiosurgery. Long-term follow-up demonstrated sustained symptom relief and AVM size reduction in 80% of treated cases, with minimal recurrences.

Embolization emerges as a cornerstone minimally invasive approach for intranidal AVFs, reducing venous hypertension and enhancing overall prognoses. This review bridges literature gaps, advocating tailored, multidisciplinary protocols to optimize patient outcomes in interventional neuroradiology. Future large-scale trials are warranted to refine techniques and long-term efficacy assessments.