# Spontaneous regression of associated aneurysms after management of arteriovenous malformation. A systematic review

## TL;DR

This study reviews how often aneurysms shrink on their own after treatment for arteriovenous malformations, finding it is rare and varies between cases.

## Contribution

The paper provides a systematic review of spontaneous aneurysm regression after AVM treatment, quantifying its low frequency and variability.

## Key findings

- Spontaneous aneurysm regression occurred in 11% of patients across 10 studies.
- Regression rates varied from 3% to 23% with no clear correlation to AVM obliteration or aneurysm type.
- Publication bias suggests the true rate of regression may be even lower than observed.

## Abstract

Assess through a systematic review the probability of spontaneous regression of aneurysms after receiving surgical, endovascular, or radiosurgical treatment of AVMs in patients with AVM-associated aneurysms.

A systematic literature review was performed in May 2025 using PubMed, Embase, and Scopus. The PRISMA flowchart for evidence screening and selection was used. Eligible studies included patients over 18 years of age with intracranial AVMs and associated FRAs, and reported spontaneous aneurysm regression following AVM treatment. Studies were excluded if they had fewer than 10 patients, non-intracranial lesions, involved only conservative management, or were not published in English or Spanish. Data on demographics, clinical presentation, interventions, and outcomes were extracted. The risk of bias was assessed using the ROBINS-I tool, and the certainty of the evidence was evaluated using the GRADE framework.

Out of 264 screened studies, 10 met the inclusion criteria, involving a total of 428 patients. Most studies were retrospective cohorts with a moderate risk of bias. Patient ages ranged from 31 to 58 years, with hemorrhagic presentation in over 50%. AVMs were mostly Spetzler-Martin grades I–III and supratentorial. Proximal and distal aneurysms were more common than intranidal types. Regression rates of aneurysms ranged from 3 to 23%, with no consistent correlation to AVM complete obliteration rates, aneurysm type, or location. Spontaneous aneurysm regression is rare, with a pooled rate of 11% across studies. Despite moderate heterogeneity, sensitivity analyses confirmed the robustness of results. Funnel plots suggested possible publication bias, indicating the true rate may be even lower. Clinically, regression should be considered exceptional, reinforcing the need for vigilant follow-up and individualized treatment.

Spontaneous aneurysm regression after AVM treatment is a recognized but variable and low-frequency phenomenon, with the highest observed probability being 23%. Further studies are needed to guide treatment strategies in these complex cases.