# Endovascular vs conservative treatment in patients with chronic subdural hematomas and mild symptoms: a study protocol for a multicenter randomized controlled trial (EMBOTRIAL-1)

## TL;DR

This study aims to compare endovascular embolization and conservative treatment for chronic subdural hematomas to determine which is more effective in preventing progression and avoiding surgery.

## Contribution

The study introduces a multicenter randomized controlled trial to evaluate the effectiveness of middle meningeal artery embolization versus conservative treatment for chronic subdural hematomas.

## Key findings

- The trial will assess whether MMA embolization reduces hematoma progression and surgical rescue events compared to conservative treatment.
- The primary outcome is defined as treatment failure based on incomplete hematoma resolution or the need for surgical intervention within six months.

## Abstract

Chronic subdural hematoma (cSDH) is a common neurosurgical condition that is prevalent in elderly patients. There are no well-defined guidelines for cSDH and management strategies vary widely among physicians and institutions, and this variability is expressed in the literature. In general, conservative management is reserved to patients who are asymptomatic or have minor symptoms with mild mass effect. Spontaneous resolution of cSDH is an unusual phenomenon and middle meningeal artery (MMA) embolization seems to reduce the recurrence and progression rate of SDH compared to conventional treatments in multiple cohort studies. A randomized controlled trial is warranted to determine the effectiveness and safety of endovascular embolization for cSDH and whether MMA embolization is superior to conservative management in reducing the progression rate and surgical rescue event.

This is an Italian multicenter prospective randomized clinical trial with open-label treatment and blinded outcome assessment (PROBE design) to assess the superiority of MMA embolization compared to conservative treatment. A total of 300 patients are planned to be randomized 1:1 to receive MMA embolization (intervention) or conventional treatments (control). The primary outcome is the treatment arm failure which is defined as a composite of incomplete hematoma resolution or surgical rescue within 6 months follow-up. Incomplete hematoma resolution is defined as a reduction of the cSDH thickness ≤50% at follow-up compared to the hematoma thickness measured at the time of randomization. Surgical rescue is intended as hematoma removal for relief or symptoms that developed with continuous growth of the cSDH. In case of bilateral cSDH, the treatment failure occurred when primary outcomes criteria are satisfied for at least one of the two hematomas.

This multi-centre randomized controlled trial is needed to evaluate the benefit-to-risk ratio of primary embolization of the MMA to facilitate resolution and prevent rescue surgical evacuation of cSDH. If MMA embolization turns out to be superior to conservative management in this trial, this may prompt further confirmatory trials and, at best, may change clinical practice and guideline recommendations.

ClinicalTrials.gov. Identifier: NCT06274580, Registered on 6 February 2024. This protocol was developed in accordance with the SPIRIT Checklist and by use of the structured study protocol template provided by BMC Trials.

The online version contains supplementary material available at 10.1186/s13063-025-09131-y.