Surreal illustration of a brain with storm clouds symbolizing hematoma risk factors.

Subdural Hematoma Recurrence: Are You at Risk?

Samir D’Costa in Health & Wellness December 2025 • 4 min read.

"A deep dive into the factors that increase the chances of repeat brain bleeds and what it means for your treatment."

Chronic subdural hematoma (CSDH), a condition where blood collects between the brain and its outer covering, is common, especially in older adults. While surgery often helps, the blood can sometimes come back, a situation known as recurrence. Knowing what makes recurrence more likely is crucial for effective treatment and peace of mind.

After surgery to remove the initial hematoma, a new membrane can form, filled with blood that enlarges the affected area, leading to the recurrence. Fortunately, initial treatments often show positive results. However, recurrence rates vary, ranging from 3% to 20%.

This article examines the latest research to identify the key factors that contribute to CSDH recurrence. By understanding these risks, patients and their families can better prepare for the road ahead and work with doctors to minimize potential complications.

What Factors Increase the Risk of CSDH Recurrence?

Surreal illustration of a brain with storm clouds symbolizing hematoma risk factors.

A recent study analyzed data from 136 patients who underwent surgery for CSDH. The goal was to pinpoint specific characteristics that made recurrence more likely. The study considered various factors, including patient demographics, medical history, and detailed analysis of brain scans.

Here’s what the research revealed about the major risk factors:

Hematoma Size: Larger hematomas, specifically those with a maximum thickness exceeding 20mm, were significantly associated with higher recurrence rates. Think of it like this: a larger initial bleed may indicate a more aggressive underlying condition or a greater disruption of blood vessels, making re-bleeding more likely.
Hematoma Density: The density of the hematoma, as seen on brain CT scans, also played a role. High-density or mixed-density hematomas (meaning they contained a mix of fresh and older blood) were linked to a higher chance of recurrence. This suggests that active bleeding or repeated small bleeds within the hematoma increase the risk of it coming back.
Surgical Technique: Interestingly, the study hinted that surgeries using two burr holes (small holes drilled in the skull to drain the hematoma) might have a slightly higher recurrence rate than those using a single hole, although this wasn't statistically significant. One possible explanation is that two holes could, in some cases, lead to a larger accumulation of air after surgery, potentially contributing to recurrence.

While the study didn't find strong links between recurrence and factors like age, alcohol consumption, or pre-existing conditions such as hypertension, the size and density of the initial hematoma emerged as key indicators. Also, although not statistically significant, it seems like surgeries using two burr holes might show higher recurrence.

What Does This Mean for You?

If you or a loved one is facing surgery for a chronic subdural hematoma, understanding these risk factors can empower you to have informed conversations with your medical team. Discuss the size and density of the hematoma based on imaging results, and ask about the rationale for the chosen surgical technique.

While these factors can help predict risk, they don't guarantee recurrence. Many people with large or dense hematomas have successful outcomes, and recurrence can happen even when risks seem low. Regular follow-up appointments and adherence to your doctor's recommendations are crucial for monitoring your progress and addressing any potential issues early.

This study underscores the importance of continued research into CSDH and its recurrence. By refining our understanding of the underlying mechanisms and risk factors, we can develop even more effective strategies for preventing and managing this condition, ultimately improving outcomes and quality of life for patients.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.13004/kjnt.2012.8.2.122, Alternate LINK

Title: Factors Affecting Postoperative Recurrence Of Chronic Subdural Hematoma

Subject: Surgery

Journal: Korean Journal of Neurotrauma

Publisher: Korean Neurotraumatology Society

Authors: Woo-Keun Kong, Byong-Chul Kim, Keun-Tae Cho, Seung-Koan Hong

Published: 2012-01-01

Everything You Need To Know

What exactly is a chronic subdural hematoma (CSDH) recurrence, and why is it important to understand?

A chronic subdural hematoma (CSDH) involves blood collecting between the brain and its outer covering. Recurrence refers to the return of this blood collection after initial treatment, such as surgery. It happens when a new membrane forms and fills with blood, enlarging the affected area.

What are the primary factors that increase the risk of a chronic subdural hematoma (CSDH) coming back after surgery?

Research indicates that larger hematomas, specifically those exceeding 20mm in thickness, show higher recurrence rates. Also, hematomas with high or mixed density on CT scans are more prone to recurrence. While the study suggests a possible link between surgical technique and recurrence, the hematoma's size and density are more statistically significant.

Besides hematoma size and density, what other patient characteristics or conditions were examined for their potential link to chronic subdural hematoma (CSDH) recurrence?

The study examined patient demographics, medical history, and brain scans. It did not find strong links between recurrence and factors like age, alcohol consumption, or pre-existing conditions such as hypertension. This doesn't entirely rule out the relevance of such factors, but the study highlights hematoma size and density as more direct indicators.

How can knowing the size and density of my initial chronic subdural hematoma (CSDH) influence my treatment plan and post-operative care?

The size and density of the initial chronic subdural hematoma (CSDH) can affect treatment decisions. Knowing these factors helps patients discuss the best surgical approach with their medical team. For example, a doctor might opt for a specific surgical technique if the hematoma is particularly large or dense, although this wasn't statistically significant, it seems like surgeries using two burr holes might show higher recurrence. Regular monitoring post-surgery can also be adjusted based on these initial characteristics.

Does the number of burr holes used during surgery to remove a chronic subdural hematoma (CSDH) affect the likelihood of it recurring?

While surgeries using two burr holes might have a slightly higher recurrence rate, this wasn't statistically significant. However, the study suggests that the potential for a larger accumulation of air after surgery using two holes could contribute to recurrence. Surgeons carefully weigh these considerations when deciding on the best approach for draining the chronic subdural hematoma (CSDH). Further research is needed to conclusively establish the relationship between the number of burr holes and recurrence rates.