Brain aneurysm with a measuring scale

Decoding Brain Bleeds: Can a New Scale Predict Recovery After Aneurysm?

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Avery Sinclair in Health & Wellness December 2025 • 5 min read.

"The BNI grading scale offers a simpler way to assess SAH and predict outcomes, potentially improving patient care and treatment strategies."


When an aneurysm ruptures and causes bleeding in the brain (aneurysmal subarachnoid hemorrhage, or aSAH), predicting how well a person will recover is a major challenge. A key complication is delayed cerebral ischemia (DCI), where blood supply to the brain is reduced, potentially causing further damage. Doctors have long relied on the Fisher scale to estimate this risk, but a newer tool, the Barrow Neurological Institute (BNI) scale, aims to provide a more straightforward and accurate assessment.

The BNI scale focuses on the thickness of blood accumulation in the brain after the bleed, offering a quantitative measure that could potentially replace or enhance the traditional Fisher score. Researchers from Switzerland undertook a large, nationwide study to validate the BNI scale and determine its effectiveness in predicting DCI and overall patient outcomes.

This article will explore the findings of that study, explaining how the BNI scale works, its potential benefits over existing methods, and what it means for people at risk of aSAH and the medical professionals who care for them. We'll break down the key results and discuss how this new tool could lead to improved treatment strategies and better recovery prospects.

The BNI Scale: A Simpler Way to Assess Risk

Brain aneurysm with a measuring scale

The BNI scale is designed to be a practical tool for doctors. Instead of complex assessments, it relies on a single measurement: the maximum thickness of the blood clot in any of the brain's fissures or cisterns (spaces around the brain). This measurement is taken from CT scans performed upon admission to the hospital.

The scale ranges from 1 to 5, with higher numbers indicating thicker blood accumulation and, consequently, a greater risk of DCI. This straightforward approach contrasts with the Fisher scale, which factors in both the amount of blood and whether it extends into the ventricles (fluid-filled spaces) of the brain. The BNI scale's simplicity could lead to more consistent and reliable assessments across different medical centers.

  • BNI Grade 1: No visible SAH
  • BNI Grade 2: Clot thickness measured till 2mm
  • BNI Grade 3: Clot thickness measured till 4mm
  • BNI Grade 4: Clot thickness measured till 6mm
  • BNI Grade 5: Clot thickness measured more than 6mm
The Swiss study involved data from 1321 patients across eight hospitals, providing a large and diverse sample. The researchers analyzed the relationship between BNI scores, the development of DCI, and patient outcomes as measured by the modified Rankin Scale (mRS), which assesses a person's level of disability after a stroke or brain injury. A score of 0-2 on the mRS indicates a favorable outcome (minimal or no disability), while 3-6 indicates an unfavorable outcome (moderate to severe disability or death).

The Future of Brain Bleed Assessment

The Swiss study provides strong evidence that the BNI scale is a valuable tool for predicting DCI and outcomes after aSAH. Patients with higher BNI grades (indicating thicker blood accumulation) were significantly more likely to develop DCI and experience unfavorable outcomes. Importantly, the BNI scale also allowed for further risk stratification within the large group of patients classified as Fisher 3, where the traditional scale provides limited differentiation.

While the BNI scale showed promise, the researchers also found that combining it with the World Federation of Neurological Surgeons (WFNS) score (a measure of a patient's clinical condition upon admission) and patient age further improved the prediction of outcomes. This suggests that a multi-faceted approach, incorporating both radiological and clinical data, may provide the most accurate assessment.

The BNI scale offers a simple, quantitative, and reliable way to assess the risk of DCI and predict outcomes after aSAH. As research continues, expect to see a refinement of risk assessment strategies. The BNI scale could play a vital role in improving treatment decisions and ultimately improving the lives of those affected by this devastating condition. The focus is to help improve treatment decisions and the lives of those affected by this devastating condition.

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.

Everything You Need To Know

1

What does the Barrow Neurological Institute (BNI) scale measure?

The Barrow Neurological Institute (BNI) scale assesses the thickness of blood accumulation in the brain after an aneurysmal subarachnoid hemorrhage (aSAH). It ranges from 1 to 5, where higher numbers indicate thicker blood accumulation and a greater risk of delayed cerebral ischemia (DCI). This scale uses CT scans to measure the maximum thickness of the blood clot in the brain's fissures or cisterns.

2

How does the BNI scale improve upon the traditional Fisher scale?

The BNI scale offers a more straightforward assessment compared to the Fisher scale. While the Fisher scale considers both the amount of blood and its extension into the brain's ventricles, the BNI scale focuses solely on the maximum thickness of the blood clot. This simplicity can lead to more consistent and reliable assessments across different medical centers. The BNI scale also allows for better risk stratification, especially within the Fisher 3 group, where the Fisher scale provides limited differentiation.

3

What is 'delayed cerebral ischemia' (DCI) and how does the BNI scale help in predicting it?

Delayed cerebral ischemia (DCI) is a major complication after aneurysmal subarachnoid hemorrhage (aSAH). It occurs when the blood supply to the brain is reduced, potentially causing further damage. The BNI scale helps predict the risk of DCI by assessing the thickness of blood accumulation in the brain, with higher BNI grades indicating a greater likelihood of developing DCI.

4

What is the modified Rankin Scale (mRS) and how is it used in the context of brain bleeds?

The modified Rankin Scale (mRS) is used to assess a person's level of disability after a stroke or brain injury, including aneurysmal subarachnoid hemorrhage (aSAH). It ranges from 0 to 6, where 0-2 indicates a favorable outcome (minimal or no disability) and 3-6 indicates an unfavorable outcome (moderate to severe disability or death). Researchers use the mRS to determine how well the BNI scale correlates with patient outcomes after aSAH.

5

What are the potential benefits of using the BNI grading scale for assessing aneurysmal subarachnoid hemorrhage (aSAH)?

The BNI grading scale offers several potential benefits, including simpler risk assessment, improved prediction of delayed cerebral ischemia (DCI) and patient outcomes, and better risk stratification compared to existing methods like the Fisher scale. By providing a more straightforward and accurate assessment, the BNI scale has the potential to improve patient care, treatment strategies, and overall recovery prospects after aneurysmal subarachnoid hemorrhage (aSAH). It could also contribute to more consistent evaluations across different medical facilities.

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