A new definition and classification of refractory hydrocephalus aim to improve diagnosis and guide more effective treatments

Refractory hydrocephalus (RH) refers to cases of fluid buildup in the brain that resist standard treatment, leading to prolonged care and high complication rates. A new study offers a clear definition and classification system for RH, highlighting infection and low-pressure hydrocephalus as the most common subtypes. By refining diagnostic criteria and outlining patient-specific management strategies, the study paves the way for more effective and standardized care.

Hydrocephalus is a condition caused by an abnormal buildup of cerebrospinal fluid (CSF) in the brain. This buildup can enlarge the brain’s ventricles, leading to headaches, cognitive difficulties, and, if untreated, severe disability or death. Standard treatment usually involves surgery to divert CSF using a shunt or to restore its natural flow. But these interventions are far from perfect: complications affect up to 40% of patients within the first year, and more than half over time. For some patients, even repeated surgeries fail to provide relief. These difficult cases are known as refractory hydrocephalus (RH).

Until now, the biggest obstacle has been the lack of a shared definition. Without one, doctors have struggled to agree on when a case qualifies as RH, how best to study it, or how to manage it consistently. This has left patients facing repeated surgeries, complications, and uncertainty.

A new study published online on August 18, 2025, in Volume 11, Issue 1 of the Chinese Neurosurgical Journal, addresses this gap by offering the first systematic definition and classification of RH. The study led by Professor Zhixiong Lin from Capital Medical University, China, defines RH as progressive hydrocephalus that fails to improve within 60 days of standard therapy, persists after two surgical attempts, or cannot be treated because of unusual conditions such as infection or abnormal CSF characteristics.

“We wanted to give doctors a clear and practical way to recognize when hydrocephalus becomes refractory,” explains Prof. Lin. “Without a definition, patients often face repeated surgeries with little benefit, which increases risks and costs.”

Beyond a definition, the review also provides a classification of RH into six subtypes. Among these, infectious hydrocephalus and low-pressure hydrocephalus stand out as the most frequent and clinically challenging. In infectious cases, bacteria or other pathogens contaminate CSF, making shunt placement risky. Here, sterilizing the CSF—completely clearing infection—becomes the top priority before any long-term solution is attempted. In low-pressure hydrocephalus, the ventricles expand despite abnormally low intracranial pressure. Treatment then focuses on restoring the brain’s elasticity and selecting drainage sites that avoid further damage.

“Infectious and low-pressure refractory hydrocephalus may look similar from the outside, but their underlying causes are completely different,” says Prof. Lin. “Recognizing the subtype helps clinicians avoid repeated ineffective surgeries and instead choose strategies that directly address the problem.”

The researchers also discuss temporary drainage methods that can stabilize patients while longer-term treatments are planned. Options such as external ventricular drains, Ommaya reservoirs, and modified shunts can relieve symptoms, yet each comes with its own drawbacks. For example, external drains provide strong control but carry a high infection risk, while Ommaya reservoirs allow greater mobility but at higher cost. Choosing the right option depends on each patient’s condition.

“Our goal is not only to define refractory hydrocephalus but also to guide its management,” Prof. Lin says. “By matching treatment to each subtype, we can improve outcomes and reduce unnecessary interventions.”

One of the study’s most important contributions is its emphasis on individualized care. By acknowledging that RH is not a single disease but a spectrum of conditions, the study challenges generic solutions that apply to everyone. Instead, it argues for tailored treatment plans, combining temporary drainage, targeted surgery, and careful monitoring.

The researchers also outline areas where future progress is needed. Reliable and rapid tools for infection detection could shorten the time required to confirm CSF sterilization. Biomarkers—measurable indicators in body fluids—may help doctors track treatment success. And improved shunt designs may address the specific problems of low-pressure hydrocephalus, where conventional devices often fail.

Looking ahead, the researchers believe that their work provides a foundation for both clinicians and researchers. “This framework is a starting point,” says Prof. Lin. “By naming and classifying RH, we hope to encourage innovation in how it is treated. Ultimately, our aim is to give patients better outcomes and better quality of life.”

Overall, the study offers the first structured definition and management roadmap for RH. It fills a critical gap in neurosurgical practice and highlights the need to move beyond repeated surgeries toward smarter, more personalized strategies. For patients and their families, this represents a step toward more hopeful and effective care.

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Reference
Title of original paper: Correct understanding of the definition and management strategies for refractory hydrocephalus
Journal: Chinese Neurosurgical Journal
DOI: 10.1186/s41016-025-00403-9

About Capital Medical University
Capital Medical University (CMU), located in Beijing, China, is a leading institution specializing in medical education, research, and healthcare. Established in 1960, CMU offers a wide range of programs across medicine, dentistry, public health, and biomedical sciences. The university is affiliated with multiple hospitals and clinical departments, providing extensive hands-on training. Known for its research excellence in fields such as neurology, immunology, and neurosurgery, CMU emphasizes innovation, international collaboration, and personalized education. It plays a key role in advancing healthcare and cultivating skilled medical professionals in China.

Website: https://ccmu.cucas.cn/

About Prof. Zhixiong Lin from Capital Medical University, China
Dr. Zhixiong Lin is a distinguished professor at Sanbo Brain Hospital, Capital Medical University, China. He has authored over 51 publications, focusing on brain tumors—particularly adamantinomatous craniopharyngiomas—and refractory hydrocephalus. His research has advanced understanding of tumor biology and improved surgical outcomes. Dr. Lin is actively involved in developing neurosurgical practices and mentoring the next generation of specialists.

Funding information
The study was supported by the Capital Health Development Research Project [2024- 1-6012].