🧠 Subdural Effusion

Subdural effusion refers to the accumulation of cerebrospinal fluid (CSF) or CSF-like fluid in the subdural space, located between the dura mater and the arachnoid mater of the brain.

A subdural effusion is a non-hemorrhagic fluid collection in the subdural space, typically composed of CSF or protein-rich CSF-like fluid. It may develop due to:

• Arachnoid membrane tears
• CSF leakage
• Postoperative changes
• Inflammatory processes

• Subdural hygroma (commonly used synonym)
• CSF subdural collection
• Non-hemorrhagic subdural collection
• Subdural cerebrospinal fluid accumulation

⚠️ Note: While “subdural hygroma” is often used interchangeably, it technically refers to pure CSF collections, whereas “effusion” may contain reactive or inflammatory components.

• CT: Hypodense crescent-shaped fluid collection
• MRI: Signal intensity similar to CSF on T1 and T2 (if uncomplicated)
• Typically no enhancement unless associated with inflammation

• Traumatic brain injury
• Decompressive craniectomy or hinged craniotomy
• Overdrainage from CSF shunting
• Post-infectious or inflammatory states
• Idiopathic (rare)

• Chronic subdural hematoma
• Subdural empyema
• Hygroma
• Reactive subdural collections

Subdural effusions may be:

• Asymptomatic (incidental findings)
• Symptomatic with headache, confusion, or focal deficits
• Risk factor for mass effect or progression to hematoma

• Observation (if small and asymptomatic)
• Serial imaging
• Surgical drainage (if mass effect or deterioration)
• Address underlying cause (e.g. revise shunt, treat infection)

In a case report, *Artem Kuptsov* et al., from the Department of Neurosurgery, Hospital General Universitario de Alicante Dr. Balmis (Alicante, Spain) and the Department of Medicine and Surgery, University of Milan Bicocca (Milan, Italy), published in *Neurocirugía (English Edition)* the first documented case of contralateral subdural effusion (CSE) following a hinged craniotomy (HC). Through a narrative literature review, they explore the pathogenesis, clinical management, and preventive strategies related to this rare complication ¹⁾.

They conclude that hinged craniotomy is a promising alternative to decompressive craniectomy (DC), as it avoids the need for secondary cranioplasty while still providing effective control of intracranial pressure. However, the case demonstrates that CSE may occur postoperatively, a complication not previously reported in association with HC.

The authors emphasize the need for:

* Greater awareness of rare HC-related complications * A better understanding of cerebrospinal fluid dynamics * Further research into postoperative monitoring and prevention following HC

While Kuptsov et al. attempt to highlight a novel postoperative complication—contralateral subdural effusion (CSE)—following hinged craniotomy (HC), their report ultimately contributes more anecdote than evidence, and raises more questions than it resolves.

🧪 1. Type of Study: Weak Evidence by Design

The article is a single case report, the lowest tier of clinical evidence, accompanied by a narrative (non-systematic) review. No attempt is made to quantify incidence, establish causality, or define a reproducible clinical protocol. The “review” lacks a defined methodology, inclusion criteria, or critical synthesis—thus offering no more than a selective literature commentary.

📉 2. Absence of Diagnostic Rigor

The diagnosis of CSE is radiological and speculative, without histological confirmation, CSF analysis, or demonstration of a clear mechanism. No preoperative imaging is presented for comparative purposes. The pathophysiological discussion remains vague, relying heavily on inference rather than demonstration.

🔬 3. Narrative Review Without Substance

Despite the authors’ claim of reviewing the literature to explore “pathogenesis, management, and prevention,” the review is methodologically hollow. It fails to:

* Classify subdural fluid collections appropriately * Differentiate effusion from hygroma or subacute hematoma * Address alternative explanations (e.g., iatrogenic CSF redistribution, intracranial compliance issues)

The few cited sources are descriptive and non-critical, reflecting a technophilic bias rather than analytical depth.

🚨 4. Overstated Conclusions

The authors describe HC as a “promising alternative” to decompressive craniectomy. Yet their own case illustrates a potentially serious, unreported complication, which undermines rather than supports this claim. They paradoxically recommend greater adoption of HC while simultaneously exposing its unknown risks—without providing actionable safety recommendations.

🤔 5. What Is Actually New?

The only novelty is the location of the fluid collection—contralateral rather than ipsilateral. However, this may simply reflect variations in CSF dynamics already well described in literature on hygromas after DC. As such, the clinical value of the article is limited, and its generalizability is nonexistent.

❌ Final Verdict

Kuptsov et al.’s report falls short of scientific rigor, offering a poorly substantiated hypothesis, disguised as a clinical insight. Rather than clarifying the risks of hinged craniotomy, it leaves readers with a sense of uncertainty amplified by weak evidence and speculative conclusions. Until supported by prospective data or mechanistic studies, the clinical significance of this case remains dubious at best, misleading at worst.