EVD Drains Compared: Which Type Reduces Your Risk of Complications?
"A Prospective Study Reveals Bolt-Connected Drains Offer a Safer Alternative to Traditional Tunnelled Drains for Managing Intracranial Pressure"
When intracranial pressure (ICP) rises to dangerous levels, swift action is crucial. One of the most common and effective interventions is external ventricular drainage (EVD). This neurosurgical procedure involves placing a catheter into the brain's ventricles to drain cerebrospinal fluid (CSF), thereby reducing pressure. While EVD can be life-saving, it's also associated with a significant risk of complications, including infections, bleeding, and catheter malfunctions.
For years, the standard approach to EVD involved a technique called tunnelled EVD (T-EVD), where the catheter is threaded under the skin to a separate exit point. However, recent research has suggested that a newer method, bolt-connected EVD (BC-EVD), might offer a safer alternative. BC-EVD involves direct connection of the catheter to a bolt secured to the skull, potentially reducing the risk of infection and other complications.
Now, a prospective study published in Acta Neurochirurgica sheds new light on the comparison between these two EVD techniques. Researchers at Aalborg University Hospital in Denmark conducted a trial to determine if BC-EVD indeed leads to fewer complications than the traditional T-EVD method. Let's dive into the details of this study and what it could mean for patients requiring EVD.
EVD Risks and Outcomes
External ventricular drain (EVD) placement is a standard neurosurgical procedure used for cerebrospinal fluid diversion and intracranial pressure monitoring. Conventional freehand techniques are associated with substantial variability in placement accuracy and complication risk. Reported complications include EVD catheter infection, intracranial hemorrhage, and suboptimal placement, while a 2025 study of patients with intraventricular hemorrhage reported 30-day mortality of 29% and good functional outcome at 90 days in 31% of patients.
Established Practice, Persistent Risk
External ventricular drainage is among the most frequent procedures in neurosurgical practice and is often performed at the bedside in a neurocritical care unit or emergency room. A review reported that complication risks may range from 5% to 39%, reflecting substantial variation across studies and clinical circumstances. Commonly documented complications include infection, hemorrhage, catheter misplacement, and mechanical blockage, with reported infection rates of about 2% to 36% and imaging-detected hemorrhage rates of roughly 7% to 33%, depending on how they are measured.
From 1744 to Modern EVDs
External ventricular drainage was first performed as early as 1744 by Claude-Nicholas Le Cat. Since then, the procedure has undergone numerous changes in technique, materials, indications, and safety. The history of EVD is described as four eras of progress, beginning with development of the technique from 1850 to 1908, while later device advances have focused on preventing occlusion and infection.
T-EVD vs. BC-EVD: What the Study Revealed
The Aalborg Bolt-Connected Drain (ABCD) study was designed to prospectively compare the outcomes of patients undergoing EVD using either the BC-EVD or T-EVD technique. From March 2017 to February 2018, patients requiring ventriculostomy were consecutively assigned to either the BC-EVD or T-EVD group based on the preference of the on-call neurosurgeon. This approach resulted in two distinct cohorts, as some surgeons favored the newer BC-EVD method while others remained more comfortable with the traditional T-EVD technique.
- CSF leakage
- Accidental Discontinuation
- Placement-related intracranial haemorrhage
- Malfunction
- Migration
- Infection
- Revision (reoperation)
Current Evidence on IVH Treatment
External ventricular drainage is a key component in the treatment of intraventricular hemorrhage (IVH), but it is associated with risks and complications. A comprehensive systematic review and meta-analysis examined treatment of IVH with external ventricular drainage and fibrinolysis. Its stated focus was to assess complications and outcomes rather than treating EVD as risk-free therapy.
Comparing Drainage Strategies
External ventricular drains are widely used, but their management varies considerably between clinical settings. A 2022 review reported that care bundles centered on aseptic techniques for EVD insertion, maintenance, and care are likely to prevent EVD-associated infections. Separately, a 2023 study compared EVDs with percutaneous continuous cerebrospinal fluid drainage through ventricular access devices for acute hydrocephalus in adults, framing the two approaches as alternatives requiring direct comparison.
The Future of EVD: A Shift Towards Safer Techniques
The ABCD study provides compelling evidence that BC-EVD is associated with a lower risk of complications compared to T-EVD. While the authors acknowledge that T-EVD may still have a role in specific situations, such as in pediatric patients or when EVD is placed intraoperatively or in the occipital region, they conclude that BC-EVD should be considered the first-line choice for most EVD placements. As the field of neurosurgery continues to evolve, embracing safer and more effective techniques like BC-EVD is crucial for improving patient outcomes and minimizing the risks associated with this life-saving procedure.
Infection as a Central Concern
External ventricular drain-related infection is a major complication of EVD insertion. A 2022 systematic review described EVD-related infection as a complication that can lead to morbidity and mortality. This makes infection prevention an important part of evaluating the safety of different drainage approaches.
Complications in Practice
For patients with acute hydrocephalus after acute aneurysmal rupture, placement of an external ventricular drain may be required. EVD-associated infections are among the most common complications of catheter placement and are reported as prevalent in the United States. Two recent studies cited by the source found overall infection rates between 9.9% and 36%, although the source also notes that global statistics for EVD-associated infection rates are lacking.