A Simple Scalp Tunneling Technique Using a Foldable Tunneling Tool for Placement of Deep Brain Stimulation Electrode Lead

Abstract

Objective

In bilateral deep brain stimulation (DBS) with a dual-channel implantable pulse generator (IPG), creating a subgaleal tunnel for the contralateral lead is challenging because existing tunneling devices are either too short or too rigid. Hardware complications, such as infection and erosion, remain among the most common sources of morbidity. We describe a simple and minimal technique using a sterile intubation guide and the straw included with the Boston Scientific tunneling tool.

Materials and Methods

We developed a tunneling technique that repurposes a sterile 14-Fr intubation stylet from a Boston Scientific tunneling kit, placed inside a plastic straw. The stylet provides both flexibility and stiffness to navigate the skull's curvature, while lubrication ensures smooth passage. After tunneling, the stylet is removed, and the DBS lead is threaded through the straw, which is then withdrawn.

Results

From 2020 to 2025, we applied this technique in 17 bilateral DBS cases (mean age 60.7 years). No additional scalp incisions were necessary. We observed no infections, erosions, or scalp injuries related to the technique, and only one case of hardware malfunction; no other complications were reported.

Conclusion

This pragmatic approach appears to provide a minimally traumatic method for subgaleal midline tunneling in bilateral DBS. By avoiding auxiliary incisions and potentially reducing mechanical stress on the lead, it may help decrease device-related morbidity.

Introduction

Deep brain stimulation (DBS) is a widely adopted therapy for medication-refractory movement disorders, providing long-lasting symptom relief in Parkinson's disease, essential tremor, and dystonia. Despite its low-risk profile, device-related complications remain clinically important. Recent single-center data involving 1,896 procedures report primary implantation infections in 5% and revision surgeries with infections in 2% of cases. ¹ A 22-year longitudinal Parkinson's cohort documented an overall infection rate of 8.7%, with risk increasing after each generator replacement. ² Hardware malfunctions, lead fractures, erosions, and pocket complications collectively affect 10 to 15% of patients and are linked to longer surgeries and extensive tissue dissection. ^{3 4} Additional series of 426 to 510 consecutive cases confirm a global complication rate of 12 to 15%, highlighting the need for technical improvements to reduce operative time and tissue trauma. ^{5 6}

To decrease pocket-related complications, many centers now prefer a single dual-channel implantable pulse generator (IPG) for bilateral DBS. This setup requires subgaleal tunneling of one lead across the cranial midline beneath the scalp. Standard tunneling devices from manufacturers are short and relatively rigid; surgeons often add a helper scalp incision or attempt a long blind pass, both of which increase tissue trauma, bleeding, and infection risk. ⁵ Earlier reports of retrograde or improvised tunneling highlight the technical challenges of creating a smooth, convex subgaleal track without a purpose-built, long, flexible instrument. ⁷

We developed a simple, disposable solution that uses readily available operating-room supplies: a flexible endotracheal intubation stylet inserted into the plastic straw supplied with the Boston Scientific tunneling kit. This blunt, shapeable assembly conforms to the skull's curvature in a single subgaleal pass, avoids additional incisions, and reduces mechanical stress on the electrode. This technical note describes the assembly steps, operative workflow, and our initial experience since 2020, during which the method has enabled midline lead passage in bilateral DBS cases without scalp injury or hardware damage.

Materials and Methods

Surgical Technique

Patient Positioning and Preparation

The patient was positioned supine with the head stabilized to allow simultaneous access to the previous cranial incision and the contralateral burr hole. The sterile field included both cranial burr holes and the retroauricular scalp on the side planned for IPG.

Surgical Exposure

Following the new contralateral incision for the second DBS lead, an additional scalp incision was made over the palpable ipsilateral connector site. Subgaleal access was obtained to permit tunneling between the cranial incisions.

Instrument Preparation

A Boston Scientific tunneling tube (DB-4254) and a 14-Fr intermediate intubating stylet (DYNJSTY14F) were used. The DB-4254 is supplied as part of the standard Boston Scientific DBS tunneling kit, which includes a rigid tunneling rod and a straight plastic tunneling tube designed to guide DBS extension leads subcutaneously. The tube is approximately 35 cm in length and has a blunt distal end with an internal lumen sufficient to accommodate a DBS lead. For the present technique, the tunneling rod was removed from the assembly, and the plastic tube was retained as a conduit. The malleable intubation stylet was then inserted into the tube's lumen, creating a composite instrument that combined the rigidity and length of the tunneling tube with the controlled malleability of the intubation guide ( Fig. 1A–D ). Light wetting of the tube lumen, or coating the guide with bacitracin followed by wiping off the excess, facilitated smooth advancement.

Fig. 1.

( A ) Preparing the Boston Scientific tunneling tube (DB-4254) and selecting a suitable intubation guide. ( B ) Wetting the straw lumen with Bacitracin to make the straw slide easily. ( C ) Threading the intubation stylet into the Boston Scientific straw. ( D ) Visualizing the route for tunnelling over the scalp before advancing the assembly.

Subgaleal Tunneling

The assembled instrument was contoured to the skull convexity and advanced through the subgaleal plane in a single pass ( Fig. 2A ). The approximately 35-cm length of the DB-4254 tube allowed traversal of the cranial midline without the need for an additional incision while maintaining a blunt, atraumatic profile.

Fig. 2.

( A ) Illustration of the prepared assembly during subgaleal entrance. ( B ) Illustration of the final view after retrieval of the intubation stylet within the straw from the other end of the tunneled route. ( C ) Illustration of passing the new DBS lead within the straw after removal of the intubation guide. DBS, deep brain stimulation.

The assembled tool provided sufficient stability and flexibility to navigate the skull's convexity without kinking.

Guide Retrieval and Lead Passage

Once the distal end emerged at the exit incision, the intubation guide was withdrawn while the tube remained in place. The DBS lead was then passed through the tube and delivered to the exit site. The tube was subsequently removed, leaving the lead positioned along the created subgaleal tract ( Fig. 2B and C ).

The Medtronic and Abbott tunneling tool designs were not suitable for the described modification.

Clinical Experience

This technique has been used routinely at our institution since 2020 for contralateral DBS lead tunneling. During this period, no cases of scalp injury, lead damage, or mechanical failure attributable to the tunneling step were observed.

Results

From 2020 to 2025, the described tunneling method was used in 17 bilateral DBS cases. The average age of patients was 60.7 ± 8.2 years (range 45–74.6 years). The male-to-female ratio was 7/10, and the race distribution was predominantly White (52.5%), followed by African American (23.5%), Asian (17.6%), and other (5.9%).

Of these, eight patients underwent subthalamic nucleus stimulation, seven underwent globus pallidus internus stimulation, and two underwent revision procedures.

The technique achieved a first-pass success rate in all cases, and no auxiliary scalp incisions were required to complete the midline subgaleal tunnel. We did not observe any surgical site infections, scalp erosions, or wound dehiscence attributable to the tunneling in the 6-month follow-up. There were no device erosions or lead fractures. Only one patient developed a hardware malfunction, which was unlikely related to our technique. We saw no intraoperative complications (e.g., tissue bleeding, vessel injury) related to the improvised tool, and lead integrity remained stable across follow-up visits. We also did not detect any delayed skin complications, such as thinning or ulceration, in the period reviewed.

Discussion

The proposed tunneling technique, using a malleable intubation stylet within a plastic straw from a Boston Scientific kit, could address the unmet need for a longer, more adaptable tunneling tool in scalp DBS procedures. As the use of dual-channel single IPGs for bilateral DBS increases, the importance of tunneling one lead across the cranial midline without additional scalp incisions or excessive tissue trauma becomes increasingly critical.

The single subgaleal pass provided by this technique, which contours to the skull without requiring a second incision, reduces surgical trauma. Minimizing incisions is known to decrease infection risk, as dehiscence or erosion often begins at suture lines or the hardware–skin interface. ^{2 3}

Combining the stiffness of the intubation stylet for safe passage through the skull—preventing kinking—and its ability to adjust to the patient's curvature, with the straw's smooth lumen for lead passage, can reduce the risk of damaging the DBS lead or stressing the connectors.

These components are standard operating room supplies and are readily available, making the technique easy to reproduce, cost-effective, and requiring no special tools or training.

In our initial experience with 17 cases, we observed no hardware erosion, scalp injury, or infections associated with this tunneling method. Only one hardware malfunction was reported, with no other complications related to this step. Since infection is often the main obstacle to long-term DBS success, any method that lowers this risk could have a significant clinical impact. ^{8 9} Our approach also points out a gap in commercially available tools. Device manufacturers might consider designing a malleable, shapeable tunneler specifically for subgaleal midline passes. Such a device could enhance safety, reduce tunneling costs, and make the procedure easier to perform.

Limitations

This report has several limitations that should be acknowledged. First, the present series is relatively small and reflects early experience with the technique, which limits the strength of any conclusions regarding safety or complication rates. Second, the study was not designed as a comparative analysis and therefore does not provide direct comparisons of outcomes with conventional tunneling devices or techniques. As a technical note, the primary aim was to describe the approach's feasibility and practical aspects rather than to evaluate its superiority. Larger studies with longer follow-up and direct comparisons with standard tunneling instruments would be necessary to assess potential clinical advantages more definitively.

Conclusion

The proposed technique, using an intubation guide through a Boston Scientific tunneling straw, offers a simple, practical method for performing bilateral subgaleal midline tunneling during DBS using widely available operating room materials. While preliminary and based on a limited series, our experience suggests that this approach may help reduce the need for additional incisions, tissue trauma, and mechanical stress on leads. Further studies with larger cohorts and comparative designs are needed to better define its clinical utility.