Expansion Duroplasty For Severe Cervical Spinal Cord Swelling After Traumatic Injury: A Step-by-Step Surgical Protocol

Summary

This protocol demonstrates expansion duroplasty as a surgical approach to address uncontrolled cervical spinal cord swelling following acute traumatic injury. By enlarging the intradural space with an artificial dural substitute, the technique aims to reduce intraspinal pressure, enhance perfusion, minimize postoperative cord tethering, and achieve watertight dural closure.

Abstract

Acute traumatic cervical spinal cord injury frequently leads to severe cord edema, elevated intraspinal pressure, reduced spinal cord perfusion, and progressive neurological deterioration. Conventional bony decompression via laminectomy may provide limited relief, as the non-elastic dura mater can continue to constrain the swollen spinal cord. Expansion duroplasty is designed to address this limitation by enlarging the intradural space using an artificial dural substitute, allowing controlled expansion of the injured spinal cord. This protocol describes patient positioning, selection of laminectomy levels based on preoperative magnetic resonance imaging, dural opening technique, preparation of an artificial dural substitute, suturing sequence, and postoperative strategies to mitigate cerebrospinal fluid leakage. Critical steps are highlighted to ensure a watertight closure, minimize infection risk, and optimize gravity-dependent wound drainage. Representative results include postoperative imaging demonstrating restoration of the cerebrospinal fluid space, reduced dural constriction, and absence of significant pseudomeningocele formation. This method is intended for patients with severe cervical spinal cord swelling within 72 hours of injury and can be implemented in centers with microsurgical spine expertise as an adjunct to standard decompression procedures.

Introduction

Early surgical decompression is currently recommended as the standard management for acute traumatic spinal cord injury (aTSCI). Contemporary clinical practice guidelines from AO Spine recommend decompressive surgery within 24 hours after injury when feasible, as early decompression is associated with improved neurological outcomes¹. Despite early decompression, many patients with severe cervical spinal cord injury develop progressive spinal cord swelling and intramedullary edema, which increase intraspinal pressure (ISP), compromise spinal cord perfusion pressure (SCPP), and contribute to secondary neurological injury^2,3,4.

Posterior decompression through laminectomy effectively relieves osseous compression; however, it may not fully address the circumferential constraint imposed by the dura mater. Intraoperative ultrasound (IoUS) has increasingly been used to assess the adequacy of decompression by demonstrating restoration of cerebrospinal fluid flow around the spinal cord following laminectomy or corpectomy⁵. However, because the spinal dura is relatively non-elastic, the edematous spinal cord may remain compressed despite adequate bony decompression, limiting restoration of cerebrospinal fluid (CSF) dynamics and spinal cord perfusion^6,7.

Expansion duroplasty is a surgical strategy designed to overcome this limitation by longitudinal dural opening and placement of an artificial dural substitute to enlarge the intradural compartment⁷. By increasing the available intradural volume, this approach aims to reduce dural constriction, restore CSF buffering capacity, and allow controlled expansion of swollen cord tissue. Experimental and clinical studies incorporating invasive ISP monitoring have demonstrated reductions in ISP and corresponding increases in SCPP following dural expansion, supporting the physiological rationale of this technique⁸.

Despite increasing interest in expansion duroplasty, standardized surgical protocols and reproducible technical guidance remain limited. Variations in dural opening length, preparation of artificial dural substitutes, suturing technique, and postoperative CSF management may influence both safety and effectiveness. Furthermore, concerns about CSF-related complications have hindered the broader adoption of the technique in many spine centers.

These evolving concepts have increased interest in strategies to optimize decompression and perfusion in acute traumatic spinal cord injury. Recent AO Spine recommendations highlight the need to evaluate surgical approaches that address persistent intradural compression, including consideration of expansion duroplasty in selected patients with severe spinal cord swelling⁹. The present protocol provides a detailed, step-by-step demonstration of expansion duroplasty for severe cervical spinal cord swelling following acute traumatic injury. Key procedural elements include patient positioning, selection of decompression levels based on preoperative imaging, dural opening technique, preparation and suturing of the artificial dural substitute, and postoperative strategies to minimize CSF leakage and infection risk. This visualized protocol is intended to facilitate reproducibility and safe implementation in centers equipped with microsurgical spine expertise. The protocol standardizes key operative steps—including the extent of the laminectomy, dural opening technique, configuration of the artificial dural substitute, and postoperative CSF management—thereby improving reproducibility compared with previously reported techniques that lack detailed technical guidance.

Expansion duroplasty may be particularly relevant when preoperative magnetic resonance imaging demonstrates near-complete obliteration of the pericord CSF space across multiple vertebral levels, suggesting persistent intradural constraint after standard decompression. While the technique requires additional operative time and advanced microsurgical skill, it offers a structured approach to achieving intradural decompression in cases where bony decompression alone may be insufficient^10,11.

Protocol

This study was approved by the Institutional Review Board of Chang Gung Medical Foundation (IRB No. 2312250059). All procedures were conducted in accordance with institutional guidelines for human research. Written informed consent was obtained from patients or their legally authorized surrogates.

1. Patient preparation and positioning

1. Induce general anesthesia with endotracheal intubation and maintain standard intraoperative monitoring, including electrocardiography, pulse oximetry, and invasive arterial blood pressure monitoring.
2. Position the patient prone on a radiolucent spinal table with the head secured in a rigid head holder, while maintaining neutral cervical alignment to avoid secondary cord compression.
3. Prepare the posterior cervical region using standard antiseptic solution and apply sterile draping in the usual fashion.
4. Make a midline posterior cervical skin incision centered over the planned decompression levels. Perform subperiosteal dissection of the paraspinal musculature to expose the laminae and lateral margins of the posterior elements while preserving the facet joint capsules whenever possible.

2. Determination of laminectomy levels

1. Review preoperative sagittal T2-weighted magnetic resonance imaging to identify the rostrocaudal extent of spinal cord swelling.
2. Define the involved segment according to the visible longitudinal extent of intramedullary T2 hyperintensity and associated obliteration of the pericord CSF space.
3. Perform posterior decompression spanning one vertebral level above and one vertebral level below the segment demonstrating the clearest T2 hyperintensity.
4. If T2 hyperintensity is faint or equivocal, determine decompression extent based on the segment of maximal spinal cord compression, cord expansion, and loss of surrounding CSF space.
5. Confirm planned decompression levels intraoperatively using fluoroscopy.
   NOTE: Adequate rostrocaudal extension of the laminectomy beyond the radiographic margins of cord swelling is critical to prevent residual dural constriction after dural expansion.

3. Laminectomy

1. After exposure of the posterior cervical elements, place retractors to maintain visualization while avoiding excessive soft-tissue traction.
2. Under microscopic visualization, thin the laminae as needed and remove them in a controlled cranial-to-caudal sequence using Kerrison rongeurs.
3. Carefully detach and remove the ligamentum flavum after adequate bony decompression, avoiding abrupt instrument passage beneath the lamina.
4. Keep all instruments tangential to the laminar surface and avoid downward force toward the swollen spinal cord.
5. Preserve the facet joints whenever possible to minimize additional destabilization.
6. Perform posterior instrumentation and fusion when instability is present or anticipated based on the underlying injury pattern.

4. Dural opening

1. Perform a longitudinal midline durotomy under microscopic visualization using a microsurgical blade, beginning cranially and extending caudally along the decompressed segment (Figure 1).
2. Open the dura gradually with a nerve hook oriented parallel to the dural surface while gently elevating the dura so as to control tension and avoid contact with the swollen spinal cord.
3. Extend the durotomy to match the decompressed segment and visually swollen cord region.
4. Selectively divide one or more dentate ligaments on each side, as needed, at the levels of maximal cord swelling to facilitate symmetric spinal cord relaxation. Adequate release is judged by reduction of asymmetric tethering and improved uniformity of cord expansion.
5. Preserve arachnoid integrity during all steps of dural opening (Figure 2).
   CAUTION: The dura should be opened gradually under microscopic visualization. Abrupt dural release may result in sudden cord bulging and increased risk of neural or venous injury. Careful division of the dentate ligaments facilitates symmetric spinal cord relaxation and minimizes asymmetric cord displacement during intradural expansion.

5. Determination of duroplasty dimensions

1. Trim the artificial dural substitute (Onlay Dura Patch, Aesculap) with sterile Metzenbaum scissors into an elliptical (“fish-mouth”) configuration.
2. Orient the long axis of the dural substitute parallel to the durotomy and prepare it to extend approximately 1 cm beyond the superior and inferior ends of the dural opening.
3. Maximize the width of the central portion of the patch so that the widest region overlies the segment of maximal cord swelling.
4. Avoid excessive patch width to reduce the risk of postoperative cord drift or adhesion formation.
5. Prepare the dural edges for patch placement under microscopic visualization (Figure 3).
   NOTE: The elliptical (fish-mouth) configuration allows gradual intradural expansion while minimizing focal stress. Excessive artificial dural substitute width may increase the risk of postoperative cord drift or adhesion formation.

6. Artificial dural substitute suturing technique

1. Secure the artificial dural substitute using interrupted 5-0 polypropylene sutures (Prolene, Ethicon) along the dural edges.
2. Place sutures at regular intervals with shallow bites to maintain a watertight seal (Figure 4).
3. Reinforce sutures at the superior and inferior junctions to minimize cerebrospinal fluid (CSF) leakage.
   NOTE: CSF leakage at closure sites is commonly due to insufficient fixation or tension at junction points. Reinforce these areas with additional sutures to achieve a watertight seal.
4. Gently elevate the artificial dural substitute during suturing to prevent direct contact with the edematous spinal cord.
5. Confirm the final elliptical (fish-mouth) configuration after completion of expansion duroplasty (Figure 5).
   NOTE: Interrupted sutures with evenly spaced, shallow dural bites are essential for achieving a watertight closure. Particular attention should be given to the superior and inferior junction points, which are common sites of cerebrospinal fluid leakage.

7. CSF leak mitigation

1. Inspect the closure line under the microscope for focal gaping, persistent tension, or visible CSF leakage, particularly at the superior and inferior junctions.
2. Add additional interrupted reinforcing sutures at these sites as needed, typically one to several sutures depending on closure tension.
3. Cover the closure site with a waterproof adhesive film dressing.
   NOTE: Regions of high dural tension should be identified intraoperatively and reinforced with additional sutures rather than relying on external measures.

8. Drain placement

1. Place a wound drain in the posterior surgical wound superficial to the dural repair and deep to the muscle/fascial closure, avoiding direct compression of the duroplasty site.
2. Maintain gravity-dependent drainage without suction.
3. Secure the drain exit site with nylon sutures to prevent CSF leakage along the tract.
   NOTE: Postoperative drainage should be maintained under gravity without suction. Negative pressure drainage may compromise the dural repair and increase the risk of cerebrospinal fluid leakage.

9. Wound closure

1. Close muscle and fascial layers using absorbable sutures in a layered fashion.
2. Close the skin using nylon sutures to enhance watertight sealing.

10. Postoperative management

1. Maintain head elevation greater than 30° for 7 days postoperatively.
   NOTE: Head elevation greater than 30° reduces hydrostatic pressure at the dural repair site and supports dural healing during the early postoperative period.
2. Remove the wound drain after 7 days if no evidence of CSF leakage is present.
   NOTE: Persistent postoperative CSF leakage should be managed with continued gravity drainage, strict head elevation, and avoidance of suction systems. Progressive wound leakage or failure of conservative measures may require revision of dural repair.

Results

Representative images are shown from a patient with severe cervical traumatic spinal cord injury (AIS A at presentation) who underwent posterior decompression and expansion duroplasty. Preoperative sagittal T2-weighted MRI demonstrated extensive cord swelling with near-complete effacement of the pericord CSF space. Postoperative MRI obtained on postoperative day 7 demonstrated interval restoration of the dorsal CSF space, with an increase in maximal dorsal CSF thickness from approximately 0–0.5 mm preoperatively to appro...

Discussion

The effectiveness and safety of expansion duroplasty depend on meticulous execution of several critical technical steps. Adequate rostrocaudal laminectomy is essential to prevent persistent dural constriction following decompression. The durotomy should be performed in a controlled, stepwise manner under microscopic visualization, allowing gradual release of intradural pressure while minimizing the risk of abrupt cord expansion and mechanical stress on the injured spinal cord. Preservation of arachnoid integrity is parti...

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Microsurgical dural scissors	Aesculap	N/A	For precise dural opening
Microsurgical dural scissors	Aesculap	N/A	For precise dural opening
Non-absorbable suture (5-0 Prolene)	Ethicon	8705H	For watertight dural closure
Non-absorbable suture (5-0 Prolene)	Ethicon	8705H	For watertight dural closure
Onlay Dura Patch	Aesculap	N/A	Used for expansion duroplasty to enlarge intradural space
Onlay Dura Patch	Aesculap	N/A	Used for expansion duroplasty to enlarge intradural space
Operative Microscope	Leica Microsystems	N/A	For microsurgical visualization during duroplasty
Operative Microscope	Leica Microsystems	N/A	For microsurgical visualization during duroplasty