General
- Developed for the treatment of Metastatic Epidural Spinal Cord Compression (MESCC).
- Shift from older, more aggressive cytoreductive surgeries towards a less invasive approach.
- Coined by Lyliana Angelov and Edward Benzel
- A procedure aimed at decompressing the spinal cord and creating a safe target for Stereotactic Body Radiation Therapy (SBRT) or Stereotactic Radiosurgery (SRS).
Multidisciplinary Approach and Indications
- The management of MESCC, especially with separation surgery, requires a multidisciplinary team involving spine surgeons, radiation oncologists, and oncologists.
- Preoperative evaluation systems like the Neurologic, Oncologic, Mechanical Instability, and Systemic Disease (NOMS) framework are used to guide decision-making.
- Separation surgery combined with SBRT is recommended for patients with high-grade ESCC (grades 2 and 3) and tumour types insensitive to radiotherapy, where conventional radiotherapy alone might be insufficient.
- Jabbari 2013
Optimal Inclusion Criteria for Spine SBRT | Relative Contraindication to Spine SBRT | Major Contraindications to Spine SBRT |
Good to excellent performance status | Moderate performance status | Poor performance status (ECOG 3-4; KPS <60) |
Oligometastatic disease (≤5 sites extracranial metastases) | Oligoprogression in patients with widely metastatic and/or rapidly progressive disease | Widely metastatic and/or rapidly progressive disease with limited life expectancy |
Oligoprogression in a patient with oligometastatic disease | >3 spinal levels involved, but nondiffuse spine disease and no more than 3 contiguous segments | >3 contiguous spinal levels involved, or diffuse spine disease |
No more than 3 spinal levels involved (contiguous or non-contiguous) | Potential spine instability (SINS 7-12) | Spine instability (SINS 13-18) |
No, or minimal spine instability (SINS 0-6) | Moderate-grade epidural disease (Bilsky 2) | High-grade epidural disease (Bilsky 3) |
No or minimal epidural disease (Bilsky 0-1) | “Radiosensitive” histology | Prior cEBRT <3 mo prior to considered course of salvage spine SBRT |
“Radioresistant” histology | Prior cEBRT delivered 3-5 mo prior to considered course of salvage spine SBRT | Spine SBRT delivered <3 mo prior to a considered 2nd course of salvage SBRT |
No prior cEBRT to affected level, or prior cEBRT delivered ≥5 mo prior to salvage spine SBRT | Spine SBRT delivered within 3-5 mo of a considered 2nd course of salvage SBRT | Unable to tolerate near-rigid/supine immobilization |
Spine SBRT delivered ≥5 mo of a considered 2nd course of salvage SBRT | If unable to have an MRI, then a treatment planning CT myelogram for CNS structure contouring provided that the target is identifiable on CT alone with sufficient clinical detail as to paraspinal disease extension/epidural disease extension | Unable to have a full spine MRI and/or CT myelogram |
Robotic Linac or subcentimeter MLC-based Linac delivery, CBCT and/or stereoscopic imaging IGRT, near-rigid body immobilization, fusion of thin-slice MRI sequences for target/CNS contouring and in selected post-op cases a treatment planning CT myelogram | ㅤ | ㅤ |
Goal
- To circumferentially decompress the spinal cord and/or nerve roots and create a safe target for high-dose SBRT.
- Create a safe distance (at least 2–3 mm) between the tumour and the spinal cord, which is crucial for delivering ablative radiation doses to the target lesion while minimising exposure to the spinal cord and avoiding radiation-induced myelopathy.
- Gonzalez 2025: The most common area for failure after SBRT was in the epidural space, where SBRT dose would have been limited by proximity to the spinal cord or cauda equina
Surgical Technique
Description | Advantages | Disadvantages |
Posterior | Removal, or opening of the posterior elements of the vertebrae.Commonly, laminectomy or laminoplasty. | Considered less technically challenging.Allows good exposure for spinal cord decompression.Less invasive. |
Anterior | Removal of the anterior elements of the vertebrae.Commonly, vertebrectomy or corpectomy. | Allows good exposure to anterior spine. |
Open | Traditional open surgical access to the spine. | Better for extensive disease.Good visibility of affected areas.Allows for stabilization of the spine with direct open views of anatomical landmarks. |
Minimally invasive | Minimally invasive access to the spine. | Less invasive/traumatic.Potentially faster recovery time.Also allows for spinal stabilization using a percutaneous approach. |
Fixation | Additional intraoperative stabilization with a mechanical construct. | Provides added mechanical stability.Allows for prolonged duration of operative outcome. |
- Open (Classic Posterior Pedicle Approach)
- General anaesthesia and prone position
- Posterior decompression:
- The spinal cord compression segment and adjacent laminae are exposed, and the compression segment's lamina is fully resected and decompressed.
- Posterior Fixation:
- Pedicle screws are used for posterior fixation in at least two adjacent segments, providing initial stability and reducing the risk of spinal cord damage. Spinal instrumentation is typically required due to tumour extension and the need for lamina and pedicle/joint removal.
- Lateral decompression
- The SAP and IAP is removed exposing the exiting nerve root.
- Pedicle drilled and removed.
- Posterior decompression
- PLL and Hoffman ligaments are cut, and soft tissues like the intervertebral disc are removed to achieve total decompression around the compressed dura mater.
- Tumour tissue adhered to the anterior dura mater is carefully peeled off, and the affected frontal vertebral body is scraped of tumour as much as possible.
- Vertebral Body Reconstruction:
- If more than 50% of the vertebral body is affected and removed, a suitable titanium mesh, massive allogeneic bone, or bone cement is placed for anterior intervertebral and bone graft reconstruction.
- Circumferential Separation:
- The dissected epidural ventral tumour is depressed anteriorly, away from the dura, using a Woodson dissector, leading to circumferential separation of the spinal cord.
- Extended tumour removal inside the vertebral body and/or into the paraspinal tissues is generally not required.
- Instrumentation Materials:
- Carbon fibre/PEEK (polyetheretherketone) instrumentation can be used to reduce scattering and artefacts during subsequent radiation treatment, compared to titanium implants.
- Intraoperative Monitoring: Intra-operative neuromonitoring is largely suggested to prevent surgical-related spinal cord damage due to high-grade ESCC.
- Minimally Invasive Surgery (MIS)
- Pros such as reduced surgical trauma, less blood loss, faster recovery times, and shorter hospital stays, allowing quicker return to radiation and systemic treatment.
- Specific techniques include
- Mini-open approaches
- Endoscopic or percutaneous techniques
- Ablative procedures like Laser Interstitial Thermal Therapy (LITT)
- Percutaneous screw fixation is considered due to limited muscle dissection, reduced blood loss, decreased postoperative pain, and earlier mobilisation.
Imaging
- Postoperative CT scans of the vertebral canal are routinely performed to determine the dura border for SBRT planning
- MRI examination can have artefacts due to internal fixation, making it difficult to judge the precise position and boundary of the dura mater.
- Intraoperative ultrasound or navigation systems can also be used to assess ventral separation.
Outcomes
- Pain Relief and Neurological Improvement:
- Patients often experience
- Significant pain relief (e.g., average VAS score decreased to 2.17 ± 0.52 points post-surgery),
- Improved neurological function (e.g., Frankel neurological function grading, muscle strength), and
- Relief of spinal cord compression (e.g., postoperative ESCC grade improved, with 38 cases achieving grade 0).
- Quality of Life:
- Karnofsky Performance Scores (KPS) are often significantly improved, indicating a better quality of life.
- Local Control:
- When combined with SBRT, separation surgery has shown promising results in achieving long-term local tumour control. The recurrence rate after separation surgery combined with SBRT was significantly lower (7.7%) compared to simple separation surgery (30.8%).
- High-dose hypofractionated SRS after separation surgery resulted in a 1-year local progression rate of 4.1%, which was superior to low-dose hypofractionated SRS (22.6%).
- Improved Survival:
- Laufer 2013: Separation surgery combined with SBRT has been identified as an independent predictor of overall survival (OS), with a significantly longer median survival time (38 months) compared to simple separation surgery (21 months).
- Reduced Trauma:
- Separation surgery is associated with smaller surgical trauma compared to more aggressive resections.
- Complication rates are generally low, with some studies reporting cases of wound infection and cerebrospinal fluid leakage, but rare incidence of radiation-induced spinal cord injury.
- Reduce spinal cord radiation toxicity
- Radiation myelopathy (permanent neurological injury from radiotherapy) rates will be lower but no literature data to prove it.
- Huo 2017: Baseline radiation myelopathy for EBRT is around 3% without separation surgery this can be an underestimation as radiation myelopathy is a longer term complication and not all patient survive till that long.
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