Neurosurgery notes/Procedures/TL spine procedures/Total En Bloc Spondylectomy/Single Posterior Approach for TES

Single Posterior Approach for TES

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Total En Bloc Spondylectomy

General

  • The Single Posterior Approach for Total En Bloc Spondylectomy (TES)
  • Developed by Tomita and colleagues
  • Favoured for lesions located higher than L3 or L4 (T3 to L1 is ideal).
  • Pros
    • Spinal cord can be observed carefully throughout the procedure.
    • Single position surgery
    • Neurological Recovery:
      • Patients who were neurologically compromised demonstrated significant recovery after circumspinal decompression and shortening of the spinal column following TES.
      • This recovery is partly attributed to an increase in spinal cord blood flow (SCBF) achieved by limited spinal shortening during the posterior reconstruction phase.
  • The TES technique allows for a wide or marginal margin around the affected vertebra(e). However, the pedicle and occasionally the spinal canal must sometimes be accepted as having an intralesional margin in order to salvage the spinal cord.

Indication

  • Tumor does not involve major vessels
    • Type 1, 2, 3, and 4 tumors

Preoperative

  • Embolization:
    • Preoperative embolization of bilateral segmental arteries at three levels (the tumor-laden level, one level cephalad, and one level caudal) is recommended within 48 hours before surgery to dramatically reduce intraoperative blood loss.

Surgical steps

Anesthesia and positioning:

  • Relatively hypotensive anesthesia (systolic blood pressure: 80–100 mm Hg) is common practice.
  • The patient is placed prone, typically over a four-poster frame (like the Relton-Hall frame) to prevent compression of the vena cava.

Approach

  • Incision:
    • A straight vertical midline incision is extended three vertebrae above and below the involved segment(s).
  • Muscle Dissection:
    • Bilateral muscle strip
    • Any prior biopsy tracts are carefully resected.
    • An articulated spinal retractor is used to obtain wide exposure.

En Bloc Laminectomy (Resection of the Posterior Element)

  • Laminectomy Preparation:
    • To expose the superior articular process of the uppermost vertebra, the spinous and inferior articular processes of the neighboring vertebra are removed.
  • T-Saw Introduction:
    • The surgeon uses a C-curved, malleable T-saw guide (or wire guide) to pass a threadwire saw (T-saw) through the neuroforamina.
    • The guide must follow the medial cortex of the lamina and pedicle to avoid spinal cord and nerve root injury.
    • The T-saw is made of multifilament twisted stainless steel wires and is designed to cut bone sharply with minimal soft tissue damage.
  • Pediculotomy:
    • A specially designed T-saw manipulator is used to position the threadwire saw beneath the superior articular and transverse processes, wrapping it around the pedicle.
    • The pedicles are then cut bilaterally with a reciprocating motion.
    • This cutting of the pedicle is typically the necessary intralesional step to excise the ring-shaped vertebral structure while preserving the spinal cord.
  • Removal of Posterior Arch:
    • The whole posterior element (spinous process, superior/inferior articular processes, transverse process, and pedicle) is then removed in one piece.
  • Contamination Control:
    • The cut surface of the pedicle is sealed with bone wax to reduce bleeding and minimize contamination by tumor cells.
    • Distilled water rinsing followed by cisplatinum solution may also be applied to eradicate contaminated cells.
  • Temporary Stabilization:
    • Segmental posterior instrumentation (usually two segments above and two below the resection site) is temporarily performed to maintain stability for the duration of the procedure.

En Bloc Corpectomy (Resection of the Anterior Column)

  • Vessel Management:
    • Segmental arteries are identified bilaterally.
    • The spinal branch of the segmental artery, which runs along the nerve root, is ligated and divided.
  • Nerve Root Sacrifice (Thoracic):
    • In the thoracic spine (T3–T11), the corresponding bilateral nerve roots are usually ligated and cut to provide additional exposure and avoid avulsion injury during manipulation of the vertebral body.
  • Blunt Anterior Dissection (Critical Step):
    • Meticulous blunt dissection is performed along the lateral walls of the vertebral body.
    • A curved vertebral spatula is used to dissect the lateral aspect, and the surgeon must carefully dissect the segmental artery(ies) and the major vessels (aorta/vena cava) away from the anterior aspect of the vertebral body.
    • The surgeon attempts to reach their fingertips anteriorly to confirm the dissection plane.
    • The maneuver carries the risk of major vessel injury, especially caudal to T5.
  • Protection:
    • Once the plane is established, a series of spatulas (or a malleable blade/silastic sheet) is inserted and kept in place to protect the vessels and tissues during the osteotomy.
  • Anterior Osteotomy:
      • The T-saws are inserted at the proximal and distal cutting levels (intervertebral disc space or adjacent vertebral body).
      • A teeth-cord protector may be applied to shield the spinal cord.
      • The T-saw is used in a reciprocating motion to cut the anterior column, including the anterior and posterior longitudinal ligaments.
      notion image
  • Removal of Vertebra:
    • The freed anterior column (the tumor-bearing vertebral body) is rotated around the spinal cord and carefully removed, achieving the en bloc resection.
    • This constitutes circumspinal decompression.
  • Epidural Tumor Extension:
    • If the tumor extended into the epidural space, the anterior column is cut approximately 10 mm above and below the extension.
    • The tumor vertebral body is then pushed ventrally (5–10 mm) to decompress the spinal cord before the adhesion to the dura is dissected, ensuring safe removal.

Reconstruction and Stabilization

  • Anterior Reconstruction:
    • A vertebral spacer, such as an autograft, allograft, or titanium mesh cylinder, is inserted into the defect.
  • Posterior compression:
    • The temporary posterior instrumentation is adjusted to slightly compress the inserted vertebral spacer.
    • This spinal shortening increases stability and can improve spinal cord blood flow.
  • Sealing:
    • A surgical mesh (e.g., Bard Marlex mesh) may cover the reconstructed areas to help suppress bleeding.

Outcomes

Oncological Outcomes and Local Control

  • Compared to conventional curettage or piecemeal excision, TES has been shown to provide superior local control and lower recurrence rates.
  • Survival Rates:
    • In a series of 17 patients with primary malignant spinal tumors (stages I and II) who underwent TES (various approaches, including posterior-only), the 5-year survival was 67%.
  • Aggressive Benign Tumors:
    • Patients with aggressive benign tumors (stages 2 and 3) who underwent TES had a 100% 5-year survival rate.
  • Local Recurrence:
    • In an early series of 7 patients treated with this aggressive technique, there was ** no local recurrence** over a follow-up period ranging from 2 to 6.5 years (excluding one early death due to metastasis unrelated to the surgery).
    • In a broader series of 97 TES patients, 95% (92 patients) had no tumor recurrence.
    • Local recurrences (5% of cases) occurred primarily at the edge of an unsuccessfully excised tumor margin, indicating residual tumor tissue was the problem.

Neurological Outcomes

  • 23 of 32 patients presenting with preoperative paraparesis improved neurologically by more than one grade according to the Frankel grading system.
  • Ischemia: There has been no neurological degradation attributable to spinal cord ischemia reported in a patient series, even those who required the ligation of segmental arteries that supply the anterior spinal artery.

Procedural Metrics and Complications

  • Operation Time: 6–8 hours.
  • Blood Loss: TES is associated with a major risk of blood loss.
    • To reduce blood loss:
      • Preoperative triple-level embolization of bilateral segmental arteries dramatically reduced average intraoperative blood loss compared to older methods.
      • Can reduce from 2.3L to 1.3L
  • Instrumentation Failure:
    • Since Titanium mesh cages were introduced as vertebral spacers, dislodgement has not been experienced.
  • Major Risks:
    • Injury to major vessels (aorta or vena cava) during the necessary blunt dissection of the anterior aspect of the vertebral body.
    • Potential damage to adjacent neural structures.
    • Unintended pleural violations, which can lead to complications such as pneumothorax or hemothorax, particularly in the thoracic spine.