Tag: thoracic spine

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Ventral Spinal Cord Displacement: A Guide to Differentiating Spinal Cord Herniation From Dorsal Arachnoid Web

Operative Neurosurgery 30:977–984, 2026

This article reviews imaging and operative distinctions between spinal arachnoid webs (SAW) and spinal cord herniation (SCH), using two detailed case illustrations with narrated 2-D operative videos. It highlights diagnostic imaging features, intraoperative findings, and tailored surgical techniques to optimize differentiation and management.

Focusing on technical nuance, the paper contrasts midline-sparing unilateral laminectomy and arachnoid lysis for SAW with bilateral laminectomy, cord mobilization, and ventral alloderm sling reconstruction for SCH, and emphasizes intraoperative ultrasound and neuromonitoring for safe reduction and decompression.

Problem: Spinal arachnoid web (SAW) and spinal cord herniation (SCH) can present similarly (myelopathy/radiculopathy) and both often look like focal anterior cord displacement on MRI, yet require very different operative strategies.

Definitions: SAW is abnormally thickened arachnoid tissue in the subarachnoid space that can tether/compress the cord and disrupt CSF flow (edema/syrinx), while SCH is cord displacement through an opening in the dura/arachnoid (often ventral).

Imaging workup: CT myelography is recommended to evaluate/confirm suspected findings because its resolution can outperform MRI for distinguishing these entities.

Key imaging clues: Visible ventral CSF between cord and ventral dura argues against herniation, while absence of ventral CSF supports SCH; cord twisting at the abnormal level is a more specific sign for SCH; the “scalpel sign” is commonly linked to SAW but can occur in both.

Limits of imaging: Arachnoid webs are below MRI/CT resolution, and diagnostic patterns are imperfect (reported SAWs can lack the scalpel sign or mimic SCH on CT myelogram).

SAW surgery: Definitive treatment is lysis/excision of the thickened arachnoid band, often via laminectomy with ultrasound localization; dentate ligament division can help inspect the ventral compartment to exclude ventral pathology.

SCH surgery: Management typically uses wider exposure (often bilateral laminectomy), spinal cord mobilization/rotation (sectioning dentate ligaments ± dorsal rootlets), reduction of the herniation, and placement/suturing of a ventral alloderm sling to span the dural defect, with close neuromonitoring and ultrasound confirmation.

Outcomes in cases: SAW case showed postoperative normalization of cord position and complete syrinx regression after web excision/lysis; SCH case showed complete reduction of herniation on postoperative MRI with substantial functional improvement (including near-resolution of bowel/bladder symptoms).

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Technique and outcomes of the trans-superior articular process approach for endoscopic thoracic discectomy

J Neurosurg Spine 42:775–783, 2025

The trans-superior articular process (SAP) approach for endoscopic thoracic discectomy enables safe, minimally invasive treatment of symptomatic thoracic disc herniation, particularly in challenging upper/mid-thoracic regions, with significant improvements in pain and disability, short operative time, and low complication rates in a 38-patient series.

• Trans-superior articular process (trans-SAP) approach for endoscopic thoracic discectomy is described for symptomatic thoracic disc herniation (TDH).

• This technique creates a controlled corridor through the SAP using a Jamshidi needle and manual bone drills, minimizing facet removal and neural injury.

• Study included 38 patients (mean age 48.9), mostly with central or middle thoracic herniations.

• Mean operative time was 42 minutes, hospital stay 1.3 days, and follow-up 11.5 months.

• Significant improvements in pain (VAS) and disability (ODI) scores were observed at all follow-up points.

• Only one complication (2.6%, recurrent herniation) was reported.

• Trans-SAP approach is safe, effective, and minimally invasive, but has a steep learning curve and is not suitable for hard disc, severe myelopathy, or ossified ligament cases.

• Technique enables treatment of central and paramedian TDH and can be performed under local anesthesia.

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Midpoint of C7 Lateral Mass Serves as an Accurate Reference Point for the Placement of T1 Pedicle Screws: An Anatomic Study

Operative Neurosurgery 26:323–329, 2024

Free-hand placement of T1 pedicle screws can often be challenging. A reliable freehand technique for placement of T1 pedicle screws can overcome some of the difficulties associated with poor fluoroscopy in this region. The purpose of this study was to propose a novel anatomic landmark for accurate identification of the T1 entry point using the midpoint of the C7 lateral mass as a reference point. Our hypothesis is that the midpoint of the C7 lateral mass is within 1–2 mm of the center of the T1 pedicle.

METHODS: Using 3-dimensional reconstruction software, the pedicle of T1 and the lateral mass of C7 were isolated to assess the location of the T1 pedicle relative to the C7 lateral mass. Specifically, the distance between the center of the T1 pedicle and the center of the C7 lateral mass was measured on 40 computed tomography scans. Furthermore, a clinical validation of this technique was performed by assessing the postoperative computed tomography scans of 53 patients undergoing cervicothoracic instrumentation. The Gertzbein and Robbins classification system was used to grade the accuracy of T1 pedicle screw placements in all patients using this technique.

RESULTS: The average horizontal deviation + SD from centers of the T1 pedicle and the C7 lateral mass was 0.398 mm ± 0.953 mm. The T1 pedicle on average was slightly medial to the center of the C7 lateral mass. A total of 98.1% of T1 pedicle screws placed in vivo using the free-hand technique were of Grade A.

CONCLUSION: In this article, we demonstrate that the center of the C7 lateral mass overlays the T1 pedicle and the optimal entry point is immediately below the midpoint of the C7 lateral mass. This approach provides a practical and accurate landmark in posterior cervicothoracic spine procedures that reduce the need for additional radiation exposure or increased operative time with image-guided techniques.

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Lateral Extracavitary vs Costotransversectomy Approaches to the Thoracic Spine

Lateral Extracavitary vs Costotransversectomy Approaches to the Thoracic Spine- Reflections on Lessons Learned Lateral Extracavitary vs Costotransversectomy Approaches to the Thoracic Spine- Reflections on Lessons Learned_2

Neurosurgery 71:1096–1102, 2012

The lateral extracavitary approach (LECA) and costotransversectomy (CTE) are 2 dorsolateral approaches that avoid entrance into the pleural cavity and facilitate ventral decompression. The indications and outcomes of each of these approaches have not been fully defined in the literature.

OBJECTIVE: To assess the techniques, indications, and complications associated with the LECA and CTE approaches to the thoracic spine.

METHODS: A retrospective analysis was performed on all patients who underwent LECA and CTE between 2000 and 2009 at our institution.

RESULTS: A total of 54 patient charts were reviewed (19 LECA, 35 CTE). Indications for operation included disk herniation, trauma, tumor, osteomyelitis, and scoliosis/kyphosis. Osteomyelitis was treated significantly more often with LECA (47%) than with CTE (9%; P = .002). Mean blood loss was 2134 mL and 1556 mL (P = .3) in LECA and CTE, respectively, and hospital stay was 17.2 days for LECA and 9.8 days for CTE (P = .07). Thirteen LECA patients (68%) and 19 CTE patients (54%; P = 1.0) had preoperative or postoperative complications.

CONCLUSION: LECA was used more often to treat complex pathologies such as osteomyelitis and trended toward significance for more frequent use in extensive procedures involving 1- or 2-level corpectomies. As can be expected, CTE was associated with slightly less blood loss and a shorter hospital stay compared with the more extensive LECA operation. Adverse outcomes occurred with similar frequency for CTE and LECA.

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Avoidance of wrong-level thoracic spine surgery: intraoperative localization with preoperative percutaneous fiducial screw placement

Journal of Neurosurgery: Spine DOI: 10.3171/2011.3.SPINE10445.

The accurate intraoperative localization of the correct thoracic spine level remains a challenging problem in both open and minimally invasive spine surgery. The authors describe a technique of using preoperatively placed percutaneous fiducial screws to localize the area of interest in the thoracic spine, and they assess the safety and efficacy of the technique.

METHODS

To avoid wrong-level surgery in the thoracic spine, the authors preoperatively placed a percutaneous 5-mm fiducial screw at the level of intended surgery using CT guidance. Plain radiographs and CT images with reconstructed views can then be referenced in the operating room to verify the surgical level, and the fiducial screw is easily identified on intraoperative fluoroscopy. The authors compared a group of 26 patients who underwent preoperative (often outpatient) fiducial screw placement prior to open or minimally invasive thoracic spine surgery to a historical group of 26 patients who had intraoperative localization with fluoroscopy alone.

RESULTS

In the treatment group of 26 patients, no complications related to fiducial screw placement occurred, and there was no incidence of wrong-level surgery. In comparison, there were no wrong-level surgeries in the historical cohort of 26 patients who underwent mini-open or open thoracic spine surgery without placement of a fiducial screw. However, the authors found that the intraoperative localization fluoroscopy time was greatly reduced when a fiducial screw localization technique was employed.

CONCLUSIONS

The aforementioned technique for intraoperative localization is safe, efficient, and accurate for identifying the target level in thoracic spine exposures. The fiducial marker screw can be placed using CT guidance on an outpatient basis. There is a reduction in the amount of intraoperative fluoroscopy time needed for localization in the fiducial screw group.

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