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Chapter Summary
• Context: The thoracic spine represents one of the most demanding territories for surgical decompression because of its narrow canal dimensions, the presence of the delicate spinal cord, unique rib head anatomy, and vulnerable regional arterial blood supply. Historically, the evolution of surgical approaches for thoracic disc herniations was driven by the imperative to avoid the direct spinal cord retraction associated with early posterior laminectomies. Costotransversectomy, lateral extracavitary approaches, transthoracic thoracotomy, and video-assisted thoracoscopy (VATS) expanded access but introduced substantial pulmonary, visceral, and chest wall morbidity. Uniportal full-endoscopic surgery emerged within this evolutionary continuum as a direct, minimally invasive alternative capable of reaching anterior and lateral canal pathologies through a targeted posterolateral/transforaminal corridor without requiring pleural entry or extensive bone disruption. The safety of the technique relies on strict patient selection, 3D anatomical understanding of the corridor between rib head and pedicle, and recognition of critical arterial supply, notably the artery of Adamkiewicz.
• Chapter Objective: Present the evolutionary history of thoracic approaches and the surgical foundations of uniportal endoscopic thoracic decompression. The chapter enables readers to master indications and contraindications, plan the transforaminal/extraforaminal corridor, perform safe bone reaming and the 'egg-shell' thinning technique for calcified herniations, and prevent dural, spinal cord, intercostal nerve, and vascular complications.
• From open approaches to endoscopyFigure 64.1 summarizes the historical evolution from laminectomy, costotransversectomy, and transthoracic approaches to endoscopic techniques. The constant goal was minimizing direct spinal cord manipulation without transferring excessive morbidity to the thoracic cavity. Uniportal endoscopy utilizes a posterolateral transforaminal corridor, executing decompression under continuous direct magnification.
• Indications and limitationsIndications include lateral and paramedian thoracic disc herniations, select soft or calcified central herniations, foraminal stenosis, synovial cysts, benign extradural tumors, and discitis with epidural collection. Significant spinal instability, severe thoracic kyphotic deformity, extensive ossification of the posterior longitudinal ligament (OPLL), and giant central calcified discs densely adherent to the dura elevate technical risk and may contraindicate endoscopic decompression alone.
• Anatomy and planningFigures 64.2 and 64.3 illustrate the complex relationship between the exiting root, neural foramen, rib head, and superior pedicle, alongside fluoroscopic trajectory landmarks. This anatomical relationship is critical to create a working corridor that avoids inadvertent medial plunging toward the cord. Preoperative CT angiography or MRI planning must identify the level of the artery of Adamkiewicz and strictly verify thoracic vertebral level counting.
• Decompression principlesTargeted foraminoplasty and partial superior articular process and pedicle reaming open the lateral corridor. Soft disc fragments are mobilized directly. In calcified herniations, the strategy emphasizes gradual bone drilling using the 'egg-shell' concept, hollowing out the disc space anterior to the fragment to allow inward collapse rather than pulling a fragment adhered to the ventral dura.
• Outcomes and risksPublished series demonstrate favorable clinical outcomes with reduced blood loss, operative time, and hospitalization compared to thoracotomy. Recognized risks include dural tears, epidural hematoma, intercostal neuralgia, and injury to radiculomedullary arterial supply. Radicular artery injury can cause catastrophic spinal cord infarction and must be meticulously avoided.
• Clinical Application: The initial step is determining whether the thoracic compression has a morphology amenable to a lateral endoscopic corridor. The mere radiographic presence of a thoracic disc herniation is not an operative indication; clinical signs of radiculopathy or progressive myelopathy must correlate. Thin-slice CT confirms calcification and osseous landmarks; T2 and CISS/FIESTA MRI sequences delineate spinal cord compression, intramedullary signal changes, and dural adhesion. Vascular anatomy must be reviewed at T8-L1 levels. Intraoperatively, the surgeon must remain lateral to the thecal sac until decompression is visually confirmed under continuous fluid flow. In calcified herniations, the anterior vertebral bone is hollowed out first, allowing the calcified shelf to be pushed away from the thecal sac rather than pulled. Figures 64.5 through 64.8 illustrate a calcified thoracic herniation presenting with paraparesis, successfully decompressed endoscopically using the egg-shell technique with full neurological recovery.
