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Chapter Summary
• Context: Posterior cervical endoscopic surgery developed as a motion-preserving, minimally invasive alternative to open foraminotomy and anterior cervical discectomy and fusion (ACDF) in selected patients. Its primary clinical attraction is achieving targeted radicular or central canal decompression while completely preserving segment motion and minimizing disruption to posterior cervical musculature. The approach is particularly suited for lateral or foraminal disc herniations and bony foraminal stenosis without segmental instability. Techniques such as 'over-the-top' laminotomy have expanded the ability to decompress the contralateral canal and lateral recess from a unilateral entry, while unilateral biportal endoscopic (UBE) systems enhance instrumental triangulation. However, the close proximity of the cervical spinal cord, exiting nerve roots, and vertebral artery, combined with a narrow working space and continuous fluid pressure, makes the procedure unforgiving. Severe myelopathy, gross instability, fixed kyphosis, and extensive OPLL remain scenarios where conventional open techniques provide greater safety.
• Chapter Objective: Equip the reader to evaluate when the posterior cervical endoscopic approach is indicated, plan the trajectory according to compressive topography, and understand the technical differences between uniportal, biportal, and over-the-top strategies. The chapter emphasizes critical safety criteria for facet preservation, neurovascular protection, fluid pressure control, and indications for open conversion.
• Selecting the posterior cervical corridorThe posterior approach is primarily targeted at posterolateral and foraminal nerve root compressions. In selected central stenosis, over-the-top laminotomy allows bilateral canal unroofing through a unilateral corridor. Biportal systems provide independent instrument manipulation. Diffuse multi-level cord compression, severe cervical myelopathy, extensive OPLL, frank segmental instability, or fixed kyphosis require caution and favor conventional anterior or open posterior techniques.
• Preoperative planningHigh-resolution MRI and CT are essential. MRI evaluates the disc, nerve root, spinal cord, and compressive pathology; CT details facet osteophytes, uncinate overgrowth, and the exact boundaries for bony resection. Positioning with head fixation in Mayfield clamp or halo, choice of endoscope optics (0° vs 30°), and portal triangulation depend on uniportal versus biportal technique. Intraoperative neuromonitoring (MEP/SSEP) is recommended when working near the cord.
• Foraminotomy and decompression techniqueThe uniportal approach identifies the 'V-point' at the laminofacet junction. Progressive unroofing of the medial facet and lateral lamina is performed with diamond burrs and micro-punches. The golden rule is preserving at least 50% to 70% of the facet joint to prevent postoperative instability. Decompression is complete when the nerve root is completely free, mobile, and visualized traversing the foramen. The vertebral artery marks the extreme lateral safety boundary.
• Expanded techniquesThe over-the-top technique angles the working channel across the base of the spinous process to decompress the contralateral thecal sac and lateral recess. In biportal systems, viewing and working portals operate independently, facilitating high-speed drilling and micro-instrumentation.
• Outcomes and complicationsThe chapter reports clinical outcomes and pain relief comparable to ACDF and open microforaminotomy, with reduced blood loss, shorter hospital stay, and preserved motion. Figures 65.1 through 65.4 demonstrate cases of foraminal radiculopathy and central stenosis treated by over-the-top endoscopy. Complications include dural tears, transient C5/C6 root neuropraxia, epidural hematoma, recurrence, and vertebral artery injury. Knowing when to convert to open surgery during uncontrolled venous bleeding or large dural lacerations is a mark of surgical mastery.
• Clinical Application: For unilateral radiculopathy caused by a soft foraminal disc herniation or lateral osteophyte, the posterior endoscopic route enables targeted decompression with full motion preservation, provided baseline cervical alignment is lordotic and stable. Central stenosis with myelopathy requires strict evaluation of the number of levels and canal reserve. Preoperative CT must calculate exactly how much medial facet bone needs removal without violating the 50% stability threshold. The vertebral artery's location must be visualized on axial CT/MRI before extending foraminotomy laterally. Intraoperatively, cloudy visualization must never be managed with blind instrument probing or excessive irrigation pump pressure; the surgeon must re-establish clear anatomical landmarks and meticulous radiofrequency coagulation. The initial learning curve should be limited to soft posterolateral single-level herniations in stable, lordotic spines before progressing to complex stenoses.
