Chapter Clinical Summary
Academic synthesis, diagnostic methodology, and surgical recommendationsThe interlaminar endoscopic approach represents the culmination of surgical refinement connecting classic microsurgical landmarks with continuous fluid full-endoscopic visualization. The development of large-channel endoscopes, high-speed motorized burrs, dedicated Kerrison rongeurs, and steerable radiofrequency probes expanded an approach originally conceived for discectomy into advanced bilateral decompression for central and lateral recess stenosis via a unilateral laminotomy (ULBD). Its major value lies in replicating the established decompression goals of open surgery with minimal muscle detachment, reduced blood loss, and direct high-definition visualization. The interlaminar route is particularly suitable for central, paracentral, and axillary disc herniations, downward migrated fragments, central spinal stenosis, lateral recess stenosis, and facet cysts, notably at L5-S1 where the interlaminar window is naturally widest. Achieving excellent outcomes requires precise patient selection, 3D anatomical understanding of the ligamentum flavum and dural borders, controlled bone resection, and strict irrigation management.
Teach the historical, diagnostic, and surgical principles of interlaminar lumbosacral endoscopy. The reader will learn to recognize precise indications and contraindications, integrate MRI, CT, and dynamic radiographs into preoperative planning, select specialized instrumentation, verify criteria for complete neural decompression, and manage complications such as dural tears, epidural hematomas, incomplete decompression, and recurrent herniation.
The chapter reviews the evolution from early percutaneous nucleotomies to modern full-endoscopic interlaminar systems. Dedicated burrs and instruments expanded discectomy to extensive bony and ligamentous decompression. The literature demonstrates favorable perioperative metrics compared to open microsurgery in equivalent indications, while comparisons with the transforaminal approach show that neither is universally superior; choice depends on anatomical level and compressive topography.
The interlaminar corridor is ideally suited for central and paracentral disc herniations (including highly migrated fragments), central canal stenosis, lateral recess stenosis, and symptomatic facet cysts. Severe gross instability, fixed deformities requiring stabilization, and isolated axial discogenic pain are contraindications for isolated decompression. Heavily calcified herniations and severe stenosis require advanced technical maturity.
MRI defines the neural compromise and soft-tissue stenosis. CT evaluates facet hypertrophy, osteophytes, calcification, and the dimensions of the interlaminar window; dynamic radiographs rule out instability. Figures 63.1 through 63.8 detail specialized endoscopes, working sleeves, diamond burrs, articulating forceps, Kerrisons, dissectors, irrigation pumps, and bipolar radiofrequency systems.
The patient is positioned in prone flexed posture to widen the interlaminar window. The approach docks on the inferior border of the cranial lamina. The ligamentum flavum serves as an essential protective shield during the initial drill work. After defining bony margins, flavectomy is performed under direct vision, exposing the thecal sac and traversing root. In disc herniations, nerve root mobilization precedes fragment extraction. Final canal exploration confirms neural pulsation, traversing root mobility, and complete hemostasis.
Incidental durotomy is a major focus. Table 63.1 organizes dural tear patterns and details endoscopic patch repair, clip application, or conversion criteria. Epidural hematoma, incomplete decompression, recurrent herniation, and infection complete the primary risk profile.
The choice between interlaminar and posterolateral endoscopic approaches must be established during preoperative planning. For central or subarticular compression, especially at L5-S1 or in patients with high iliac crests, the interlaminar approach provides the most direct and familiar corridor. Window dimensions, calcification degree, and the need for bilateral decompression over-the-top guide the surgical plan. In the early learning curve, surgeons should start with single-level soft paracentral L5-S1 disc herniations before attempting multi-level central stenosis or revision cases. Bony resection must allow safe instrument maneuverability while preserving facet integrity to prevent iatrogenic instability. During surgery, fluid irrigation, venous bleeding, and neural safety are interrelated: continuous low pressure prevents intracranial hypertension, while meticulous radiofrequency coagulation prevents delayed epidural hematoma after irrigation cessation. Figures 63.20 and 63.21 demonstrate focal discectomy and bilateral over-the-top canal decompression.