Spontaneous regression is most commonly seen with which combination of stages?

• A. Disc Extrusion and Sequestration
• B. Disc Prolapse and Extrusion
• C. Disc Degeneration and Prolapse
• D. Disc Sequestration Only

Answer: (A)

Spontaneous regression happens most when the herniated disc material is free outside the annulus, as in extrusion and especially sequestration. When nucleus pulposus protrudes through the annulus or becomes a free fragment in the epidural space, it becomes exposed to the body's immune and inflammatory processes. Macrophages and new blood vessels infiltrate the fragment, leading to phagocytosis and gradual resorption over weeks to months. Contained herniations, such as prolapse or contained extrusion, have a fibrous/ligamentous cap that limits immune access, so they are less likely to regress spontaneously. Therefore, extruded and sequestrated disc material is most prone to natural regression.