IRRIGATION DURING LUMBAR SPINAL ENDOSCOPY: IMPORTANT CONSIDERATIONS

Endoscopic spine surgery is an evolving field within minimally invasive spine surgery. However, patients undergoing percutaneous endoscopic lumbar discectomy (PELD) might experience neurologic complications such as headaches or seizures. It is hypothesized that these issues may arise from elevated intra-/epidural pressures due to fluid irrigation during the procedure. The exact causes of these complications remain unclear. This research aims to investigate the impact of different irrigation pressures on intra-/epidural pressures during PELD. Pressure measurements within the spinal compartments were conducted using sensors inserted via a sacral approach to levels L3/4, T8/9, and C5/6 in human cadavers. An epidural probe at L3/4 and an intracranial sensor were precisely positioned, confirmed by contrast-enhanced X-rays imaging. The dural sac was infused with Ringer's solution to a physiological pressure of 15 cm H 2 O. Lumbar endoscopy was then performed at L3/4 using an interlaminar approach, and the effects of varying irrigation pressures from different endoscopic pumps and gravity-fed systems on spinal and cranial pressures were assessed. Additionally, assessments were made after controlled durotomy at L3/4. The intradural pressure at L3/4 showed a direct linear relationship with the increase in pump pressure for both types of endoscopic pump systems (system I: ρ=0.94, p<0.05; system II: ρ=0.89, p<0.05; gravity: ρ=0.93, p>0.05). This relationship was consistent across all measured spinal levels and was also observed in the epidural and intracranial compartment. Pressure increases were more significant with backflow-occlusion at the endoscope and a durotomy present. A linear relationship between the irrigation pressures used during PELD and the measured intra- and epidural, as well as intracranial pressures was observed. Surgeons should be aware that with a dural tear under high pump pressures and backflow-occlusion, intradural and intracranial pressures could reach clinically critical levels. **Mazda Farshad and Jana Felicitas Schader contributed equally to this study as co-first authors.