A Natural Anatomical Channel for Percutaneous Transforaminal Endoscopic Surgery: Concept and Initial Outcomes of the BEIS Technique

Objective To introduce the Broad Easy Immediate Surgical (BEIS technique) technique, a novel transforaminal endoscopic approach that utilizes a natural anatomical corridor through the superior foraminal zone, and to evaluate its initial clinical outcomes. Methods This retrospective case-series study included 392 patients. The BEIS technique is characterized by a working cannula trajectory that enters the spinal canal dorsally to the exiting nerve root via the upper foramen, requiring only minimal resection of the superior articular process (SAP) apex. With the patient in a lateral position, the puncture needle was advanced under fluoroscopy along the ventral aspect of the SAP apex (the BEIS point) to the posterior-superior edge of the vertebral body. A midline-directed channel was established using a TOMshidi needle and graduated bone drills (Ø4-9mm), followed by systematic endoscopic decompression. Results The safety of the BEIS channel was confirmed in relation to the exiting nerve root, traversing nerve root, and spinal dura. The technique demonstrated a significantly enlarged operational field and 94% patient satisfaction. Compared to conventional foraminoplasty, it achieved minimal bone resection. It also improved accessibility at the L5/S1 level in cases with a high iliac crest. Quantitative outcomes showed significant improvements in leg pain VAS (from 72.8 ± 20.9 to 22.9 ± 9.8) and ODI (from 38.3 ± 19.2 to 11.1 ± 5.2) at 1-year follow-up (P < 0.001 for both). Conclusion As an evolution of the TESSYS technique, BEIS successfully navigates the traditional "forbidden zone" of the upper foramen to establish a novel, safer anatomical corridor. Its advantages in bone preservation and surgical accessibility support its consideration as a valuable addition to the minimally invasive spine surgeon's armamentarium.