7.3. Approach
@ProfFishchenkoIn my practice, for an interlaminar BESS/UBE approach, I position the patient prone on a Wilson frame to provide flexion of the lumbar spine. This widens the interlaminar space and helps limit unnecessary bone resection. We coordinate the position of the head and trunk with the anesthesiologist to maintain ventilation and venous drainage. We keep the head in a neutral position and avoid pressure on the eyes and abdomen. The anesthesiologist determines the target blood pressure individually, taking baseline pressure, comorbidities, and organ perfusion into account. In my practice, a systolic pressure of approximately 100 mmHg may serve as a guide when clinically appropriate. We place soft cushions under the knees and lower legs.
Before incision, we confirm the operative level with the C-arm, correlating vertebral numbering with the preoperative images. We obtain an anteroposterior image. We use a lateral projection whenever there is uncertainty about the level or instrument depth, particularly in the presence of lumbarization, sacralization, or hyperlordosis. If needed, we repeat lateral imaging after trocar and dilator placement.
Left-sided approach
The fluoroscopic landmark is the interlaminar space at the relevant level. I mark the intervertebral disc level on the skin. I plan the proximal endoscopic portal immediately lateral to the spinous process of the cranial vertebra, at the level of the inferior portion of the lamina. I position the distal working portal 2–3 cm caudally in patients with a slender or average build and 3–4 cm caudally in overweight patients.
Right-sided approach
The fluoroscopic landmark is the interlaminar space at the relevant level. I mark the intervertebral disc level on the skin. I plan the distal endoscopic portal immediately lateral to the spinous process at the level of the lamina of the caudal vertebra. I position the proximal working portal 2–3 cm cranially in patients with a slender or average build and 3–4 cm cranially in overweight patients.
Endoscopic portal. Using a pointed scalpel, we incise the skin, subcutaneous fat, and outer layer of the fascia of the longissimus muscle. Through the opening created, we introduce the first and second dilators until they contact the lamina. Using the dilators or dedicated muscle dissectors, we separate the muscles from the lamina. We identify the bony landmarks by touch: the lamina, inferior articular process, and slope into the interlaminar space. We palpate them carefully without dropping into the interlaminar space. We remove the dilators and introduce the trocar into the portal tract created, again confirming contact with bone.
Note. Marked degenerative changes in the posterior vertebral elements may make tactile identification of bony landmarks difficult. In this situation, I obtain additional imaging.
Working portal. Using a pointed scalpel, we incise the skin, subcutaneous fat, and outer layer of the thoracolumbar fascia (fascia thoracolumbalis). We rotate the scalpel 90° and make a transverse fascial incision. This creates a cruciate fascial incision to ensure free irrigation fluid outflow. We introduce three dilators of sequentially increasing diameter. We palpate the bone and bring the dilators together with the trocar passed through the endoscopic portal until “metal-to-metal” contact is achieved. If instrument positioning or depth is uncertain, we obtain lateral imaging.
If needed, I obtain lateral imaging. I replace the trocar stylet with the endoscope and camera.
References
1. Park DK, Weng C, Zakko P, Choi DJ. Unilateral Biportal Endoscopy for Lumbar Spinal Stenosis and Lumbar Disc Herniation. JBJS Essent Surg Tech. 2023;13(2):e22.00020. doi:10.2106/JBJS.ST.22.00020.
2. Choi CM, Chung JT, Lee SJ, Choi DJ. How I do it? Biportal endoscopic spinal surgery (BESS) for treatment of lumbar spinal stenosis. Acta Neurochir (Wien). 2016;158(3):459–463. doi:10.1007/s00701-015-2670-7.
3. Saugel B, Fletcher N, Gan TJ, et al; POQI XI Workgroup. PeriOperative Quality Initiative (POQI) international consensus statement on perioperative arterial pressure management. Br J Anaesth. 2024;133(2):264–276. doi:10.1016/j.bja.2024.04.046.
4. American Society of Anesthesiologists Task Force on Perioperative Visual Loss; North American Neuro-Ophthalmology Society; Society for Neuroscience in Anesthesiology and Critical Care. Practice Advisory for Perioperative Visual Loss Associated with Spine Surgery 2019. Anesthesiology. 2019;130(1):12–30. doi:10.1097/ALN.0000000000002503.
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