Full-Endoscopic Interlaminar Approach for Decompression of Lateral Recess Stenosis

Technical advances and increased experience in full-endoscopic spinal surgeries enable these procedures to be performed with minimal incision, muscle retraction, and bone removal.

For lateral recess stenosis, extensive decompression with laminectomy is still performed in most centers. However, tissue-sparing surgeries are becoming more common. Full-endoscopic spinal surgeries have the advantages of being less invasive and offering a shorter recovery time. Here, we describe the technique of the full-endoscopic interlaminar approach for the decompression of lateral recess stenosis. The full-endoscopic interlaminar approach for the lateral recess stenosis procedure took approximately 51 min (range of 39-66 min). Blood loss could not be measured due to continuous irrigation. However, no drainage was required. There were no dura mater injuries reported in our institution. Furthermore, there were no injuries to the nerves, no cauda equine syndrome, and no hematoma formation. The patients were mobilized on the same day as surgery and discharged the next day. Therefore, the full-endoscopic technique for lateral recess stenosis decompression is a feasible procedure that lowers the operational time, complications, traumatization, and rehabilitation duration.

Spinal stenosis, both central and lateral recess stenosis, is the most common pathology in the elderly population¹. Lateral recess stenosis can cause symptoms of neurogenic claudication, radicular pain, and motor and sensory deficits. If present, back pain is usually attributed to accompanying segmental instability^2,3.

Numerous surgical procedures have been described to date, some of which are still controversial⁴. Over the years, the trend has developed from more aggressive to more selective and minimally invasive techniques. In conventional surgery, epidural fibrosis and scarring may become symptomatic, making revision surgery more difficult. It may cause surgery-induced instability due to unnecessary bone removal and tissue damage^5,6.

The stenotic zone in lumbar spinal stenosis can be in the central, lateral recess, or intervertebral foramen. The full-endoscopic approach depends on the pathology and the surgeon's preferences, and can be interlaminar, transforaminal, or extraforaminal^7,8. The anatomy of the foramen and the exiting nerve can make the foraminal approaches challenging. Therefore, the interlaminar approach enables better access and understanding of the pathology and the opportunity to decompress. Patient selection is important; patients with ligamentum flavum hypertrophy, facet joint hypertrophy, and sequestered and non-sequestered disc herniations can be operated on with this technique, and these pathologies can be addressed. Patients with compressive foraminal or extraforaminal pathologies, extensive spinal canal stenoses, a significant bony shift in the interlaminar window, and instability in the spinal canal are excluded. The goal of this study is to describe the full-endoscopic interlaminar approach for lumbar lateral recess stenosis.

The study protocol was approved by the institutional review board of the Istanbul Faculty of Medicine.

1. Preoperative procedures

1. Perform the surgeries under general anesthesia. Set the endoscopic and optic instruments, and C-arm devices in the operation room.
2. Ensure that the following tools are available for the procedure: dilator, working sleeve, endoscope with a 20° viewing angle and 177 mm in length with a 9.3 mm diameter oval shaft with a 5.6 mm diameter working channel, Kerrison punch (5.5 mm), rongeur (3-4 mm), punch (3-5.4 mm), tip control radioablator probe that applies the radiofrequency current of 4 MHz, fluid control irrigation and suction pump device, 5.5 mm oval burr with lateral protection, burr round, and the diamond round.

2. Surgical technique

1. Place the patient in a prone position with thorax and pelvis support pillows. Flex the hip and the knee at the adjustable operation table to provide a wider interlaminar window. While the surgery can be performed by one surgeon, an assistant would ease the procedure.
2. Obtain an anteroposterior (AP) X-ray view to mark the L4-5 interlaminar window near the midline on the ipsilateral side. Ensure that the entry point is close to the midline to enable lateral access below the zygapophyseal joints.
   NOTE: The C-arm is a device that can rotate 360° around the patient and obtain AP and lateral X-ray views intraoperatively.
3. Make a 1 cm incision with a #20 blade until the fascia of the paraspinal muscle is passed. Insert the dilator till it touches the facet joint. Acquire AP and lateral X-ray views to confirm the location of the dilator.
   NOTE: The dilator is inserted toward the facet joint so that it does not pass through the interlaminar window and injure the neural structures.
4. Introduce the working sleeve over the dilator with an oblique opening showing the medial side. Acquire the lateral X-ray view again, confirming the position of the working sleeve. Then, remove the dilator.
5. Introduce the endoscope through the working sleeve. Perform the remaining procedure under continuous irrigation with isotonic saline to the operation field.
6. After access has been achieved, remove the soft tissues-mainly the paraspinal muscles-using the rongeur. Expose the bony structures of the facet and the ligamentum flavum. Remove the superficial layer of the ligamentum flavum with a 5.4 mm punch for total exposure of the descending facet.
7. Begin the bone removal from the medial side of the descending facet from its inferior tip, using the 5.5 mm oval burr with lateral protection to expose the ascending facet.
8. Then, expose the ascending facet and its superior tip. The synovial joint is disrupted in this stage, and the ascending facet cartilage can be appreciated. Visualize the deeper layer of the ligamentum flavum here, attaching to the medial side of the ascending facet.
9. Use the oval burr with lateral protection again for thinning the ascending facet so that the total removal can be achieved by the Kerrison punch. Use the Kerrison punch for further bone removal toward the lateral.
10. The extent of the resection is recommended to reach from the tip of the ascending facet to the middle of the caudal pedicle. Then, resect the ligamentum flavum using the punch from the midline toward the lateral.
11. Ensure that the removal of the ligamentum flavum is medial to lateral and cranial to caudal to completely visualize the below lateral recess. Doing this otherwise would risk a dural tear, since the dura is more prominent in the midline.
12. While resecting the ligamentum flavum, use the long side of the working sleeve to achieve some tension in the ligament. This way, the dura will separate from the ligament, and the ligament resection will be safer.
13. Remove the epidural fat tissue with caution, using the rongeur, until adequate exposure to the neural structures is obtained. After caudal removal of the ligamentum flavum, remove the superior border of the caudal lamina using the Kerrison punch.
14. Here, we expect to see the axilla of the nerve root. Mobilize the nerve root medially using the dissector to relieve it from any adhesions. If there is a discopathy contributing to the lateral recess stenosis, address it.
15. Medialize the nerve root using the dissector, or turn the long side of the working sleeve. If there is a sequestrated or extruded material, remove it using the rongeur directly from an existing annulus defect. If there is a subligamentous protruding material, use the punch to open the posterior longitudinal ligament and the annulus fibrosis. In that case, evacuate the disc space by using the rongeur (Video 1).
16. Coagulate the soft tissues using the radioablator. Here, obtain a lateral X-ray view to understand if the end plates are parallel and how deep it has proceeded. Establish the decompression by resecting parts of the medial descending and ascending facet, the cranial and caudal lamina, and the ligamentum flavum.
17. Sufficient decompression of the neural structures can be appreciated. Achievedecompression by resecting half of the pedicle and the ligamentum flavum at the lateral recess.
18. After achieving hemostasis using the radioablator, complete the procedure by removing the endoscopic system. Close the wound with a single suture without any drainage.

3. Postoperative procedures and follow-up

1. The hospital stay is short. Mobilize the patients on the same day as the procedure.
2. If there are no further complaints, discharge the patients the next day.
   NOTE: Postoperative pain is low; thus, no need for extended painkiller use. Nonsteroidal anti-inflammatory drugs are commonly used agents if there is pain at the operation site. Rehabilitation and physical therapy are not necessary.
3. Recommend the patients to be admitted to the outpatient clinic in the first and fourth weeks.

The preoperative and postoperative sagittal and axial magnetic resonance images (MRIs) show right-sided lateral recess stenosis. (Figure 1). Due to the continuous irrigation and suction system in full-endoscopic surgery, the blood loss could not be measured. However, postoperative hemoglobin levels indicate that no significant blood loss is experienced. Early postoperative mobilization is encouraged for the patients, who are usually discharged the day after. A lumbar corset is not required since the facet joints are preserved during the procedure, and no instability is expected.

The mean operation time of 56 patients operated on in the last three years is 51 min (39-66 min) in our institution. With a full-endoscopic technique, adequate decompression of the lateral recess is easy and feasible. No drainage is required. Intraoperative conversion to the microscopic procedure has not been encountered in any cases. Postoperative wound healing is shorter. The patients are mobilized in the early postoperative period and usually discharged the day after. There have been no significant complications like spondylodiscitis or wound detachment. There have also been no recurrences in the follow-up period.

Figure 1: MRI of a patient with right unilateral recess stenosis. (A) Lumbar preoperative and (B) postoperative sagittal and axial MRI of a patient with right unilateral recess stenosis in the L4-5 level (his image was obtained from the hospital imaging system-PACS). Please click here to view a larger version of this figure.

Video 1: Full-endoscopic left L4-5 lateral recess stenosis decompression. Ligamentum flavum exposure, resection of the descending and ascending facets, caudal lamina, and caudal pedicle can be appreciated stepwise. Hypertrophied ligamentum flavum in the lateral recess and the resection of it can be seen. A minimal disc protrusion is encountered in this patient; therefore, a discectomy is performed. In the end, a decompressed left L5 nerve root is appreciated. Please click here to download this Video.

Conventional surgeries for lateral recess stenosis decompression include laminectomy and extensive resection of the soft and bony tissues⁴. Epidural fibrosis and scarring can be problematic, become symptomatic, and make revision surgery more complex⁹. Resection of the posterior musculature and the bony elements can cause surgery-induced segmental instability¹⁰. This has led to the need for more tissue-sparing surgeries. Technical advances have enabled full-endoscopic surgeries to be performed extensively in the spine^11,12.

The development of endoscopic and optic instruments have expanded the intervention approaches to the spine¹³. The mean operation time was 51 min, no significant blood loss was observed, and no drainage was required. Ruetten et al. showed that, compared to microscopic techniques in lateral stenosis decompression, there was a reduction in operation time, traumatization, and operation-related sequelae in the full-endoscopic group⁸. In the literature, clinical results with the full-endoscopic and microsurgical techniques were compared, and no significance in a 2 year follow-up was observed. More patients suffered from postoperative back pain after the microsurgical intervention¹⁴.

Our experience shows that, in patients with single-level, unilateral stenosis, the complete endoscopic technique can preserve structures and avoids surgery-related instability. We think this procedure can even be applied bilaterally on multiple levels if the facet joints and ligamentum flavum are kept intact. If the patient does not have coexistent pathologies, such as extensive spinal canal stenosis, and instability findings, for isolated lateral recess stenosis, there is no clear limitation for the technique.

The authors report no conflict of interest concerning the materials or methods used in this study.

There is no funding source for this study.