Microscopic extra-laminar sequestrectomy (MELS) for the treatment of hidden zone lumbar disc herniation: report of the surgical technique, patient selection, and clinical outcomes.

BACKGROUND: The area which located at the medial pedicle, posterior vertebral body and ventral hemilamina is defined as the hidden zone. Surgical management of hidden zone lumbar disc herniation (HZLDH) is technically challenging due to its difficult surgical exposure. The conventional interlaminar approach harbors the potential risk of post-surgical instability, while other approaches consist of complicated procedures with a steep learning curve and prolonged operation time. OBJECTIVE: To introduce microscopic extra-laminar sequestrectomy (MELS) technique for treatment of hidden zone lumbar disc herniation and present clinical outcomes. METHODS: Between Jan 2016 to Jan 2018, twenty one patients (13 males) with HZLDH were enrolled in this study. All patients underwent MELS (19 patients underwent sequestrectomy only, 2 patients underwent an additional inferior discectomy). The nerve root and fragment were visually exposed using MELS. The operation duration, blood loss, intra- and postoperative complications, and recurrences were recorded. The Visual Analog Scale (VAS), Oswestry Disability Index (ODI), and the modified MacNab criteria were used to evaluate clinical outcomes. Postoperative stability was evaluated both radiologically and clinically. RESULTS: The mean follow-up period was 20.95 ± 2.09 (18-24) months. The mean operation time was 32.43 ± 7.19 min and the mean blood loss was 25.52 ± 5.37 ml. All patients showed complete neurological symptom relief after surgery. The VAS and ODI score were significantly improved at the final follow-up compared to those before operation (7.88 ± 0.70 vs 0.10 ± 0.30, 59.24 ± 10.83 vs 11.29 ± 3.59, respectively, p < 0.05). Seventeen patients (81%) obtained an "excellent" outcome and the remaining four (19%) patients obtained a "good" outcome based the MacNab criteria. One patient suffered reherniation at the same level one year after the initial surgery and underwent a transforaminal endoscopic discectomy. No major complications and postoperative instability were observed. CONCLUSIONS: Our observation suggest that MELS is safe and effective in the management of HZLDH. Due to its relative simplicity, it comprises a flat surgical learning curve and shorter operation duration, and overall results in reduced disturbance to lumbar stability.

Translaminar Approach for Treatment of Hidden Zone Foraminal Lumbar Disc Herniations: Surgical Technique and Preoperative Selection of Patients with Long-Term Follow-Up.

BACKGROUND: Lumbar disc herniation is a common degenerative disease of the lumbar spine with a prevalence of 1%-3% in some population studies. In 10% of patients, there is a fragment migrated cranially in Macnab's "hidden zone." In selected cases, this fragment can be removed with a translaminar approach that was described in 1998. We provide a detailed description of the technical advantages and pitfalls of the translaminar approach in a consecutive series of 32 patients treated at our institution. METHODS: Patients were divided preoperatively and postoperatively into 5 classes based on the Oswestry Disability Index (ODI): class 1, ODI 0%-20% (minimal disability); class 2, 20%-40% (moderate disability); class 3, 40%-60% (severe disability); 60%-80% (crippled); 80%-100% (bedridden or disabling symptoms). RESULTS: Four (12.5%) patients were upgraded 1 ODI class after the operation; 6 (18.7%) patients were upgraded 2 classes, 8 (25%) patients were upgraded 3 classes, and 11 (34.4%) patients were upgraded 4 classes. In 3 (9.4%) patients, ODI class did not change after the operation. After surgery, 7 (21.9%) patients developed mild low back pain. Mean follow-up was 25 months. CONCLUSIONS: When performed by dedicated spinal neurosurgeons, the translaminar approach is safe and effective in patients with long-term follow-up. Most patients showed an improvement in ODI. Major pitfalls were related to surgical selection and the narrow working space.

Percutaneous endoscopic transpedicle approach for herniated nucleus pulposus in the lumbar hidden zone.

INTRODUCTION: Although endoscopic procedures for lumbar disc diseases have improved greatly, treating migrated disc herniation is still a challenging task. Because of anatomic limitations, a rigid endoscope cannot effectively reach the herniated nucleus pulposus (HNP) in the hidden zone. The purpose of this study was to describe the transpedicle approach for HNP in the hidden zone using the percutaneous endoscopic lumbar discectomy system and to demonstrate the clinical results. Materials and Surgical Technique: Under fluoroscopy, the percutaneous endoscopic lumbar discectomy cannula is placed on the superior articular process, and a trephine with a diameter of 7.3 mm is used to make a bone hole. Through the bone hole, an HNP in the hidden zone can be detected with a rongeur for percutaneous endoscopic lumbar discectomy, the HNP can be removed, and then the decompressed nerve root is verified. We have treated two cases of hidden-zone HNP using the transpedicle approach. In all cases, the HNP was successfully removed, as confirmed by postoperative MRI. Clinical outcomes were acceptable. DISCUSSION: The percutaneous endoscopic transpedicle approach is an effective technique for managing HNP in the lumbar hidden zone.

Endoscopic Intralaminar Approach for the Treatment of Lumbar Disc Herniation.

BACKGROUND: Almost every surgical approach carries the risk of causing some degree of spinal instability, especially in cases of excessive resection of the lamina and facet joint. This study describes the endoscopic intralaminar approach (ILA) for the treatment of cranially and caudally migrated lumbar disc herniation. METHODS: Thirty-one patients who underwent endoscopic ILA for 26 caudally and 5 cranially migrated lumbar disc herniations were identified from a prospectively database. At final follow-up, a personal examination and a standardized questionnaire evaluation were conducted, including the Oswestry Disability Index (ODI) and functional outcome according to modified MacNab criteria. In addition, particular reference was given to back pain, leg pain, and repeat procedures. RESULTS: The mean final follow-up was 37.0 months (range, 5-57 months) at which 29 patients attended (93.5%). No leg pain was noted in 95.0%, no back pain in 85.0%, full motor strength in 95.0%, and no sensory deficit in 95.0% of patients with ILA. Clinical success was reported by 95.0% of patients and the mean ODI was 9% in patients with ILA. Ten patients had an enlargement of ILA to conventional laminotomy (32.3%). By comparison of clinical outcome and repeat procedure rate in patients with ILA with patients with enlargement to laminotomy, no significant differences were identified except for higher ODI (i.e., 16%) in patients with enlargement of ILA. CONCLUSIONS: Endoscopic ILA is a safe technique for the treatment of cranially and caudally migrated lumbar disc herniations. Careful procedural planning is recommended to protect soft tissue and osseous structures and to achieve excellent clinical outcome.

A novel translaminar crossover approach for pathologies in the lumbar hidden zone.

We report eight patients with disc herniations who underwent sequestrectomy via a crossover translaminar technique. The lateral lumbar spinal canal can be divided into several regions: the subarticular, foraminal and extraforaminal zone. Due to its difficult surgical exposure, some authors refer to part of the subarticular and foraminal region as the hidden zone. Conventional approaches involve partial or total facet joint resection, introducing risk of postoperative instability. Under fluoroscopic guidance, a high speed drill was used to create a small, angled fenestration at the base of the spinous process aimed at the contralateral hidden zone. The nerve root was visualized and disc fragments were removed without facet joint violation. Patients were registered in the International Spine Registry, Spine Tango. Numeric rating scale (NRS), Oswestry disability index (ODI) and core outcome measures index (COMI) were used to evaluate outcome after 6 weeks and 3 months. Outcome was further statistically matched with the Spine Tango pool of patients who underwent sequestrectomy via conventional techniques. Postoperative CT scans showed the translaminar crossover approach with the preserved facet joints. There was significant postoperative improvement of NRS scores and ODI at all follow-up intervals. COMI achieved significant improvement at 3 months. Statistical comparison with Spine Tango data confirmed that the translaminar crossover approach matches the clinical results of the conventional techniques. This series is a proof of principle for a successful translaminar crossover approach to the lumbar hidden zone. The outcome is not inferior to conventional inter- and translaminar routes and the technique potentially offers risk reduction for postoperative instability by preserving facet joint function, especially in the case of recurrent disease.

Technical note: microdiscectomy and translaminar approach.

Lumbar disk herniation (LDH) is a degenerative pathology. Although LDH generally occurs without migration of the fragment to the levels above or below, in 10% of the cases, this circumstance might happen. In these cases, the standard interlaminar approach, described by Caspar cannot be performed without laminotomies, interlaminectomies, or partial or total facetectomies. The translaminar approach is the only "tissue-sparing" technique viable in cases of cranially migrated LDH encroaching on the exiting nerve root in the preforaminal zones, for the levels above L2-L3, and in the preforaminal and foraminal zones, for the levels below L3-L4 (L5-S1 included, if a total microdiscectomy is unnecessary). This approach is more effective than the standard one, because it resolves the symptoms; it is associated with less postoperative pain and faster recovery times without the risk of iatrogenic instability, and it can also be used in cases with previous signs of radiographic instability. The possibility to spare the flavum ligament is one of the main advantages of this technique. For these reasons, the translaminar approach is a valid technique in terms of safety and efficacy. In this article the surgical technique will be extensively analyzed and the tips and tricks will be highlighted.

Microdiskectomy and translaminar approach: minimal invasiveness and flavum ligament preservation.

Study Design Retrospective study. Objective The interlaminar approach represents the standard procedure for the surgical treatment of lumbar disk herniation (LDH). In the case of disk herniations in the "hidden zone," it could be necessary to perform laminotomies or laminectomies and partial or total facetectomies to remove the herniated fragment, thus leading to iatrogenic instability. The objective of the study is to evaluate the translaminar approach, in terms of the results, safety, and efficacy compared with the standard approach. Methods Since February 2010, 38 patients (26 men and 12 women; mean age 50.9 years, range 31 to 78 years) with LDH and migration into the hidden zone underwent a microdiskectomy by the translaminar approach. Using a micro-diamond dust-coated burr, a translaminar hole (8 ± 2 mm) was made, with subsequent exposure of the involved root and removal of the fragment. A clinical follow-up was performed at months 1, 3, 6, and 12 using the visual analog scale and the Oswestry Disability Index. All patients were evaluated according to the Spangfort score. Postoperative radiographic evaluations were done at 1, 6, and 12 months (dynamic radiographic studies done at 6 and 12 months). Results In over 60% of cases, L4-L5 was the involved disk. The visualization of the roots was successfully achieved through a translaminar approach. No laminotomies, laminectomies, or partial or total facetectomies were performed. The flavum ligament was always spared. A severe intraoperative bleeding episode occurred in 5% of the cases, due to involvement of the epidural veins, but it did not result in prolonged operative time (mean duration 60 ± 10 minutes). The patients showed a gradual resolution of the back pain and a progressive resolution of the radicular pain and the neurologic deficits. No sign of radiographic instability was documented during the follow-up. No infections, dural tears, or spinal cord injuries occurred. No revision surgery was performed. Conclusion The translaminar approach is the only tissue-sparing technique viable in case of cranially migrated LDH encroaching on the exiting nerve root in the preforaminal zones, for the levels above L2-L3, and in the preforaminal and foraminal zones, for the levels below L3-L4 (L5-S1 included, if a total microdiskectomy is not necessary). The possibility to spare the flavum ligament is one of the main advantages of this technique. According to our experience, the translaminar approach is an effective and safe alternative minimally invasive surgical option.

Endoscopic foraminal decompression for failed back surgery syndrome under local anesthesia.

BACKGROUND: The most common causes of failed back surgery are residual or recurrent herniation, foraminal fibrosis and foraminal stenosis that is ignored, untreated, or undertreated. Residual back ache may also be from facetal causes or denervation and scarring of the paraspinal muscles.(1-6) The original surgeon may advise his patient that nothing more can be done on the basis of his opinion that the nerve was visually decompressed by the original surgery, supported by improved post-op imaging and follow-up studies such as EMG and conduction velocity studies. Post-op imaging or electrophysiological assessment may be inadequate to explain all the reasons for residual or recurrent symptoms. Treatment of Failed back surgery by repeat traditional open revision surgery usually incorporates more extensive decompression causing increased instability and back pain, therefore necessitating fusion. The authors, having limited their practice to endoscopic MIS surgery over the last 15-20 years, report on their experience gained during that period to relieve pain by endoscopically visualizing and treating unrecognized causative patho-anatomy in FBSS.(7.) METHODS: Thirty consecutive patients with FBSS presenting with back and leg pain that had supporting imaging diagnosis of lateral stenosis and /or residual / recurrent disc herniation, or whose pain complaint was supported by relief from diagnostic and therapeutic injections (Figure 1), were offered percutaneous transforaminal endoscopic discectomy and foraminoplasty over a repeat open procedure. Each patient sought consultation following a transient successful, partially successful or unsuccessful open translaminar surgical treatment for disc herniation or spinal stenosis. Endoscopic foraminoplasty was also performed to either decompress the bony foramen for foraminal stenosis, or foraminoplasty to allow for endoscopic visual examination of the affected traversing and exiting nerve roots in the axilla, also known as the "hidden zone" of Macnab (Figure 2).(8, 9) The average follow up time was, average 40 months, minimum 12 months. Outcome data at each visit included Macnab, VAS and ODI. Fig. 1A diagnostic and therapeutic epidural gram may help identify unrecognized lateral recess stenosis underestimated by MRI. An excellent result from a therapeutic block lends excellent prognosis for a more lasting and "permanent" result from transforaminal endoscopic lateral recess decompression.Fig. 2Kambin's Triangle provides access to the "hidden zone" of Macnab by foraminoplasty. The foramen and lateral recess is decompressed by removing the ventral aspect and tip of the superior articular process to gain access to the axilla between the traversing and exiting nerve. FBSS contains patho-anatomy in the axilla between the traversing and exiting nerve that hides the pain generators of FBSS. RESULTS: The average pre-operative VAS improved from 7.2 to 4.0, and ODI 48% to 31%. While temporary dysesthesia occurred in 4 patients in the early post-operative period, all were happy, as all received additional relief of their pre-op symptoms. They were also relieved to be able to avoid "open" decompression or fusion surgery. CONCLUSIONS / LEVEL OF EVIDENCE 3: The transforaminal endoscopic approach is effective for FBSS due to residual/recurrent HNP and lateral stenosis. Failed initial index surgery may involve failure to recognize patho-anatomy in the axilla of the foramen housing the traversing and the exiting nerve, including the DRG, which is located cephalad and near the tip of SAP.(10) The transforaminal endoscopic approach effectively decompresses the foramen and does not further destabilize the spine needing stabilization.(11) It also avoids going through the previous surgical site. CLINICAL RELEVANCE: Disc narrowing as a consequence of translaminar discectomy and progressive degenerative narrowing and spondylolisthesis (Figure 3) as a natural history of degenerative disc disease can lead to central and lateral stenosis. The MRI may underestimate the degree of stenosis from a bulging or a foraminal disc protrusion and residual lateral recess stenosis. Pain can be diagnosed and confirmed by evocative discography and by clinical response to transforaminal diagnostic and therapeutic steroid injections.(12) Foraminal endoscopic decompression of the lateral recess is a MIS technique that does not "burn bridges" for a more conventional approach and it adds to the surgical armamentarium of FBSS. Fig. 3Cadaver Illustration of Foraminal Stenosis (courtesy of Wolfgang Rauschning). As the disc narrows, the superior articular process impinges on the exiting nerve and DRG, creating lateral recess stenosis, lumbar spondylosis, and facet arthrosis.