Risk factor for unsatisfactory outcome after lumbar foraminal and far lateral microdecompression

Percutaneous endoscopic lumbar foraminotomy: an advanced surgical technique and clinical outcomes

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BACKGROUND:

Although several authors have reported the use of endoscopic techniques to treat lumbar foraminal stenosis, the practical application of these techniques has been limited to soft disc herniation.

OBJECTIVE:

To describe the details of the percutaneous endoscopic lumbar foraminotomy (ELF) technique for bony foraminal stenosis and to demonstrate the clinical outcomes.

METHODS:

Two years of prospective data were collected from 33 consecutive patients with lumbar foraminal stenosis who underwent ELF. The surgical outcomes were assessed using the visual analog scale, Oswestry Disability Index, and modified MacNab criteria. The procedure begins at the safer extraforaminal zone rather than the riskier intraforaminal zone. Then, a full-scale foraminal decompression can be performed using a burr and punches under endoscopic control.

RESULTS:

The mean age of the 18 female and 15 male patients was 64.2 years. The mean visual analog scale score for leg pain improved from 8.36 at baseline to 3.36 at 6 weeks, 2.03 at 1 year, and 1.97 at 2 years post-surgery (P < .001). The mean Oswestry Disability Index improved from 65.8 at baseline to 31.6 at 6 weeks, 19.7 at 1 year, and 19.3 at 2 years post-surgery (P < .001). Based on the modified MacNab criteria, excellent or good results were obtained in 81.8% of the patients, and symptomatic improvements were obtained in 93.9%.

CONCLUSION:

Percutaneous ELF under local anesthesia could be an efficacious surgical procedure for the treatment of foraminal stenosis. This procedure may offer safe and reproducible results, especially for elderly or medically compromised patients.

ABBREVIATIONS:

ELF,endoscopic lumbar foraminotomy

ODI, Oswestry Disability Index

VAS, visual analog scale

Percutaneous endoscopic decompression for lumbar spinal stenosis

Percutaneous endoscopic lumbar discectomy has become a representative minimally invasive spine surgery for lumbar disc herniation. Due to the remarkable evolution in the techniques available, the paradigm of spinal endoscopy is shifting from treatments of soft disc herniation to those of lumbar spinal stenosis. Lumbar spinal stenosis can be classified into three categories according to pathological zone as follows: central stenosis, lateral recess stenosis and foraminal stenosis. Moreover, percutaneous endoscopic decompression (PED) techniques may vary according to the type of lumbar stenosis, including interlaminar PED, transforaminal PED and endoscopic lumbar foraminotomy. However, these techniques are continuously evolving. In the near future, PED for lumbar stenosis may be an efficient alternative to conventional open lumbar decompression surgery.

Extraforaminal compression of the L-5 nerve root at the lumbosacral junction: clinical analysis, decompression technique, and outcome

OBJECT

Extraforaminal compression of the L-5 nerve encompasses multiple pathological entities and may result from disc herniations as well as bony (osteophytes or sacral ala) or ligamentous (sacroiliac ligament and lumbosacral band) compression. Several other factors, such as disc space collapse or coronal wedging, can also contribute to narrowing of the extraforaminal space. The extraforaminal space at L5-S1 has unique anatomical features compared with the upper lumbar levels, which makes surgical access to this region difficult. Minimally invasive techniques offer easier access to the region. The purpose of this study was to analyze the contributing factors for extraforaminal compression of the L-5 nerve and assess clinical outcome following surgical decompression.

METHODS

Fifty-two consecutive patients who underwent a minimally invasive far-lateral approach for extraforaminal compression of the L-5 nerve were retrospectively analyzed for clinical data, outcomes, and imaging features (type of disc prolapse, coronal wedging, degree of disc and facet degeneration, facet tropism, foraminal stenosis, osteophytes, and adjacent-level disease). The authors describe the surgical technique used in this study.

RESULTS

The mean age of the patient sample was 57 years. Sixteen patients each had an extraforaminal ruptured disc or contained protrusion, and the remaining 20 patients had disc protrusions extending into the foraminal region or the lateral recess. Associated foraminal stenosis was found in 38.5%, and adjacent-level stenosis was noted in 22 cases (42.3%) and spondylolisthesis in 4 (7.7%). Osteophytes were noted in 18 cases. A coronal wedging angle ≥ 3° was found in 46.2%, and the laterality of wedging corresponded to the symptomatic side in 91% of cases. Fifteen patients (28.8%) complained of postoperative dysesthesias, which completely resolved in all cases within 6 months. The incidence of dysesthesias was more common in the ruptured disc group. There were no differences in clinical outcome among the different types of disc prolapses. The mean preoperative and postoperative visual analog scale scores were 7.6 and 3.6, respectively. The mean preoperative and postoperative Japanese Orthopaedic Association (JOA) scores were 6.4 and 13.8, respectively. The mean JOA recovery rate was 86.1%. According to the Macnab functional grading system, 96% of the patients had excellent or good grades at follow-up.

CONCLUSIONS

A minimally invasive far-lateral approach to L5-S1 requires a good understanding of the regional anatomy and can provide good to excellent clinical results in properly selected cases. This approach is effective in decompressing the far-lateral and foraminal zones. Adequate preoperative diagnosis and tailoring the surgical procedure to address the relevant compressive element in each case is essential to achieving good clinical results.

The Comparisons of Surgical Outcomes and Clinical Characteristics between the Far Lateral Lumbar Disc Herniations and the Paramedian Lumbar Disc Herniations

Objective

The purpose of this study is to analyze clinical characteristics and surgical outcomes of the far lateral and the paramedian disc herniations.

Methods

The 88 patients who underwent an operation for lumbar disc herniations were reviewed. Visual analogue scale of leg and back pain, occurrence of sensory dysesthesia and motor deficit before and after operations were used to compare the far lateral with the paramedian disc herniations.

Results

Statistically, the far lateral herniations had more severe radicular leg pain and showed more frequent occurrence of sensory dysesthesia than paramedian herniations before operation (p<0.05). In the far lateral herniation group, preoperatively, 15 patients (75%) had sensory dysesthesia and among them, 4 patients (27%) showed improvement. In the paramedian herniation group, preoperatively, 25 patients (37%) had sensory dysesthesia and among them, 21 patients (84%) showed improvement. The degree of improvement in sensory dysesthesia was statistically higher in paramedian herniation group (p<0.05). In the far lateral herniation group, preoperatively, 11 patients (55%) had motor deficit and among them, 10 patients (91%) showed improvement. In the paramedian herniations, preoperatively, 29 patients (43%) had motor deficit and among them, 25 patients (86%) showed improvement. The degree of improvement in motor deficit was not statistically significant between groups (p>0.05).

Conclusion

Preoperatively, the far lateral herniations had more severe radicular leg pain and frequent occurrence of sensory dysesthesia. Postoperatively, the sensory dysesthesia was less improved and back pain was more severe in the far lateral herniations.

Factors affecting dynamic foraminal stenosis in the lumbar spine

BACKGROUND CONTEXT

Lumbar foraminal stenosis is a common clinical problem and a significant cause of lower extremity radiculopathy. Minimal in vivo data exists quantifying changes in foraminal area (FA) as the spine moves from flexion to extension in the lumbar spine or on the relationship between FA and lumbar segmental angular motion, translational motion (TM), or disc bulge migration.

PURPOSE

To use kinetic magnetic resonance imaging (kMRI) to evaluate changes in dimensions of lumbar neural foramina during weight bearing in neutral, flexion, and extension positions. To evaluate the relationship between foraminal stenosis and lumbar segmental angular motion, TM, and disc bulge migration.

STUDY DESIGN

A retrospective radiographic study.

PATIENT SAMPLE

Forty-five patients with a mean age of 44 years undergoing kMRI for symptoms of low back pain or radiculopathy.

OUTCOME MEASURES

Magnetic resonance imaging measurements of FA, angular motion, TM, and disc bulge migration.

METHODS

Kinetic magnetic resonance imaging of the lumbar spine was reviewed in 45 patients with low back pain or radiculopathy, and parasagittal images were evaluated for changes in neural foraminal dimensions in various degrees of motion with weight bearing. The changes in foraminal dimension were correlated to the amount of segmental angular motion, TM, and disc bulge migration at each level. Neural foramina were also assessed qualitatively by Wildermuth criteria. Only those foramina that were clearly visualized with well-defined anatomic boundaries in all three positions were taken into consideration. Patients with previous surgery, tumor, and scoliosis were excluded from the study.

RESULTS

There was a significant decrease in the FA from flexion to neutral (p<.05) at all levels except L5-S1 and from neutral to extension at all levels (p<.05). The average percent decrease in FA was 30.0% with the greatest decrease from flexion to extension occurring at L2-L3 (167-107 mm(2)) and the smallest change occurring at L5-S1 (135-106 mm(2)) (p<.05). The magnitude of change in FA increased as angular motion at a segment increased. The mean change in FA was 32.3 mm(2) when angular motion was less than 5° and was 75.16 mm(2) when angular motion exceeded 15°. The extent of disc bulging posteriorly in the neural foramen was also correlated with the reduction in the FA from flexion to extension, but TM had no effect.

CONCLUSIONS

Foraminal area decreased significantly in extension compared with flexion and neutral on MRI. Lumbar disc bulge migration and angular motion at each level contributed independently to the decrease in FA in extension, whereas TM had no effect on FA.

Clinical and radiological outcomes of microscopic partial pediculectomy for degenerative lumbar foraminal stenosis

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

To investigate the clinical outcomes of microscopic partial pediculectomy for degenerative lumbar craniocaudal foraminal stenosis, risk factors for postsurgical scoliosis progression, and feasibility of postsurgical pedicle screw insertion.

SUMMARY OF BACKGROUND DATA

Previous studies have evaluated surgical strategies for degenerative lumbar foraminal stenosis. Although less invasive decompression surgery is an option for surgical treatment, postsurgical instability and salvaging fusion surgery remain as problems. No analysis has focused on the radiological progression and feasibility of pedicle screw setting after pediculectomy.

METHODS

Microscopic partial pediculectomy by our original method was performed as a first-choice surgical treatment for lumbar radiculopathy due to degenerative craniocaudal foraminal stenosis. This study included 50 consecutive patients followed up for a minimum of 2 years. Clinical outcomes were evaluated with Japanese Orthopaedic Association (JOA) scores and a numerical rating scale. Radiological changes were obtained from standing radiographs. Foraminal height and the minimum pedicle diameter were measured by reconstructed images on multidetector row computed tomography.

RESULTS

The preoperative Japanese Orthopaedic Association score of 14.2 ± 4.2 significantly improved to 21.5 ± 6.2, and 60% of patients were satisfied. The numerical rating scale for lumbar back pain, leg pain, and leg numbness significantly improved. Nine patients (18%) showed lumbar Cobb angle progression of 5° or more within 2 years, and the risk factor for scoliosis progression was surgery at L3-L4 or L4-L5 by multivariate logistic regression analysis. Foraminal height was enlarged from 5.4 mm preoperatively to 8.9 mm postoperatively. The postoperative minimum pedicle diameter was 8.7 ± 1.6 (5.9-11.7) mm.

CONCLUSION

Microscopic lumbar partial pediculectomy provided satisfactory clinical outcomes, but early postsurgical scoliosis progression was likely to occur in patients who underwent the surgery at L3-L4 or L4-L5. Even if a second surgical procedure is needed, pedicle screws can be set on the resected pedicle.

LEVEL OF EVIDENCE

4.

Factores de riesgo para la recurrencia de hernia de disco lumbar

OBJETIVO: La recurrencia de hernia del disco lumbar es un padecimiento que implica algunas dificultades en relación con el diagnóstico y tratamiento. Es importante tratar de identificar los factores que puedan influir en la presentación de la recurrencia. MÉTODOS: Se revisaron los casos de pacientes operados por hernia de disco lumbar recurrente entre los años de 2006 y 2008, buscando identificar los factores que tuvieran relación con dicha patología, y también se revisaron los casos de pacientes operados por hernia de disco lumbar en forma primaria. RESULTADOS: Se analizaron los casos de 20 pacientes con hernia discal lumbar recurrente y de 27 con hernia discal lumbar operados en forma primaria. Para los pacientes con recurrencia, se encontró que el 95% de ellos presentaban algún grado de obesidad, determinado por la Fórmula de Quetelet basada en el Índice de Masa Corporal; se observó también que el 75% de los casos tenían protrusión, con resultados excelentes en 35%, y buenos en 55%, el 10% presentó molestias residuales de forma grave. Para los pacientes con hernia primaria se estudiaron 27 casos, en los que se observó que el 92% de ellos se operaron antes de los 6 meses de iniciado el cuadro, 38% tuvieron resultados excelentes, 40% buenos y el 19% malos resultados. Al estudiar las variables, con el índice de Pearson, se encontró relación de la recurrencia con tabaquismo, trabajo, diabetes e hipertensión, y nivel de estudios, no con la obesidad. CONCLUSIONES: es destacable que dos de los factores relacionados son susceptibles de modificación antes del evento quirúrgico o posteriormente a este, lo cual puede beneficiar el desenlace del mismo.

Ultra-long-term outcome of surgically treated far-lateral, extraforaminal lumbar disc herniations: a single-center series

PURPOSE

Far-lateral extraforaminal lumbar disc herniation is an uncommon cause of nerve root entrapment, and studies addressing the long-term outcome of surgically treated patients are few. The purpose of this study was to analyze the ultra-long-term outcome of patients who were treated via a lateral approach.

METHODS

The medical reports of 138 consecutive patients were analyzed with regard to signs and symptoms, operative findings, complications, and short-term outcome (6 weeks). To assess long-term results, standardized telephone interviews were performed using a structured questionnaire. The patients were questioned about pain using the verbal rating scale and persisting symptoms, if any. Other queries were related to the Oswestry Disability Index. Subjective satisfaction with the result of surgery was classified as excellent (no pain), good (some pain), fair (moderate pain), and poor (unchanged or worse) based on MacNab classification.

RESULTS

At short-term follow-up, major and moderate leg pain had decreased from 99.3 to 5.1% and low back pain from 97.8 to 2.8%. Sensory and motor deficits, however, were still present in the majority of patients. A total of 87 telephone interviews were conducted, and the mean follow-up was 146 months. As many as 49 patients (56.3%) reported complete relief of symptoms, 14 patients (16.1%) had minor ailments under physical stress, and 24 patients (27.6%) had permanent residual symptoms. The most common complaint was remaining sensory disturbance. Despite residual symptoms, the vast majority of patients expressed satisfaction with the result of surgery. The outcome was subjectively rated as follows: 75.9% excellent (66 patients), 18.4% good (16 patients), 4.6% fair (4 patients), and 1.1% poor (1 patient).

CONCLUSIONS

The lateral approach is a minimally invasive and safe procedure with low complication rates. The profit from surgery is maintained beyond the usual postoperative observation periods. Thus, ultimate outcome at ultra-long-term follow-up is very gratifying in the vast majority of patients.

Paraspinal-approach transforaminal lumbar interbody fusion for the treatment of lumbar foraminal stenosis

OBJECT

Foraminal stenosis is a common cause of lumbar radicular symptoms. Recognition of the dynamic pathology, as well as the static anatomical changes, is important to achieving successful surgical outcomes. Excessive facet and anulus removal leads to subsequent disc space narrowing and/or segmental instability, which can cause poor results after decompressive surgery. The objective of this study was to evaluate the efficacy of the paraspinal-approach transforaminal lumbar interbody fusion (TLIF) in the treatment of lumbar foraminal stenosis.

METHODS

Twenty levels of lumbar foraminal stenosis in 16 patients were treated using an instrumented paraspinal-approach TLIF. There were 12 single-level and 4 two-level cases. Pathologies included foraminal stenosis at 13 levels and lateral disc herniation with disc space narrowing at 7.

RESULTS

In all patients, preoperative radicular symptoms and mechanical low-back pain were resolved immediately after the operation and leg weakness improved gradually. The recovery rate using the Japanese Orthopaedic Association score was 89.1%. Bony union was achieved within 6 months after the operation in all cases. Postoperative MR imaging showed minimal changes in the paraspinal muscles in the single-level cases.

CONCLUSIONS

The paraspinal-approach TLIF is a minimally invasive, safe, and secure procedure for treating lumbar foraminal lesions. Direct visualization and decompression for the foraminal lesion, distraction of the collapsed disc space, and stabilization of the unstable segments can be achieved simultaneously through the paraspinal approach, which produces successful clinical and radiological results.

Clinical outcomes of microscopic decompression for degenerative lumbar foraminal stenosis: a comparison between patients with and without degenerative lumbar scoliosis

We performed microscopic lumbar foraminotomy in all the patients diagnosed with degenerative lumbar foraminal stenosis (DLFS) and retrospectively reviewed the clinical outcomes and the factors influencing them. The preoperative Japanese Orthopaedic Association (JOA) score of 13.8 significantly improved to 21.9 postoperatively. Although leg pain reduced in 44 patients (95.7%) immediately after surgery, it recurred in 9 patients (19.6%). The recurrence frequency was significantly higher and the JOA score improvement ratios significantly lower in patients with degenerative lumbar scoliosis (DLS) than in those without DLS. Even among patients with DLS, those with <3° Cobb angle difference between the supine and standing positions showed satisfactory results, with no recurrence. In conclusion, microscopic lumbar foraminotomy for DLFS produced satisfactory clinical outcomes even in patients with DLS. However, the outcomes were poor in patients with unstable DLS.

Microdecompression for extraforaminal L5-s1 disc herniation; the significance of concomitant foraminal disc herniation for postoperative leg pain

OBJECTIVE

To analyze the relationship of concomitant foraminal lumbar disc herniation (FLDH) with postoperative leg pain after microdecompression for extraforaminal lumbar disc herniation (EFLDH) at the L5-S1 level.

METHODS

Sixty-five patients who underwent microdecompression for symptomatic EFLDH at the L5-S1 level were enrolled. According to the severity of accompanying FLDH, EFLDH was classified into four categories (Class I : no FLDH; Class II : mild to moderate FLDH confined within a lateral foraminal zone; Class III : severe FLDH extending to a medial foraminal zone; Class IV : Class III with intracanalicular disc herniation). The incidence of postoperative leg pain, dysesthesia, analgesic medication, epidural block, and requirement for revision surgery due to leg pain were evaluated and compared at three months after initial surgery.

RESULTS

The incidences of postoperative leg pain and dysesthesia were 36.9% and 26.1%, respectively. Pain medication and epidural block was performed on 40% and 41.5%, respectively. Revision surgery was recommended in six patients (9.2%) due to persistent leg pain. The incidences of leg pain, dysesthesia, and requirement for epidural block were higher in Class III/IV, compared with Class I/II. The incidence of requirement for analgesic medication was significantly higher in Class III/IV, compared with Class I/II (p=0.02, odds ratio=9.82). All patients who required revision surgery due to persistent leg pain were included in Class III/IV.

CONCLUSION

Concomitant FLDH seems related to postoperative residual leg pain after microdecompression for EFLDH at the L5-S1 level.

The effect of removing the lateral part of the pars interarticularis on stress distribution at the neural arch in lumbar foraminal microdecompression at L3-L4 and L4-L5: anatomic and finite element investigations

STUDY DESIGN

The assessment of L3 and L4 pars interarticularis thickness and finite element analysis of stress distribution across L3 and L4 pars interarticularis.

OBJECTIVE

To quantify the morphology of the region of the L3 and L4 pars interarticularis and to assess the stress increase as a function of access size using the finite element lumbar spine model.

SUMMARY OF BACKGROUND DATA

Inadequate decompression and traction of the nerve structures are several causes of the unsatisfactory outcomes in patients after foraminal stenosis decompression and far lateral disc herniation removal by extraforaminal exposure. Enlarging the access of the foraminal exposure by the removal of the lateral aspect of the pars interarticularis may be able to diminish the inadequate decompression and traction of the nerve structures; however, it may lead to increase stress and fracture of the neural arch.

METHODS

We used 15 human cadaver L3 and L4 lumbar vertebrae for measuring the thickness of the pars interarticularis. The ventral and dorsal surfaces were subdivided into 4 equal parts, and the thickness of each part was measured using a digital caliper. An experimentally validated 3-dimensional nonlinear finite element model of the intact L3-S1 segment was used to simulate the lateral removal of one fourth and one half of the L3 and L4 pars interarticularis.

RESULTS

The mean thicknesses of the pars interarticularis showed a gradual increase toward the lateral edge. Finite element model analyses predicted stresses increased to 35% and 40% after removal of one half of the lateral part of the L3 and L4 pars interarticularis, respectively, and were much closer to the intact spine after removal of one fourth of the lateral part of the pars interarticularis.

CONCLUSION

The removal of one fourth of the lateral aspect of the pars interarticularis has minimal influence on the stresses in the remaining L3 and L4 neural arches. The lateral half of the pars has the largest thickness, and its removal leads to considerable stress increases.