A posterolateral microsurgical approach to extreme-lateral lumbar disc herniation

Beyond traditional surgery for far lateral lumbar herniation: transforaminal full endoscopic discectomy

INTRODUCTION

This study aimed to evaluate the clinical outcomes of transforaminal full-endoscopic lumbar discectomy (FELD) for treating lateral lumbar disc herniation.

METHODS

A retrospective single-center study was conducted at Centre Orthopédique Santy, Lyon, France, including 58 adult patients with foraminal or extraforaminal lumbar disc herniations who underwent surgery between October 2020 and January 2023. Inclusion criteria were patients with significant functional impairment due to unilateral radicular pain unresponsive to conservative treatment for over six weeks. Data on demographics, clinical characteristics, and outcomes were collected, evaluated preoperatively and at 12 months postoperatively using Visual Analog Scale (VAS) for pain, Oswestry Disability Index (ODI), and Macnab criteria.

RESULTS

The cohort had a mean age of 56.5 years and consisted predominantly of males, with 35 men (60%). Most herniations were at the L4-L5 level (29 patients, 50%). Significant improvements were observed in lumbar VAS (mean reduction of 1.9 points, p < 0.001), radicular VAS (mean reduction of 4.9 points, p < 0.001), and ODI (mean reduction of 41.9 points, p < 0.001) scores. Patient satisfaction was high, with 91% (53 patients) reporting excellent or good outcomes. The reoperation rate was 6.9% (4 patients). Linear regression analysis indicated that longer symptom duration and higher preoperative radicular VAS scores predicted greater satisfaction.

CONCLUSIONS

Transforaminal FELD is a safe and effective technique for treating lateral lumbar disc herniation, offering high patient satisfaction. Symptom duration and preoperative radicular VAS scores are key predictors of positive outcomes. Further studies with larger sample sizes and longer follow-up periods are necessary to confirm these findings.

Comparative Analysis on Surgical Operability and Degree of Exposure of Microsurgical Approaches to Intraforaminal Lumbar Disk Herniations

BACKGROUND

 Intraforaminal lumbar disk herniations (IFDHs) represent a heterogeneous and relatively uncommon disease; their treatment is technically demanding due to the anatomical relationships with nerve roots and vertebral joints. Over time, several approaches have been developed without reaching a consensus about the best treatment strategy.

MATERIALS AND METHODS

 Authors comparatively analyze surgical operability and exposure in terms of quantitative variables between the different microsurgical approaches to IFDHs, defining the impact of each approach on surgical maneuverability and exposure on specific targets.A comparative microanatomical laboratory investigation was conducted. The operability score (OS) was applied for quantitative analysis of surgical operability.

RESULTS

 Transarticular and combined translaminar-trans-pars-interarticularis approaches result in providing the best surgical exposure and maneuverability on all targets with surgical controls on both nerve roots, at the expense of a higher risk of iatrogenic instability. Trans-pars-interarticularis approach reaches comparable levels of operability, even limited to the pure foraminal area (lateral compartment); similar findings were recorded for partial facetectomy on the medial compartment. The contralateral interlaminar approach provides good visualization of the foramen without consensual favorable maneuverability, which should be considered the main drawback.

CONCLUSIONS

 Approach selection has to consider disease location, the possible migration of disk fragments, the degree of nerve root involvement, and risk of iatrogenic instability. According to the findings, authors propose an operative algorithm to tailor the surgical strategy, based both on the precise definition of anatomic boundaries of exposure of each approach and on surgical maneuverability on specific targets.

Long-term follow-up results of surgically treated patients with foraminal and far lateral disc herniations

PURPOSE

Foraminal and far lateral disc herniations are rarer cause of nerve root compression. There are reports regarding the outcome, however long-term follow-up results of surgically treated patients are few. The purpose of this retrospective study is to analyze the clinical characteristics and long-term surgical outcomes of the foraminal and far lateral disc herniations.

MATERIALS AND METHODS

The 114 patients who underwent an operation for foraminal and far lateral disc herniaitions were reviewed. Visual analogue scale of back and leg pain, the ocurrence of motor deficit and sensory dysesthesia before and after operations were used to compare the results of early and long-term outcome.

RESULTS

A total of 114 telephone interviews were conducted. The mean follow up was 134 months. Complete relief of symptoms were reported by 77 patients (67.1%). The average VAS of radicular leg pain was 7.5 Post-operatively the average VAS of radicular pain decreased to 2.2. Preoperatively, 9 patients (7.6%) had motor deficit and 17 (14.4%) patients had sensory dysesthesia. Post-operatively 9 (100%) of the patients showed motor, and 12 (70.6%) of the patients showed sensory improvement. In 17 patients with hypoesthesia the complaints continued during 2 weeks to 6 months. They were given gabapentin as medical treatment, however 5 of these patients still have sensory dysesthesia. The outcome was: 67.1% excellent (77 patients), 26.3% good (30 patients), 6.1% fair (7 patients).

CONCLUSION

The far lateral approach is a minimally invasive and safe procedure with low complication rates.

Extreme lateral and interlaminar approach for intra-canal and foraminal double disc herniation at lumbosacral level

INTRODUCTION AND OBJECTIVES

There are several approaches for double disc herniation consisting of an intracanal and foraminal lesion. Of several approaches, we introduced extreme lateral and interlaminar approach (ELIA). And we aimed to compare the approach with the conventional combined interlaminar and paraisthmic approach (CIPA).

PATIENTS AND METHODS

The authors reviewed the medical charts of patients who underwent a procedure for a double disc herniation at the lumbosacral level between March 2012 and February 2016 and patients who underwent CIPA or ELIA were selected. For preoperative testing, simple X-ray, computed tomography (CT), and magnetic resonance imaging (MRI) scans were performed. For postoperative outcomes, the Korean version of the Oswestry Disability Index (K-ODI) and Numeric Rating Scale (NRS) at one, two, and three months post-operation were checked.

RESULTS

Eleven patients were given ELIA and twenty-four patients were involved in CIPA. The mean pre K-ODI was 34.1 (±13.9) and 32.4 (±4.0) at each group. 1st, 2nd and 3rd month post-operative K-ODI was 8.2 (±4.1), 6.4 (±2.1) and 5.3 (±2.4) in ELIA and 8.1 (±3.2), 7.1 (±3.5) and 8.4 (±6.4) in CIPA. Post-operative 3rd month K-ODI showed significant difference between two groups (p: 0.005). The mean pre NRS was 8 (±0.9) and 8.6 (±1.0). 1st, 2nd and 3rd month post-operative NRS was 2.4 (±1.5), 2.2 (±1.5) and 2.0 (±0.9) in ELIA and 3.3 (±1.4), 3.3 (±1.6) and 3.7 (±1.9). Post-operative 3rd month NRS showed significant difference between two groups as well (p: 0.001). There were four (19.0%) recurrence cases in CIPA patients group, otherwise there was no recurrence case in ELIA group.

CONCLUSIONS

In the treatment of L5-S1 double disc herniation, the ELIA surgical approach showed better outcomes than the CIPA surgical approach did with respect to pain and K-ODI during a mid-term follow-up examination conducted three months post-operation.

A Posterior Oblique Approach to the Lumbar Disk Spaces, Vertebral Bodies, and Lumbar Plexus: A Cadaveric Feasibility Study

STUDY DESIGN

A laboratory cadaveric study.

OBJECTIVE

We aimed to demonstrate the feasibility of a posterior oblique approach, sharing the same advantages as the transpsoas technique while minimizing the risk of lumbar plexus or psoas muscle injuries.

SUMMARY OF BACKGROUND DATA

The transpsoas approach for interbody fusion and corpectomy offers advantages over posterior and anterior approaches. However, possible risks include traumatization of the psoas muscle or lumbar plexus.

METHODS

All lumbar disk spaces and vertebral bodies were exposed by a posterior oblique approach from left and right on a human cadaveric specimen. The exposure obtained and a step-by-step documentation of the procedure is outlined in detail.

RESULTS

We were able to achieve wide exposure of all lumbar disk spaces and vertebral bodies above the L5/S1 disk space. Only the psoas muscle was retracted, and the lumbar plexus nerves were easily visualized and gently retracted. Sharp dissection was only required around the tip of the transverse processes.

CONCLUSIONS

A posterior oblique approach seems to be less invasive than the transpsoas approach. Exposure of the anterior column structures above the iliac crest is comparable. The oblique approach offers direct access to the lumbar plexus and the extraforaminal segments of the nerve roots.

Surgical treatment of intraforaminal/extraforaminal lumbar disc herniations: Many approaches for few surgical routes

BACKGROUND

Several disc disease nomenclatures and approaches for LDH exist. The traditional midline bone-destructive procedures together with approaches requiring extreme muscular retraction are being replaced by muscle sparing, targeted, stability-preserving surgical routes. The increasing speculation on LDHs and the innovative corridors described to treat them have lead to an extensive production of papers frequently treating the same topic but adopting different terminologies and reporting contradictory results.

METHODS

The review of such literature somehow confounding gave us the chance to regroup by surgical corridors the vast amount of approaches for LDH differently renamed over time. Likewise, LDHs were simplified in intra-foraminal (ILDH), extra-foraminal (ELDH), and intra-/extra-foraminal (IELDH) in relation to precise anatomical boundaries and extent of bulging disc.

RESULTS

Through the analysis of the papers, it was possible to identify ideal surgical corridors for ILDHs, ELDHs, and IELDHs, distinguishing for each approach the exposure provided and the technical advantages/disadvantages in terms of muscle trauma, biomechanical stability, and nerve root preservation. A significant disproportion was noted between studies discussing traditional midline approaches or variants of the posterolateral route and those investigating pros and cons of simple or combined alternative corridors. Although rarely discussed, these latter represent valuable strategies particularly for the challenging IELDHs, thanks to the optimal compromise between herniation exposure and bone-muscle preservation.

CONCLUSIONS

The integration of adequate mastery of traditional approaches together with a greater confidence through unfamiliar surgical corridors can improve the development of combined mini-invasive procedures, which seem promising for future targeted LDH excisions.

Transpars Microscopic Approach for the Treatment of Purely Foraminal Herniated Lumbar Disc: A Clinical, Radiological, Two-center Study

STUDY DESIGN

This is a prospective two-center study.

OBJECTIVE

The aim of this study was to assess the safety and efficacy of treating patients with lumbar foraminal disc herniations via a microscopic transpars approach, with a clinical and radiological follow-up evaluation.

SUMMARY OF BACKGROUND DATA

Purely foraminal lumbar disc herniations comprise about 5% of all lumbar herniated intervertebral discs. Operative management can be technically difficult, and the optimum surgical treatment remains controversial.

METHODS

From January 2012 to January 2015, 47 patients were prospectively recruited. Patients were followed-up as outpatients at 1 week after discharge, then at 1, 6, and 12 months.A clinical multiparametric evaluation of patients including numeric rating scale (NRS), drugs intake, Macnab criteria, and working days lost was used.Postoperative dynamic x-rays (flexion, extension) were performed in all cases 12 months after surgery.

RESULTS

No surgery-related complications occurred.Among the 35 patients who were not retired at the time of the study, 29 patients returned to work and to normal daily activities within 60 days after surgery.Pain evaluation at discharge showed a significant improvement of NRS score, from 8.93 to 1.45 at 12 months. Root palsy significantly improved in all cases already at 1-month follow-up. Drugs intake analysis showed that at 6-month follow-up, no patients used steroids, or opioids, 17 patients used non-steroidal anti-inflammatory drugs when needed, and 29 patients (61.7%) used no drugs for pain relief. No significant variations occurred at 12-month-follow-up.At 12-month follow-up, excellent or good outcome (following Macnab criteria) was achieved in 36 (76.6%) and 8 (17%) patients, respectively.There were no cases of spinal instability at 12-month radiological evaluation.No recurrence occurred at follow-up.

CONCLUSION

Transpars microscopic approach is effective and safe for the treatment of FLDH, but larger studies are needed.

LEVEL OF EVIDENCE

3.

Three-Years Outcome of Microdiscectomy via Paramedian Approach for Lumbar Foraminal or Extraforaminal Disc Herniations in Elderly Patients over 65 Years Old

OBJECTIVE

Lumbar foraminal or extraforaminal disc herniations (FEFDH) have unusual clinical features and higher incidence in elderly patients compared to usual intraspinal canal disc herniations. We evaluated the efficacy of microdiscectomy via paramedian approach for lumbar FEFDH in elderly patients over the age of 65.

METHODS

Retrospective study was performed in 68 patients over the age of 65 (23 male and 45 female patients; 71.46±3.87 years) who underwent microdiscectomy via paramedian approach for unilateral lumbar FEFDH causing sciatica. The radiological factors including degree of slippage, presence of instability, disc height, and degree of disc degeneration; pain and functional status by the means of visual analogue scale score, Oswestry Disability Index score, and Macnab classification were analyzed preoperatively and during the postoperative follow-up period of 3 years to evaluate the efficacy of the surgical treatment.

RESULTS

Pain and functional status improved according to short- and long-term follow-up evaluations after surgery. Radiological changes following surgery, which can be understood as structural deteriorations and deformations, did not represent patient condition. Nine patients underwent additional surgery due to sustained or recurring leg pain of aggravation of back pain, and fusion surgery was required for 3 patients. Degree of preoperative slippage was the only statistically significant factor related to additional surgery (p<0.05).

CONCLUSION

Microdiscectomy via paramedian approach for FEFDH may be a good surgical alternative in elderly patients. Radiological changes after surgery did not show a concordance with patients' actual functional status. The excessive preoperative slippage tended to lead to unfavorable result after surgery and was associated with additional surgery.

Combined Interlaminar and Paraisthmic Approach for Co-existing Intracanal and Foraminal Lesion

Objective

Stenosis or herniated nucleus pulposus (HNP) occupying lumbar intracanal and foraminal area is an important cause of double radicular symptoms. Using the combined interlaminar and paraisthmic approach, we performed decompression surgery in patients with co-existing intracanal and foraminal lesions. The objective of this study is to describe usefulness and outcome of combined interlaminar and paraisthmic approach surgery and to analysis the cause of poor outcome.

Methods

Between Apr 2009 and Apr 2014, 78 patients (42 males and 36 females) with intracanal and foraminal lesions were enrolled in this study. Patients with a vacuum disc, spondylolisthesis, instability or an isthmic defect on the preoperative dynamic view radiograph were excluded from this study. All patients underwent surgery through a combined approach for discectomy and decompression. The outcome of surgery was evaluated and classified into excellent, good, fair and poor.

Results

The results were excellent in 53 patients, good in 9, fair in 6 and poor in 10 during the follow-up. The outcome of the combined approach was excellent to fair in 87% (68 of 78) patients in our study. In the poor outcome group, three patients complained of early-onset relapsed pain (<1 month) and another seven patients complained of delayed-onset pain (>3 months).

Conclusion

Combined approach for both intracanal and foraminal area lesions may be useful if selectively performed on patients whose facet joint is relatively intact, and that it is worthy of consideration as an alternative to fusion surgery; however, further studies are needed.

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.

Percutaneous endoscopic treatment of foraminal and extraforaminal disc herniation at the L5-S1 level

BACKGROUND

Microsurgery of foraminal and extraforaminal disc herniation at the L5-S1 level remains a challenge because of the limited access by a high iliac crest, the sacral ala, large transverse processes of L5 and hidden disc fragments lateral to the zygapophyseal joint. Our aim was to present the outcome of percutaneous endoscopic lumbar discectomy (PELD) of these lateral and far lateral disc herniations at the L5-S1 level using the newly described foraminal retreat technique in a group of patients with similar preoperative diagnostic studies.

METHODS

A total of 22 patients, 13 males and 9 females, with foraminal and extraforaminal lumbar disc herniation at the L5-S1 level were treated by applying the PELD between September 2004 and April 2010. The clinical findings and MRI were the main diagnostic methods. Preoperative evaluation was performed with clinical examinations, the Visual Analog Pain Scale (VAS) and Oswestry Low Back Disability Index (ODI).

FINDINGS

According to the Macnab criteria, overall excellent or good outcomes were obtained in 18 patients (81.8 %), fair outcomes in 3 patients (13.6 %) and a poor outcome in 1 patient (4.5 %) at the last follow-up. The mean ODI was 67.3 ± 19.4 preoperatively and 26.7 ± 23.4 postoperatively. Preoperative VAS was 88.6 ± 7.6 and 28.6 ± 22.8 at 2 days, 40.5 ± 22.8 at 3 weeks, 34.3 ± 25.1 at 6-months and 32 at the last follow-up. At follow-up, two patients (9.1 %) had recurrent disc herniations that were corrected with open surgery. At the time of surgery, 16 patients held jobs. Fifteen (15) patients (93.8 %) returned to their original jobs postoperatively; one patient could not return to his original job postoperatively because of a comorbidity.

CONCLUSIONS

Percutaneous endoscopic discectomy using the foraminal retreat technique is an effective treatment method for patients with foraminal and extraforaminal disc herniations at the L5-S1 level on appropriately selected patients.

Extreme lateral lumbar disc herniation in a 12-year child: case report and review of the literature

Extreme lateral lumbar disc herniations (ELLDHs) occur more frequently among elderly patients, with a peak incidence in the sixth decade, and are rarely found in children. The patient presented is a 12-year-old boy with a 3-month history of right-sided leg pain. Computerized tomography and magnetic resonance imaging demonstrated an extreme lateral disc herniation on the right at L4-L5 with compression of the L4 nerve root. He subsequently underwent removal of extreme lateral herniated disc through an intertransverse approach under general anesthesia. At 11-month follow-up, the patient maintained resolution of preoperative symptoms and a neurological examination revealed no sensory or motor deficit. Surgical intervention may be indicated for patients with ELLDHs that fail with conservative treatment.

Minimally invasive strategies and options for far-lateral lumbar disc herniation

OBJECTIVE

To investigate the surgical procedures, options and surgical indications for far-lateral lumbar disc herniation between three different minimally invasive procedures.

METHODS

From January 2000 to October 2006, 52 patients with far-lateral lumbar disc herniation (29 males and 23 females, with the average age of 41.5 years) were treated with minimally invasive procedures. All the patients were assessed by X-ray and CT. Some were given additional myeography, discography, Computerized tomography mye-lography (CTM) and MRI examination. Yeung Endoscopy Spine System (YESS), METRx and X-tube procedures were performed in 25, 13 and 14 cases, respectively. All patients were followed up for a mean period of 13.5 months. Clinical outcomes were assessed by visual analog score (VAS) and Nakai criteria.

RESULTS

The results indicated that the three procedures could significantly improve the radiating leg symptoms (P less than 0.05). The postoperative overall excellent and good rates of YESS, METRx and X-tube procedures were 84.0%, 84.6% and 92.8% respectively, with no statistical difference among three groups (P larger than 0.05). The YESS procedure had several advantages including shortest operation time, simplest anesthesia and least trauma as compared with the other two procedures, especially for simple type I far-lateral lumbar disc herniation. METRx procedure was specially suitable for simple type II. And the procedure of posterior endoscopic facetectomy, posterior lumbar interbody fusion and unilateral pedicle screw instrumentation with X-tube was designed for far-lateral disc herniation combined with degenerative lumbar instability.

CONCLUSION

Minimally invasive strategies and options should be determined by different types of far-lateral lumbar disc herniation.

[Minimally invasive transmuscular approach for the treatment of lumbar far lateral disc herniation]

BACKGROUND

The purpose of this study was to evaluate a minimally invasive surgical technique for the treatment of lumbar far lateral disc herniation. This technique combines the tubular retractor with the operative microscope.

OBJECTIVE AND METHODS

This retrospective study analyzed the files of 26 patients: 15 men and 11 women. The average age was 56 years (range, 19-83 years). The most commonly operated level was L3-L4 (46%), then L4-L5 (30.5%) and finally L2-L3 (15.5%). All patients were operated under general anesthesia. The intraoperative radioscopic location was absolutely necessary. A 12-15 mm paramedian incision was made on the side of the herniation (30 mm from the medial line). We then inserted the tubular muscular retraction system followed by the 14 mm diameter working channel. Guided by operating microscope, the articular isthmus was reamed to expose the root and the disc. The disc herniation was then removed after opening and removing the inter-transverse ligament.

RESULTS

The average duration of the surgery was 55 min. This operating time decreased as the surgeons gained experience. The radicular pain, estimated using the analogical visual scale, varied from seven before surgery to two during the postoperative period. All the patients were standing up the day after surgery. The average duration of the postoperative stay in the hospital was three days (range, 1-5 days). We noted no complications from the surgical procedure. The average duration of the follow-up was two years (range, 6-36 months).

CONCLUSION

This technique combines the advantages of endoscopic surgery (less muscular and osseous damage) and microscope-guided surgery (three-dimensional vision) and provided good functional results in this series.

A minimally invasive technique for L5–S1 intraforaminal disc herniations: microdiscectomy with a tubular retractor via a contralateral approach

✓ Surgical treatment of intraforaminal disc herniations at the L5–S1 level is technically demanding. The 2 most commonly used procedures involve either a medial or lateral ipsilateral approach and often require a partial or even complete facet resection, which may in turn result in vertebral instability and/or back pain, as well as, in some cases, a fusion or stabilization procedure. In this report, the authors present a new minimally invasive technique for the treatment of L5–S1 intraforaminal disc herniations. Using this technique, which involves tubular retractors and an operative microscope to approach the neural foramen from the contralateral side, the authors could easily visualize and remove the herniated disc material and perform a thorough microdiscectomy with minimal resection of osseous and ligamentous structures. To illustrate this new minimally invasive technique for the treatment of intraforaminal disc herniations at L5–S1, they describe the cases of 2 patients who underwent the procedure and in whom successful results were achieved.

Minimally invasive far lateral microendoscopic discectomy for extraforaminal disc herniation at the lumbosacral junction: cadaveric dissection and technical case report

BACKGROUND CONTEXT

Extraforaminal lumbar disc herniations (ELDHs) at the lumbosacral junction are an uncommon cause of L5 radiculopathy. The surgical anatomy of the extraforaminal space at L5-S1 is uniquely challenging for the various open surgical approaches that have been described for ELDHs in general. Reports specifically describing minimally invasive surgical approaches to lumbosacral ELDHs are lacking.

PURPOSE

To report the novel use of a far lateral microendoscopic (FLMED) approach to lumbosacral ELDH. To better define the unique anatomical features of extraforaminal approaches to the lumbosacral junction as they apply to minimal access techniques.

STUDY DESIGN/SETTING

A cadaveric investigation and clinical case were performed at a single institution. A thorough review of the literature was conducted.

PATIENT SAMPLE

A single patient with an extraforaminal disc herniation at the lumbosacral junction underwent evaluation and surgery.

OUTCOME MEASURES

The patient's self-reported pain levels were documented. Physiologic outcome was judged on pre- and postoperative motor and sensory examinations. Functional capacity was assessed by work status and ability to perform activities of daily living.

METHODS

FLMED was performed in two fresh human cadavers at the lumbosacral junction. Qualitative assessments of the surgical anatomy were made, and intraoperative fluoroscopy and endoscopic photographs were obtained to document the findings. A patient with refractory pain and sensorimotor deficits from compression of the L5 nerve root by an ELDH underwent FLMED. The literature was carefully reviewed for the epidemiology of ELDHs at the lumbosacral junction and the surgical techniques used to treat them.

RESULTS

The posterolateral surgical corridor to the lumbosacral disc was consistently constrained by the sacral ala and to a lesser extent the lateral facet and L5 transverse process. Resection of the superior ala exposed the exiting nerve root and provided ample access to the disc. In the clinical case, the patient enjoyed immediate pain relief, was discharged in 3 hours, and returned to full work and social activities. Follow-up neurological examination revealed no sensory or motor deficit.

CONCLUSIONS

FLMED offers a safe and efficacious approach to ELDHs at the lumbosacral junction by combining satisfactory visualization for adequate resection of the sacral ala with the benefits of reduced tissue injury and faster recovery times that accompany minimally invasive techniques.

A minimally invasive transmuscular approach to far-lateral L5-S1 level disc herniations: a prospective study

BACKGROUND

Among all lumbar disc herniations, L5-S1 far-lateral disc herniations are rare entities. Besides, surgical approach may be difficult because of the very narrow passage at this level. For these 2 reasons, most spine surgeons are not experienced in herniations at this level. According to new microanatomic studies, previous lateral approaches at this level often do not allow access to the neuroforamen without partial or total destruction of the L5-S1 facet joint. To preserve the facet joint, an approach was developed.

PURPOSE

To assess the efficacy of a surgical technique that is a minimally invasive intermuscular approach (MIIMA) for decompression of L5-S1 far-lateral level disc herniation (FLLDH).

STUDY DESIGN

We present a prospective clinical study analysis of 14 patients with L5-S1 far-lateral disc herniations in a period between 2000 and 2004, treated with microsurgical technique.

METHODS

An imaging study revealed consistency with the patient's clinical presentation. In our department, a total of 580 patients underwent discectomy between 2000 and 2004 for lumbar disc herniation.

RESULT

Twenty-eight patients had foraminal or extraforaminal herniations (4.8%). Fourteen patients had FLLDH at the L4-L5 level (2.4%), whereas the other 14 were cases of FLLDH at the L5-S1 level (2.4%). One patient had FLLDH at both L5-S1 and L4-L5 levels (7.1%). The mean age of patients was 53.6 years, and the male:female ratio was approximately 5:9. All patients failed to recover after at least 6 weeks of conservative therapy. The mean duration of symptoms until the time of surgery was 7.2 months. Using this MIIMA technique, the authors removed the herniated discs compressing the (L5) nerve roots. Clinical outcome was measured using the visual analog scale. Every patient was discharged within 24 hours. Satisfactory (excellent or good) results were demonstrated in 13 patients (92.9%), because, except for 1 (7.1) permanent dysesthesia case, 4 cases (21.3%) were temporary dysesthesia. Postoperatively all patients reported excellent relief of their sciatic pains, and there were no technique-associated complications. No recurrence was observed during the follow-up period ranging from 10 to 60 months (mean, 29 mo). This is one of the major complications of any approach to a far-lateral disc.

CONCLUSIONS

The authors describe a MIIMA for excising herniated discs that is applicable to all types of far-lateral lumbar herniations. Postoperative dysesthesia is the most important complication and may persist as it did in our cases. Consequently, manipulation of the ganglion should be avoided at all costs, if possible. The MIIMA procedure provides a simple alternative for treating lumbar foraminal or lateral exit zone herniated discs in selected cases. This approach is effective, allowing the preservation of the L5-S1 facet joint, saving the facet joint, preventing postoperative instability, and offering a direct view of the L5-S1 neuroforamen.

Translaminar microsurgical approach for lumbar herniated nucleus pulposus (HNP) in the "hidden zone": clinical and radiologic results in a series of 24 patients

STUDY DESIGN

Clinical series.

OBJECTIVE

To describe an alternative surgical approach for disc herniations in the "hidden zone."

SUMMARY OF BACKGROUND DATA

Many spine surgeons have suggested different surgical approaches for symptomatic preforaminal and foraminal disc herniations. However, almost every surgical approach has certain shortcomings when it comes to exposing the "hidden zone" without causing some degree of spinal instability.

METHODS

Twenty-four patients with preforaminal and foraminal disc herniation underwent surgical treatment via a translaminar microsurgical approach. RESULTS.: Excellent results were obtained in all patients in terms of pain relief, and all had improvement in motor strength except for 1 patient. No spinal instability was seen at the latest follow-up.

CONCLUSIONS

A classic interlaminar interspace approach combined with a very limited translaminar fenestration seem to be an acceptable surgical method for accessing a preforaminal disc herniation, and this technique has proven to be safe and did not cause any instability at the latest follow-up.

Vascular injury and complication in neurosurgical spine surgery

Vascular injury is an uncommon, but not rare complication of spine surgery. The consequence of vascular injury may be quite devastating, but its incidence can be reduced by understanding the mechanisms of injury. Properly managing vascular injury can reduce mortality and morbidity of patients. A review of the literature was conducted to provide an update on the etiology and management of vascular injury and complication in neurosurgical spine surgery. The vascular injuries were categorized according to each surgical procedure responsible for the injury, i.e., anterior screw fixation of the odontoid fracture, anterior cervical spine surgery, posterior C1-2 arthrodesis, posterior cervical spine surgery, anterolateral approach for thoracolumbar spine fracture, posterior thoracic spine surgery, scoliosis surgery, anterior lumbar interbody fusion (ALIF), lumbar disc arthroplasty, lumbar discectomy, and posterior lumbar spine surgery. The incidence, mechanisms of injury, and reparative measures were discussed for each surgical procedure. Detailed coverage was especially given to vascular injury associated with ALIF, which may have been underestimated. The accumulation of anatomical knowledge and advanced imaging studies has made complex spine surgery safer and more reliable. It is not clear, however, whether the incidence of vascular injury has been reduced significantly in all procedures of spine surgery. Emerging new techniques, such as microendoscopic discectomy and lumbar disc arthroplasty, seem to be promising, but we need to keep in mind their safety issues, including vascular injury and complication.

[Transsacral approach to lumbosacral extraforaminal disc herniations]

INTRODUCTION

The lateral approach is classically used for surgical treatment of extraforminal disc herniations (EDH). However, its use at the level of the L5-S1 space can require more or less extensive resection of the facet joint. This study reports our experience in the treatment of L5-S1 EDH using the transsacral approach described by Muller and Reulen in 1998.

MATERIAL AND METHODS

From February 2002 to October 2004, 12 patients presenting EDH at the L5-S1 level underwent treatment using the transsacral approach. There were 8 men and 4 women. Mean age was 55 years (range: 36 to 75 years). All patients presented lumbalgia and L5radiculalgia. Only one patient had dysesthesia. Five patients presented motor deficits and 3 presented sensory deficits. Surgical treatment was proposed after failure of medical treatment and two L5 corticoids infiltrations.

RESULTS

All patients were re-examined two months after the procedure. Mean follow-up was 15 months. Complete resolution of radiculalgia with no paresthesia was achieved in all patients. Patients presenting preoperative motor deficit recovered fully after treatment. All patients resumed normal activity.

CONCLUSION

The transsacral approach is a valid alternative to the lateral approach for treatment of L5-S1 EDH. The amount of operative exposure achieved using this technique is sufficient to avoid joint injury that can result in chronic postoperative lumbalgia. Another advantage is that excision of the protruding disc fragment can be achieved without mobilization of the nerve root or dorsal root ganglion, thus avoiding postoperative dysesthesia.

Lateral Lumbar Disc Herniations Treated With a Paraspinal Approach

In this independent review, at an average of 5.5 years after surgical excision of a lateral zone disc herniation using a paraspinal approach, 51 of 60 patients (85%) were satisfied with the results. Pain was eliminated in 36 (60%) and reduced in all but 3 (5%). Two-thirds of patients had no residual weakness or numbness. Thirty patients (50%) developed some new low-grade back pain, 17 (28%) developed some radicular pain, 9 (19%) developed some degree of radiographic instability, and 9 (15%) required further operative procedures. Based on this information, surgeons should be able to provide realistic expectations for their patients regarding outcomes. Based on our review of the literature, results using the paraspinal window appear similar, but not superior, to other available techniques, and the choice of approach should be based on the comfort of the surgeon.

Micro-endoscopic-discectomy (MED) for far lateral disc herniation in the lumbar spine. Technical note

This study describes a new experience of the authors in the treatment of extraforaminal disc herniation via the micro-endoscopic far lateral approach to establish a less traumatic approach to extraforaminal disc herniation with less stay in hospital and less cost. Seventeen patients who underwent surgery for extraforaminal disc herniation were analysed and long-term follow up was done revisiting all of them in hospital. The results of surgical decompression via the micro-endoscopic far lateral approach were good in all patients with minimal discomfort. There was complete resolution of leg pain presented. Dysesthesia subsided after 2-3 weeks. Extraforaminal disc herniation can be diagnosed with the aid of CT scan and MRI. The minimally invasive surgical treatment via the micro-endoscopic far lateral approach, in our initial experience, has a high rate of succes.

Combined intra-extracanal approach to lumbosacral disc herniations with bi-radicular involvement. Technical considerations from a surgical series of 15 cases

Large lumbosacral disc herniations effacing both the paramedian and the foraminal area often cause double radicular compression. Surgical management of these lesions may be difficult. A traditional interlaminar approach usually brings into view only the paramedian portion of the intervertebral disc, unless the lateral bone removal is considerably increased. Conversely, the numerous far-lateral approaches proposed for removing foraminal or extraforaminal disc herniations would decompress the exiting nerve root only. Overall, these approaches share the drawback of controlling the neuroforamen on one side alone. A combined intra-extraforaminal exposure is a useful yet rarely reported approach. Over a 3-year period, 15 patients with bi-radicular symptoms due to large disc herniations of the lumbar spine underwent surgery through a combined intra-extracanal approach. A standard medial exposure with an almost complete hemilaminectomy of the upper vertebra was combined with an extraforaminal exposure, achieved by minimal drilling of the inferior facet joint, the lateral border of the pars interarticularis and the inferior margin of the superior transverse process. The herniated discs were removed using key maneuvers made feasible by working simultaneously on both operative windows. In all cases the disc herniation could be completely removed, thus decompressing both nerve roots. Radicular pain was fully relieved without procedure-related morbidity. The intra-extraforaminal exposure was particularly useful in identifying the extraforaminal nerve root early. Early identification was especially advantageous when periradicular scar tissue hid the nerve root from view, as it did in patients who had undergone previous surgery at the same site or had long-standing radicular symptoms. Controlling the foramen on both sides also reduced the risk of leaving residual disc fragments. A curved probe was used to push the disc material outside the foramen. In conclusion, specific surgical maneuvers made feasible by a simultaneous extraspinal and intraspinal exposure allow quick, safe and complete removal of lumbosacral disc herniations with paramedian and foraminal extension.

Aspects techniques de la chirurgie endoscopique des hernies discales foraminales lombaires

BACKGROUND

We analyzed the contribution of endoscopic surgery for lumbar foraminal disc herniation in a series of 191 patients.

METHODS

All the patients underwent a posterior paramedian endoscopic procedure performed by the same operator. This prospective study concerned 191 consecutive patients included between April 1999 and March 2002. Outcome was assessed with a self-administered questionnaire. Prolo's criteria were used.

RESULTS

Of the 191 patients, 144 questionnaires (75%) were returned showing results were excellent in 130 (90%), good in 1 (0.7%) and poor in 13 (9%). The complications observed were: aseptic discitis (n=1); approach of two levels due to incorrect fluoroscopic guidance (n=2); dural tear (n=1); partial nerve root lesion (n=3); a second operation was necessary in 4 patients but only once at the same level and on the same side. Of the 80 patients who were working before the operation, 77 were able to return to work with an average delay of 3 weeks, 2 did not return to work and one worked only part time.

CONCLUSIONS

These good results associated with a high rate of patient satisfaction demonstrate that endoscopic surgery is an effective technique for the foramen. Endoscopy allow complete exposure decompression of the nerve root all along the foraminal canal.

Extraforaminal lumbar arterial anatomy

BACKGROUND

There are few studies carried out to reveal lumbar arterial anatomy. The studies of vascular anatomy of the lumbar zone are usually based on the angiographic imaging methods and barium injected radiographic sections of human specimens.

METHODS

Upon the recent breakthroughs in the microscopic anatomic dissections, the vascular structure of this zone is examined in 16 cadavers. Arterial anatomies of the extraforaminal zones of 80 lumbar vertebral objects were studied.

RESULTS

In each segment, lumbar artery, extraforaminal branches of the lumbar artery and the spinal (foraminal) branch were described. The spinal branch is originated from lumbar artery and extends as the dorsal branch. The dorsal branch is divided into 4 branches: ganglionic, transverse, ascending, and descending. Diameters of the lumbar artery, spinal, dorsal, and ganglionic branches were measured at each stage. The mean diameter of the lumbar artery was 2.7 mm, the dorsal branch was 2.0 mm, the foraminal branch was 1.9 mm, and the ganglionic branch was 1.0 mm, respectively.

CONCLUSION

Knowledge of lumbar arterial anatomy is needed for carrying out a successful surgical operation and reducing complications.

Combined Approach for Far-Lateral Lumbar Disc Herniation

This study evaluated the combination of the classical interlaminar approach and the intertransverse route through a midline approach for the treatment of 18 patients with far-lateral lumbar disc herniations, as identified by magnetic resonance imaging. The patients presented with acute severe sciatica, antalgic posture, positive Lasègue sign and femoral stretch test, motor and sensory deficits, and reflex loss findings. Discectomy of all 18 patients was performed by the combined approach. Neurological outcome of all patients was excellent in the follow-up period, ranging from 5 to 8 years. This combined midline approach permits complete evacuation of the involved disc level and treatment of additional bone resection procedures. Therefore, we advocate this approach in far-lateral lumbar disc herniation cases.

Extraforaminal Lumbar Herniation

The first anatomic description of extraforaminal herniation found in the literature was published in 1944. This was followed by several definitions regarding the anatomic site of this pathology. We consider correct the definition of lumbar extraforaminal herniation concerning the anatomic site of the herniated fragment. This fragment compresses the nervous root after its exit from the foramen, thus causing the compression of the spinal ganglion against the strong intertransverse ligament. The incidence of the pathology shifts from 1% to 12% and in our study was 4.2%. Over these years, the surgical approach has changed mainly because of two requirements: good exposition both of the foramen and of the herniation and the necessity of preserving stability of the spinal column as much as possible. In the last 30 years, less invasive approaches, paramedian, para- and transmuscular, lateral, and tangential, have been preferred to an interlaminar medial approach with a subtotal and/or complete facetectomy. In the last 4 years, 46 patients presenting with pure extraforaminal herniation have been treated in our institute through a far lateral microsurgical approach, avoiding resection of bone and reducing to the minimum the muscular retraction and the closure of blood vessels. We advocate a far lateral microsurgical approach, with no resection of bone and with highest respect for the osseous articular and muscular structures.

Extraforaminal lumbar disc herniations: microsurgical anatomy and surgical approach

OBJECT

Familiarity with the microsurgical anatomy of the far-lateral compartment is essential for operating in patients with far-lateral discs. In this report the authors address the microsurgical anatomy studied in 24 extraforaminal lumbar disc spaces in three cadavers.

METHODS

Cadaveric dissections confirmed the authors' operative experience in which they found an arterial arcade to be associated with the nerve trunk. The main trunk of the lumbar artery was located lateral to the exiting nerve root in the region of intervertebral foramen. The trunk of the lumbar spinal nerve descending from the level above was 7 mm (+/- 3 mm [standard deviation]) lateral to the lumbar artery.

CONCLUSIONS

Clarification of the microsurgical anatomy of the far-lateral compartment confirmed the authors' clinical impression that the optimum approach to far-lateral discs is via the inferomedial quadrant of the extraforaminal compartment. In this quadrant, exposure of the main nerve root can be facilitated by dividing the posterior primary ramus and a newly described arterial arcade that envelops the nerve trunk. Once this arcade is divided, the nerve can be retracted with relative ease and safety, and the disc can be removed more easily.

Combined transarticular lateral and medial approach with partial facetectomy for lumbar foraminal stenosis. Technical note

The authors performed a microsurgical combined transarticular lateral and medial procedure with partial facetectomy in 24 patients (16 men and nine women) with lumbar intervertebral foraminal stenosis to decompress the affected nerve root. The goal of this surgery was to maintain the integrity of the facet joint, to guarantee satisfactory exploration, and to obtain a sufficient decompression of the intervertebral foramen. Because only minimal bone resection is required, the risk of secondary instability induced by complete facetectomy is avoided. The clinical results of this procedure were excellent in the majority of cases. The mean follow-up period was 21.8 months.

Speculum lumbar extraforaminal microdiscectomy

BACKGROUND CONTEXT

Public interest, monetary pressures and improving diagnostic techniques have placed an increasing emphasis on minimalism in lumbar disc excision. Current techniques include microlumbar discectomy and minimally invasive spinal surgery. Both are good techniques but may be painful, require a hospital stay and/or are not widely used because of difficulty acquiring the necessary skills. The author therefore developed a less invasive microscopic technique that may be performed on a consistent outpatient basis with easily acquired skills.

PURPOSE

The purpose of this study was to describe a variant of minimally invasive lumbar disc excision, while assessing the effects on a small group of patients.

STUDY DESIGN

The treatment protocol was a prospective community hospital-based case study designed to evaluate a less invasive method of excising herniated lumbar discs residing in the canal, foraminal or far lateral space.

PATIENT SAMPLE

This study is comprised of 50 patients with all anatomic forms of lumbar disc herniations, inside or outside the canal, at all levels except the lumbosacral joint.

OUTCOME MEASURES

Clinical results were measured by return to work time, the criteria of MacNab and by Prolo et al.'s economic and functional criteria.

METHODS

Selection criteria included adult patients with intractable low back and leg pain, plus an imaging study revealing a lumbar disc herniation consistent with the patient's clinical presentation. Mean patient age was 48 years. The male:female ratio was approximately 2:1. All patients failed at least 3 weeks of conservative therapy. Herniations occurred from the L2-3 space through L4-5, with 30 herniations being within and 20 outside the spinal canal. Both contained and extruded/sequestered herniations were treated. Excluded from the study were patients with herniations inside the spinal canal at the L5-S1 level. Surgical approach was by microscopic speculum transforaminal route for discs residing both within and outside the lumbar canal.

RESULTS

The initial 50 consecutive patients had successful technical operations performed on an outpatient basis by this less invasive technique. By the criteria of MacNab (Table 3), 84% (42 of 50) had an excellent or good result, returning to work at a mean time of 3.5 weeks. Per Prolo et al.'s economic scale, 72% were disabled at levels I and II before surgery. Postoperatively, 92% had improved to levels IV and V. Similarly, on his functional scale, 94% functioned at levels I and II before surgery, whereas 88% achieved levels IV and V after surgery. Eighty percent required no pain medications 1 week after surgery. The only complication was an L3 minor nerve root injury as it exited the L3-4 foramen.

CONCLUSION

The author has described a minimally invasive technique for excising herniated discs that is applicable to all types of lumbar herniations, except for those residing in the canal at L5-S1. Clinical outcomes are comparable to those of other forms of discectomy.

Anatomic considerations of the posterolateral lumbar disk region

Sixteen embalmed cadavers were dissected to determine the location of the lumbar nerve root and sympathetic trunk with reference to the superior border of transverse process. In the posterolateral lumbar disk region, a safe zone was found between the anterior limit of the lumbar nerve and the posterior limit of the sympathetic trunk. It has a transverse dimension of 22 mm at the T12-L1 disk region and 25 mm at the L4-L5 disk region. The only exception to this was the genitofemoral nerve running close to the lateral margin of the L2-L3 disk. The study provides an understanding of the posterolateral orientation of the lumbar nerves and sympathetic trunk.

A keyhole approach for endoscopically assisted pedicle screw fixation in lumbar spine instability

OBJECTIVE

The standard approach for dorsal transpedicular fixation in lumbar spine instability requires extensive exposure of the vertebral column. This increases the risk of potential complications and possibly destabilizes healthy neighboring segments because of the dissection and denervation of paravertebral muscles. The majority of spinal disorders are currently treated successfully via limited and tailored approaches. Accordingly, a keyhole approach for dorsal fusion of the lumbar spine was developed on the basis of an anatomic study.

METHODS

The new endoscopic technique entails the transmuscular insertion of a pedicle screw-rod fixation device via a rigid operating sheath. As a prerequisite, the endoscopic microanatomy of the target area, as visible through the operating sheath, was first evaluated on lumbar bone specimens. To localize the exact screw entry point into the pedicle, we identified the bony and ligamentous landmarks on partly macerated specimens. To determine the course of the pedicle screws, we deduced the corresponding angles of convergence from transparent polyester casting models of average vertebrae from T12 to S1. These angles were transferred into the operative situation and measured on-line with an inclinometer. The approach was finally tested on 12 cadavers for clinical feasibility and accuracy of screw placement and then successfully implemented in patients.

RESULTS

After extracutaneous localization of the pedicles at lateral fluoroscopy, paramedian skin incisions were made above the pedicles of the motion segment to be stabilized. The operative windows were exposed by use of a rigid operating sheath (length, 50 mm; diameter, 15 mm), which was inserted transmuscularly in the pedicle axis. The screw entry point into the pedicles was localized by endoscopic dissection of the mamilloaccessory ligament, bridging the mamilloaccessory notch. The pilot holes were created via insertion of a blunt-tipped pedicle probe. The adequate angles of convergence were constantly controlled during hollowing of the pedicles by an inclinometer mounted to the pedicle probe handle. The pedicle screws were then inserted through the operating sheaths. After removal of the operating sheaths, the connecting rods were inserted transmuscularly and anchored in the pedicle screw heads. Posterior bone grafting was performed after completion of the dorsal instrumentation. The dorsal fusion site was exposed by reinserting the operating sheath and tilting it medially.

CONCLUSION

This new approach significantly reduces surgical traumatization and destabilization of adjacent motion segments. An endoscopic operating sheath, adopted from thoracoscopic surgery, creates space for visualization and surgical manipulations. The newly defined anatomic landmarks provide guidance to the screw entry point into the pedicle in the center of the exposure. Observation of the exact corresponding angles of convergence during screw insertion by an inclinometer facilitates correct screw placement. In accordance with the initial anatomic studies, this approach was successfully performed on 12 cadavers and then used in six patients. Two illustrative cases are presented.

Surgical treatment of far lateral lumbar disc herniation. Identification of compressed root and discectomy by lateral approach

STUDY DESIGN

A new method is described of compressed root identification and discectomy for extraforaminal disc herniation, by a lateral intertransversalis approach.

OBJECTIVES

To describe a safe surgical approach that does not require resection of adjacent bone structures during extraforaminal discectomy.

SUMMARY OF BACKGROUND DATA

Most earlier series have reported approaches that damaged bordering bone structures with wide laminoarthrectomy. This is an attempt at a safer, simpler surgical approach.

METHODS

Thirteen patients with lateral hernia have undergone this surgical procedure since 1995. Herniectomy was performed after identification of the compressed root within the iliopsoas muscle.

RESULTS

All the patients resumed the upright position with the aid of semirigid brace 24 hours after surgery. Upon awakening from the anesthesia, no patient reported peripheral pain. Motor deficits resolved after physical rehabilitation in all but one patient. At a mean follow-up of 14 months, there was no report of back pain.

CONCLUSION

The procedure described in this article offers a simple alternative to the valid procedures presently at hand. It offers the advantage of no bone resection and of minimizing nerve structures manipulation.

Morphometric aspects of extraforaminal lumbar nerve roots

OBJECTIVE

In the posterolateral extraforaminal and anterolateral retroperitoneal approaches to lumbar spinal lesions, the neural structures in the lumbar extraforaminal region are unfamiliar to many spinal surgeons. The purpose of this study was to determine the normal anatomic morphometric parameters for all lumbar nerve roots around their exits, from the intervertebral foramen to the surrounding bony structure.

METHODS

A total of 15 adult fixed cadavers were studied. The extraforaminal course of the lumbar nerve roots and the forming plexus were measured segmentally, using standard calipers, and we selected the shortest distance from the bony landmarks to the nerve roots in the horizontal plane. The bony landmarks were the most medial superior border of the transverse process (TP), the most medial inferior border of the TP, the tip of the superior articular process, and the most dorsolateral margin of the intervertebral disc space. In addition, the angle of each root exiting from the intervertebral foramen was measured using a goniometer.

RESULTS

The mean distance from the medial superior border of the TP to the upper segment of the nerve root was 5.1 to 6.4 mm at L2-L5. The mean distance from the medial inferior border of the TP to the corresponding nerve root was 8.5 mm at L2 and L3 and 6 mm at L4 and L5. The mean distance from the tip of the superior articular process to the most dorsal border of the descending nerve trunk was 19 mm at L2 and L3 and 22 mm at L4 and L5. The main lumbar nerve trunk was located close to the most dorsolateral surface of the vertebral body and the intervertebral disc space, and it was topographically arranged dorsoventrally from the L5 to L2 nerve components. The average widths of the nerve trunk were 10, 14, and 25 mm at L3-L4, L4-L5, and L5-S1, respectively. The mean angles of the exiting roots in the extraforaminal region were 16 degrees at L2 and L3 and 25 degrees at L4 and L5.

CONCLUSION

The lumbar nerve component, including both the lumbar trunk and each exiting nerve root in the extraforaminal region (the so-called "danger zone"), was located anteriorly at a distance more than 5 mm from the TP, more than 19 mm from the superior articular process, and up to 25 mm from the intervertebral disc space. Based on our results, the danger zone occupied up to 25 mm forward from the intervertebral foramen at the lower lumbar segments. Therefore, during operations such as percutaneous posterolateral procedures and open posterolateral or anterolateral approaches, great care should be taken within 25 mm of the extraforaminal region, especially for the lower lumbar spine.

Long-term follow up of patients surgically treated by the far-lateral approach for foraminal and extraforaminal lumbar disc herniations

OBJECT

This study was undertaken to evaluate the long-term benefit in 202 patients who were surgically treated via a microsurgical far-lateral approach for foraminal or extraforaminal lumbar disc herniations.

METHODS

All patients underwent surgery at the authors' institute since 1987 and represented 6.5% of all lumbar spinal disc surgeries. There were 67 women and 135 men who ranged in age from 19 to 78 years (mean age 58 years). All patients had unilateral leg pain due to lumbar disc herniations into or lateral to the lateral interpedicular compartment. One patient underwent surgery at the L1-2 level, nine at L2-3, 48 at L3-4, 86 at L4-5, and 58 at the L5-S1 level. The mean follow-up period was 50 months (range 12-120 months). Outcome was defined as excellent (no pain), good (some back pain), fair (moderate radiculopathy), and poor (unchanged or worse) based on Macnab classification. Overall, excellent and good results were achieved in 62 (31%) and 85 (42%) patients, respectively, and fair and poor results in 40 (20%) and 15 (7%) patients, respectively. Of 11 recurrent disc herniations, four presented in an extreme-lateral position, five in a paramedian location, and two on the contralateral side. There were three minor complications related to surgery, seven general complications, and no case of spinal instability.

CONCLUSIONS

The far-lateral approach is a safe, effective procedure that avoids the risk of secondary spinal instability.

A paramedian tangential approach to lumbosacral extraforaminal disc herniations

OBJECTIVE

Extraforaminal disc herniations today are operated on via the so-called lateral approach. Clinical experience has shown that in contrast to levels L2/3-L4/5, this approach may become extremely difficult at the L5-S1 level. According to new microanatomic studies, the previous lateral approaches at this level often do not allow access to the neuroforamen without partial or total destruction of the L5-S1 facet joint. Postoperatively, this may lead to joint irritation with consecutive low back and pseudoradicular pain. To preserve the facet joint, a new approach was developed based on an anatomic study.

METHODS

The approach was first considered with the help of bone specimens including ilium, vertebra 5, and sacrum. Thereafter, lumbar maceration specimens were prepared leaving ligaments, intervertebral discs, and joints intact. From these specimens, bony and ligamentous landmarks were deduced. Finally, the approach was tested on seven cadavers. Subsequently, the approach was performed on 13 patients and the intraoperative findings, the clinical feasibility, and the postoperative results were analyzed.

APPROACH

After a transverse skin incision above the dorsal curvature of the ilium, the paravertebral muscles are dissected from the ilium medially toward the spinous process. Lateral from the apophyseal joint, a canal is drilled through the spongiosa of the sacrum. Primarily, a thin layer of inner cortex is spared to protect the content of the neuroforamen. Subsequently, it can easily be removed with the dissector to enter the extraforaminal space. In the depth of the drilled canal, the nerve root is found, because it is fixed at the sacrum near the disc space by the anterior lumbosacral ligaments. Riding on the nerve root, the intertransverse ligament and muscle can be removed with the punch. It is then possible to see the neuroforamen and extraforaminal space in front of the joint. Free fragments and contained discs can then easily be found and removed.

CONCLUSION

Using this new approach, the L5-S1 joint remains intact. Space for instrumental manipulations is created in areas not essential for joint function. For this procedure, newly defined anatomic landmarks, such as the ileolumbar ligament, upper edge of the sacrum, lateral rim of the apophyseal joint, and para-articular notch, guide the operative route. In accordance with the preliminary anatomic studies, this approach was successfully used in 13 patients, and we think that it is a promising alternative that helps to preserve joint function and dorsal root ganglion integrity.

Pars interarticularis fenestration in the treatment of foraminal lumbar disc herniation: a further surgical approach

OBJECTIVE

A new surgical approach to foraminal disc herniation is proposed.

METHODS

The procedure was performed in 28 patients during a span of 3 years. The herniation was purely foraminal in 18 patients and mainly foraminal with a definite extraforaminal component in the other 10 patients. Surgical treatment was offered only after 6 weeks of therapy with anti-inflammatory drugs and strict bed rest had proved to be ineffective.

SURGICAL TECHNIQUE

To unroof the foraminal compartment, an ovoid fenestration (10 x 5 mm) is cut, with its major longitudinal axis at the level of the pars interarticularis, just medially and slightly off-center under the lateral isthmic notch, i.e., below the pedicle projection. This fenestration exposes the foraminal root compressed by the herniated disc, which can be easily removed.

RESULTS

Treatment was successful in all patients, with swift remission of pain and only mild postoperative discomfort. All patients resumed their occupations as usual within 10 to 30 days after the operation, according to type of work. Mean follow-up is 24 months (range, 12-36 mo), without any return of pain.

CONCLUSION

We propose pars interarticularis fenestration because it spares, with minimal bone removal, the facet joints and the anatomic continuity of the pars interarticularis, yet properly exposes the foraminal compartment both medially and laterally and thereby permits optimal removal of the disc herniation.

Endoscopically assisted open removal of laterally herniated lumbar discs

BACKGROUND

Adequate treatment of laterally herniated lumbar discs presents a surgical challenge. All fragments compressing the nerve root should be removed without destruction of the overlying facet joint. To accomplish this goal many techniques have been proposed, each with specific limitations.

METHODS

In a small group of patients we have used a small malleable endoscope to assist in the removal of laterally herniated discs. Via a small laminotomy, the nucleus was removed in a standard manner and then the lateral disc material removed under direct endoscopic visualization.

RESULTS

There were no operative complications and the nerve root was visualized and decompressed in all patients. There has been no recurrence of pain or development of spondylolisthesis.

CONCLUSION

This technique negates removal of portions of the facet joint and provides adequate nerve root decompression.

Removal of a lateral disc herniation with malleable endoscopic forceps: technical note

OBJECTIVE

The use of "seeing" endoscopic malleable pituitary forceps in the removal of a lateral herniated lumbar disc is evaluated.

METHODS

A malleable pituitary forceps with an attached endoscope was used to explore the neuroforamina and remove laterally herniated disc fragments without a lateral approach or disruption of the facet joint.

RESULTS

In the described case, endoscopic forceps provided easy localization and removal of the disc fragments.

CONCLUSION

Because this instrument was used successfully in this case, further evaluation of the use of the endoscopic pituitary forceps should be made.

Microsurgical management of lateral lumbar disc herniations: combined lateral and interlaminar approach

Seventy-three patients presenting either with biradicular symptoms caused by involvement of the upper and lower root or with monoradicular symptoms caused by affection of the upper root were treated between January 1993 and July 1995 in our department. An interlaminar and lateral access was used to decompress both the upper and lower root by combining the conventional interlaminar approach and a lateral partial facetectomy. With this technique, satisfactory to excellent results were obtained in 92% of the patients. The advantages of the combined approach are (i) optimized visualization of the disc and surrounding anatomical structures, (ii) improved exposure of the lateral foramen and thorough removal of disc material, (iii) minimal risk of root injury by improved visualization, (iv) preservation of a functional facet joint and thereby reduction of postoperative instability with persistent back pain. Since occasionally lateral disc herniations are poorly visualized by computed tomography or magnetic resonance imaging, the decision to use the combined approach should be guided by the patient's clinical presentation rather than by radiological findings.