Microendoscopy-assisted muscle-preserving interlaminar decompression for lumbar spinal stenosis: clinical results of consecutive 105 cases with more than 3-year follow-up

Analyses of imaging presentations, full endoscopic and pathological features of a novel interlaminar ligament

BACKGROUND

To analyze the characteristics of an unnamed interlaminar ligaments(ILL) through magnetic resonance image (MRI), endoscopy and pathological examination.

METHOD

A retrospective study was conducted to analyze the clinical data of patients who underwent posterior endoscopic surgery for lumbar disc herniation or lumbar spinal stenosis from January 2021 to February 2022 at our medical center. The height, width and cross-sectional thickness of the ligament was analyzed using T2 weighted MRI. Meanwhile, the morphological and pathological characteristics were also compared with those of the ligamentum flavum to highlight the differences between above mentioned ligaments.

RESULT

Forty-three patients were included in this study, including 27 males and 16 females, with an average age of 46.6 ± 12.1y. There were 20 cases of lumbar disc herniation and 23 cases of lumbar spinal stenosis. The width, length, thickness of the ILL, the thickness of LF and surgical time in the lumbar disc group were 17.7 ± 3.5 mm, 4.3 ± 1.3 mm, 18.3 ± 3.5 mm, 5.3 ± 1.9 mm, 53.2 ± 14.5 min, respectively. In the lumbar spinal stenosis group, the corresponding parameters were 16.0 ± 3.1 mm, 4.1 ± 1.6 mm, 17.6 ± 4.8 mm, 6.3 ± 0.8 mm, 61.8 ± 12.4 min, respectively. The intergroup difference in thickness of the ligamentum flavum was statistically significant (P = 0.02). The difference in surgical time was also established(P = 0.04). Endoscopic differences were identified as to the location of the anchor points and appearances among the two ligaments. Significant differences in the density and direction of fibrous structures were also observed under biopsy. Under endoscopy, significant difference as to the grade of ILL thickness was established when compared regarding disease spectrum (P = 0.09.) CONCLUSION: The interlaminar ligament is a structure that has not yet been officially named, which has significant structural differences from those of the ligamentum flavum. For posterior endoscopic procedure, its clinical significance lies in its ability to serve as the endpoint of soft tissue channel establishment. The thickness of the ligamentum flavum in MRI and the thickness of ILL under endoscopy vary according to the disease spectrum.

A comparative analysis of neuroendoscopic foramen magnum decompression versus traditional open surgery for Chiari Malformation Type I

PURPOSE

Chiari Malformation Type I (CM1) is characterized by the downward displacement of the cerebellar tonsils below the foramen magnum. The standard surgical treatment for CM1 is foramen magnum decompression and atlas laminectomy (FMD-AL). However, there is a growing interest in exploring minimally invasive techniques, such as neuroendoscopically assisted FMD-AL, to optimize surgical outcomes. The aim is to present the results of the less invasive neuroendoscopic-assisted system application as an alternative to decompression surgery in patients with CM-1 with/without syringomyelia.

PATIENTS AND METHODS

A retrospective analysis was conducted on 76 patients with CMI who underwent either neuroendoscopic-assisted FMD-AL (n = 23) or open surgery (n = 53). Preoperative and postoperative assessments were performed, including pain levels, functional assessment, outcome and serum creatinine kinase (CK) levels. Surgical parameters and radiological imaging were also evaluated and compared.

RESULTS

Both surgical groups showed improvements in pain levels and increase in postoperative CK levels. There were no statistically significant differences between the groups in terms of postoperative JOA scores, VAS scores, CCOS, or syrinx resolution. However, the neuroendoscopic group had significantly lower CK levels, shorter hospital stays, less blood loss, and shorter operation times compared to the open surgery group, indicating reduced muscle damage and potential benefits of the neuroendoscopic assisted approach.

CONCLUSION

Both neuroendoscopy and open surgery groups can effectively alleviate symptoms and improve outcomes in patients with CM1. The neuroendoscopic assisted technique offers the advantage of reduced muscle damage and shorter hospital stays. The choice of surgical technique should be based on individual patient characteristics and preferences.

LEVEL OF EVIDENCE

3 (Retrospective case-control study) according to using the Oxford Centre for Evidence-Based Medicine (CEBM) Table.

Broad and Asymmetric Lower Extremity Myotomes: Results From Intraoperative Direct Electrical Stimulation of the Lumbosacral Spinal Roots

STUDY DESIGN

Retrospective review of prospectively collected data.

OBJECTIVE

This study aimed to accurately map the lower extremity muscles innervated by the lumbar spinal roots by directly stimulating the spinal roots during surgery.

SUMMARY OF BACKGROUND DATA

Innervation of the spinal roots in the lower extremities has been estimated by clinical studies, anatomic studies, and animal experiments. However, there have been discrepancies between studies. Moreover, there are no studies that have studied the laterality of lower limb innervation.

MATERIALS AND METHODS

In 73 patients with lumbar degenerative disease, a total of 147 spinal roots were electrically stimulated and the electromyographic response was recorded at the vastus medialis (VM), gluteus medius (GM), tibialis anterior (TA), biceps femoris (BF), and gastrocnemius (GC). The asymmetry index (AI) was obtained using the following equation to represent the left-right asymmetry in the compound muscle action potential (CMAP) amplitude. Paired t tests were used to compare CMAP amplitudes on the right and left sides. Differences in the AI among the same spinal root groups were determined using one-way analysis of variance.

RESULTS

The frequency of CMAP elicitation in VM, GM, TA, BF, and GC were 100%, 75.0%, 50.0%, 83.3%, and 33.3% in L3 spinal root stimulation, 90.4%, 78.8%, 59.6%, 73.1%, and 59.6% in L4 spinal root stimulation, 32.2%, 78.0%, 93.2%, 69.5%, and 83.1% in L5 spinal root stimulation, and 40.0%, 100%, 80.0%, 70.0%, and 80.0% in S1 spinal root stimulation, respectively. The most frequent muscle with maximum amplitude of the CMAP in L3, L4, L5, and S1 spinal root stimulation was the VM, GM, TA, and GM, respectively. Unilateral innervation occurred at high rates in the TA in L4 root stimulation and the VM in L5 root stimulation in 37.5% and 42.3% of patients, respectively. Even in patients with bilateral innervation, a 20% to 38% AI of CMAP amplitude was observed.

CONCLUSIONS

The spinal roots innervated a much larger range of muscles than what is indicated in general textbooks. Furthermore, a non-negligible number of patients showed asymmetric innervation of lower limb by the lumbar spinal roots.

Association of central sensitization, visceral fat, and surgical outcomes in lumbar spinal stenosis

BACKGROUND

Controversy remains regarding predictors of surgical outcomes for patients with lumbar spinal stenosis (LSS). Pain sensitization may be an underlying mechanism contributing to LSS surgical outcomes. Further, obesity is associated with dissatisfaction and poorer outcomes after surgery for LSS. Therefore, this study aimed to examine the relationship between central sensitization (CS), visceral fat, and surgical outcomes in LSS.

METHODS

Patients with LSS were categorized based on their central sensitization inventory (CSI) scores into low- (CSI < 40) and high- (CSI ≥ 40) CSI subgroups. The participants completed clinical outcome assessments preoperatively and 12 months postoperatively.

RESULTS

Overall, 60 patients were enrolled in the study (28 men, 32 women; mean age: 62.1 ± 2.8 years). The high-CSI group had significantly higher mean low back pain (LBP), leg pain, and leg numbness visual analogue scale (VAS) scores than the low-CSI group (p < 0.01). The high-CSI group had a significantly higher mean visceral fat area than the low-CSI group (p < 0.01). Postoperatively, LBP VAS score was significantly worse in the high-CSI group. Relative to preoperatively, postoperative leg pain and leg numbness improved significantly in both groups.

CONCLUSIONS

We believe that neuro decompression can be effective for LSS surgical outcomes in patients with CS; nonetheless, it should be approached with caution owing to the potential for worsening LBP. Additionally, visceral fat is an important indicator suggesting the involvement of CS.

Utility of Flexion-Extension Radiographs with Brackets and Magnetic Resonance Facet Fluid for the Assessment of Lumbar Instability in Degenerative Lumbar Spondylolisthesis

OBJECTIVE

To propose a new standardized technique for evaluating lumbar stability in degenerative lumbar spondylolisthesis using lumbar lateral flexion-extension radiographs with brackets and magnetic resonance facet fluid.

METHODS

A retrospective analysis of 57 patients diagnosed with lumbar (L4-5) spondylolisthesis was performed. We analyzed lateral flexion-extension radiographs obtained with a bracket (LFEB) and without a bracket (LFE). Sagittal translation, segmental angulation, posterior opening, lumbar instability, and changes in lumbar lordosis were compared using functional radiographs. The mean width and maximum width of the facet fluid, mean facet joint length, and facet fluid index (FFI) of the 2 groups were compared using sagittal translation.

RESULTS

The average value of sagittal translation was 1.68 ± 0.96 mm in LFE and 3.07 ± 1.29 mm in LFEB, and the difference was significant (P < 0.05). Segmental angulation, posterior opening, and changes in lumbar lordosis were significantly greater in LFEB than in LFE. The instability detection rate was 14.0% in LFE and 35.1% in LFEB. The FFI, maximum width, and mean width were significantly increased in the unstable lumbar spondylolisthesis group compared with the stable group in LFEB. The FFI and maximum width of the facet fluid were significantly increased in the unstable lumbar spondylolisthesis group compared with the stable group in LFE.

CONCLUSIONS

Lumbar lateral flexion-extension radiographs with brackets can standardize the operation process and provide sufficient hyperflexion and hyperextension images. The width of the facet fluid and FFI are significant factors in the evaluation of lumbar stability in patients with lumbar spondylolisthesis.

Degenerative Lumbar Spondylolisthesis Patients With Movement-related Low Back Pain Have Less Postoperative Satisfaction After Decompression Alone

STUDY DESIGN

Retrospective analysis of prospectively collected multicenter observational data.

OBJECTIVE

The aim was to examine the preoperative factors affecting postoperative satisfaction following posterior lumbar interbody fusion (PLIF) and microendoscopic muscle-preserving interlaminar decompression (ME-MILD) in patients with degenerative lumbar spondylolisthesis (DLS).

SUMMARY OF BACKGROUND DATA

The technique involved in DLS surgery may either be decompression alone or decompression-fixation. Poor performance may occur after either of these surgical treatments. The author hypothesized that evaluating the correlation between preoperative quality of life and postoperative performance would aid in determining the optimal procedure.

MATERIALS AND METHODS

This study included 138 patients who underwent surgery for 1-level mild DLS. The authors performed PLIF for 79 patients and ME-MILD for 59 patients. When the satisfaction subscale of the Zurich Claudication Questionnaire exceeded 2 points, postoperative satisfaction was considered poor. The clinical characteristics were investigated. Responses to preoperative health-related quality of life questionnaires, such as the Japanese Orthopedic Association Back Pain Evaluation Questionnaire (JOABPEQ), short form-36 health survey (SF-36), and visual analog scale, were compared between the satisfied and unsatisfied groups.

RESULTS

In the PLIF group, no endogenous factors influenced postoperative satisfaction. The ME-MILD cohort's satisfied and unsatisfied patients differed significantly in terms of preoperative lumbar spine dysfunction ( P <0.001) items of the JOABPEQ, role physical ( P =0.03), and role emotional ( P =0.03) items of the SF-36. A strong correlation ( r =-0.609 P =0.015) was found between preoperative lumbar spine dysfunction and postoperative satisfaction.

CONCLUSIONS

In the ME-MILD group, preoperative lumbar spine function was correlated with postoperative satisfaction. Decompression alone may be ineffective in cases with decreased lumbar spine function prior to surgery. The degree of low back pain on movement should be considered before selecting the surgical method.

LEVEL OF EVIDENCE

3.

Utility of a fulcrum for positioning support during flexion-extension radiographs for assessment of lumbar instability in patients with degenerative lumbar spondylolisthesis

OBJECTIVE

The authors investigated a new standardized technique for evaluating lumbar stability in lumbar lateral flexion-extension (LFE) radiographs. For patients with lumbar spondylolisthesis, a three-part fulcrum with a support platform that included a semiarc leaning tool with armrests, a lifting platform for height adjustment, and a base for stability were used. Standard functional radiographs were used for comparison to determine whether adequate flexion-extension was acquired through use of the fulcrum method.

METHODS

A total of 67 consecutive patients diagnosed with L4-5 degenerative lumbar spondylolisthesis were enrolled in the study. The authors analyzed LFE radiographs taken with the patient supported by a fulcrum (LFEF) and without a fulcrum. Sagittal translation (ST), segmental angulation (SA), posterior opening (PO), change in lumbar lordosis (CLL), and lumbar instability (LI) were measured for comparison using functional radiographs.

RESULTS

The average value of SA was 5.76° ± 3.72° in LFE and 9.96° ± 4.00° in LFEF radiographs, with a significant difference between them (p < 0.05). ST and PO were also significantly greater in LFEF than in LFE. The detection rate of instability was 10.4% in LFE and 31.3% in LFEF, and the difference was significant. The CLL was 27.31° ± 11.96° in LFE and 37.07° ± 12.963.16° in LFEF, with a significant difference between these values (p < 0.05).

CONCLUSIONS

Compared with traditional LFE radiographs, the LFEF radiographs significantly improved the detection rate of LI. In addition, this method may reduce patient discomfort during the process of obtaining radiographs.

Long-Term Outcomes After Minimally Invasive Bilateral or Unilateral Laminotomy for Degenerative Lumbar Spinal Stenosis: A Minimum 10-Year Follow-Up Study

OBJECTIVE

The optimal surgical procedure for minimal surgical intervention in symptomatic degenerative lumbar spinal stenosis (DLSS) is unknown. This article presents a method of minimally invasive decompression alone and reports the long-term outcomes and complications of patients treated with minimally invasive bilateral or unilateral laminotomy decompression performed by one surgeon.

METHODS

Patients with DLSS who underwent minimally invasive laminotomy decompression alone from March 2008 to October 2010 were included in the study, and 106 patients were followed up for at least 10 years. Clinical outcomes were assessed by Japanese Orthopedic Association, Oswestry Disability Index, and visual analog scale for back pain scores, and changes in walking tolerance and leg numbness were evaluated. Complications were recorded.

RESULTS

A total of 106 patients who met the inclusion and exclusion criteria were included in the study (mean age = 64 years, range = 43-83). The Japanese Orthopedic Association, Oswestry Disability Index, and visual analog scale back pain scores of patients significantly changed between before surgery and at subsequent follow-up (P < 0.001). The walking tolerance and leg numbness of patients significantly improved (P < 0.001), and these functions were well maintained during follow-up. Complications included intraoperative dural tears (n = 5), a wound infection (n = 1), deep vein thrombosis (n = 1), and nerve root lesions on the asymptomatic side (n = 2), all of which recovered within 3 months.

CONCLUSIONS

Minimally invasive laminotomy decompression is an effective procedure and achieves beneficial long-term clinical results for DLSS.

Is Decompression and Partial Discectomy Advantageous Over Decompression Alone in Microendoscopic Decompression Of Monosegmental Unilateral Lumbar Recess Stenosis?

BACKGROUND

Endoscopic techniques are well accepted as surgical technique for decompression of lumbar lateral recess stenosis (LRS). It is uncertain if there is a difference in clinical outcome for decompression alone (DA) or decompression with partial discectomy (DPD) for the treatment of LRS.

METHODS

All files of patients who underwent an endoscopic procedure for lumbar LRS were identified from a prospectively collected database. Preoperative magnetic resonance imaging and endoscopic video were analyzed with special focus on the technique of nerve root decompression. Clinical outcome was assessed via a personal examination, a standardized questionnaire including the numeric rating scale (NRS) for leg and back pain, the Oswestry disability index (ODI), and the modified MacNab criteria to assess functional outcome and clinical success.

RESULTS

Sixty-six patients were identified of which 57 attended for evaluation (86.4%). DA was performed in 15 (26.3%) patients and DPD in 42 patients (73.7%). The mean follow-up was 45.0 months (range: 16-82 months). Fifty-two patients reported to be free of leg pain (91.1%), 42 patients had no noticeable back pain (73.7%), 49 patients had full muscle strength (85.9%), and 48 patients had no sensory disturbance (84.2%). The mean NRS for leg pain was 1, the mean NRS for back pain was 2, mean ODI was 16% (range: 0%-60%). Clinical success was noted in 49 patients (85.9%) and it was significantly higher for patients following DPD (P = .024). The overall repeat procedure rate was 12% with reoperation rate at the index segment in 10.5% of cases. There were no significant differences with respect to leg and back pain, ODI, and reoperation between both groups.

CONCLUSION

Microendoscopic DPD of LRS achieves a 92% clinical success rate which is significantly higher compared to 67% clinical success achieved by DA. There was no significant difference for the rate of reoperation, leg and back pain, and ODI.

LEVEL OF EVIDENCE

4.

The impact of posterior epidural adipose tissue on postoperative outcomes after posterior decompression surgery for lumbar spinal stenosis: A prospectively randomized non-inferiority trial

STUDY DESIGN

The present study is a prospectively randomized study.

OBJECTIVE

The objective of the study was to evaluate the impact of posterior epidural adipose tissue (PAT) on postoperative outcome following lumbar decompression surgery for lumbar spinal stenosis (LSS) by whether PAT was removed or preserved during the surgical procedure.

SUMMARY OF BACKGROUND DATA

In posterior decompression surgery for LSS, PAT is routinely removed without knowledge of its role and significance. However, considering adipose tissue has regenerative properties of damaged neighboring tissues or itself, PAT, which is adipose tissue located at peridural space, might also have a potential to regenerate the neighboring damaged tissue, including dura and nerve root in the lumbar spine, but this has not been thoroughly studied.

METHODS

Of the 185 eligible patients screened for the current study, 181 patients were enrolled and randomly allocated into either group A (PAT removal, n = 90) or group B (PAT retention, n = 91). The primary outcome measure was pain intensity on the lower back and lower extremity. The secondary outcome measures were functional outcome based on the Oswestry disability index (ODI) and walking distance, complications during the surgical procedure, and surgical outcomes.

RESULTS

Postoperative pain intensity on the lower back and lower extremity was greater in group A than in group B. Functional status on ODI and walking distance was also worse in group B than in group A (64.9% in group A and 66.2% in group B). The number of patients with aggravated pain intensity and deteriorated functional status in postoperative follow-up times was significantly greater in group A than in group B. There were no significant differences in surgical outcome and complications between the groups.

CONCLUSION

Preserving epidural fat may be favorable in postoperative outcomes of posterior decompression surgery for LSS compared to removing epidural fat.

Building block osteotomy, a new back muscle-preserving laminoplasty for lumbar spinal stenosis

In order to preserve paravertebral muscles and posterior ligaments complex (PLC), this paper proposes a new lumbar laminoplasty surgery for lumbar spinal stenosis (LSS). According to the anatomy of back muscles insertions, building block osteotomy (BBO) which aimed to achieve precise osteotomy and reconstruction based on modular design theory was firstly put forward, and supposed to be achieved by an ultrasound bone scalpel (UBS). In details, lumbar spinous processes are longitudinally split, then supraspinous and interspinous ligaments are sharply cut off longitudinally. After converting to lumbar flexion, lamina osteotomy is innovatively finished by an UBS through interspinous space. After decompression, hollow screws are firstly suggested to be used on each side to fix lamina and spinous processes, and PLC is reconstructed by interrupted suture. Feasibility of this method is evaluated in details. Challenges, advantages and disadvantages are also discussed.

Microendoscopic discectomy versus minimally invasive transforaminal lumbar interbody fusion for lumbar spinal stenosis without spondylolisthesis

Micoendoscopic discectomy (MED) and minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) has become alternatives of the traditional open decompression surgery alone and decompression plus fusion surgery in the treatment of lumbar spinal stenosis (LSS). To date, there is no study focusing on the comparison of clinical outcomes after MED and MIS-TLIF for LSS without spondylolisthesis.Four hundred ninety-seven patients who underwent MED (236 cases) or MIS-TLIF (261 cases) for LSS without spondylolisthesis were included in this study. Perioperative outcomes (hospital stay, operation time and blood loss), cost, functional scores (Oswestry Disability Index, 12-item short form health survey) with a 24-month follow-up visit, complication and reoperation condition within 24 months after surgery were recorded and assessed.No significant difference of clinical outcomes over time was observed between these 2 surgical approaches. Compared with MIS-TLIF, MED was associated with greater satisfaction at 1-month time point postoperatively, whereas this effect was equalized at 3-month time point postoperatively. MED brought advantages in shorter hospital stay, shorter operation time, less blood loss, and less cost over MIS-TLIF.There was no significant difference in 24-month function scores over time between MED group and MIS-TLIF group. Compared with MIS-TLIF, MED could result in a better perioperative effect and less cost.

Do We Have Adequate Flexion-extension Radiographs for Evaluating Instability in Patients With Lumbar Spondylolisthesis?

STUDY DESIGN

A retrospective cohort study of consecutive patients.

OBJECTIVE

To investigate whether adequate flexion-extension was acquired in standard functional radiographs in lumbar spondylolisthesis.

SUMMARY OF BACKGROUND DATA

In lumbar spondylolisthesis, flexion-extension radiographs taken in the standing position are most commonly used to evaluate spinal instability. However, these functional radiographs occasionally depend on the patient's effort and cooperation, they can provide different results.

METHODS

This study included 92 consecutive patients diagnosed with L4-5 degenerative lumbar spondylolisthesis. We analyzed the flexion-extension radiographs taken with the patient being led by the hand (LH) and those taken without LH (NLH). Sagittal translation (ST), segmental angulation (SA), posterior opening (PO), and lumbar lordosis (LL) were measured on functional radiographs taken in both tests. Then, ST, SA, PO, detection rate of instability, and LL observed in LH were compared with those observed in NLH. Furthermore, the correlation of the difference was evaluated between ST, lumbar angulation, and LL.

RESULTS

A relative value of ST was 9.5% ± 4.3% in LH and 5.6% ± 3.3% in NLH, which differed significantly (P < 0.001). SA and PO were also significantly greater in LH than in NLH. The detection rate of instability was 71.7% in LH and 30.4% in NLH (P < 0.001). LL measurement on flexion showed 17.6° ± 13.5° in LH and 28.2° ± 12.2° in NLH, which differed significantly (P < 0.001). However, no significant difference was found in LL on extension between LH and NLH. There was a moderate correlation between the difference of ST, SA, PO, and LL on flexion.

CONCLUSION

Flexion with physical assistance was useful for the detection of abnormal lumbar mobility. Taking radiation exposure into consideration, physical assistance such as using a table in front of a patient could lead the similar evaluation of the segmental instability.

LEVEL OF EVIDENCE

2.

Comparison of Posterior Lumbar Interbody Fusion and Microendoscopic Muscle-preserving Interlaminar Decompression for Degenerative Lumbar Spondylolisthesis With >5-Year Follow-up

STUDY DESIGN

Retrospective analysis of prospectively collected observational multicenter data.

OBJECTIVE

To compare the clinical results and rates of revision surgery after posterior lumbar interbody fusion (PLIF) and microendoscopic muscle-preserving interlaminar decompression (ME-MILD) in patients with single-level, mild degenerative lumbar spondylolisthesis (DLS) and follow-up of at least 5 years.

SUMMARY OF BACKGROUND DATA

Surgery for symptomatic DLS remains controversial. Evaluating long-term results may reveal problems such as adjacent segmental diseases of the PLIF and decreased quality of life because of slippage and restenosis of the ME-MILD.

METHODS

We enrolled 116 patients who underwent PLIF (79 patients) or ME-MILD (37 patients). Operative times, blood losses, surgical complications, Short-Form 36 (SF-36), Japanese Orthopedic Association (JOA) score, the JOA Back Pain Questionnaire (JOABPEQ), visual analog scales (VAS), and Zurich Claudication Questionnaire (ZCQ) were evaluated.

RESULTS

PLIF was observed to require significantly longer operative times and entailed greater operative blood losses than did ME-MILD (151.1 vs. 119.9 min; 202.2 vs. 6.4 mL, respectively). Surgery-related complications were identified in 3 cases in the PLIF group and 2 cases in the ME-MILD group. Seventy-eight patients (50 and 28 patients in the PLIF and ME-MILD groups, respectively) were successfully followed-up for >5 years. The follow-up rate was 67.2%. No significant differences between the groups were found in terms of preoperative and postoperative JOA scores, postoperative JOABPEQ, VAS, or ZCQ. Significant improvements in JOA scores were observed in both groups. Significant improvements in the SF-36 were observed in all subscales except in role physical, general health, vitality, and mental health in the ME-MILD group. Revision surgical procedures were performed in 2 patients in the ME-MILD group and 4 patients in the PLIF group.

CONCLUSIONS

PLIF and ME-MILD resulted in equivalent improvements in SF-36 and JOA scores. There were no differences in revision surgery rates among patients with single-level, mild DLS.

LEVEL OF EVIDENCE

Level III-a retrospective analysis.

Tubular surgery with the assistance of endoscopic surgery via a paramedian or midline approach for lumbar spinal canal stenosis at the L4/5 level

BACKGROUND

Lumbar spinal canal stenosis surgery has recently improved with the use of minimally invasive techniques. Less invasive procedures have emerged, and microendoscopic decompression through smaller incisions is frequently performed. Tubular surgery with the assistance of endoscopic surgery procedures has led to particularly remarkable changes in surgery, with reduced tissue trauma and morbidity.

PURPOSE

The purpose of this study was to compare the clinical outcomes of two different minimally invasive decompressive surgical techniques (microendoscopic bilateral decompression surgery using the unilateral approach [microendoscopic laminectomy (MEL)] and microendoscopy-assisted muscle-preserving interlaminar decompression (MILD; ME-MILD)) using spinal endoscopy for lumbar spinal canal stenosis measured using a visual analog scale (VAS), the Japanese Orthopedic Association (JOA) score, and the JOA Back Pain Evaluation Questionnaire (JOABPEQ), which is based on a patient-oriented scoring system.

STUDY DESIGN

This study was a retrospective review of prospectively collected surgical data.

METHODS

The study included 81 patients (MEL 39 patients, 20 men and 19 women, mean age 68.9 years; and ME-MILD 42 patients, 22 men and 20 women, mean age 73.1 years) with lumbar spinal stenosis (LSS). The indications for surgery were moderate-to-severe stenosis, persistent neurological symptoms, and failure of conservative treatment over 3 months, with a JOA score under 15 points or intermittent claudication at 100 m. This study included patients having LSS at a single vertebral level (L4/5).

RESULTS

Low back pain, buttock-leg pain, and numbness were significantly improved in terms of the VAS score from 3 months with both MEL and ME-MILD. In all periods, JOA scores over 3 years of follow-up were significantly higher than those obtained before surgery with both MEL and ME-MILD, and there were improvements of low back pain and walking function.

CONCLUSIONS

These observations demonstrate that ME-MILD is a safe and very effective minimally invasive technique for degenerative LSS, similar to MEL.

Influence of incidental dural tears and their primary microendoscopic repairs on surgical outcomes in patients undergoing microendoscopic lumbar surgery

BACKGROUND CONTEXT

Dural tear represents a common complication of microendoscopic spine surgery that may lead to postoperative sequelae including insufficient decompression, cerebrospinal fluid fistula, intracranial hypotension, and subdural/intraparenchymal bleeding. The gold standard to manage intraoperative dural tears is primary repair. However, the downside of conversion to open surgery can be detrimental. Therefore, understanding the most appropriate strategy for microendoscopic dural repair and its impact on postoperative outcomes is of importance.

PURPOSE

The purpose of this study was to investigate the incidence of dural tears in patients undergoing microendoscopic lumbar surgery and to elucidate their influence on surgical outcomes whenever proper repair is accomplished microendoscopically without conversion to open surgery.

STUDY DESIGN/SETTING

A retrospective multicenter cohort study of prospectively enrolled patients using a propensity-matched analysis.

PATIENT SAMPLE

A total of 922 consecutive patients underwent microendoscopic surgery of the lumbar spine between February and December 2012 in the three institutions belonging to our study group.

OUTCOME MEASURES

Outcome measures included the Numeric Rating Scale for back and leg pain, Oswestry Disability Index, Japanese Orthopaedic Association score, Short Form-36, and a patients' satisfaction scale.

METHODS

All incidental dural tears were repaired by microendoscopic suture of the dura mater from inside to outside using double-arm needles and/or by fibrin glue coverage without being converted to open surgery. Surgical outcomes were compared between patients with and without dural tears using a propensity-matched analysis.

RESULTS

Microendoscopic discectomy for lumbar disc herniation was performed on 474 patients, whereas microendoscopic laminectomy and posterior lumbar interbody fusion for lumbar canal stenosis were performed on 271 and 177 patients, respectively. Dural tears occurred in 49 (5.3%) patients. Of these, 23 (2.5%) patients required suture repair, whereas the rest received a fibrin patch for a pinhole tear, all of which were successfully performed under microendoscopy. Six hundred (65.1%) patients responded pre- and postoperatively to the questionnaire. Of them, the responses of 38 patients with dural tears were compared with those of 38 matched patients. No significant differences in any outcome measures were observed between the two groups.

CONCLUSIONS

In conclusion, all dural tears in our cases were managed without conversion to open surgery and did not influence surgical outcomes.

Mid-term Clinical Results of Microendoscopic Decompression for Lumbar Foraminal Stenosis

Introduction

There have been several reports on surgical techniques involving microendoscopy or percutaneous endoscopy for treating lumbar foraminal stenosis (LFS). However, no studies have assessed the mid-term clinical results of endoscopic techniques in spite of their relatively long history. In this study, we report 20 consecutive cases of LFS treated by our microendoscopic technique focusing on clinical results with a follow-up of at least two years.

Methods

Twenty consecutive cases of LFS treated with microendoscopic decompression were followed up at 1, 2, 6, and 12 months postoperatively and annually thereafter. The patients were 14 males and 6 females, and the mean age at the time of surgery was 64.7 years. The Japanese Orthopaedic Association (JOA) score was used as the clinical outcome index.

Results

Of the 20 patients, 16 were monitored successfully for more than 2 years. The follow-up rate was 80.0%, and the mean follow-up period was 66.3 months. The JOA score improved from 13.8 points before surgery to 24.6 points at final follow-up. Revision fusion surgeries were performed in two cases for LFS recurrence.

Conclusions

The microendoscopic technique effectively treats LFS.

Early Outcomes of Endoscopic Contralateral Foraminal and Lateral Recess Decompression via an Interlaminar Approach in Patients with Unilateral Radiculopathy from Unilateral Foraminal Stenosis

OBJECTIVE

Percutaneous endoscopic contralateral interlaminar lumbar foraminotomy (PECILF) for lumbar degenerative spinal stenosis is an established procedure. Better preservation of contralateral facet joint compared with that of the approach side has been shown with uniportal bilateral decompression. The aim of this retrospective case series was to analyze the early clinical and radiologic outcomes of stand-alone contralateral foraminotomy and lateral recess decompression using PECILF.

METHODS

Twenty-six consecutive patients with unilateral lower limb radiculopathy underwent contralateral foraminotomy and lateral recess decompression using PECILF. Their clinical outcomes were evaluated with visual analog scale leg pain score, Oswestry Disability Index, and the MacNab criteria. Completeness of decompression was documented with a postoperative magnetic resonance imaging.

RESULTS

Mean age for the study group was 62.9 ± 9.2 years and the male/female ratio was 4:9. A total of 30 levels were decompressed, with 18 patients (60%) undergoing decompression at L4-L5, 9 at L5-S1 (30%), 2 at L3-L4 (6.7%), and 1 at L2-L3 (3.3%). Mean estimated blood loss was 27 ± 15 mL per level. Mean operative duration was 48 ± 12 minutes/level. Visual analog scale leg score improved from 7.7 ± 1 to 1.8 ± 0.8 (P < 0.0001). Oswestry Disability Index improved from 64.4 ± 5.8 to 21 ± 4.5 (P < 0.0001). Mean follow-up of the study was 13.7 ± 2.7 months. According to the MacNab criteria, 10 patients (38.5%) had good results, 14 patients (53.8%) had excellent results, and 2 patients (7.7%) had fair results. One patient required revision surgery.

CONCLUSIONS

Facet-preserving contralateral foraminotomy and lateral recess decompression with PECILF is effective for treatment of lateral recess and foraminal stenosis. Thorough decompression with acceptable early clinical outcomes and minimal perioperative morbidity can be obtained with the contralateral endoscopic approach.

Lumbar Degenerative Spondylolisthesis: Changes in Surgical Indications and Comparison of Instrumented Fusion With Two Surgical Decompression Procedures

STUDY DESIGN

Single-center retrospective case series.

OBJECTIVE

To compare outcomes of instrumented fusion and two methods of decompression for degenerative spondylolisthesis.

SUMMARY OF BACKGROUND DATA

There is no consensus on the surgical indications or optimum techniques for lumbar degenerative spondylolisthesis.

METHODS

We analyzed the data of 140 patients treated by fusion (n = 80; mean follow-up, 77.9 months) or decompression (n = 60; mean follow-up, 38.0 months) and examined changes in surgical indications over a 12-year period. We compared the outcomes of instrumented fusion with the outcomes of two decompression techniques, the first employing a unilateral approach for bilateral decompression and the second employing a bilateral approach for contralateral decompression, with contralateral foraminal decompression as needed. Postoperative evaluation was made at the final follow-up visit beginning in 2007 by analyzing patient interviews and neurological examination data. We compared results with the Japanese Orthopedic Association symptom score before surgery and at final follow-up.

RESULTS

Surgical indications for fusion narrowed over time, with fusion used less frequently and decompression used more frequently. Similar decreases in clinical symptoms, including low back pain, were achieved with all methods. In the decompression groups, preoperative slip distance and instability, and postoperative slip progression or development of instability, did not correlate significantly with clinical outcome. Slip progression occurred in 8 of 10 levels in patients with preoperative translation ≥5 mm, but these patients showed no increase in instability, defined as translation ≥ 2 mm, at final follow-up.

CONCLUSION

Our findings raise a question about the value of the radiologic criteria for performing fusion used in the late period, namely translation ≥5 mm and/or rotation ≥ 10°. If discogenic pain is excluded, decompression alone may be suitable even for patients with severe low back pain and translation ≥5 mm.

LEVEL OF EVIDENCE

4.

Efficacy of intraoperative direct electrical stimulation of the spinal root and measurement of distal motor latency in lumbar spinal stenosis

PURPOSE

The measurement of distal motor latency (DML) is an established method for diagnosing entrapment peripheral neuropathy. DML can also serve as an index for disease severity and prognosis. We considered that measuring DML could be useful in estimating the severity of spinal root impairment and predicting prognosis in patients with lumbar spinal stenosis (LSS). The purpose of this study was to investigate the efficacy of intraoperative direct electrical stimulation of the spinal root and the measurement of DML in LSS.

METHODS

In 39 patients with LSS, a total of 93 spinal roots were stimulated, and evoked electromyography was recorded at the leg muscles after decompression. DML was measured and its correlation with clinical severity, as evaluated by Zurich claudication questionnaire (ZCQ) and Short Form 36 (SF-36), was investigated.

RESULTS

For the stimulation of the L3, L4, and L5 spinal root, the mean DML (ms) were 6.8 (±1.4), 7.4 (±1.3), and 6.0 (±1.3) in gluteus medius, 9.3 (±1.5), 9.2 (±1.5), and 9.0 (±1.6) in biceps femoris, 9.7 (±1.0), 9.8 (±1.8), and 9.4 (±1.2) in vastus medialis, 16.1 (±1.0), 14.7 (±1.3), and 14.1 (±1.5) in tibialis anterior, and 16.4 (±1.4), 14.3 (±1.8), and 13.9 (±1.9) in gastrocnemius muscles. Statistically significant positive correlations were observed between DML and height. Preoperative symptom and function scores of ZCQ and postoperative bodily pain scores of SF-36 were significantly worse in the patients with prolonged DML.

CONCLUSIONS

DML is thought to be useful for estimating the severity of spinal root impairment and for predicting the prognosis.

Significance of Coronal Proset Magnetic Resonance Imaging to Detect Hidden Zone of the Mid-Zone Stenosis in the Lumbar Spine and Morphometric Analysis of the Mid-Zone Stenosis

STUDY DESIGN

Retrospective exploratory imaging study.

PURPOSE

To investigate the significance of the coronal magnetic resonance imaging (MRI) using Proset technique to detect the hidden zone in patients with mid-zone stenosis by comparing with conventional axial and sagittal MRI and to explore the morphologic characteristic patterns of the mid-zone stenosis.

OVERVIEW OF LITERATURE

Despite advancements in diagnostic modalities such as computed tomography and MRI, stenotic lesions under the pedicle and pars interarticularis, also called the mid-zone, are still difficult to definitely detect with the conventional axial and sagittal MRI due to its inherited anatomical peculiarity.

METHODS

Of 180 patients scheduled to undergo selective nerve root block, 20 patients with mid-zone stenosis were analyzed using MRI. Characteristic group patterns were also explored morphologically by comparing MRI views of each group after verifying statistical differences between them. Hierarchical cluster analysis was performed to classify morphological characteristic groups based on three-dimensional radiologic grade for stenosis at all three zones.

RESULTS

At the mid-zone, the stenosis of grade 2 or more was found in 14 cases in the coronal image,13 cases in the sagittal image, and 9 cases in the axial image (p<0.05). Especially, mid-zone stenosis was not detected in six of 20 cases at the axial images. At the entrance and exit-zone, coronal image was also associated with more accurate detection of hidden zone compared to other views such as axial and sagittal images. After repeated statistical verification, the morphological patterns of hidden zone were classified into 5 groups: 6 cases in group I; 1 case in group II; 4 cases in group III; 7 cases in group IV; and 2 cases in group V.

CONCLUSIONS

Coronal MRI using the Proset technique more accurately detected hidden zone of the mid-zone stenosis compared to conventional axial and sagittal images.