How to Prevent Nerve Root Injury in Uniportal Full Endoscopic Lumbar Fusion Surgery? Insights from a Cadaveric Anatomical Study with Simulation Surgery.

STUDY DESIGN: The study included two fresh-frozen cadavers. OBJECTIVE: To elucidate the positional relationship between surgical instruments and nerve roots during full endoscopic facet-sparing (FE fs-TLIF) and facet-resecting (FE fr-TLIF) lumbar interbody fusion and propose safe instrumentation insertion procedures and recommend cage glider designs aimed at protecting nerve roots. SUMMARY OF BACKGROUND DATA: Endoscopic surgical techniques are increasingly used for minimally invasive lumbar fusion surgery with FE fr-TLIF and FE fs-TLIF being common approaches. However, the risk of nerve root injury remains a significant concern during these procedures. METHODS: Eight experienced endoscopic spine surgeons performed uniportal FE fr-TLIF and FE fs-TLIF on cadaveric lumbar spines, totaling 16 surgeries. Post-operation, soft tissues were removed to assess the positional relationship between the cage entry point and nerve roots. Distances between the cage entry point, traversing nerve root, and exiting nerve root were measured. Safe instrumentation design and insertion procedures were determined. RESULTS: In FE fr-TLIF, the mean distance between the cage entry point and traversing nerve root was significantly shorter compared to FE fs-TLIF (3.30±1.35 mm vs. 8.58±2.47 mm, respectively; P<0.0001). Conversely, the mean distance between the cage entry point and the exiting nerve root was significantly shorter in FE fs-TLIF compared to FE fr-TLIF (3.73±1.97 mm vs. 6.90±1.36 mm, respectively; P<0.0001). For FE fr-TLIF, prioritizing the protection of the traversing root using a two-bevel tip cage glider was crucial. In contrast, for FE fs-TLIF, a single-bevel tip cage glider placed in the caudal location was recommended. CONCLUSION: This study elucidates the anatomical relationship between cage entry points and nerve roots in uniportal endoscopic lumbar fusion surgery. Protection strategies should prioritize the traversing root in FE fr-TLIF and the exiting root in FE fs-TLIF, with corresponding variations in surgical techniques. LEVEL OF EVIDENCE: V.

Percutaneous endoscopic lumbar discectomy versus open lumbar microdiscectomy for treating lumbar disc herniation: Using the survival analysis.

Objectives: This study compared the risk of symptomatic recurrent disc herniation and clinical outcomes of percutaneous endoscopic lumbar discectomy (PELD) versus open lumbar microdiscectomy (OLM) for lumbar disc herniation with 2 years of follow-up. Materials and Methods: We analyzed 23 patients who underwent PELD and 32 patients who underwent OLM for lumbar disc herniation. The numeric rating scale of back and leg pain, Oswestry Disability Index (ODI), and Roland-Morris Disability Questionnaire (RMDQ) were assessed before and at 12 and 24 months after the surgery. The wound pain and complications were also recorded. Survival analysis was performed to estimate the risk of symptomatic recurrent disc herniation. Results: In the comparison of groups, the reductions in back and leg pain, ODI, and RMDQ were not significantly different at 12 and 24 months. For patients who underwent PELD, the wound pain was significant lower at the day of surgery. The survival rate of patients who were free from symptomatic recurrent disc herniation at 24 months was 0.913 in PELD and 0.875 in OLM, and the log-rank test revealed no significant difference between the two survival curves. The incidence of complication was not significantly different between groups. Conclusion: Both PELD and OLM are effective treatments for lumbar disc herniation because they have similar clinical outcomes. PELD provided patients with less painful wounds. The survival analysis revealed that the risk of symptomatic recurrent disc herniation in 2 years of follow-up was not different between PELD and OLM.

Full Endoscopic Spine Surgery for Cervical Spondylotic Myelopathy: A Systematic Review.

BACKGROUND: Cervical spondylotic myelopathy (CSM) may seriously affect quality of life. In the literature, there is scarce evidence of the pros and cons of full endoscopic spine surgery in the treatment of CSM. The main purpose of this study was to conduct a systematic review to elucidate the efficacy of full endoscopic spine surgery in the management of patients with CSM. METHODS: This systematic review was conducted in accordance with the PRISMA guidelines. A systematic search of Web of Science, PubMed MEDLINE, Embase, and Cochrane Library was conducted from the database inception to February 1, 2023. RESULTS: The study included 183 patients and their age was 56.78 ± 7.87 years. The average surgical time calculated was 96.34 ± 33.58 minutes. Intraoperative blood loss ranged from a minimal amount to 51 mL. The average duration of hospital stay was 3.56 ± 1.6 days. The average span for follow-up was on an interval of 18.7 ± 6.76 months. Significant improvements were noted in all aspects of functional outcomes and image results after full endoscopic cervical spine surgery, with no major complications. CONCLUSIONS: The current study found that both anterior transcorporeal and posterior surgical approaches could be used for the treatment of CSM with a full endoscopic technique. Indications of full endoscopic cervical spine surgery for CSM included cervical disc herniation, central canal stenosis, calcified ligamentum flavum, and ossification of the posterior longitudinal ligament. Improved postoperative outcomes with acceptable surgical complications were noted in this systematic review.

Near infrared imaging system for preventing blood vision obstruction in endoscopy.

Spinal endoscopy procedure is commonly used in the diagnosis and treatment of various health problems and is effective. Bleeding is one of the most common complications of spinal endoscopy procedures. Blood vision obstruction (BVO), that is, obstruction of the endoscopic camera lens caused by the accumulation of blood in the surgical field, is a serious problem in endoscopic procedures. This study presents what we believe to be a new approach to addressing BVO with external multispectral imaging. The study was completed using a BVO simulation model, and the results reveal that this technology can be used to effectively overcome BVO and provide clear images of the anatomy, enabling more effective diagnosis and treatment. This technique may enable improvement of the outcomes of endoscopic procedures and could have far-reaching implications in the field of endoscopy.

Comparison Between Lumbar Endoscopic Unilateral Laminotomy for Bilateral Decompression and Other Decompression Approaches for Lumbar Spinal Stenosis: A Systematic Review.

BACKGROUND: Lumbar spinal stenosis affects numerous people globally. Full-endoscopic uniportal interlaminar decompression (FEUID) for lumbar spinal stenosis results in satisfactory outcomes. In this systematic review, we compared technical methods, surgical outcomes, and complications among different types of surgical techniques and discussed the effect of different surgical skill levels. METHODS: A systematic review of studies published from 1990 to January 2022 was performed. Studies related to FEUID were identified using the keywords "interlaminar decompression," "endoscopy," "uniportal," and "percutaneous." The outcomes measured were operative time, blood loss, hospital stay, complications, visual analog scale scores, Oswestry Disability Index scores, and the Macnab criteria. RESULTS: Ten of 306 studies were eligible for inclusion. For FEUID, data for 580 patients and more than 367 levels were collected. All the studies reported significant improvement in mean visual analog scale and Oswestry Disability Index scores, and the mean overall complication rate was 9.5%. Compared with other surgical techniques, FEUID resulted in lower visual analog scale and Oswestry Disability Index scores, complication rates, and blood loss and shorter hospital stay. These surgical parameters were considerably affected by a surgeon's skill level. CONCLUSION: FEUID results in better patient satisfaction with more favorable surgical outcomes and fewer complications. Although more prospective randomized controlled studies are required to confirm these findings, our results indicate that FEUID is a reasonable alternative to traditional lumbar spinal surgery.

Cauda equina syndrome caused by the application of DuraSealTM in a microlaminectomy surgery: A case report.

BACKGROUND: The management of dural tears is important. While a massive dura can be repaired with absorbable suture lines, cerebrospinal fluid leakage can be attenuated by dural sealant when an unintended tiny durotomy occurs intraoperatively. DuraSeal is often used because it can expand to seal tears. This case emphasizes the need for caution when DuraSeal is used as high expansion can cause complications following microlaminectomy. CASE SUMMARY: A 77-year-old woman presented with L2/3 and L3/4 lateral recess stenosis. She underwent microlaminectomy, foraminal decompression, and disk height restoration using an IntraSPINE® device. A tiny incident durotomy occurred intraoperatively and was sealed using DuraSealTM. However, decreased muscle power, urinary incontinence, and absence of anal reflexes were observed postoperatively. Emergent magnetic resonance imaging revealed fluid collection causing thecal sac indentation and central canal compression. Surgical exploration revealed that the gel-like DuraSeal had entrapped the hematoma and, consequently, compressed the thecal sac and nerve roots. While we removed all DuraSealTM and exposed the nerve root, the patient's neurological function did not recover postoperatively. CONCLUSION: DuraSeal expansion must not be underestimated. Changes in neurological status require investigation for cauda equina syndrome due to expansion.

Correlation between corneal dynamic responses and keratoconus topographic parameters.

OBJECTIVE: To investigate the correlation between corneal biomechanical properties and topographic parameters using machine learning networks for automatic severity diagnosis and reference benchmark construction. METHODS: This was a retrospective study involving 31 eyes from 31 patients with keratonus. Two clustering approaches were used (i.e., shape-based and feature-based). The shape-based method used a keratoconus benchmark validated for indicating the severity of keratoconus. The feature-based method extracted imperative features for clustering analysis. RESULTS: There were strong correlations between the symmetric modes and the keratoconus severity and between the asymmetric modes and the location of the weak centroid. The Pearson product-moment correlation coefficient (PPMC) between the symmetric mode and normality was 0.92 and between the asymmetric mode and the weak centroid value was 0.75. CONCLUSION: This study confirmed that there is a relationship between the keratoconus signs obtained from topography and the corneal dynamic behaviour captured by the Corvis ST device. Further studies are required to gather more patient data to establish a more extensive database for validation.

Comparison of anterior cervical discectomy and fusion versus artificial disc replacement for cervical spondylotic myelopathy: a meta-analysis.

OBJECTIVE: Anterior cervical discectomy and fusion (ACDF) has long been regarded as a gold standard in the treatment of cervical myelopathy. Subsequently, cervical artificial disc replacement (c-ADR) was developed and provides the advantage of motion preservation at the level of the intervertebral disc surgical site, which may also reduce stress at adjacent levels. The goal of this study was to compare clinical and functional outcomes in patients undergoing ACDF with those in patients undergoing c-ADR for cervical spondylotic myelopathy (CSM). METHODS: A systematic literature review and meta-analysis were performed using the Embase, PubMed, and Cochrane Central Register of Controlled Trials databases from database inception to November 21, 2021. The authors compared Neck Disability Index (NDI), SF-36, and Japanese Orthopaedic Association (JOA) scores; complication rates; and reoperation rates for these two surgical procedures in CSM patients. The Mantel-Haenszel method and variance-weighted means were used to analyze outcomes after identifying articles that met study inclusion criteria. RESULTS: More surgical time was consumed in the c-ADR surgery (p = 0.04). Shorter hospital stays were noted in patients who had undergone c-ADR (p = 0.04). Patients who had undergone c-ADR tended to have better NDI scores (p = 0.02) and SF-36 scores (p = 0.001). Comparable outcomes in terms of JOA scores (p = 0.24) and neurological success rate (p = 0.12) were noted after the surgery. There was no significant between-group difference in the overall complication rates (c-ADR: 18% vs ACDF: 25%, p = 0.17). However, patients in the ACDF group had a higher reoperation rate than patients in the c-ADR group (4.6% vs 1.5%, p = 0.02). CONCLUSIONS: At the midterm follow-up after treatment of CSM, better functional outcomes as reflected by NDI and SF-36 scores were noted in the c-ADR group than those in the ACDF group. c-ADR had the advantage of retaining range of motion at the level of the intervertebral disc surgical site without causing more complications. A large sample size with long-term follow-up studies may be required to confirm these findings in the future.

The Influence of Nordic Walking on Spinal Posture, Physical Function, and Back Pain in Community-Dwelling Older Adults: A Pilot Study.

Nordic walking is an increasingly popular form of exercise among the elderly. Using poles is thought to facilitate a more upright posture; however, previous studies primarily investigated the effects of Nordic walking on respiratory function and physical fitness. The aims of this study were to investigate the influence of Nordic walking on spinal posture, physical functions, and back pain in community-dwelling older adults. Thirty-one community-dwelling older adults aged ≥ 60 years participated in a twice weekly Nordic walking training program for 12 weeks. The outcome measures, including spinal posture, physical functions, back pain, and the strength and endurance of back extensor muscles were assessed before and after a 12-week program. After training, spinal posture, back pain, and the strength and endurance of back extensor muscles did not show any statistically significant changes. Among the seven clinical tests of physical function, only the 30 s arm curl test, the 30 s chair stand test, and the single leg stance test showed significant improvements. Nordic walking has limited influence on age-related hyperkyphosis and back pain, but may be effective for physical function. The results of this study can provide useful information for people involved in the prevention and treatment of physical dysfunction in community-dwelling older adults.

Outcome analysis of lumbar endoscopic unilateral laminotomy for bilateral decompression in patients with degenerative lumbar central canal stenosis.

BACKGROUND CONTEXT: Lumbar endoscopic unilateral laminotomy for bilateral decompression (LE-ULBD) has been reported as an alternative treatment for degenerative lumbar central canal stenosis (DLCS). PURPOSE: To investigate the outcomes of LE-ULBD for different types of DLCS, including simple DLCS, DLCS with degenerative spondylolisthesis (DSL), and DLCS with degenerative scoliosis (DSC). STUDY DESIGN/SETTING: Prospective cohort study. PATIENT SAMPLE: One-hundred sixteen patients with DLCS who underwent LE-ULBD at a spine center from April 2015 to June 2017 were enrolled in this study. OUTCOME MEASURES: Operative time, postoperative duration of hospitalization, and clinical outcomes (Oswestry disability index [ODI], visual analog scale [VAS], and modified Macnab outcome scale), and adverse events. METHODS: A comparative analysis was performed evaluating medical records, radiological studies, and patient reported outcomes including ODI score, VAS scores and modified Macnab outcome scales in patients who underwent LE-ULBD. Data were prospectively collected at preoperative, postoperative 3-, 6-, 12-, 24-month to assess clinical and radiological outcomes and complications. RESULTS: The study analyzed 106 patients (45 men and 61 women, with a mean age of 69.5 years); 40 (37.8%) had simple DLCS, 41 (38.7%) had DLCS with DSL, and 25 (23.5%) had DLCS with DSC. The mean follow-up period was 33.3 months. The mean preoperative and postoperative follow-up ODI score and VAS scores for leg and back pain showed significant improvement in all time points. No significant difference was found among different pathologies in terms of VAS scores for back and leg pain, ODI scores and modified Macnab outcome scales at all follow-up periods. CONCLUSIONS: LE-ULBD is a feasible treatment method for DLCS. It did not result in worse outcomes in cases with DLCS with DSL or DLCS with DSC as compared with cases with simple DLCS.

Full endoscopic interlaminar discectomy (FEID) for recurrent lumbar disc herniation: surgical technique, clinical outcome, and prognostic factors.

BACKGROUND: The objective of this study is to determine the effectiveness and prognostic factors of revisional full endoscopic interlaminar discectomy (FEID) for recurrent herniation after conventional open disc surgery. The major concerns of the repeated discectomy for recurrent lumbar disc herniation (RLDH) are the epidural scar and postoperative segmental instability. Compared to open discectomy, endoscopic method has advantages of less tissue traumatization, clearer visualization and better tissue identification. With the improvement of endoscopic technique and instrument, the problems related to adhesive scar tissues or postoperative instability could be overcome. METHODS: From June 2014 to December 2016, FEID was performed in consecutive 24 patients for RLDH. The age ranged from 25 to 60 years (mean 44.6 years). The level operated was L5-S1 in 16 cases and L4-5 in 8 cases. To avoid injury to the neural tissue, we started with the bony structure. A small part of facet or lamina might be resected in severe stenotic or adhesive condition. Aggressive separation of the scar from the neural tissue might lead to dural tear and should be avoided. The herniated disc material was removed after neural tissue had been clearly identified and protected. RESULTS: The follow-up period was at least 24 months. The visual analog scale (VAS) for leg pain and back pain, and Oswestry disability index (ODI) showed significant improvement after treatment. Excellent or good outcome by the modified Macnab's criteria was obtained in 22 of 24 patients at two years follow-up. Excellent outcome was noted in 100 percent patients younger than 50 years. Small durotomy occurred in 2 patients and no visible cerebrospinal fluid (CSF) leakage was detected despite repair was not performed. Two additional surgery was performed including one repeated FEID for re-recurrence of disc herniation and one fusion surgery for postoperative back pain. CONCLUSIONS: FEID is a safe and effective alternative for recurrent disc herniation. The successful rate was greater than 90 percent, especially in the younger patients with the advantages of early recovery and no need for fusion.

A rare complication of ipsilateral femoral neck fracture after removal of the long Gamma nail in a healed intertrochanteric fracture.

Ipsilateral femoral neck fracture after hardware removal in healed trochanteric fracture is a rare complication. We reported a case of a 79-year-old woman who had undergone open reduction and internal fixation for her left intertrochanteric fracture with a long Gamma nail about 1 year ago. She asked for implants removal due to local irritation. However, 5 days after implants removal, left subcapital femoral neck fracture occurred. Removal of implants under elective indications could lead to high complication rate. Orthopedic surgeons should perform the removal of hardware in healed intertrochanteric fracture for very selected cases.

Full Endoscopic Uniportal Unilateral Laminotomy for Bilateral Decompression in Degenerative Lumbar Spinal Stenosis: Highlight of Ligamentum Flavum Detachment and Survey of Efficacy and Safety in 2 Years of Follow-up.

OBJECTIVE: Conventional laminectomy for spine decompression involves inherent complications resulting from perioperative traumatization of posterior structures. Minimally invasive decompression was developed to address these issues. Full endoscopic spine surgery has shifted the paradigm from disc pathology to spinal stenosis by overcoming the limitation of bony procedures with evolving endoscopic instruments. However, a steep learning curve restricts the development of endoscopic decompression. The purpose of this study is to describe full endoscopic uniportal unilateral laminotomy for bilateral decompression through the interlaminar approach and to evaluate its efficacy and safety in 2 years of follow-up. METHODS: A total of 106 patients (45 men, 61 women) with degeneration lumbar stenosis involving 165 segments were enrolled from April 2015 to June 2017, and treated by full endoscopic uniportal unilateral laminotomy for bilateral decompression. We made an 8-mm incision and used a general-size endoscope (working channel 4.3 mm) to avoid neurological compromise during the demonstration. RESULTS: The visual analogue scale (VAS) results for back pain revealed a significant reduction from preoperative 6.8 ± 2.1 to 1.7 ± 1.7 after 2 years (P < 0.001). The VAS results for leg pain revealed a significant reduction from preoperative 7.6 ± 1.3 to 1.3 ± 1.6 after 2 years (P < 0.001). The Oswestry Disability Index showed significant improvement from preoperative 62.0 ± 13.9 to 14.6 ± 15.7 after 2 years (P < 0.001). The average operation time was 68.9 ± 10.0 minutes per level. One case had iatrogenic durotomy, 1 case underwent revision surgery due to incomplete decompression, and 2 cases had delayed wound healing. CONCLUSIONS: This procedure obtained successful and satisfactory outcomes for patients, and was more feasible for surgeons.

Topically Applied Cross-Linked Hyaluronan Attenuates the Formation of Spinal Epidural Fibrosis in a Swine Model of Laminectomy.

Epidural fibrosis is an inevitable aspect of the postoperative healing process which is one of the causes of failed back surgery syndrome following spinal surgery. The aim of the present study was to examine the inhibitory effect of 1,4-butanediol diglycidyl ether-crosslinked hyaluronan (cHA) on spinal epidural fibrosis in a swine model. Epidural fibrosis was induced through conduction of hemi-laminotomy (L2 and L3) or laminectomy (L4 and L5), while L1 was assigned as the control group in six pigs. The cHA was applied to L3 and L5 surgical sites. MRI evaluation, histologic examination, expressions of matrix metalloproteinases (MMPs), and cytokines in scar tissue were assessed four months after surgery. cHA treatment significantly decreased the scar formation in both hemi-laminotomy and laminectomy sites. cHA also significantly increased MMP-3 and MMP-9 expression in scar tissue. Further, the epithelial-mesenchymal transition -related factors (transforming growth factor-ß and vimentin) were suppressed and the anti-inflammatory cytokines (CD44 and interleukin-6) were increasingly expressed in cHA-treated sites. The current study demonstrated that cHA may attenuate spinal epidural fibrosis formation after laminectomy surgery by enhancing the expression of MMPs and anti-inflammatory pathways.

Technique using the modified rolling hitch for split peroneus brevis tendon transfer in lateral ankle stabilization.

We report our technique for split peroneus brevis lateral ankle stabilization using the modified rolling hitch for tendon graft fixation. Applying the modified rolling hitch for tendon grasping in this procedure was useful, and it could decrease the surgical time and avoid the tendon injury caused by the needle.

Efficacy of topical cross-linked hyaluronic acid hydrogel in preventing post laminectomy/laminotomy fibrosis in a rat model.

Post-laminectomy/laminotomy epidural fibrosis (EF) has been implicated as an important cause of failed back syndrome (FBS). The various clinical approaches used to control EF yield mixed outcomes. Cross-linked hyaluronic acid hydrogel (cHA) was synthesized to increase mechanical stability and residence time. We evaluated the therapeutic attenuation of proliferative EF in laminectomy/laminotomy groups treated and not treated with cHA. A bilateral T11-L1 total laminectomy or unilateral T12 laminotomy was done on four groups (n = 10 each) of Sprague-Dawley rats and then histologically examined 2 months post-surgery: (I) laminectomy group treated with and (II) not treated with cHA, (III) laminotomy group treated with and (IV) not treated with cHA. The grade of EF, the diameters within the spinal canal, dura mater thickness, and the area of the epidural space, subarachnoid space, and conus medullaris space were assessed. The cHA-treated subgroups (I, III) had a significantly lower grade of EF, thinner dura mater, and larger epidural and subarachnoid spaces than did the control subgroups (II, IV) (p < 0.05). The cHA formed a solid interpositional membrane barrier that prevented invasive fibrosis, and also helped reduce pathological changes to the adjacent structures. In conclusion, topically applied cHA is effective for reducing EF.

Citing a Data Repository: A Case Study of the Protein Data Bank.

The Protein Data Bank (PDB) is the worldwide repository of 3D structures of proteins, nucleic acids and complex assemblies. The PDB's large corpus of data (> 100,000 structures) and related citations provide a well-organized and extensive test set for developing and understanding data citation and access metrics. In this paper, we present a systematic investigation of how authors cite PDB as a data repository. We describe a novel metric based on information cascade constructed by exploring the citation network to measure influence between competing works and apply that to analyze different data citation practices to PDB. Based on this new metric, we found that the original publication of RCSB PDB in the year 2000 continues to attract most citations though many follow-up updates were published. None of these follow-up publications by members of the wwPDB organization can compete with the original publication in terms of citations and influence. Meanwhile, authors increasingly choose to use URLs of PDB in the text instead of citing PDB papers, leading to disruption of the growth of the literature citations. A comparison of data usage statistics and paper citations shows that PDB Web access is highly correlated with URL mentions in the text. The results reveal the trend of how authors cite a biomedical data repository and may provide useful insight of how to measure the impact of a data repository.

Changes in excursion and strain in the rat sciatic nerve under cauda equina compression induced by epidural balloon inflation.

BACKGROUND CONTEXT: Healthy nerves are able to stretch and glide as responses to normal physiological movement. Injury to the nerve may alter the nerve's mechanical properties and result in neuropathy. Whether cauda equina compression alters the mechanical properties of the sciatic nerve is still unclear. PURPOSE: The purpose of this study was to demonstrate the changes in excursions and strains of the sciatic nerve in vivo after acute cauda equina compression was induced by epidural balloon compression. STUDY DESIGN: An animal comparative study with induced cauda equina compression was designed for in situ measurements of nerve properties. METHODS: Twenty-six adult Sprague-Dawley rats were divided into three groups. The balloon group (n=10) underwent epidural compression induced by inflation of an embolectomy balloon catheter that was inserted through an L6 laminotomy. The control group (n=10) underwent laminotomy but without compression. The normal group (n=6) received no back surgery. This model of neuropathy was confirmed with electrophysiological examination. The excursions and strains of the sciatic nerve in response to the modified straight leg-raising (SLR) test were measured in situ and analyzed. RESULTS: The scales of the excursions were lower in the balloon group than in the other two groups, in both 90° flexion and extension of the knee. The balloon group was more sensitive to positional changes. The strain was significantly higher under the condition of epidural balloon compression. CONCLUSIONS: We concluded that cauda equina compression decreased the excursion and increased the strain of the sciatic nerve in response to a modified SLR test. These findings might indicate one of the mechanisms of the pain provoked by the SLR test and also possibly contribute to an understanding of the pathogenesis of the neuropathy in the lower limbs of patients with cauda equina compression.

Significance of the mass-compression effect of postlaminectomy/laminotomy fibrosis on histological changes on the dura mater and nerve root of the cauda equina: an experimental study in rats.

PURPOSE: The precise mechanism and pathological role of postlaminectomy/laminotomy fibrosis (PLF) in postoperative neurological deficits have not been established. Many studies use magnetic resonance imaging (MRI) to prove that there is no consistent correlation between PLF and postoperative neurological deficits and back pain (PNDBP). Therefore, we assumed that the direct-compression effect may not be the only factor but that other neurological deficits associated with pathological mechanisms should exist and need more investigation. The purpose of this study was to compare over time the differences and changes in histopathological properties of PLF in rats. METHODS: We used a rat model with walking-track analysis for neurologic evaluation, grading scale to evaluate PLF, histomorphometric measurements of dura sac diameter, and histological tissue reactions (dura mater and spinal rootlets) juxtaposed to the postlaminectomy/laminotomy defect. The 54 adult Sprague-Dawley rats were divided into laminotomy (n = 18), laminectomy (n = 18), and sham-operation groups (n = 18). All groups were subdivided into three equal subgroups based on different postoperative time points (1, 2, and 3 months). All sections of vertebral column were stained with hematoxylin and eosin and with Masson's trichrome. RESULTS: The results showed that only a slight compression effect reflected by nonsignificant changes in the maximum anterior-posterior diameters within the dura sac, in the walking tract test, and increased grades of PLF over time. In addition, significant pathological inflammatory changes, such as thickening of the dura mater, axonal swelling, and neovascularization, were found in the post-laminectomy/laminotomy groups at each time point. CONCLUSION: Laminectomy-/laminotomy-related inflammation may lead to PLF, and these pathological changes may be the main cause of postoperative neurological deficits. These findings show that research on preventing PLF should include perioperative modulation of inflammatory reactions induced by laminectomy/laminotomy.

A ν-support vector regression based approach for predicting imputation quality.

BACKGROUND: Decades of genome-wide association studies (GWAS) have accumulated large volumes of genomic data that can potentially be reused to increase statistical power of new studies, but different genotyping platforms with different marker sets have been used as biotechnology has evolved, preventing pooling and comparability of old and new data. For example, to pool together data collected by 550K chips with newer data collected by 900K chips, we will need to impute missing loci. Many imputation algorithms have been developed, but the posteriori probabilities estimated by those algorithms are not a reliable measure the quality of the imputation. Recently, many studies have used an imputation quality score (IQS) to measure the quality of imputation. The IQS requires to know true alleles to estimate. Only when the population and the imputation loci are identical can we reuse the estimated IQS when the true alleles are unknown. METHODS: Here, we present a regression model to estimate IQS that learns from imputation of loci with known alleles. We designed a small set of features, such as minor allele frequencies, distance to the nearest known cross-over hotspot, etc., for the prediction of IQS. We evaluated our regression models by estimating IQS of imputations by BEAGLE for a set of GWAS data from the NCBI GEO database collected from samples from different ethnic populations. RESULTS: We construct a ν-SVR based approach as our regression model. Our evaluation shows that this regression model can accomplish mean square errors of less than 0.02 and a correlation coefficient close to 0.75 in different imputation scenarios. We also show how the regression results can help remove false positives in association studies. CONCLUSION: Reliable estimation of IQS will facilitate integration and reuse of existing genomic data for meta-analysis and secondary analysis. Experiments show that it is possible to use a small number of features to regress the IQS by learning from different training examples of imputation and IQS pairs.