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A Retrospective Analysis of Pedicle Screw Placement Accuracy Using the ExcelsiusGPS Robotic Guidance System

Operative Neurosurgery 24:242–247, 2023

Robotic guidance has become widespread in spine surgery. Although the intent is improved screw placement, further system-specific data are required to substantiate this intention for pedicle screws in spinal stabilization constructs.

OBJECTIVE: To determine the accuracy of pedicle screws placed with the aid of a robot in a cohort of patients immediately after the adoption of the robot-assisted surgery technique.

METHODS: A retrospective, Institutional Review Board–approved study was performed on the first 100 patients at a single facility, who had undergone spinal surgeries with the use of robotic techniques. Pedicle screw accuracy was graded using the Gertzbein– Robbins Scale based on pedicle wall breach, with grade A representing 0 mm breach and successive grades increasing breach thresholds by 2 mm increments. Preoperative and postoperative computed tomography scans were also used to assess offsets between the objective plan and true screw placements.

RESULTS: A total of 326 screws were analyzed among 72 patients with sufficient imaging data. Ages ranged from 21 to 84 years. The total accuracy rate based on the Gertzbein– Robbins Scale was 97.5%, and the rate for each grade is as follows: A, 82%; B, 15.5%; C, 1.5%; D, 1%; and E, 0. The average tip offset was 1.9 mm, the average tail offset was 2.0 mm, and the average angular offset was 2.6°.

CONCLUSION: Robotic-assisted surgery allowed for accurate implantation of pedicle screws on immediate adoption of this technique. There were no complications attributable to the robotic technique, and no hardware revisions were required.

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Rod fractures in thoracolumbar fusions to the sacrum/pelvis for adult symptomatic lumbar scoliosis

J Neurosurg Spine 38:217–229, 2023

Previous reports of rod fracture (RF) in adult spinal deformity are limited by heterogeneous cohorts, low follow-up rates, and relatively short follow-up durations. Since the majority of RFs present > 2 years after surgery, true occurrence and revision rates remain unclear. The objectives of this study were to better understand the risk factors for RF and assess its occurrence and revision rates following primary thoracolumbar fusions to the sacrum/pelvis for adult symptomatic lumbar scoliosis (ASLS) in a prospective series with long-term follow-up.

METHODS Patient records were obtained from the Adult Symptomatic Lumbar Scoliosis–1 (ASLS-1) database, an NIH-sponsored multicenter, prospective study. Inclusion criteria were as follows: patients aged 40–80 years undergoing primary surgeries for ASLS (Cobb angle ≥ 30° and Oswestry Disability Index ≥ 20 or Scoliosis Research Society-22r ≤ 4.0 in pain, function, and/or self-image) with instrumented fusion of ≥ 7 levels that included the sacrum/pelvis. Patients with and without RF were compared to assess risk factors for RF and revision surgery.

RESULTS Inclusion criteria were met by 160 patients (median age 62 years, IQR 55.7–67.9 years). At a median followup of 5.1 years (IQR 3.8–6.6 years), there were 92 RFs in 62 patients (38.8%). The median time to RF was 3.0 years (IQR 1.9–4.54 years), and 73% occurred > 2 years following surgery. Based on Kaplan-Meier analyses, estimated RF rates at 2, 4, 5, and 8 years after surgery were 11%, 24%, 35%, and 49%, respectively. Baseline radiographic, clinical, and demographic characteristics were similar between patients with and without RF. In Cox regression models, greater postoperative pelvic tilt (HR 1.895, 95% CI 1.196–3.002, p = 0.0065) and greater estimated blood loss (HR 1.02, 95% CI 1.005–1.036, p = 0.0088) were associated with increased risk of RF. Thirty-eight patients (61% of all RFs) underwent revision surgery. Bilateral RF was predictive of revision surgery (HR 3.52, 95% CI 1.8–6.9, p = 0.0002), while patients with unilateral nondisplaced RFs were less likely to require revision (HR 0.39, 95% CI 0.18–0.84, p = 0.016).

CONCLUSIONS This study provides what is to the authors’ knowledge the highest-quality data to date on RF rates following ASLS surgery. At a median follow-up of 5.1 years, 38.8% of patients had at least one RF. Estimated RF rates at 2, 4, 5, and 8 years after surgery were 11%, 24%, 35%, and 49%, respectively. Greater estimated blood loss and postoperative pelvic tilt were significant risk factors for RF. These findings emphasize the importance of long-term follow-up to realize the true prevalence and cumulative incidence of RF.

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Computational fluid dynamic analysis of the initiation of cerebral aneurysms

J Neurosurg 137:335–343, 2022

Relationships between aneurysm initiation and hemodynamic factors remain unclear since de novo aneurysms are rarely observed. Most previous computational fluid dynamics (CFD) studies have used artificially reproduced vessel geometries before aneurysm initiation for analysis. In this study, the authors investigated the hemodynamic factors related to aneurysm initiation by using angiographic images in patients with cerebral aneurysms taken before and after an aneurysm formation.

METHODS The authors identified 10 cases of de novo aneurysms in patients who underwent follow-up examinations for existing cerebral aneurysms located at a different vessel. The authors then reconstructed the vessel geometry from the images that were taken before aneurysm initiation. In addition, 34 arterial locations without aneurysms were selected as control cases. Hemodynamic parameters acting on the arterial walls were calculated by CFD analysis.

RESULTS In all de novo cases, the aneurysmal initiation area corresponded to the highest wall shear stress divergence (WSSD point), which indicated that there was a strong tensile force on the arterial wall at the initiation area. The other previously reported parameters did not show such correlations. Additionally, the pressure loss coefficient (PLc) was statistically significantly higher in the de novo cases (p < 0.01). The blood flow impact on the bifurcation apex, or the secondary flow accompanied by vortices, resulted in high tensile forces and high total pressure loss acting on the vessel wall.

CONCLUSIONS Aneurysm initiation may be more likely in an area where both tensile forces acting on the vessel wall and total pressure loss are large.

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Characteristics of Sagittal Spinopelvic Alignment Changes After Symptom Relief After Simple Lumbar Decompression

 Neurosurgery 91:331–338, 2022

Sagittal spinopelvic alignment (SSPA) parameters are essential for the diagnosis of adult spinal deformities (ASDs) and their progression. Certain clinical symptoms that occur in patients with lumbar spinal stenosis (LSS) and herniated nucleus pulposus (HNP) may distort the SSPA and mimic ASD.

OBJECTIVE: To differentiate SSPA in symptomatic patients from asymptomatic patients within 10 minutes in the standing position.

METHODS: This retrospective cohort study evaluated changes in SSPA after simple lumbar decompression surgery in patients with LSS and HNP. Relative sagittal alignment (RSA), relative pelvic version, relative lumbar lordosis (RLL), Lordosis Distribution Index (LDI), and global alignment and proportion (GAP) values were calculated using the conventional Schwab classification method. First, the preoperative and postoperative SSPA parameters were compared. Second, patients were subgrouped into symptomatic within 10 minutes of standing (SP group) and other symptoms of LSS and HNP as controls. Changes in SSPA parameters after symptom relief after simple lumbar decompression surgery were compared between the two groups.

RESULTS: Overall, all SSPA parameters improved after surgery. However, after subgrouping, patients in the control group did not show significant SSPA alterations, except for LDI, whereas patients in the SP group significantly improved in terms of their RSA, RLL, LDI, and GAP values after symptom relief after surgery.

CONCLUSION: Patients with pain on standing within 10 minutes showed significant correction in RSA, RLL, and GAP values after simple lumbar decompression. Therefore, it is important to observe such clinical symptoms to avoid misdiagnosis of ASD.

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Data fusion and 3D visualization for optimized representation of neurovascular relationships in the posterior fossa

Acta Neurochirurgica (2022) 164:2141–2151

Reliable 3D visualization of neurovascular relationships in the posterior fossa at the surface of the brainstem is still critical due to artifacts of imaging. To assess neurovascular compression syndromes more reliably, a new approach of 3D visualization based on registration and fusion of high-resolution MR data is presented.

Methods A total of 80 patients received MRI data with 3D-CISS and 3D-TOF at 3.0 Tesla. After registration and subsequent segmentation, the vascular information of the TOF data was fused into the CISS data. Two 3D visualizations were created for each patient, one before and one after fusion, which were verified with the intraoperative situation during microvascular decompression (MVD). The reproduction quality of vessels was evaluated with a rating system.

Results In all cases, the presented approach compensated for typical limitations in the 3D visualization of neurovascular compression such as the partial or complete suppression of larger vessels, suppression of smaller vessels at the CSF margin, and artifacts from heart pulsation. In more than 95% of the cases of hemifacial spasm and glossopharyngeal neuralgia, accurate assessment of the compression was only possible after registration and fusion. In more than 50% of the cases with trigeminal neuralgia, the presented approach was crucial to finding the actually offending vessel.

Conclusions 3D visualization of fused image data allows for a more complete representation of the vessel-nerve situation. The results from this approach are reproducible and the assessment of neurovascular compression is safer. It is a powerful tool for planning MVD.

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Motor skills, cognitive impairment, and quality of life in normal pressure hydrocephalus: early effects of shunt placement

Traditionally, clinical findings of normal pressure hydrocephalus are mainly characterized by the Hakim triad. The aim of this study is to evaluate the performance of patients suffering from idiopathic normal pressure hydrocephalus (iNPH) in a more holistic manner regarding motor skills, cognitive impairment, and quality of life.

Methods In total, 30 individuals diagnosed with iNPH as well as a reference group with another 30 individuals were included. The iNPH patients and the reference group were age, educational, and morbidity matched. A standardized test battery for psychomotor skills, gait, neuropsychological abilities as well as questionnaires for quality of life was applied. The iNPH group was tested prior to surgery, at 6 weeks, and 3 months postoperatively. The reference group was tested once.

Results Patients showed a significant improved performance in various items of the test battery during the first 3 months postoperatively. This included neuropsychological evaluation, motor skills including gait and upper motor function as well as the quality of life of the patients. Compared to reference individuals, neuropsychological aspects and quality of life of iNPH patients improved in some parts nearly to normal values.

Conclusion Our findings underline that shunt surgery does not only improve the symptoms in iNPH patients but also ameliorates the quality of life to a great extent close to those of age and comorbidity matched reference individuals. This data enables an optimized counseling of iNPH patients regarding the expectable outcome after shunt surgery especially regarding cognitive performance, motor skills as well as life quality.

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The meningioma surface factor: a novel approach to quantify shape irregularity on preoperative imaging and its correlation with WHO grade

J Neurosurg 136:1535–1541, 2022

Atypical and anaplastic meningiomas account for 20% of all meningiomas. An irregular tumor shape on preoperative MRI has been associated with WHO grade II–III histology. However, this subjective allocation does not allow quantification or comparison. An objective parameter of irregularity could substantially influence resection strategy toward a more aggressive approach. Therefore, the aim of this study was to objectively quantify the level of irregularity on preoperative MRI and predict histology based on WHO grade using this novel approach.

METHODS A retrospective study on meningiomas resected between January 2010 and December 2018 was conducted at two neurosurgical centers. This novel approach relies on the theory that a regularly shaped tumor has a smaller surface area than an irregularly shaped tumor with the same volume. A factor was generated using the surface area of a corresponding sphere as a reference, because for a given volume a sphere represents the shape with the smallest surface area possible. Consequently, the surface factor (SF) was calculated by dividing the surface area of a sphere with the same volume as the tumor with the surface area of the tumor. The resulting value of the SF ranges from > 0 to 1. Finally, the SF of each meningioma was then correlated with the corresponding histopathological grading.

RESULTS A total of 126 patients were included in this study; 60.3% had a WHO grade I, 34.9% a WHO grade II, and 4.8% a WHO grade III meningioma. Calculation of the SF demonstrated a significant difference in SFs between WHO grade I (SF 0.851) and WHO grade II–III meningiomas (SF 0.788) (p < 0.001). Multivariate analysis identified SF as an independent prognostic factor for WHO grade (OR 0.000009, 95% CI 0.000–0.159; p = 0.020).

CONCLUSIONS The SF is a proposed mathematical model for a quantitative and objective measurement of meningioma shape, instead of the present subjective assessment. This study revealed significant differences between the SFs of WHO grade I and WHO grade II–III meningiomas and demonstrated that SF is an independent prognostic factor for WHO grade.

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Gut‑disc axis: A cause of intervertebral disc degeneration and low back pain?

European Spine Journal (2022) 31:917–925

Low back pain (LBP), a widely prevalent and costly disease around the world, is mainly caused by intervertebral disc (IVD) degeneration (IDD). Although numerous factors may trigger this degenerative process, microbiome dysbiosis has recently been implicated as one of the likely causes. However, the exact relationship between the microbiome and IDD is not well understood. This review summarizes the potential mechanisms and discusses microbiome dysbiosis’s possible influence on IDD and LBP.

Methods Prospective literature review.

Results Alterations in microbiome composition and host responses to the microbiota causing pathological bone development and involution, led to the concept of gut-bone marrow axis and gut-bone axis. Moreover, the concept of the gut-disc axis was also proposed to explain the microbiome’s role in IDD and LBP. According to the existing evidence, the microbiome could be an important factor for inducing and aggravating IDD through changing or regulating the outside and inside microenvironment of the IVD. Three potential mechanisms by which the gut microbiota can induce IVD and cause LBP are: (1) translocation of the bacteria across the gut epithelial barrier and into the IVD, (2) regulation of the mucosal and systemic immune system, and (3) regulation of nutrient absorption and metabolites formation at the gut epithelium and its diffusion into the IVD. Furthermore, to investigate whether IVD is initiated by pathogenic bacteria and establish the correlation between the presence of certain microbial groups with the disease in question, microbiome diversity analysis based on16S rRNA data can be used to characterise stool/blood microbiota from IVD patients.

Conclusion Future studies on microbiome, fungi and viruses in IDD is necessary to revolutionize our thinking about their possible role in the development of IVD diseases. Furthermore, we believe that inflammation inhibition and interruption of amplification of cascade reaction in IVD by targeting the gut and IVD microbiome is worthwhile for the treatment of IDD and LBP.

Level of Evidence I Diagnostic: individual cross-sectional studies with the consistently applied reference standard and blinding.

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The precuneal interhemispheric, trans‑tentorial corridor to the pineal region and brainstem, surgical anatomy, and case illustration

Acta Neurochirurgica (2022) 164:1095–1103

The pineal region and dorsal midbrain are among the most challenging surgical targets. To approach lesions in this region that harbor a superior to inferior long axis, we describe the basic steps of the precuneal, interhemispheric, transtentorial approach and illustrate anatomical landmarks of this established, but not so popular, surgical trajectory.

Method To study the anatomical landmarks and safety of this approach, the neurovascular anatomy was studied on 22 sides of 11 formalin-fixed latex-injected anatomical specimens. A step-by-step dissection of the precuneal interhemispheric trans-tentorial approach and study of the key anatomical landmarks was performed. An illustrative clinical case of a pontomesencephalic cavernous malformation (CM) resected through this approach is also detailed.

Results The mean distance from the transverse sinus to the most posterior cortical vein draining into the superior sagittal sinus was 6.4 cm. The mean distance from the calcarine sulcus to the most posterior cortical vein was 5.3 cm. Key steps of the dissection are as follows: craniotomy exposing the posterior aspect of the superior sagittal sinus (SSS), durotomy and gentle retraction of the SSS edge, dissection of the interhemispheric fissure, linear incision of the tentorium that extends anteriorly to the incisura and lateral reflection of the tentorium, and arachnoidal dissection and exposure of the cerebellomesencephalic fissure.

Conclusion The precuneal, interhemispheric, trans-tentorial approach affords excellent access to the falcotentorial junction, splenium, pineal region, quadrigeminal cistern, and dorsal pons once the cerebellomesencephalic fissure has been dissected.

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Cauda equina ependymomas: surgical treatment and long-term outcomes in a series of 125 patients

J Neurosurg Spine 36:452–463, 2022

Cauda equina ependymoma (CEE) is a rare tumor for which little information is available on the oncological and clinical outcomes of patients. In this study the authors aimed to address functional, oncological, and quality-of- life (QOL) outcomes in a large series of consecutive patients operated on at their institution during the past 20 years.
METHODS The records of 125 patients who underwent surgery between January 1998 and September 2018 were reviewed. Analyzed variables included demographic, clinical, radiological, surgical, and histopathological features. Neurological outcomes were graded according to the McCormick and Kesselring scales. The QOL at follow-up was evaluated by administering the EQ-5DL questionnaire.
RESULTS On admission, 84% of patients had a McCormick grade of I and 76.8% had a Kesselring score of 0. At follow-up (clinical 8.13 years; radiological 5.87 years) most scores were unchanged. Sacral level involvement (p = 0.029) and tumor size (p = 0.002) were predictors of poor functional outcome at discharge. Tumor size (p = 0.019) and repeated surgery (p < 0.001) were predictors of poor outcome. A preoperative McCormick grade ≥ III and Kesselring grade ≥ 2 were associated with worse outcomes (p = 0.035 and p = 0.002, respectively). Myxopapillary ependymoma (MPE) was more frequent than grade II ependymoma (EII). The overall rate of gross-total resection (GTR) was 91.2% and rates were significantly higher for patients with EII (98%) than for those with MPE (84%) (p = 0.0074). On multivariate analysis, the only factor associated with GTR was the presence of a capsule (p = 0.011). Seventeen patients (13.7%) had recurrences (13 MPE, 4 EII; 76.4% vs 23.6%; p = 0.032). The extent of resection was the only factor associated with recurrence (p= 0.0023) and number of surgeries (p = 0.006). Differences in progression-free survival (PFS) were seen depending on the extent of resection at first operation (p < 0.001), subarachnoid seeding (p = 0.041), piecemeal resection (p = 0.004), and number of spine levels involved (3 [p = 0.016], 4 [p = 0.011], or ≥ 5 [p = 0.013]). At follow-up a higher proportion of EII than MPE patients were disease free (94.7% vs 77.7%; p = 0.007). The QOL results were inferior in almost all areas compared to a control group of subjects from the Italian general population. A McCormick grade ≥ 3 and repeated surgeries were associated with a worse QOL (p = 0.006 and p = 0.017).
CONCLUSIONS An early diagnosis of CEE is important because larger tumors are associated with recurrences and worse functional neurological outcomes. Surgery should be performed with the aim of achieving an en bloc GTR. The histological subtype was not directly associated with recurrences, but some of the features more commonly encountered in MPEs were. The outcomes are in most cases favorable, but the mean QOL perception is inferior to that of the general population.

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The rhinopharyngeal flap for reconstruction of lower clival and craniovertebral junction defects

J Neurosurg 135:1319–1327, 2021

The endoscopic endonasal approach (EEA) to the lower clivus and craniovertebral junction (CVJ) has been traditionally performed via resection of the nasopharyngeal soft tissues. Alternatively, an inferiorly based rhinopharyngeal (RP) flap (RPF) can be dissected to help reconstruct the postoperative defect and separate it from the oropharynx. To date, there is no evidence regarding the viability and potential clinical impact of the RPF. The aim of this study was to assess RPF viability and its impact on clinical outcome.

METHODS A retrospective cohort of 60 patients who underwent EEA to the lower clivus and CVJ was studied. The RPF was used in 30 patients (RPF group), and the nasopharyngeal soft tissues were resected in 30 patients (control group).

RESULTS Chordoma was the most common surgical indication in both groups (47% in the RPF group vs 63% in the control group, p = 0.313), followed by odontoid pannus (20% in the RPF group vs 10%, p = 0.313). The two groups did not significantly differ in terms of extent of tumor (p = 0.271), intraoperative CSF leak (p = 0.438), and skull base reconstruction techniques other than the RPF (nasoseptal flap, p = 0.301; fascia lata, p = 0.791; inlay graft, p = 0.793; and prophylactic lumbar drain, p = 0.781). Postoperative soft-tissue enhancement covering the lower clivus and CVJ observed on MRI was significantly higher in the RPF group (100% vs 26%, p < 0.001). The RPF group had a significantly lower rate of nasoseptal flap necrosis (3% vs 20%, p = 0.044) and surgical site infection (3% vs 27%, p = 0.026) while having similar rates of postoperative CSF leakage (17% in the RPF group vs 20%, p = 0.739) and meningitis (7% in the RPF group vs 17%, p = 0.424). Oropharyngeal bacterial flora dominated the infections in the control group but not those in the RPF group, suggesting that the RPF acted as a barrier between the nasopharynx and oropharynx.

CONCLUSIONS The RPF provides viable vascularized tissue coverage to the lower clivus and CVJ. Its use was associated with decreased rates of nasoseptal flap necrosis and local infection, likely due to separation from the oropharynx.

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Retrograde ejaculation following anterior lumbar surgery: a systematic review and pooled analysis

J Neurosurg Spine 35:427–436, 2021

The present systematic review and pooled analysis aims to assess the incidence and risk factors for the development of retrograde ejaculation (RE) following first-time open anterior lumbar surgery.

METHODS A systematic MEDLINE review via PubMed was performed, identifying 130 clinical papers relating to the topic. Eighteen publications were selected according to predetermined inclusion and exclusion criteria and were used to determine the incidence of RE. Only the publications that provided data on surgical risk factors present specifically in the men in the study were included in the analysis of risk factors.

RESULTS Of the 2503 men included, there were 57 reported events of RE (2.3%). Of the cases for which long-term data were provided, 45.8% had resolved by final follow-up. There was a statistically significant increased risk associated with a transperitoneal as opposed to a retroperitoneal approach (8.6% vs 3.2%), as well as with the use of recombinant human bone morphogenetic protein–2 (rhBMP-2) in anterior lumbar interbody fusion (ALIF) as opposed to ALIF with bone graft or arthroplasty in controls (5.0% vs 1.8%). However, when excluding from analysis the patients operated on prior to the FDA’s 2008 warning that commented on the drug’s neuroinflammatory properties, there was no significant difference in rates of RE in patients receiving rhBMP-2 versus the control group (2.4% vs 2.5%). There was no significant difference in risk based on single- versus multilevel procedure or on ALIF versus arthroplasty.

CONCLUSIONS In a pooled analysis of currently published data on men undergoing first-time open anterior lumbar surgery, this study found an overall incidence of RE of 2.3%. Nearly half of these patients recovered, reporting resolution of symptoms anywhere between 3 months and 48 months. Analysis of risk factors was limited by a paucity of published literature segregating data by sex. However, there was an increased risk associated with rhBMP-2 only when including data collected prior to the FDA warning on its detrimental properties. The authors therefore posit that the risk of RE is probably overestimated in the literature, given that the vast majority of the data available were collected prior to this warning and given the subsequent implementation of precautions when handling rhBMP-2.

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The effect of minimally invasive lumbar decompression surgery on sagittal spinopelvic alignment in patients with lumbar spinal stenosis

J Neurosurg Spine 35:177–184, 2021

Several studies have examined the relationship between sagittal spinopelvic alignment and clinical outcomes after spinal surgery. However, the long-term reciprocal changes in sagittal spinopelvic alignment in patients with lumbar spinal stenosis after decompression surgery remain unclear. The aim of this study was to investigate radiographic changes in sagittal spinopelvic alignment and clinical outcomes at the 2-year and 5-year follow-ups after minimally invasive lumbar decompression surgery.

METHODS The authors retrospectively studied the medical records of 110 patients who underwent bilateral decompression via a unilateral approach for lumbar spinal stenosis. Japanese Orthopaedic Association (JOA) and visual analog scale (VAS) scores for low-back pain (LBP), leg pain, leg numbness, and spinopelvic parameters were evaluated before surgery and at the 2-year and 5-year follow-ups. Sagittal malalignment was defined as a sagittal vertical axis (SVA) ≥ 50 mm.

RESULTS Compared with baseline, lumbar lordosis significantly increased after decompression surgery at the 2-year (30.2° vs 38.5°, respectively; p < 0.001) and 5-year (30.2° vs 35.7°, respectively; p < 0.001) follow-ups. SVA significantly decreased at the 2-year follow-up compared with baseline (36.1 mm vs 51.5 mm, respectively; p < 0.001). However, there was no difference in SVA at the 5-year follow-up compared with baseline (50.6 mm vs 51.5 mm, respectively; p = 0.812). At the 5-year follow-up, 82.5% of patients with preoperative normal alignment maintained normal alignment, whereas 42.6% of patients with preoperative malalignment developed normal alignment. Preoperative sagittal malalignment was associated with the VAS score for LBP at baseline and 2-year and 5-year follow-ups and the JOA score at the 5-year follow-up. Postoperative sagittal malalignment was associated with the VAS score for LBP at the 2-year and 5-year follow-ups and the VAS score for leg pain at the 5-year follow-up. There was a trend toward deterioration in clinical outcomes in patients with persistent postural malalignment compared with other patients.

CONCLUSIONS After minimally invasive surgery, spinal sagittal malalignment can convert to normal alignment at both short-term and long-term follow-ups. Sagittal malalignment has a negative impact on the VAS score for LBP and a weakly negative impact on the JOA score after decompression surgery.

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How I do it: endoscopic endonasal resection of tuberculum sellae meningioma

Acta Neurochirurgica (2021) 163:2193–2197

Tuberculum sellae meningiomas (TSMs) adherent to neurovascular structures are particularly challenging lesions requiring delicate and precise microneurosurgery. There is an ongoing debate about the optimal surgical approach.

Method We describe technical nuances and challenges in TSM resection using the endoscopic endonasal approach (EEA) in two cases of fibrous tumors with adherence to neurovascular structures. The cases are illustrated with a video (case 1) and figures (cases 1 and 2).

Conclusion A dedicated team approach and precise microsurgical technique facilitate safe resection of complex TSMs through the EEA.

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Does Myelopathy Increase the Morbidity and Mortality of Elective Single-Level Anterior Cervical Discectomy and Fusion?

Neurosurgery 89:109–115, 2021

Myelopathy is thought to be associated with higher morbidity and mortality after anterior cervical discectomy and fusion (ACDF); however, the literature investigating this association has limitations.

OBJECTIVE: To investigate the influence of myelopathy on early perioperative complications of elective single-level ACDF.

METHODS: Patients who underwent ACDF between 2016 and 2018 were reviewed from the American College of Surgeons National Surgical Quality Improvement Program (ACSNSQIP) database. Propensity score matching analysis was used.

RESULTS: Twenty percent of the cohort wasmyelopathic. These patientswere significantly older, had more comorbidities, more likely to be functionally dependent, and to undergo emergency surgery when compared to the nonmyelopathic cohort. When 1969 myelopathic patients were 1:1 propensity matched with nonmyelopathic patients, there was no difference between themyelopathic and nonmyelopathic patients in incidence of postoperative intensive care unit admission or death. Patients in the myelopathic group were significantly more likely to have a nonhome discharge and less likely to be discharged on the first postoperative day. Myelopathic patients had a higher rate of return to operating room within the same admission (2.2%) as well as a higher unplanned readmission rate (4.2%). The total operation time (143 min) and average length of hospital stay (52 h) were significantly higher in the myelopathic group when compared to the nonmyelopathic group (117 min) and (33 h), respectively.

CONCLUSION: Patients with myelopathy who undergo elective single-level ACDF have higher risks of several perioperative events including longer operative time, longer hospital stay, higher return to operating room, and unplanned readmission rates, when compared to nonmyelopathic patients. On the other hand, myelopathic patients did not exhibit higher mortality rate.

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Predictors of indirect neural decompression in minimally invasive transpsoas lateral lumbar interbody fusion

J Neurosurg Spine 35:80–90, 2021

An advantage of lateral lumbar interbody fusion (LLIF) surgery is the indirect decompression of the neural elements that occurs because of the resulting disc height restoration, spinal realignment, and ligamentotaxis. The degree to which indirect decompression occurs varies; no method exists for effectively predicting which patients will respond. In this study, the authors identify preoperative predictive factors of indirect decompression of the central canal.

METHODS The authors performed a retrospective evaluation of prospectively collected consecutive patients at a single institution who were treated with LLIF without direct decompression. Preoperative and postoperative MRI was used to grade central canal stenosis, and 3D volumetric reconstructions were used to measure changes in the central canal area (CCA). Multivariate regression was used to identify predictive variables correlated with radiographic increases in the CCA and clinically successful improvement in visual analog scale (VAS) leg pain scores.

RESULTS One hundred seven levels were treated in 73 patients (mean age 68 years). The CCA increased 54% from a mean of 0.96 cm2 to a mean of 1.49 cm2 (p < 0.001). Increases in anterior disc height (74%), posterior disc height (81%), right (25%) and left (22%) foraminal heights, and right (12%) and left (15%) foraminal widths, and reduction of spondylolisthesis (67%) (all p < 0.001) were noted. Multivariate evaluation of predictive variables identified that preoperative spondylolisthesis (p < 0.001), reduced posterior disc height (p = 0.004), and lower body mass index (p = 0.042) were independently associated with radiographic increase in the CCA. Thirty-two patients were treated at a single level and had moderate or severe central stenosis preoperatively. Significant improvements in Oswestry Disability Index and VAS back and leg pain scores were seen in these patients (all p < 0.05). Twenty-five (78%) patients achieved the minimum clinically important difference in VAS leg pain scores, with only 2 (6%) patients requiring direct decompression postoperatively due to persistent symptoms and stenosis. Only increased anterior disc height was predictive of clinical failure to achieve the minimum clinically important difference.

CONCLUSIONS LLIF successfully achieves indirect decompression of the CCA, even in patients with substantial central stenosis. Low body mass index, preoperative spondylolisthesis, and disc height collapse appear to be most predictive of successful indirect decompression. Patients with preserved disc height but severe preoperative stenosis are at higher risk of failure to improve clinically.

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Triple motor mapping: transcranial, bipolar, and monopolar mapping for supratentorial glioma resection adjacent to motor pathways

J Neurosurg 134:1728–1737, 2021

Maximal safe resection of gliomas near motor pathways is facilitated by intraoperative mapping. The authors and other groups have described the use of bipolar or monopolar direct stimulation to identify functional tissue, as well as transcranial or transcortical motor evoked potentials (MEPs) to monitor motor pathways. Here, the authors describe their initial experience using all 3 modalities to identify, monitor, and preserve cortical and subcortical motor systems during glioma surgery.

METHODS Intraoperative mapping data were extracted from a prospective registry of glioma resections near motor pathways. Additional demographic, clinical, pathological, and imaging data were extracted from the electronic medical record. All patients with new or worsened postoperative motor deficits were followed for at least 6 months.

RESULTS Between January 2018 and August 2019, 59 operations were performed in 58 patients. Overall, patients in 6 cases (10.2%) had new or worse immediate postoperative deficits. Patients with temporary deficits all had at least Medical Research Council grade 4/5 power. Only 2 patients (3.4%) had permanently worsened deficits after 6 months, both of which were associated with diffusion restriction consistent with ischemia within the corticospinal tract. One patient’s deficit improved to 4/5 and the other to 4/5 proximally and 3/5 distally in the lower limb, allowing ambulation following rehabilitation. Subcortical motor pathways were identified in 51 cases (86.4%) with monopolar high-frequency stimulation, but only in 6 patients using bipolar stimulation. Transcranial or cortical MEPs were diminished in only 6 cases, 3 of which had new or worsened deficits, with 1 permanent deficit. Insula location (p = 0.001) and reduction in MEPs (p = 0.01) were the only univariate predictors of new or worsened postoperative deficits. Insula location was the only predictor of permanent deficits (p = 0.046). The median extent of resection was 98.0%.

CONCLUSIONS Asleep triple motor mapping is safe and resulted in a low rate of deficits without compromising the extent of resection.

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Comparison of first-time microvascular decompression with percutaneous surgery for trigeminal neuralgia: long-term outcomes and prognostic factors

Acta Neurochirurgica (2021) 163:1623–1634

Common surgical treatments for trigeminal neuralgia (TN) include microvascular decompression (MVD) and percutaneous procedures (glycerol rhizolysis; thermocoagulation; and balloon compression). Although the efficacy of each procedure has been documented, direct comparisons of their relative efficacies for TN are lacking. We aimed to directly compare long-term outcomes after first-time MVD with percutaneous surgery in primary (idiopathic and classical) TN and identify predictors of outcome.

Methods We conducted a retrospective analysis of prospectively collected data on 185 patients undergoing MVD and 129 undergoing percutaneous surgery. Procedures were performed by one of two neurosurgeons in a single centre; an independent observer collected long-term follow-up data by interviews, using the same outcome measures for all procedures.

Results MVD patients were younger than those undergoing percutaneous surgery (P <.001). MVD provided superior initial pain relief (P <.001): 87.0% had Barrow Neurological Institute class I or II pain scores after MVD compared with 67.2% after percutaneous surgery. The complication rate for percutaneous procedures was 35.7% and for MVDs was 24.9% (P =.04), including minor and transient complications. Kaplan-Meier analysis demonstrated that MVD provided longer pain relief than percutaneous procedures (P <.001); 25%of patients had recurrence at 96 months followingMVD compared with 12 months after percutaneous surgery. Subgroup analysis showed that balloon compression provided more durable relief amongst percutaneous procedures. Multivariate analysis revealed that post-operative numbness and age were prognostic factors for percutaneous procedures (P =.03 and .01, respectively).

Conclusions MVD provides better initial pain relief and longer durability of relief than percutaneous surgery, although carrying a small risk of major complications. Amongst percutaneous procedures, balloon compression gave the most durable relief from pain. Older age and post-operative numbness were predictors of good outcome from percutaneous surgery. These results can help clinicians to counsel patients with primary TN on neurosurgical treatment selection for pain relief.

Keywords Microvascular decompression . Balloon compression . Glycerol . Thermocoagulation . Trigeminal neuralgia . Pain

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Differences in surgical outcome between petroclival meningioma and anterior petrous meningioma

Acta Neurochirurgica (2021) 163:1697–1704

Petroclival meningiomas (PC MNGs) and anterior petrous meningiomas (AP MNGs) have similar locations.
However, these are different tumors clearly divided by the trigeminal nerve. There has never been a study on the comparison
of the surgical outcomes of these two meningiomas. In this study, we compared and analyzed the surgical outcome of PCMNGs
and AP MNGs.

Methods The charts of 85 patients diagnosed with PC MNGs of AP MNGs who underwent surgical treatment were retrospectively
reviewed. And we analyzed the characteristics of 49 PC MNGs (57.6%) and compared them with those of 36 AP MNGs.

Results Preoperative brainstemedema was observed in 11 patients (22.4%) of the PCMNG group and 1 patient (2.8%) of the AP
MNG group (p = 0.024). Total tumor removal was achieved in 21 patients (58.3%) of the AP MNG group, but only 17 patients
(34.7%) of the PC MNG group were able to completely (p = 0.047). In addition, sixth cranial nerve palsy occurred in 17 patients
(34.7%) of the PC MNG group and 4 patients (11.1%) of the AP MNG group (p = 0.025).

Conclusions In this study, we found that PC MNGs has a worse surgical outcome than AP MNGs, because PC MNGs were
difficult to completely remove and were more likely to damage abducens nerve.

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Intraoperative Cognition Mapping and Monitoring “à la carte” in Brain Tumor Patients

Neurosurgery 88:919–930, 2021

The purpose of surgery for brain tumors involving eloquent neural circuits is to maximize the extent of resection while preserving an optimal quality of life. To this end, especially in diffuse glioma, the goal is to remove the cerebral parenchyma invaded by the neoplasm up to the individual cortico-subcortical networks critical for brain functions.

Intraoperative mapping combined with real-time cognitive monitoring throughout the resection in awake patient is thus highly recommended to resume a normal life. Indeed, beyond avoiding hemiplegia or aphasia, enjoying a familial, social, and professional life implies that motor and language mapping is not sufficient.

Identifying and sparing neural networks that subserve cognition (movement control, visuospatial cognition, executive functions, multimodal semantics, metacognition) andmentalizing (theory ofmind, which plays a key role for social cognition) is essential to preserve an adapted behavior.

Here, the aim is to review when and how to map these critical functions, which have nonetheless been neglected for many decades by neurosurgeons. In fact, the disorders generated by surgical injuries of circuits underpinning nonmotor and nonspeech functions are usually not immediately visible on postoperative standard clinical examination, leading the physician to believe that the patient has no deficit. Yet, cognitive or emotional disturbances may subsequently prevent to resume an active life, as to work full time.

Therefore, a systematic neuropsychological assessment should be performed before, during, and after mapping-guided surgery, regardless of the tumor location, to preserve the functional connectome intraoperatively and to plan a postoperative tailored cognitive rehabilitation according to the patient’s needs.

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