Author: cba

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Radiographic Risk Factors for Adjacent Segment Disease Following Anterior Cervical Discectomy and Fusion (ACDF): A Systematic Review and Meta-Analysis

Global Spine Journal 2024, Vol. 14(7) 2183–2200

Study Design: Systematic review and meta-analysis.

Objectives: To assess the radiographic risk factors for adjacent segment disease (ASD) following anterior cervical discectomy and fusion (ACDF) for degenerative cervical spine pathologies.

Methods: PubMed, Embase and the Cochrane Library databases were searched up to December 2023. The primary inclusion criteria were degenerative spinal conditions treated with ACDF, comparing radiological parameters in patients with and without postoperative ASD. The radiographic parameters included intervertebral disc height, cervical sagittal alignment, sagittal segmental alignment, range of motion, segmental height, T1 slope, sagittal vertical axis (SVA), thoracic inlet angle (TIA), and plate to disc distance (PPD). Risk of bias was assessed for all studies. The Cochrane Review Manager was utilized to perform the meta-analysis.

Results: From 7044 articles, 13 retrospective studies were included in the final analysis. Three studies had “not serious” bias and the other 10 studies had serious or very serious bias. The total number of patients in the included studies was 1799 patients. Five studies included single-level ACDF, 2 studies included multi-level ACDF, and 6 studies included single or multi-level ACDF. On meta-analysis, the significant risk factors associated with ASD development were reduced postoperative cervical lordosis (mean difference [MD] = 3.35°, P = .002), reduced last-follow-up cervical lordosis (MD = À3.02°, P = .0003), increased preoperative to postoperative cervical sagittal alignment change (MD = À3.68°, P = .03), and the presence of developmental cervical canal stenosis (Odds ratio [OR] = 4.17, P < .001).

Conclusions: Decreased postoperative cervical lordosis, greater change in cervical sagittal alignment and developmental cervical canal stenosis were associated with an increased risk of ASD following ACDF.

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Preoperative Opioid Use and Postoperative Outcomes in Patients Undergoing Microvascular Decompression for Trigeminal Neuralgia

Neurosurgery 95:548–555, 2024

The prescription of opioid analgesics for trigeminal neuralgia (TN) is controversial, and their effect on postoperative outcomes for patients with TN undergoing microvascular decompression (MVD) has not been reported. We aimed to describe the relationship between preoperative opioid use and postoperative outcomes in patients with TN undergoing MVD.

METHODS: We reviewed the records of 920 patients with TN at our institution who underwent an MVD between 2007 and 2020. Patients were sorted into 2 groups based on preoperative opioid usage. Demographic information, comorbidities, characteristics of TN, preoperative medications, pain and numbness outcomes, and recurrence data were recorded and compared between groups. Multivariate ordinal regression, Kaplan–Meier survival analysis, and Cox proportional hazards were used to assess differences in pain outcomes between groups.

RESULTS: One hundred and forty-five (15.8%) patients in this study used opioids preoperatively. Patients who used opioids preoperatively were younger (P = .04), were more likely to have a smoking history (P < .001), experienced greater pain in modified Barrow Neurological Institute pain score at final follow-up (P = .001), and were more likely to experience pain recurrence (P = .01). In addition, patients who used opioids preoperatively were more likely to also have been prescribed TN medications including muscle relaxants and antidepressants preoperatively (P < .001 and P < .001, respectively). On multivariate regression, opioid use was an independent risk factor for greater postoperative pain at final follow-up (P = .006) after controlling for variables including female sex and age. Opioid use was associated with shorter time to pain recurrence on Kaplan–Meier analysis (P = .005) and was associated with increased risk for recurrence on Cox proportional hazards regression (P = .008).

CONCLUSION: Preoperative opioid use in the setting of TN is associated with worse pain outcomes and increased risk for pain recurrence after MVD. These results indicate that opioids should be prescribed cautiously for TN and that worse post-MVD outcomes may occur in patients using opioids preoperatively.

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Posterolateral lumbar spine fixation and decompression with navigation interfaced with a robotic exoscope with head mounted display

Acta Neurochirurgica (2024) 166:342

Lumbar spine fixation and fusion is currently performed with intraoperative tools such as intraoperative CT scan integrated to navigation system to provide accurate and safe positioning of the screws. The use of microscopic visualization systems enhances visualization and accuracy during decompression of the spinal canal as well.

Methods We introduce a novel setting in microsurgical decompression and fusion of lumbar spine using an exoscope with robotized arm (RoboticScope) interfaced with navigation and head mounted displays.

Conclusion Spinal canal decompression and fusion can effectively be performed with RoboticScope, with significant advantages especially regarding ergonomics.

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Single-stage correction of severe scoliosis with syringomyelia: performed with traction assistance without prophylactic neurosurgical decompression

J Neurosurg Spine 41:316–324, 2024

There is still controversy about whether it is necessary to perform prophylactic neurosurgical decompression for severe scoliosis (SS) with syringomyelia (SM) to reduce the risk of neurological complications during subsequent spinal correction. This study aimed to explore the safety and effectiveness of using traction-assisted single-stage spinal correction as a treatment for patients who had SS with SM (SS-SM).

METHODS The patients who had SS-SM without previous neurosurgical intervention and who underwent traction-assisted single-stage posterior spinal correction at a single center were included, and the initial, posttraction, and postoperative clinical data were reviewed. Based on preoperative MRI, the included patients were divided into two categories: those with versus those without Chiari malformation type I (CM-I–related SM [CS] vs idiopathic SM [IS]), and those with a moderate syrinx (MS) versus those with a large syrinx (LS). Different groups’ traction and operation contributions were calculated for comparisons (CS vs IS, MS vs LS).

RESULTS A total of 28 patients were included. The initial mean major scoliosis was 101.0° with a mean flexibility of 21.4%. After the operation, the mean total correction rate for scoliosis was 63.9%. The mean traction and operation contributions were 61.5% and 38.5%, respectively. Most of the patients (75%) underwent spinal corrections without 3-column osteotomies, and only 1 patient reported postoperative regional numbness without motor deficits. No differences were found in the mean total correction rates, traction, and operation contributions when comparing CS versus IS and MS versus LS with the comparable initial clinical data (p > 0.05). More than 50% of the total corrections were achieved by preoperative traction in all groups.

CONCLUSIONS Traction-assisted single-stage spinal correction can safely and effectively correct SS-SM without prophylactic neurosurgical decompression under strict patient selection. Additionally, traction can achieve more than half of the final spinal correction, even for patients with varying sizes of SMs.

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Standard operating procedure and surgical technique innovation in fully endoscopic microvascular decompression for trigeminal neuralgia

Acta Neurochirurgica (2024) 166:351

Microvascular decompression (MVD) is a well-established and effective treatment for primary trigeminal neuralgia (TN). Endoscopy has been implemented to provide a comprehensive view of neurovascular conflict and minimizes the damages of brain retraction during MVD.

Objectives To preliminarily evaluate the surgical safety and efficacy of fully endoscopic microvascular decompression (EMVD) for primary TN with surgeon performing two-hand manipulation and assistant holding endoscope.

Methods Retrospective clinical analysis of 189 patients with primary TN underwent EMVD between June 2019 and August 2022 was performed. By analyzing the intraoperative situation, the outcomes of postoperative symptoms and the main complications, we evaluated the reliability and effectivity of the operative technique in the treatment of primary TN.

Results We summarized the standard operating procedure of EMVD for primary TN with surgeon performing two-hand manipulation and assistant holding endoscope. In addition, acicular bipolar electrocoagulation technique was developed to handle venous compression. During the follow-up period, good pain relief was achieved in 178 patients (94.2%) and recurrence of pain was observed in 4 patients (2.1%). Postoperative temporary complications included trigeminal dysesthesias (7 patients, 4.8%), cerebrospinal fluid leak (2 patients, 1.1%), hearing difficulty (3 patient, 1.6%), facial paresis (2 patients, 1.1%) and vertigo (5 patients, 2.7%). There were no cases of intracranial hemorrhage, cerebellar swelling and death.

Conclusion This EMVD technique is reliable and effective, and can be used as a routine surgical procedure for primary TN.

 

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Impact of Molecular Subgroups on Prognosis and Survival Outcomes in Posterior Fossa Ependymomas: A Retrospective Study of 412 Cases

Neurosurgery 95:651–659, 2024

Posterior fossa ependymomas (PFEs) are rare brain tumors classified as PF-EPN-A (PFA) and PF-EPN-B (PFB) subgroups. The study aimed to evaluate the prognosis and survival outcomes in PFEs, with a focus on the impact of molecular subgroups.

METHODS: A retrospective study was conducted on 412 patients with PFEs. Kaplan–Meier survival analyses were conducted to evaluate the overall survival (OS) and progression-free survival. Cox regression analyses were conducted to assess the prognostic factors. A nomogram was developed to predict the OS rates of PFEs.

RESULTS: The study revealed significant differences between PFA and PFB in patient and tumor characteristics. PFAs were associated with poorer OS (hazard ratios [HR] 3.252, 95% CI 1.777-5.950, P < .001) and progression-free survival (HR 4.144, 95% CI 2.869-5.985, P < .001). World Health Organization grade 3 was associated with poorer OS (HR 2.389, 95% CI 1.236-4.617, P = .010). As for treatment patterns, gross total resection followed by radiotherapy or the combination of radiotherapy and chemotherapy yielded the most favorable OS for PFA (P = .025 for both), whereas gross total resection followed by radiotherapy rather than observation showed improved OS for PFB (P = .046). The nomogram demonstrated a high degree of accuracy and discrimination capacity for the prediction of OS rates for up to 10 years. In addition, 6 cases of PFA (3.51%) with H3K27M mutations were identified.

CONCLUSION: PFAs demonstrate worse prognosis and survival outcomes compared with PFBs. Both PFAs and PFBs necessitate maximal resection followed by intensive adjuvant therapies in long-term effects.

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Optimal Implant Sizing Using Machine Learning Is Associated With Increased Range of Motion After Cervical Disk Arthroplasty

Neurosurgery 95:627–633, 2024

Cervical disk arthroplasty (CDA) offers the advantage of motion preservation in the treatment of focal cervical pathology. At present, implant sizing is performed using subjective tactile feedback and imaging of trial cages. This study aims to construct interpretable machine learning (IML) models to accurately predict postoperative range of motion (ROM) and identify the optimal implant sizes that maximize ROM in patients undergoing CDA.

METHODS: Adult patients who underwent CDA for single-level disease from 2012 to 2020 were identified. Patient demographics, comorbidities, and outcomes were collected, including symptoms, examination findings, subsidence, and reoperation. Affected disk height, healthy rostral disk height, and implant height were collected at sequential time points. Linear regression and IML models, including bagged regression tree, bagged multivariate adaptive regression spline, and k-nearest neighbors, were used to predict ROM change. Model performance was assessed by calculating the root mean square error (RMSE) between predicted and actual changes in ROM in the validation cohort. Variable importance was assessed using RMSE loss. Area under the curve analyses were performed to identify the ideal implant size cutoffs in predicting improved ROM.

RESULTS: Forty-seven patients were included. The average RMSE between predicted and actual ROM was 7.6°(range: 5.8-10.1) in the k-nearest neighbors model, 7.8°(range: 6.5-10.0) in the bagged regression tree model, 7.8°(range: 6.210.0) in the bagged multivariate adaptive regression spline model, and 15.8°(range: 14.3-17.5°) in a linear regression model. In the highest-performing IML model, graft size was the most important predictor with RMSE loss of 6.2, followed by age (RMSE loss = 5.9) and preoperative caudal disk height (RMSE loss = 5.8). Implant size at 110% of the normal adjacent disk height was the optimal cutoff associated with improved ROM.

CONCLUSION: IML models can reliably predict change in ROM after CDA within an average of 7.6 degrees of error. Implants sized comparably with the healthy adjacent disk may maximize ROM.

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Evaluation of the extent of resection of intracranial tumors with virtual intraoperative MRI

J Neurosurg 141:695–701, 2024

Intraoperative MRI (iMRI) is the gold-standard technique for intraoperative evaluation of the extent of resection in brain tumor surgery. Unfortunately, it is currently available at only a few neurosurgical centers. A commercially available software, Virtual iMRI Cranial, provides an elastic fusion between preoperative MRI and intraoperative CT (iCT). The aim of this study was to evaluate the accuracy of this software in determining the presence of residual tumor.

METHODS Virtual iMRI was performed in patients who underwent iCT after intracranial tumor resection. The results of the software in terms of presence or absence of tumor residual were then compared with postoperative MRI performed within 48 hours after surgery to evaluate the diagnostic accuracy of virtual iMRI.

RESULTS Sixty-six patients were included in the present study. The virtual iMRI findings were concordant with the postoperative MRI data in 35 cases (53%) in the detection of tumor residual (p = 0.006). No false-negative findings (i.e., presence of residual on postoperative MRI and absence of residual on virtual iMRI) were encountered. Virtual iMRI had a sensitivity of 1 (95% CI 0.86–1), specificity of 0.26 (95% CI 0.14–0.42), positive predictive value of 0.44 (95% CI 0.3–0.58), and negative predictive value of 1 (95% CI 0.72–1). Subgroup analysis revealed that the virtual iMRI findings were concordant with postoperative MRI findings in all cases (n = 9) of lower-grade glioma (LGG) with a sensitivity of 1 (95% CI 0.59–1) and a specificity of 1 (95% CI 0.16–1) (p = 0.003); a statistically significant association was also found for grade 4 gliomas with a sensitivity of 1 (95% CI 0.69–1) and a specificity of 0.33 (95% CI 0.08–0.7) (p = 0.046) (19 patients). No significant association was found when considering meningiomas or metastases.

CONCLUSIONS The commercially available virtual iMRI can predict the presence or absence of tumor residual with high sensitivity. The diagnostic accuracy of this method was higher in LGGs and much lower for meningiomas or metastases; these findings must be evaluated in prospective studies in a larger population.

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What is the Marginal Cost of Using Robot Assistance or Navigation for Transforaminal Lumbar Interbody Fusion? A Time-Driven Activity-Based Cost Analysis

Neurosurgery 95:556–565, 2024

Our primary objective was to compare the marginal intraoperative cost of 3 different methods for pedicle screw placement as part of transforaminal lumbar interbody fusions (TLIFs). Specifically, we used time-driven activity-based costing to compare costs between robot-assisted TLIF (RA-TLIF), TLIF with intraoperative navigation (ION-TLIF), and freehand (non-navigated, nonrobotic) TLIF.

METHODS: Total cost was divided into direct and indirect costs. We identified all instances of RA-TLIF (n = 20), ION-TLIF (n = 59), and freehand TLIF (n = 233) from 2020 to 2022 at our institution. Software was developed to automate the extraction of all intraoperatively used personnel and material resources from the electronic medical record. Total costs were determined through a combination of direct observation, electronic medical record extraction, and interdepartmental collaboration (business operations, sterile processing, pharmacy, and plant operation departments). Multivariable linear regression analysis was performed to compare costs between TLIF modalities, accounting for patient-specific factors as well as number of levels fused, surgeon, and hospital site.

RESULTS: The average total intraoperative cost per case for the RA-TLIF, ION-TLIF, and freehand TLIF cohorts was $24 838 ± $10 748, $15 991 ± $6254, and $14 498 ± $6580, respectively. Regression analysis revealed that RA-TLIF had significantly higher intraoperative cost compared with both ION-TLIF ( β -coefficient: $7383 ± $1575, P < .001) and freehand TLIF ( β -coefficient: $8182 ± $1523, P < .001). These cost differences were primarily driven by supply cost. However, there were no significant differences in intraoperative cost between ION-TLIF and freehand TLIF (P = .32).

CONCLUSION: We demonstrate a novel use of time-driven activity-based costing methodology to compare different modalities for executing the same type of lumbar fusion procedure. RA-TLIF entails significantly higher supply cost when compared with other modalities, which explains its association with higher total intraoperative cost. The use of ION, however, does not add extra expense compared with freehand TLIF when accounting for confounders. This might have implications as surgeons and hospitals move toward bundled payments.

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Microsurgical Resection of Brainstem Cavernous Malformations in Older Adults: A Multicenter, 30-Year Experience

Neurosurgery 95:669–675, 2024

Microsurgical resection is the only curative intervention for symptomatic brainstem cavernous malformations (BSCMs), but the management of these lesions in older adults (≥65 years) is not well described. This study sought to address this gap by examining the safety and efficacy of BSCM resection in a cohort of older adults.

METHODS: Records of patients who underwent BSCM resection over a 30-year period were reviewed retrospectively. Baseline characteristics and outcomes were compared between older (≥65 years) and younger (<65 years) patients.

RESULTS: Of 550 patients with BSCM who met inclusion criteria, 41 (7.5%) were older than 65 years. Midbrain (43.9% vs 26.1%) and medullary lesions (19.5% vs 13.6%) were more common in the older cohort than in the younger cohort (P = .01). Components of the Lawton BSCM grading system (ie, lesion size, crossing axial midpoint, developmental venous anomaly, and timing of hemorrhage) were not significantly different between cohorts (P ≥ .11). Mean (SD) Elixhauser comorbidity score was significantly higher in older patients (1.86 [1.06]) than in younger patients (0.66 [0.95]; P < .001). Older patients were significantly more likely than younger patients to have poor outcomes at final follow-up (28.9% vs 13.8%, P = .01; mean follow-up duration, 28.7 [39.1] months). However, regarding relative neurological outcome (preoperative modified Rankin Scale to final modified Rankin Scale), rate of worsening was not significantly different between older and younger patients (23.7% vs 14.9%, P = .15).

CONCLUSION: BSCMs can be safely resected in older patients, and when each patient’s unique health status and life expectancy are taken into account, these patients can have outcomes similar to younger patients.

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Efficacy of Biportal Endoscopic Decompression for Lumbar Spinal Stenosis: A Meta-Analysis With Single-Arm Analysis and Comparative Analysis With Microscopic Decompression and Uniportal Endoscopic Decompression

Operative Neurosurgery 27:158–173, 2024

Biportal endoscopic decompression is a minimally invasive surgical technique for lumbar spinal stenosis (LSS). This meta-analysis aimed to evaluate the efficacy and safety of biportal endoscopic decompression through both a single-arm analysis and a comparative analysis.

METHODS: A comprehensive literature search was conducted to identify eligible studies reporting the outcomes of biportal endoscopic decompression for LSS. Single-arm analysis and comparisons with microscopic and uniportal endoscopic decompression were performed. Evaluated outcomes included visual analog scale (VAS) scores for back pain and leg pain, Oswestry Disability Index (ODI) scores, operation time, estimated blood loss, duration of hospital stay, and adverse events.

RESULTS: Single-arm analysis demonstrated significant improvements in VAS back pain, VAS leg pain, and ODI scores after biportal endoscopic decompression at postoperative 1-day to 36-month follow-up (all P < .001), compared with preoperative levels. The pooled mean single-level operation time was 71.44 min, and the pooled mean hospital stay was 3.63 days. The overall adverse event rate was 4.0%, with dural tear being the most common complication (3.0%). Compared with microscopic decompression, biportal endoscopic decompression showed significantly lower VAS back pain at 1-month (P < .001) and 6-month (P < .001) follow-up; lower VAS leg pain at 1-month (P = .045) follow-up; lower ODI scores at 3-month (P < .001), 12-month (P = .017), and >12-month (P = .007) follow-up; lower estimated blood loss (P = .003); and shorter hospital stay (P < .001). Adverse event rates did not differ between the techniques. No significant differences were observed between biportal endoscopic and uniportal endoscopic decompression groups for most efficacy and safety outcomes.

CONCLUSION: Biportal endoscopic decompression emerges as a safe and effective alternative for LSS, presenting potential advantages over the microscopic technique and comparable efficacy with the uniportal endoscopic technique.

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Microcirculatory Impairment and Cerebral Injury in Hydrocephalus and the Effects of Cerebrospinal Fluid Diversion

Neurosurgery 95:469–479, 2024

Hydrocephalus is characterized by progressive enlargement of cerebral ventricles, resulting in impaired microvasculature and cerebral hypoperfusion. This study aimed to demonstrate the microvascular changes in hydrocephalic rats and the effects of cerebrospinal fluid (CSF) release on cerebral blood flow (CBF).

METHODS: On postnatal day 21 (P21), male Wistar rats were intracisternally injected with either a kaolin suspension or saline. On P47, Evan’s ratio (ER) was measured using MRI. On P49, the arteriolar diameter and vascular density of the pia were quantified using a capillary video microscope. The CBF was measured using laser Doppler flowmetry. The expressions of NeuN and glial fibrillary acidic protein determined by immunochemical staining were correlated with the ER. The CBF and rotarod test performance were recorded before and after CSF release. The expressions of 4-hydroxynonenal (4-HNE) and c-caspase-3 were studied on P56.

RESULTS: Ventriculomegaly was induced to varying degrees, resulting in the stretching and abnormal narrowing of pial arterioles, which regressed with increasing ER. Quantitative analysis revealed significant decreases in the arteriolar diameter and vascular density in the hydrocephalic group compared with those in the control group. In addition, the CBF in the hydrocephalic group decreased to 30%–50% of that in the control group. In hydrocephalus, the neurons appear distorted, and the expression of 4-HNE and reactive astrogliosis increase in the cortex. After CSF was released, improvements in the CBF and rotarod test performance were inversely associated with the ER. In addition, the levels of 4-HNE and c-caspase-3 were further elevated.

CONCLUSION: Rapid ventricular dilatation is associated with severe microvascular distortion, vascular regression, cortical hypoperfusion, and cellular changes that impair the recovery of CBF and motor function after CSF release. Moreover, CSF release may induce reperfusion injury. This pathophysiology should be taken into account when treating hydrocephalus.

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Standard operating procedure and surgical technique innovation in fully endoscopic microvascular decompression for trigeminal neuralgia: technical note on 189 patients

Acta Neurochirurgica (2024) 166:351

Microvascular decompression (MVD) is a well-established and effective treatment for primary trigeminal neuralgia (TN). Endoscopy has been implemented to provide a comprehensive view of neurovascular conflict and minimizes the damages of brain retraction during MVD.

Objectives To preliminarily evaluate the surgical safety and efficacy of fully endoscopic microvascular decompression (EMVD) for primary TN with surgeon performing two-hand manipulation and assistant holding endoscope.

Methods Retrospective clinical analysis of 189 patients with primary TN underwent EMVD between June 2019 and August 2022 was performed. By analyzing the intraoperative situation, the outcomes of postoperative symptoms and the main complications, we evaluated the reliability and effectivity of the operative technique in the treatment of primary TN.

Results We summarized the standard operating procedure of EMVD for primary TN with surgeon performing two-hand manipulation and assistant holding endoscope. In addition, acicular bipolar electrocoagulation technique was developed to handle venous compression. During the follow-up period, good pain relief was achieved in 178 patients (94.2%) and recurrence of pain was observed in 4 patients (2.1%). Postoperative temporary complications included trigeminal dysesthesias (7 patients, 4.8%), cerebrospinal fluid leak (2 patients, 1.1%), hearing difficulty (3 patient, 1.6%), facial paresis (2 patients, 1.1%) and vertigo (5 patients, 2.7%). There were no cases of intracranial hemorrhage, cerebellar swelling and death.

Conclusion This EMVD technique is reliable and effective, and can be used as a routine surgical procedure for primary TN.

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Etiology and Management of Recurrent and Persistent Hemifacial Spasm

Neurosurgery 95:418–427, 2024

Despite a 90% success rate, microvascular decompression occasionally fails to resolve hemifacial spasm (HFS), necessitating revision surgery. We investigated recurrent cases to identify underlying causes. METHODS: We evaluated patients at our institution who underwent revision microvascular decompression because of recurrent or persistent HFS, assessing recurrence causes, decompression techniques, complications, and outcomes. Data considered included demographics, preoperative symptoms, disease duration, offending vessel, and magnetic resonance findings. Surgical notes and intraoperative videos were reviewed, and telephone interviews were conducted for recent outcomes.

RESULTS: Out of our ongoing series of 493 patients, 43 patients (8.7%) required revision surgery with a patient cohort of 33 females and 10 males. The average symptom duration was 10 years. The median time between primary and revision surgery was 14 months. Thirteen patients (30.2%) underwent initial surgery elsewhere. Adhesions of Teflon pledgets to the facial nerve were the primary cause of nonresolution in 23 patients (53.5%), while in 13 (30.2%), a missed vascular compression was identified. Sixteen patients (37.2%) had sufficient decompression by removing the conflicting pledgets. During 10 revisions (23.3%), additional Teflon pledgets were necessary. After a median follow-up of 67 months after revision surgery, 27 patients (62.8%) reported complete spasm resolution. Six patients (14.0%) had a good outcome with over 90% reduction of their spasms, 3 patients (7.0%) stated a fair outcome (50% improvement), while 7 patients (16.3%) had no improvement.

CONCLUSION: According to our results, adhesions of Teflon to the facial nerve may cause HFS recurrence. Therefore, whenever possible, Teflon should be placed without nerve contact between the brainstem and the offending vessel. Using a sling or bridge technique seems to be beneficial because it leaves the facial nerve completely free. Persistent symptoms often result from missed offending vessels in the pontomedullary sulcus indicating the benefit of endoscopic inspection of this area with an endoscope.

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The Safety and Efficacy of Dorsal Root Entry Zone Lesioning for Pain Management in Patients With Brachial Plexus Avulsion

Neurosurgery 95:259–274, 2024

Persistent neuropathic pain after brachial plexus avulsion (BPA) is common and generally nonresponsive to medical management. Dorsal root entry zone (DREZ) lesioning is the last resort for pain management in patients with BPA. This study aims to investigate and compare the outcomes and complications of DREZ procedures.

METHODS: A systematic literature search was conducted to identify all related studies. Comparisons were based on the number of patients with preoperative pain vs postoperative pain, with the effect size calculated using the risk ratio. Mean visual analog scale (VAS) scores were extracted and analyzed between interventions. A meta-regression analysis was performed to identify risk factors for final outcomes. The rates of complications were also assessed and analyzed between interventions.

RESULTS: A total of 30 studies with 917 patients (90.0% male and 10.0% female, mean age: 42.9 ± 16.6) were included in this systematic review. Of the 917 patients who underwent surgery, 655 (71.4%) patients had significant pain reduction at the last follow-up (P < .05). The weighted mean preoperative VAS score was 8.3 ± 1.3, compared with postoperative VAS scores (1.9 ± 2.2); a significant improvement was observed (P < .05). The subgroup analysis showed that microsurgical DREZotomy (MDT) is associated with better outcomes in terms of VAS score improvements compared with radiofrequency (RF)-assisted DREZ lesioning (P < .05). Meta-analysis showed that the relative risk of motor deficits was significantly lower in the MDT group, compared with the RF-assisted group (P < .05). Meta-regression showed that older age is correlated with an elevated risk of postoperative motor deficits compared with the incidence of sensory loss.

CONCLUSION: DREZ lesioning is effective for intractable pain alleviation after BPA. Compared with RF-assisted DREZ lesioning, MDT is associated with better VAS score improvements and a lower rate of postoperative motor weakness.

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The role of medical illustration in the evolution of transsphenoidal pituitary surgery

J Neurosurg 141:491–499, 2024

Medical illustration played a crucial, yet often overlooked, role in the evolution of pituitary surgery. From the late 1800s to the present, many preeminent surgeons, in partnership with their surgical illustrator collaborators, developed and then shifted the paradigm of pituitary surgery, from an open procedure with high mortality and morbidity, to an endonasal approach with high success rates that is widely utilized today. This work aims to highlight the role of surgical illustrators as partners to their physician colleagues, creating artistically accessible road maps that shaped the development of the transsphenoidal approach.

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A retrospective analysis of perioperative complications of lateral approach lumbar interbody fusion in patients with prior abdominal surgery or a history of colonic inflammatory disease

The Spine Journal 24 (2024) 1451−1458

Lateral approaches for lumbar interbody fusion (LIF) allow for access to the lumbar spine and disc space by passing through a retroperitoneal corridor either preor trans-psoas. A contraindication for this approach is the presence of retroperitoneal scarring that may occur from prior surgical intervention in the retroperitoneal space or from inflammatory conditions with fibrotic changes and pose challenges for the mobilization and visualization needed in this approach. However, there is a paucity of evidence on the prevalence of surgical complications following lateral fusion surgery in patients with a history of abdominal surgery.

PURPOSE: The primary aim of this study is to describe the association between surgical complications following lateral interbody fusion surgery and prior abdominal surgical.

STUDY DESIGN: Retrospective study.

PATIENT SAMPLE: Patients over the age of 18 who underwent lateral lumbar interbody fusion at a large, tertiary care center between 2011 and 2019 were included in the study.

OUTCOME MEASURES: The primary outcome included medical, surgical, and thigh-related complications either in the intraoperative or 90-day postoperative periods. Additional outcome metrics included readmission rates, length of stay, and operative duration.

METHODS: The electronic health records of 250 patients were reviewed for demographic information, surgical data, complications, and readmission following surgery. The association of patient and surgical factors to complication rate was analyzed using multivariable logistic regression. Statistical analysis was performed using R statistical software (R, Vienna, Austria).

RESULTS: Of 250 lateral interbody fusion patients, 62.8% had a prior abdominal surgery and 13.8% had a history of colonic disease. The most common perioperative complication was transient thigh or groin pain/sensory changes (n=62, 24.8%). A multivariable logistic regression considering prior abdominal surgery, age, BMI, history of colonic disease, multilevel surgery, and the approach relative to psoas found no significant association between surgical complication rates and colonic disease (OR 0.40, 95% CI 0.02−2.22) or a history of prior abdominal surgeries (OR 0.56, 95% CI 0.20−1.55). Further, the invasiveness of prior abdominal surgeries showed no association with overall spine complication rate, lateral-specific complications, or readmission rates (p>.05).

CONCLUSION: Though retroperitoneal scarring is an important consideration for lateral approaches to the lumbar spine, this study found no association between lateral lumbar approach complication rates and prior abdominal surgery. Further study is needed to determine the impact of inflammatory colonic disease on lateral approach spine surgery.

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Challenges with segmenting intraoperative ultrasound for brain tumours

Challenges with segmenting intraoperative ultrasound for brain tumours

Acta Neurochirurgica (2024) 166:317

Addressing the challenges that come with identifying and delineating brain tumours in intraoperative ultrasound. Our goal is to both qualitatively and quantitatively assess the interobserver variation, amongst experienced neuro-oncological intraoperative ultrasound users (neurosurgeons and neuroradiologists), in detecting and segmenting brain tumours on ultrasound. We then propose that, due to the inherent challenges of this task, annotation by localisation of the entire tumour mass with a bounding box could serve as an ancillary solution to segmentation for clinical training, encompassing margin uncertainty and the curation of large datasets.

Methods – 30 ultrasound images of brain lesions in 30 patients were annotated by 4 annotators – 1 neuroradiologist and 3 neurosurgeons. The annotation variation of the 3 neurosurgeons was first measured, and then the annotations of each neurosurgeon were individually compared to the neuroradiologist’s, which served as a reference standard as their segmentations were further refined by cross-reference to the preoperative magnetic resonance imaging (MRI). The following statistical metrics were used: Intersection Over Union (IoU), Sørensen-Dice Similarity Coefficient (DSC) and Hausdorff Distance (HD). These annotations were then converted into bounding boxes for the same evaluation. Results – There was a moderate level of interobserver variance between the neurosurgeons [ IoU : 0.789, DSC : 0.876, H D : 103.227 ] and a larger level of variance when compared against the MRI-informed reference standard annotations by the neuroradiologist, mean across annotators [ IoU : 0.723, DSC : 0.813, H D : 115.675 ] . After converting the segments to bounding boxes, all metrics improve, most significantly, the interquartile range drops by [ IoU : 37%, DSC : 41%, H D : 54% ] .

Conclusion This study highlights the current challenges with detecting and defining tumour boundaries in neuro-oncological intraoperative brain ultrasound. We then show that bounding box annotation could serve as a useful complementary approach for both clinical and technical reasons.

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Intraoperative ultrasound and magnetic resonance comparative analysis in brain tumor surgery: a valuable tool to flatten ultrasound’s learning curve

Acta Neurochirurgica (2024) 166:337

Intraoperative ultrasound (IOUS) is a profitable tool for neurosurgical procedures’ assistance, especially in neuro-oncology. It is a rapid, ergonomic and reproducible technique. However, its known handicap is a steep learning curve for neurosurgeons. Here, we describe an interesting postoperative analysis that provides extra feedback after surgery, accelerating the learning process.

Method We conducted a descriptive retrospective unicenter study including patients operated from intra-axial brain tumors using neuronavigation (Curve, Brainlab) and IOUS (BK-5000, BK medical) guidance. All patients had preoperative Magnetic Resonance Imaging (MRI) prior to tumor resection. During surgery, 3D neuronavigated IOUS studies (n3DUS) were obtained through craniotomy N13C5 transducer’s integration to the neuronavigation system. At least two n3DUS studies were obtained: prior to tumor resection and at the resection conclusion. A postoperative MRI was performed within 48 h. MRI and n3DUS studies were posteriorly fused and analyzed with Elements (Brainlab) planning software, permitting two comparative analyses: preoperative MRI compared to pre-resection n3DUS and postoperative MRI to post-resection n3DUS. Cases with incomplete MRI or n3DUS studies were withdrawn from the study.

Results From April 2022 to March 2024, 73 patients were operated assisted by IOUS. From them, 39 were included in the study. Analyses comparing preoperative MRI and pre-resection n3DUS showed great concordance of tumor volume (p < 0,001) between both modalities. Analysis comparing postoperative MRI and post-resection n3DUS also showed good concordance in residual tumor volume (RTV) in cases where gross total resection (GTR) was not achieved (p < 0,001). In two cases, RTV detected on MRI that was not detected intra-operatively with IOUS could be reviewed in detail to recheck its appearance.

Conclusions Post-operative comparative analyses between IOUS and MRI is a valuable tool for novel ultrasound users, as it enhances the amount of feedback provided by cases and could accelerate the learning process, flattening this technique’s learning curve.

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