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Microsurgery versus Microsurgery With Preoperative Embolization for Brain Arteriovenous Malformation Treatment: A Systematic Review and Meta-analysis

Neurosurgery 92:27–41, 2023

Preoperative embolization has traditionally been regarded as a safe and effective adjunct to microsurgical treatment of brain arteriovenous malformations (bAVM). However, there is currently no high-level evidence to ascertain this presumption.

OBJECTIVE: To compare the outcomes of microsurgery (MS) vs microsurgery with preoperative embolization (E + MS) in patients with bAVM through systematic review.

METHODS: We searched MEDLINE, PubMed, and Embase. The primary outcome was bAVM obliteration. Secondary outcomes were intraoperative bleeding (mL), complications, worsened modified Rankin Scale (mRS), and mortality. The pooled proportions of outcomes were calculated through the logit transformation method. The odds ratio (OR) of categorical data and mean difference of continuous data were estimated through the Mantel-Haenszel and the inverse variance methods, respectively.

RESULTS: Thirty-two studies met the eligibility criteria. One thousand eight hundred twenty-eight patients were treated by microsurgery alone, and 1088 were treated by microsurgery with preoperative embolization, respectively. The meta-analysis revealed no significant difference in AVM obliteration (94.1% vs 95.6%, OR = 1.15 [0.63-2.11], P = .65), mortality (1.7% vs 2%, OR = 0.88 [0.30-2.58], P = .82), procedural complications (18.2% vs 27.2%, OR = 0.47 [0.19-1.17], P = .10), worsened mRS (21.2% vs 18.5%, OR = 1.08 [0.33-3.54], P = .9), and intraoperative blood loss (mean difference = 182.89 [À87.76, 453.55], P = .19).

CONCLUSION: The meta-analysis showed no significant difference in AVM obliteration, mortality, complications, worse mRS, and intraoperative blood loss between MS and E + MS groups. For AVMs where MS alone has acceptable results, it is reasonable to bypass unnecessary preoperative embolization given higher postoperative complication risk.

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Natural history of meningiomas: a serial volumetric analysis of 240 tumors

J Neurosurg 137:1639–1649, 2022

The management of asymptomatic intracranial meningiomas is controversial. Through the assessment of growth predictors, the authors aimed to create the basis for practicable clinical pathways for the management of these tumors.

METHODS The authors volumetrically analyzed meningiomas radiologically diagnosed at their institution between 2003 and 2015. The primary endpoint was growth of tumor volume. The authors used significant variables from the multivariable regression model to construct a decision tree based on the exhaustive Chi-Square Automatic Interaction Detection (CHAID) algorithm.

RESULTS Of 240 meningiomas, 159 (66.3%) demonstrated growth during a mean observation period of 46.9 months. On multivariable logistic regression analysis, older age (OR 0.979 [95% CI 0.958–1.000], p = 0.048) and presence of calcification (OR 0.442 [95% CI 0.224–0.872], p = 0.019) had a negative predictive value for tumor growth, while T2-signal iso-/hyperintensity (OR 4.415 [95% CI 2.056–9.479], p < 0.001) had a positive predictive value. A decision tree model yielded three growth risk groups based on T2 signal intensity and presence of calcifications. The median tumor volume doubling time (Td) was 185.7 months in the low-risk, 100.1 months in the intermediate-risk, and 51.7 months in the highrisk group (p < 0.001). Whereas 0% of meningiomas in the low- and intermediate-risk groups had a Td of ≤ 12 months, the percentage was 8.9% in the high-risk group (p = 0.021).

CONCLUSIONS Most meningiomas demonstrated growth during follow-up. The absence of calcifications and iso-/ hyperintensity on T2-weighted imaging offer a practical way of stratifying meningiomas as low, intermediate, or high risk. Small tumors in the low- or intermediate-risk categories can be monitored with longer follow-up intervals.

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Expanded endoscopic endonasal approach for the resection of midline craniopharyngiomas with hypothalamic involvement

Acta Neurochirurgica (2022) 164:3291–3296

With relevant surrounding neurological structures and potential involvement of the hypothalamus, the surgical management of craniopharyngiomas is complex. Compared to the transcranial approach, the expanded endoscopic endonasal approach provides direct access to the supradiaphragmatic and retrochiasmatic areas without crossing nerves and arteries.

Method Based on our substantial experience of 68 patients operated on between 2008 and 2022 by endoscopic surgery, our strategy has evolved such that all of our midline infundibular craniopharyngiomas with hypothalamic involvement are currently treated with an expanded endonasal route, except for tumours isolated to the third ventricle. Vascularized mucosal nasoseptal flaps are required for closure. Fine details of the related anatomy and surgical technique are described.

Conclusion Expanded endoscopic endonasal approach is a safe and effective route for resection of midline suprasellar craniopharyngiomas with hypothalamic involvement in centres of expertise.

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Audiovestibular symptoms and facial nerve function comparing microsurgery versus SRS for vestibular schwannomas

Acta Neurochirurgica (2022) 164:3221–3233

Surgery and radiosurgery represent the most common treatment options forcvestibular schwannoma. A systematic review and meta-analysis were conducted to compare the outcomes of surgery versus stereotactic radiosurgery (SRS).

Methods The Cochrane library, PubMed, Embase, and clinicaltrials.gov were searched through 01/2021 to find all studies on surgical and stereotactic procedures performed to treat vestibular schwannoma. Using a random-effects model, pooled odds ratios (OR) and their 95% confidence intervals (CI) comparing post- to pre-intervention were derived for pre-post studies, and pooled incidence of adverse events post-intervention were calculated for case series and stratified by intervention type.

Results Twenty-one studies (18 pre-post design; three case series) with 987 patients were included in the final analysis. Comparing post- to pre-intervention, both surgery (OR: 3.52, 95%CI 2.13, 5.81) and SRS (OR: 3.30, 95%CI 1.39, 7.80) resulted in greater odds of hearing loss, lower odds of dizziness (surgery OR: 0.10; 95%CI 0.02, 0.47 vs. SRS OR: 0.22; 95%CI 0.05, 0.99), and tinnitus (surgery OR: 0.23; 95%CI 0.00, 37.9; two studies vs. SRS OR: 0.11; 95%CI 0.01, 1.07; one study). Pooled incidence of facial symmetry loss was larger post-surgery (14.3%, 95%CI 6.8%, 22.7%) than post-SRS (7%, 95%CI 1%, 36%). Tumor control was larger in the surgery (94%, 95%CI 83%, 98%) than the SRS group (80%, 95%CI 31%, 97%) for small-to-medium size tumors.

Conclusion Both surgery and SRS resulted in similar odds of hearing loss and similar improvements in dizziness and tinnitus among patients with vestibular schwannoma; however, facial symmetry loss appeared higher post-surgery.

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Favorable long‐term outcome in young adults undergoing surgery for lumbar disc herniation

Acta Neurochirurgica (2022) 164:3155–3164

The purpose of the study was to evaluate the long-term outcome after surgery for lumbar disc herniation in a young adult population.

Methods A total of 526 consecutive patients between 18 and 40 years of age who underwent surgery for lumbar disc between 1990 and 2005 were included in the study. The primary outcomes were the need for new lumbar spine surgery during the follow-up and secondary outcomes were short-term subjective outcome, the Oswestry Disability Index (ODI) score, and the ability to carry out employment at the end of the long-term follow-up.

Results A total of 96% of the patients had a reduction in their symptoms at the clinical follow-up (median of 50 days post- surgery). Twenty-one patients (4.0%) had a reoperation within 28 days. Excluding these early reoperations, 136 patients (26%) had additional lumbar spine surgery and 18 patients (3.4%) underwent lumbar fusion during the follow-up of median 18 years. The annual risk for new surgery was 1.4%. In total, 316 patients (60%) returned the ODI questionnaire, and their mean score was 8.1. Patients with a higher number of additional lumbar spine surgeries (p < 0.001) reported deteriorating ODI scores.

Conclusion Patients showed excellent short-term recovery from their symptoms. In the long term, the mean ODI score for the patients was comparable to the normative population. However, a notable proportion of the patients required additional lumbar surgery during the follow-up period, and a higher number of lumbar surgeries was associated with poor ODI scores.

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Ideal entry point and trajectory for C2 pedicle screw placement in children: a 3D computed tomography study

European Spine Journal (2022) 31:3426–3432

Purpose To identify the ideal entry point for pediatric C2 pedicle screw and to obtain parameters of it for the indication of pediatric atlantoaxial fusion arthrodesis.

Methods The pediatric cervical CT images were reconstructed into the 3D digital models and the C2 vertebrae were separated. The location of ideal entry point and screw placement related linear and angular parameters were assessed on the 3D digital models.

Results A total of 214 pedicles from 107 C2 digital models were analyzed. The average entry point for C2 was 3.80 ± 2.78 mm medial to the lateral notch (LN) and 2.57 ± 1.70 mm superior to the LN. The average pedicle diameter (PD) was 6.02 ± 1.31 mm, and the average pedicle screw length (PSL) was 25.63 ± 3.46 mm. Statistical differences were found between different sex for PD and PSL (P < 0.05). As patient age increases, using the most lateral and inferior edge of the lateral mass as a reference marker, the entry point tends to move medial and cephalad, when using the LN as a reference marker, the entry point tends to move medial and slightly caudad. Univariate linear regression analysis suggested that these linear parameters were associated with age (P < 0.01).

Conclusion In this study, we found that the measurement results of C2 pedicle screw varied based on sex, laterality, and ages for children younger than 18 years. The entry point of the screws facilitating ideal trajectory tends to change in a linear way as a function of age. This information helps the surgeon to establish the specific anatomy related to C2 pedicle screw placement to facilitate fixation in the pediatric patients.

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Adult diffuse intrinsic pontine glioma: clinical, radiological, pathological, molecular features, and treatments of 96 patients

J Neurosurg 137:1628–1638, 2022

Unlike its pediatric counterpart, adult diffuse intrinsic pontine glioma (DIPG) remains largely unelucidated. In this study, the authors examined the clinical, radiological, pathological, molecular, and clinical aspects of 96 adult DIPGs.

METHODS The National Brain Tumor Registry of China (April 2013–December 2019) was used to collect data on radiologically diagnosed adult DIPG patients. Survival analysis was conducted using Kaplan-Meier curves and univariate and multivariate Cox regression. The chi-square test/Wilcoxon rank-sum test and multivariable logistic regression were used to examine the clinical and radiological characteristics of patients with long-term survival (LTS). Interaction analyses between clinical factors were also conducted.

RESULTS The median age at symptom onset was 33.5 years, and the median duration of symptoms was 4.5 months. The frequencies of H3K27M and IDH1 mutations were 37.2% and 26.5%, respectively. All adult DIPG patients had a median overall survival (OS) of 19.5 months, with 1-, 2-, and 3-year survival rates of 67.0%, 42.8%, and 36.0%, respectively. The median OS of 40 patients who did not undergo treatment was 13.4 months. Patients with H3K27M-mutant tumors had a poorer prognosis than those with IDH-mutant tumors (p < 0.001) and H3K27M(−)/IDH–wild-type tumors (p = 0.002), with a median OS of 11.4 months. The median OSs of patients with H3K27M-mutant tumors who received treatment and those who did not were 13.8 months and 7.5 months, respectively (p = 0.016). Among patients with and without a pathological diagnosis, H3K27M mutation (p < 0.001) and contrast enhancement on MRI (p = 0.003), respectively, imparted a worse prognosis. Treatments were the predictive factor for patients with H3K27M-mutant tumors (p = 0.038), whereas contrast enhancement on MRI was the prognostic factor for the H3K27M(−) group (p = 0.038). In addition, H3K27M mutation and treatment were significant predictors for patients with symptom duration ≤ 4 months (H3K27M, p = 0.020; treatment, p = 0.014) and tumors with no contrast enhancement (H3K27M, p = 0.003; treatment, p = 0.042). Patients with LTS were less likely to have cranial nerve palsy (p = 0.002) and contrast enhancement on MRI at diagnosis (p = 0.022).

CONCLUSIONS It is recommended that all adult DIPG patients undergo genomic testing for H3K27M and IDH mutations. Despite the low prevalence, additional study is needed to better characterize the efficacy of various treatment modalities in adults with DIPG.

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Operative treatment outcomes for adult cervical deformity: a prospective multicenter assessment with mean 3-year follow-up

J Neurosurg Spine 37:855–864, 2022

Adult cervical deformity (ACD) has high complication rates due to surgical complexity and patient frailty. Very few studies have focused on longer-term outcomes of operative ACD treatment. The objective of this study was to assess minimum 2-year outcomes and complications of ACD surgery.

METHODS A multicenter, prospective observational study was performed at 13 centers across the United States to evaluate surgical outcomes for ACD. Demographics, complications, radiographic parameters, and patient-reported outcome measures (PROMs; Neck Disability Index, modified Japanese Orthopaedic Association, EuroQol-5D [EQ-5D], and numeric rating scale [NRS] for neck and back pain) were evaluated, and analyses focused on patients with ≥ 2-year follow-up.

RESULTS Of 169 patients with ACD who were eligible for the study, 102 (60.4%) had a minimum 2-year follow-up (mean 3.4 years, range 2–8.1 years). The mean age at surgery was 62 years (SD 11 years). Surgical approaches included anterior-only (22.8%), posterior-only (39.6%), and combined (37.6%). PROMs significantly improved from baseline to last follow-up, including Neck Disability Index (from 47.3 to 33.0) and modified Japanese Orthopaedic Association score (from 12.0 to 12.8; for patients with baseline score ≤ 14), neck pain NRS (from 6.8 to 3.8), back pain NRS (from 5.5 to 4.8), EQ-5D score (from 0.74 to 0.78), and EQ-5D visual analog scale score (from 59.5 to 66.6) (all p ≤ 0.04). More than half of the patients (n = 58, 56.9%) had at least one complication, with the most common complications including dysphagia, distal junctional kyphosis, instrumentation failure, and cardiopulmonary events. The patients who did not achieve 2-year follow-up (n = 67) were similar to study patients based on baseline demographics, comorbidities, and PROMs. Over the course of follow-up, 23 of the total 169 enrolled patients were reported to have died. Notably, these represent all-cause mortalities during the course of follow-up.

CONCLUSIONS This multicenter, prospective analysis demonstrates that operative treatment for ACD provides significant improvement of health-related quality of life at a mean 3.4-year follow-up, despite high complication rates and a high rate of all-cause mortality that is reflective of the overall frailty of this patient population. To the authors’ knowledge, this study represents the largest and most comprehensive prospective effort to date designed to assess the intermediate-term outcomes and complications of operative treatment for ACD.

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Psoas weakness following oblique lateral interbody fusion surgery: a prospective observational study with an isokinetic dynamometer

The Spine Journal 22 (2022) 1990−1999

Although the surgical corridor used for oblique lateral interbody fusion (OLIF) protects the intrapsoas nerves by causing minimal compression, transient weakness remains the most commonly reported postoperative complication.

PURPOSE: Using a dynamometer to evaluate how the hip flexor strength changes following OLIF.

STUDY DESIGN/SETTING: A prospective observational study.

PATIENT SAMPLE: Forty-six patients who underwent single or multi-level OLIF for lumbar spondylolisthesis.

OUTCOME MEASURES: Isokinetic dynamometer values (peak torque, total work, average power), visual analogue scale (VAS) scores for leg pain, hypoesthesia, subjective weakness of the left hip flexor muscle, Oswestry disability index, body mass index, bone mineral density, radiologic findings of the psoas muscle (cross-sectional area, Hounsfield unit (HU), fat portion grade), and psoas retraction time.

METHODS: The isokinetic muscle strength of the hip flexor was measured five times (preoperatively and postoperatively at 2 days, 1 week, 1 month, and 3 months) for both legs. The peak torque was defined as the postoperative strength of the left hip flexor muscles, and was compared to the preoperative baseline value. The strength of the left and right hip flexor muscles were also compared at each time point. For logistic regression analysis, when the peak torque was below the median value, it was defined as lower peak torque.

RESULTS: Up to 1 week after surgery, the strength of the left hip flexor muscle decreased significantly (paired difference in peak torque was 22.6%, p<.001). In the results of multivariate logistic regression analysis, diabetes (odds ratio [OR]=8.43, p=.020) and the HU of the psoas muscle (OR=0.916, p=.034) were associated with lower peak torque 1 week after surgery. From 1 month after surgery, postoperative weakness of the psoas muscle was not significant. In the questionnaire survey, subjective left hip flexion weakness was reported in 8.5% (4/47) of patients 1 week after surgery, and it remained in only 2.1% (1/47) of patients after 3 months of operation. The frequency of left anterior thigh pain and hypoesthesia decreased from 85.1% (40/47) at 1 week to 2.1% (1/47) at 3 months after surgery. The mean VAS score for left anterior thigh or groin pain decreased significantly at 1 month after surgery (PO2D: 4.04§1.84, PO1M: 1.67§1.10, p<.001).

CONCLUSIONS: Dynamometer measurement showed that psoas strength declined significantly up to 1 week after OLIF surgery. Patients with diabetes or lower HU of the psoas muscle showed delayed recovery from postoperative weakness of the psoas muscle. However, the weakness was insignificant from 1 month after surgery. At 3 months after surgery, the other psoas-related problems (left anterior thigh pain and hypoesthesia) also disappeared.

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Frameless neuronavigation‑assisted brain biopsy with electromagnetic tracking

Acta Neurochirurgica (2022) 164:3317–3322

In recent years, thanks to several technological innovations, stereotactic cerebral biopsies have evolved from frame-based to frameless neuronavigation-assisted techniques.

Methods The authors provide herein a detailed step-by-step description of the technique, shedding light on surgical tips and how to avoid complications. The practical application of the technique is demonstrated with a high-quality video.

Conclusion The neuronavigation-assisted brain biopsy with electromagnetic tracking is a “true frameless” procedure. It represents a simple, safe, and effective innovation for frameless biopsy of cerebral lesions. This technique is time efficient, offering a high degree of accuracy required for the establishment of a definitive diagnosis, enabling optimal further treatment, and thus improving patient outcome.

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Reoperations after primary and revision lumbar discectomy

The Spine Journal 22 (2022) 1983−1989

Published rates for disc reherniation following primary discectomy are around 6%, but the ultimate reoperation outcomes in patients after receiving revision discectomy are not well understood. Additionally, any disparity in the outcomes of subsequent revision discectomy (SRD) versus subsequent lumbar fusion (SLF) following primary/revision discectomy remains poorly studied.

PURPOSE: To determine the 8-year SRD/SLF rates and time until SRD/SLF after primary/revision discectomy respectively.

STUDY DESIGN: Retrospective cohort study.

PATIENT SAMPLE: Patients undergoing primary or revision discectomy, with records in the PearlDiver Patient Records Database from the years 2010 to 2019.

OUTCOME MEASURES: Subsequent surgery type and time to subsequent surgery.

METHODS: Patients were grouped into primary or revision discectomy cohorts based off of the nature of “index” procedure (primary or revision discectomy) using ICD9/10 and CPT procedure codes from 2010 to 19 insurance data sets in the PearlDiver Patient Records Database. Preoperative demographic data was collected. Outcome measures such as subsequent surgery type (fusion or discectomy) and time to subsequent surgery were collected prospectively in PearlDiver Mariner database. Statistical analysis was performed using BellWeather statistical software. A Kaplan-Meier survival analysis of time to SLF/SRD was performed on each cohort, and log-rank test was used to compare the rates of SLF/SRD between cohorts.

RESULTS: A total of 20,147 patients were identified (17,849 primary discectomy, 2,298 revision discectomy). The 8-year rates of SRD (6.1% in revision cohort, 4.8% in primary cohort, p<.01) and SLF (10.4% in revision cohort, 6.2% in primary cohort, p<.01) were higher after revision versus primary discectomy. Time to SLF was shorter after revision versus primary discectomy (709 vs. 886 days, p<.01). After both primary and revision discectomy, the 8-year rate of SLF (10.4% in revision cohort, 6.2% in primary cohort, p<.01) is greater than SRD (6.1% in revision cohort, 4.8% in primary cohort, p<.01).

CONCLUSIONS: Compared to primary discectomy, revision discectomy has higher rates of SLF (10.4% vs. 6.2%), and faster time to SLF (2.4 vs. 1.9 years) at 8-year follow up.

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Classification system for cervical spine deformity morphology: a validation study

J Neurosurg Spine 37:865–873, 2022

OBJECTIVE The objective of this study was to initially validate a recent morphological classification of cervical spine deformity pathology.

METHODS The records of 10 patients for each of the 3 classification subgroups (flat neck, focal deformity, and cervicothoracic), as well as for 8 patients with coronal deformity only, were extracted from a prospective multicenter database of patients with cervical deformity (CD). A panel of 15 physicians of various training and professional levels (i.e., residents, fellows, and surgeons) categorized each patient into one of the 4 groups. The Fleiss kappa coefficient was utilized to evaluate intra- and interrater reliability. Accuracy, defined as properly selecting the main driver of deformity, was reported overall, by morphotype, and by reviewer experience.

RESULTS The overall classification demonstrated a moderate to substantial agreement (round 1: interrater Fleiss kappa = 0.563, 95% CI 0.559–0.568; round 2: interrater Fleiss kappa = 0.612, 95% CI 0.606–0.619). Stratification by level of training demonstrated similar mean interrater coefficients (residents 0.547, fellows 0.600, surgeons 0.524). The mean intrarater score was 0.686 (range 0.531–0.823). A substantial agreement between rounds 1 and 2 was demonstrated in 81.8% of the raters, with a kappa score > 0.61. Stratification by level of training demonstrated similar mean intrarater coefficients (residents 0.715, fellows 0.640, surgeons 0.682). Of 570 possible questions, reviewers provided 419 correct answers (73.5%). When considering the true answer as being selected by at least one of the two main drivers of deformity, the overall accuracy increased to 86.0%.

CONCLUSIONS This initial validation of a CD morphological classification system reiterates the importance of dynamic plain radiographs for the evaluation of patients with CD. The overall reliability of this CD morphological classification has been demonstrated. The overall accuracy of the classification system was not impacted by rater experience, demonstrating its simplicity.

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Strategies, considerations, and recent advancements in the development of liquid biopsy for glioblastoma

Neurosurg Focus 53 (6):E14, 2022

Glioblastoma (GBM) is a devasting primary brain tumor with less than a 5% 5-year survival. Treatment response assessment can be challenging because of inflammatory pseudoprogression that mimics true tumor progression clinically and on imaging. Developing additional noninvasive assays is critical. In this article, the authors review various biomarkers that could be used in developing liquid biopsies for GBM, along with strengths, limitations, and future applications. In addition, they present a potential liquid biopsy design based on the use of an extracellular vesicle–based liquid biopsy targeting nonneoplastic extracellular vesicles.

METHODS The authors conducted a current literature review of liquid biopsy in GBM by searching the PubMed, Scopus, and Google Scholar databases. Articles were assessed for type of biomarker, isolation methodology, analytical techniques, and clinical relevance.

RESULTS Recent work has shown that liquid biopsies of plasma, blood, and/or CSF hold promise as noninvasive clinical tools that can be used to diagnose recurrence, assess treatment response, and predict patient outcomes in GBM. Liquid biopsy in GBM has focused primarily on extracellular vesicles, cell-free tumor nucleic acids, and whole-cell isolates as focal biomarkers. GBM tumor signatures have been generated via analysis of tumor gene mutations, unique RNA expression, and metabolic and proteomic alterations. Liquid biopsies capture tumor heterogeneity, identifying alterations in GBM tumors that may be undetectable via surgical biopsy specimens. Finally, biomarker burden can be used to assess treatment response and recurrence in GBM.

CONCLUSIONS Liquid biopsy offers a promising avenue for monitoring treatment response and recurrence in GBM without invasive procedures. Although additional steps must be taken to bring liquid biopsy into the clinic, proof-of-principle studies and isolation methodologies are promising. Ultimately, CSF and/or plasma-based liquid biopsy is likely to be a powerful tool in the neurosurgeon’s arsenal in the near future for the treatment and management of GBM patients.

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Risk Factors for Fracture Nonunion and Transverse Atlantal Ligament Injury After Isolated Atlas Fractures: A Case Series of 97 Patients

Neurosurgery 91:900–905, 2022

The management of atlas fractures is controversial and hinges on the integrity of transverse atlantal ligament (TAL).

OBJECTIVE: To identify risk factors for atlas fracture nonunion, with and without TAL injury.

METHODS: All isolated, traumatic atlas fractures treated at our institution between 1999 and 2016 were analyzed. Multivariable logistic regression was used to identify variables associated with TAL injury confirmed on MRI, occult TAL injury seen on MRI but not suspected on computed tomography (CT), and with fracture nonunion on follow-up CT at 12 weeks.

RESULTS: Lateral mass displacement (LMD) ≥ 7 mm had a 48.2% sensitivity, 98.3% specificity, and 82.6% accuracy for identifying TAL injury. MRI-confirmed TAL injury was independently associated with LMD > 7 mm (P = .004) and atlanto-dental interval (P = .039), and occult TAL injury was associated with atlanto-dental interval (P = .019). Halo immobilization was associated with having a Gehweiler type 3 fracture (P = .020), a high-risk injury mechanism (P = .023), and an 18.1% complication rate. Thirteen patients with TAL injury on MRI and/or LMD ≥ 7 mm were treated with a cervical collar only, and 11 patients (84.6%) healed at 12 weeks. Nonunion rates at 12 weeks were equivalent between halo (11.1%) and cervical collar (12.5%). Only age independently predicted nonunion at 12 weeks (P = .026).

CONCLUSION: LMD > 7 mm on CT is not sensitive for TAL injury. Some atlas fractures with TAL injury can be managed with a cervical collar. Nonunion rates are not different between halo immobilization and cervical collar, but a strong selection bias precludes directly comparing the efficacy of these modalities. Age independently predicts nonunion.

 

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Personalized surgery of brain tumors in language areas: the role of preoperative brain mapping in patients not eligible for awake surgery

Neurosurg Focus 53 (6):E3, 2022

Awake surgery represents the gold standard for resection of brain tumors close to the language network. However, in some cases patients may be considered not eligible for awake craniotomy. In these cases, a personalized brain mapping of the language network may be achieved by navigated transcranial magnetic stimulation (nTMS), which can guide resection in patients under general anesthesia. Here the authors describe their tailored nTMS-based strategy and analyze its impact on the extent of tumor resection (EOR) and language outcome in a series of patients not eligible for awake surgery.

METHODS The authors reviewed data from all patients harboring a brain tumor in or close to the language network who were considered not eligible for awake surgery and were operated on during asleep surgery between January 2017 and July 2022, under the intraoperative guidance of nTMS data. The authors analyzed the effectiveness of nTMS-based mapping data in relation to 1) the ability of the nTMS-based mapping to stratify patients according to surgical risks, 2) the occurrence of postoperative language deficits, and 3) the EOR.

RESULTS A total of 176 patients underwent preoperative nTMS cortical language mapping and nTMS-based tractography of language fascicles. According to the nTMS-based mapping, tumors in 115 patients (65.3%) were identified as true-eloquent tumors because of a close spatial relationship with the language network. Conversely, tumors in 61 patients (34.7%) for which the nTMS mapping disclosed a location at a safer distance from the network were identified as false-eloquent tumors. At 3 months postsurgery, a permanent language deficit was present in 13 patients (7.3%).

In particular, a permanent deficit was observed in 12 of 115 patients (10.4%) with true-eloquent tumors and in 1 of 61 patients (1.6%) with false-eloquent lesions. With nTMS-based mapping, neurosurgeons were able to distinguish trueeloquent from false-eloquent tumors in a significant number of cases based on the occurrence of deficits at discharge (p < 0.0008) and after 3 months from surgery (OR 6.99, p = 0.03). Gross-total resection was achieved in 80.1% of patients overall and in 69.5% of patients with true-eloquent lesions and 100% of patients with false-eloquent tumors.

CONCLUSIONS nTMS-based mapping allows for reliable preoperative mapping of the language network that may be used to stratify patients according to surgical risks. nTMS-guided asleep surgery should be considered a good alternative for personalized preoperative brain mapping of the language network that may increase the possibility of safe and effective resection of brain tumors in the dominant hemisphere whenever awake mapping is not feasible.

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Novel artificial intelligence algorithm: an accurate and independent measure of spinopelvic parameters

J Neurosurg Spine 37:893–901, 2022

The analysis of sagittal alignment by measuring spinopelvic parameters has been widely adopted among spine surgeons globally, and sagittal imbalance is a well-documented cause of poor quality of life. These measurements are time-consuming but necessary to make, which creates a growing need for an automated analysis tool that measures spinopelvic parameters with speed, precision, and reproducibility without relying on user input. This study introduces and evaluates an algorithm based on artificial intelligence (AI) that fully automatically measures spinopelvic parameters.

METHODS Two hundred lateral lumbar radiographs (pre- and postoperative images from 100 patients undergoing lumbar fusion) were retrospectively analyzed by board-certified spine surgeons who digitally measured lumbar lordosis, pelvic incidence, pelvic tilt, and sacral slope. The novel AI algorithm was also used to measure the same parameters. To evaluate the agreement between human and AI-automated measurements, the mean error (95% CI, SD) was calculated and interrater reliability was assessed using the 2-way random single-measure intraclass correlation coefficient (ICC). ICC values larger than 0.75 were considered excellent.

RESULTS The AI algorithm determined all parameters in 98% of preoperative and in 95% of postoperative images with excellent ICC values (preoperative range 0.85–0.92, postoperative range 0.81–0.87). The mean errors were smallest for pelvic incidence both pre- and postoperatively (preoperatively −0.5° [95% CI −1.5° to 0.6°] and postoperatively 0.0° [95% CI −1.1° to 1.2°]) and largest preoperatively for sacral slope (−2.2° [95% CI −3.0° to −1.5°]) and postoperatively for lumbar lordosis (3.8° [95% CI 2.5° to 5.0°]).

CONCLUSIONS Advancements in AI translate to the arena of medical imaging analysis. This method of measuring spinopelvic parameters on spine radiographs has excellent reliability comparable to expert human raters. This application allows users to accurately obtain critical spinopelvic measurements automatically, which can be applied to clinical practice. This solution can assist physicians by saving time in routine work and by avoiding error-prone manual measurements.

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Indication for a skull base approach in microvascular decompression for hemifacial spasm

Acta Neurochirurgica (2022) 164:3235–3246

A thorough observation of the root exit zone (REZ) and secure transposition of the offending arteries is crucial for a successful microvascular decompression (MVD) for hemifacial spasm (HFS). Decompression procedures are not always feasible in a narrow operative field through a retrosigmoid approach. In such instances, extending the craniectomy laterally is useful in accomplishing the procedure safely. This study aims to introduce the benefits of a skull base approach in MVD for HFS.

Methods The skull base approach was performed in twenty-eight patients among 335 consecutive MVDs for HFS. The site of the neurovascular compression (NVC), the size of the flocculus, and the location of the sigmoid sinus are measured factors in the imaging studies. The indication for a skull base approach is evaluated and verified retrospectively in comparison with the conventional retrosigmoid approach. Operative outcomes and long-term results were analyzed retrospectively.

Results The extended retrosigmoid approach was used for 27 patients and the retrolabyrinthine presigmoid approach was used in one patient. The measurement value including the site of NVC, the size of the flocculus, and the location of the sigmoid sinus represents well the indication of the skull base approach, which is significantly different from the conventional retrosigmoid approach. The skull base approach is useful for patients with medially located NVC, a large flocculus, or repeat MVD cases. The long-term result demonstrated favorable outcomes in patients with the skull base approach applied. Conclusions Preoperative evaluation for lateral expansion of the craniectomy contributes to a safe and secure MVD.

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Microsurgical sealing for symptomatic sacral Tarlov cysts: a series of 265 cases

J Neurosurg Spine 37:905–913, 2022

Tarlov cysts (TCs) are a common cystic entity in the sacral canal, with a reported prevalence between 1.5% and 13.2%; 10%–20% of patients are symptomatic and need appropriate clinical intervention. However, the choice of treatment remains controversial. The goal of this study was to describe a new microsurgical sealing technique for symptomatic sacral TCs (SSTCs) as well as its long-term outcomes.

METHODS Microsurgical sealing was performed using a short incision, leakage coverage with a piece of autologous fat, and cyst sealing with fibrin glue. Postoperative data were collected at three stages: discharge, 1-year follow-up, and a follow-up of 3 years or more. According to the improvement in neurological deficits and degree of pain relief, outcomes were divided into four levels: excellent, good, unchanged, and deteriorated.

RESULTS A total of 265 patients with SSTCs were treated with microsurgical sealing from January 2003 to December 2020. The mean follow-up was 44.69 months. The percentages of patients who benefited from the operation (excellent and good) at the three stages were 87.55%, 84.89%, and 80.73%, respectively, while those who received no benefit (unchanged and deteriorated) were 12.45%, 15.11%, and 19.27%, respectively. Of the patients with postoperative MRI, the cysts were reduced in size or disappeared in 209 patients (94.14%). CSF leakage from the wound was observed in 15 patients, and 4 patients experienced an infection at the incision. There were no cases of new-onset nerve injury or aseptic meningitis after the operation.

CONCLUSIONS SSTC patients undergoing microsurgical sealing had persistently high rates of symptom relief and few postoperative complications. Microsurgical sealing is an effective, simple, and low-risk method for treating SSTCs.

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Geniculate Neuralgia: A Case Report and Systematic Review

Neurosurgery Open 2022;3(4):e00022.

Geniculate neuralgia (GN) is a rare disorder characterized by brief paroxysms of pain felt deeply in the auditory canal, like shock. The diagnosis of GN is essentially clinical and requiring the exclusion of other causes. The aim of this study was to report a case of surgical treatment of the disease and perform a systematic review of surgical treatment options.

CLINICAL PRESENTATION: A 62-year-old female patient has had severe, sharp pain in her left ear—like an ice pick—for the past 8 months, without any history of trauma or infection. She had triggers for pain, such as talking or swallowing. Imaging investigation showed a vessel touching VIIth and VIIIth nerves, possibly the anterior inferior cerebellar artery. After finding a clinical presentation compatible with GN, treatment with anticonvulsants, gabapentinoids, and opioids was attempted, but without success with such conservative treatments. Therefore, we opted for microvascular decompression and section of the nervus intermedius, which were performed without complications. Neurophysiological assessment was essential to monitor the long tracts and stimulate VIIth and VIIIth nerves to help identify the intermediate nerve. After the procedure, the patient was without pain, and after 12 months of follow-up, she remains without any pain.

CONCLUSION: Surgical treatment of GN might be beneficial when medical treatment has not worked. Cranial nerves neurophysiological monitoring is not routinely performed, and the identification is based on anatomy. A more comprehensive knowledge of this condition will help in the surgical treatment choice and in achieving better results.

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Risk for Hemorrhage the First 2 Years After Gamma Knife Surgery for Arteriovenous Malformations: An Update

Neurosurgery 91:920–927, 2022

Knowledge about the natural course of brain arteriovenous malformations (AVMs) have increased during the past 20 years, as has the number of AVMs treated, especially larger ones. It is thus timely to again analyze the risk for hemorrhage after Gamma Knife Surgery (GKS).

OBJECTIVE: To confirm or contradict conclusions drawn 20 years ago regarding factors that affect the risk for post-GKS hemorrhage.

METHODS: The outcome after GKS was studied in 5037 AVM patients followed for up to 2 years. The relation between post-treatment hemorrhage rate and a number of patient, AVM, and treatment parameters was analyzed. The results were also compared with the results from our earlier study.

RESULTS: The annual post-treatment hemorrhage rate was 2.4% the first 2 years after GKS. Large size, low treatment dose, and old age were independent risk factors for AVM hemorrhage. After having compensated for the factors above, peripheral AVM location and female sex, at least during their child bearing ages, were factors associated with a lower post-GKS hemorrhage rate.

CONCLUSION: Large AVMs (>5 cm3) treated with low doses (≤16 Gy) had higher and small AVMs treated with high doses a lower risk for hemorrhage as compared with untreated AVMs. This was detectable within the first 6 months after GKS. No difference in hemorrhage rate could be detected for the other AVMs. Based on our findings, it is advisable to prescribe >16 Gy to larger AVMs, assuming that the risk for radiation-induced complications can be kept at an acceptable level.

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