Deep Learning for Outcome Prediction in Neurosurgery

Neurosurgery 90:16–38, 2022

Deep learning (DL) is a powerful machine learning technique that has increasingly been used to predict surgical outcomes. However, the large quantity of data required and lack of model interpretability represent substantial barriers to the validity and reproducibility of DL models.

The objective of this study was to systematically review the characteristics of DL studies involving neurosurgical outcome prediction and to assess their bias and reporting quality.

Literature search using the PubMed, Scopus, and Embase databases identified 1949 records of which 35 studies were included. Of these, 32 (91%) developed and validated a DL model while 3 (9%) validated a pre-existing model. The most commonly represented subspecialty areas were oncology (16 of 35, 46%), spine (8 of 35, 23%), and vascular (6 of 35, 17%). Risk of bias was low in 18 studies (51%), unclear in 5 (14%), and high in 12 (34%), most commonly because of data quality deficiencies.

Adherence to transparent reporting of a multivariable prediction model for individual prognosis or diagnosis reporting standards was low, with a median of 12 transparent reporting of a multivariable prediction model for individual prognosis or diagnosis items (39%) per study not reported. Model transparency was severely limited because code was provided in only 3 studies (9%) and final models in 2 (6%).

With the exception of public databases, no study data sets were readily available. No studies described DL models as ready for clinical use. The use of DL for neurosurgical outcome prediction remains nascent. Lack of appropriate data sets poses a major concern for bias. Although studies have demonstrated promising results, greater transparency in model development and reporting is needed to facilitate reproducibility and validation.

Racial and Socioeconomic Disparities in Patients With Meningioma: A Retrospective Cohort Study

Neurosurgery 90:114–123, 2022

Meningiomas are the most common intracranial neoplasms. Although genomic analysis has helped elucidate differences in survival, there is evidence that racial disparities may influence outcomes. African Americans have a higher incidence of meningiomas and poorer survival outcomes. The etiology of these disparities remains unclear, but may include a combination of pathophysiology and other factors.

OBJECTIVE: To determine factors that contribute to different clinical outcomes in racial populations.

METHODS: We retrospectively reviewed 305 patients who underwent resection for meningiomas at a single tertiary care facility. We used descriptive statistics and univariate, multivariable, and Kaplan-Meier analyses to study clinical, radiographical, and histopathological differences.

RESULTS: Minority patients were more likely to present through the emergency department than an outpatient clinic (P < .0001). They were more likely to present with more advanced clinical symptoms with lower Karnofsky Performance scores, more frequently had peritumoral edema (P = .0031), and experienced longer postoperative stays in the hospital (P = .0053), and African-American patients had higher hospitalization costs (P = .046) and were more likely to be publicly insured. Extent of resection was an independent predictor of recurrence freedom (P = .039). Presentation in clinic setting trended toward an association with recurrence-free survival (P = .055). We observed no significant difference in gross total resection rates, postoperative recurrence, or recurrence-free survival.

CONCLUSION: Minority patients are more likely to present with severe symptoms, require longer perioperative hospitalization, and generate higher hospitalization costs. This may be due to socioeconomic factors that affect access to health care. Targeting barriers to access, especially to subspecialty care, may facilitate more appropriate and timely diagnosis, thereby improving patient care and outcomes.

 

 

Proposal of a new grading system for meningioma resection: the Copenhagen Protocol

Acta Neurochirurgica (2022) 164:229–238

The extent of meningioma resection is the most fundamental risk factor for recurrence, and exact knowledge of extent of resection is necessary for prognostication and for planning of adjuvant treatment. Currently used classifications are the EANO-grading and the Simpson grading. The former comprises radiological imaging with contrast-enhanced MRI and differentiation between “gross total removal” and “subtotal removal,” while the latter comprises a five-tiered differentiation of the surgeon’s impression of the extent of resection. The extent of resection of tumors is usually defined via analyses of resection margins but has until now not been implemented for meningiomas. PET/MRI imaging with 68Ga-DOTATOC allows more sensitive and specific imaging than MRI following surgery of meningiomas.

Objective To develop an objective grading system based on microscopic analyses of resection margins and sensitive radiological analyses to improve management of follow-up, adjuvant therapy, and prognostication of meningiomas. Based on the rationale of resection-margin analyses as gold standard and superior imaging performance of 68Ga DOTATOC PET, we propose “Copenhagen Grading” for meningiomas.

Results Copenhagen Grading was described for six pilot patients with examples of positive and negative findings on histopathology and DOTATOC PET scanning. The grading could be traceably implemented and parameters of grading appeared complementary. Copenhagen Grading is prospectively implemented as a clinical standard at Rigshospitalet, Copenhagen.

Conclusion Copenhagen Grading provided a comprehensive, logical, and reproducible definition of the extent of resection. It offers promise to be the most sensitive and specific imaging modality available for meningiomas. Clinical and cost-efficacy remain to be established during prospective implementation.

Clinical outcomes in revision lumbar spine fusions: an observational cohort study

J Neurosurg Spine 35:437–445, 2021

The authors compared primary lumbar spine fusions with revision fusions by using patient Oswestry Disability Index (ODI) scores to evaluate the impact of the North American Spine Society (NASS) evidence-based medicine (EBM) lumbar fusion indications on patient-reported outcome measures of revision surgeries.

METHODS This study was a retrospective analysis of a prospective observational cohort of patients who underwent elective lumbar fusion between January 2018 and December 2019 at a single quaternary spine surgery service and had a minimum of 6 months of follow-up. A prospective quality improvement database was constructed that included the data from all elective lumbar spine surgeries, which were categorized prospectively as primary or revision surgeries and EBM-concordant or EBM-discordant revision surgeries based on the NASS coverage EBM policy. In total, 309 patients who met the inclusion criteria were included in the study. The ODIs of all groups (primary, revision, revision EBM concordant, and revision EBM discordant) were statistically compared. Differences in frequencies between cohorts were evaluated using chi-square and Fisher’s exact tests. The unpaired 2-tailed Student t-test and the Mann-Whitney U-test for nonparametric data were used to compare continuous variables. Logistic regression was performed to determine the associations between independent variables (surgery status and NASS criteria indications) and functional outcomes.

RESULTS Primary lumbar fusions were significantly associated with improved functional outcomes compared with revisions, as evidenced by ODI scores (OR 1.85, 95% CI 1.16–2.95 to achieve a minimal clinically important difference, p = 0.01). The percentage of patients whose functional status had declined at the 6-month postoperative evaluation was significantly higher in patients who had undergone a revision surgery than in those who underwent a primary surgery (23% vs 12.3%, respectively). An increase in ODI score, indicating worse clinical outcome after surgery, was greater in patients who underwent revision procedures (OR 2.14, 95% CI 1.17–3.91, p = 0.0014). Patients who underwent EBMconcordant revision surgery had significantly improved mean ODI scores compared with those who underwent EBMdiscordant revision surgery (7.02 ± 5.57 vs −4.6 ± 6.54, p < 0.01).

CONCLUSIONS The results of this prospective quality improvement program investigation illustrate that outcomes of primary lumbar fusions were superior to outcomes of revisions. However, revision procedures that met EBM guidelines were associated with greater improvements in ODI scores, which indicates that the use of defined EBM guideline criteria for reoperation can improve clinical outcomes of revision lumbar fusions.

 

Outcomes of stereotactic radiosurgery for hemorrhagic arteriovenous malformations with or without prior resection or embolization

J Neurosurg 135:733–741, 2021

The major concern about ruptured arteriovenous malformations (rAVMs) is recurrent hemorrhage, which tends to preclude stereotactic radiosurgery (SRS) as a therapeutic modality for these brain malformations. In this study, the authors aimed to clarify the role of SRS for rAVM as a stand-alone modality and an adjunct for a remnant nidus after surgery or embolization.

METHODS Data on 410 consecutive patients with rAVMs treated with SRS were analyzed. The patients were classified into groups, according to prior interventions: SRS-alone, surgery and SRS (Surg-SRS), and embolization and SRS (Embol- SRS) groups. The outcomes of the SRS-alone group were analyzed in comparison with those of the other two groups.

RESULTS The obliteration rate was higher in the Surg-SRS group than in the SRS-alone group (5-year cumulative rate 97% vs 79%, p < 0.001), whereas no significant difference was observed between the Embol-SRS and SRS-alone groups. Prior resection (HR 1.78, 95% CI 1.30–2.43, p < 0.001), a maximum AVM diameter ≤ 20 mm (HR 1.81, 95% CI 1.43–2.30, p < 0.001), and a prescription dose ≥ 20 Gy (HR 2.04, 95% CI 1.28–3.27, p = 0.003) were associated with a better obliteration rate, as demonstrated by multivariate Cox proportional hazards analyses. In the SRS-alone group, the annual post-SRS hemorrhage rates were 1.5% within 5 years and 0.2% thereafter and the 10-year significant neurological event–free rate was 95%; no intergroup difference was observed in either outcome. The exclusive performance of SRS (SRS alone) was not a risk for post-SRS hemorrhage or for significant neurological events based on multivariate analyses. These results were also confirmed with propensity score–matched analyses.

CONCLUSIONS The treatment strategy for rAVMs should be tailored with due consideration of multiple factors associated with the patients. Stand-alone SRS is effective for hemorrhagic AVMs, and the risk of post-SRS hemorrhage was low. SRS can also be favorably used for residual AVMs after initial interventions, especially after failed resection.

Surgery versus radiosurgery for facial nerve schwannoma

J Neurosurg 135:542–553, 2021

Intracranial facial nerve schwannomas (FNS) requiring treatment are frequently recommended for surgery or stereotactic radiosurgery (SRS). The objective of this study was to compare facial nerve function outcomes between these two interventions for FNS via a systematic review and meta-analysis.

METHODS A search of the Ovid EMBASE, PubMed, SCOPUS, and Cochrane databases from inception to July 2019 was conducted following PRISMA guidelines. Articles were screened against prespecified criteria. Facial nerve out- comes were classified as improved, stabilized, or worsened by last follow-up. Incidence was pooled by random-effects meta-analysis of proportions.

RESULTS Thirty-three articles with a pooled cohort of 519 patients with FNS satisfied all criteria. Twenty-five articles described operative outcomes in 407 (78%) patients; 10 articles reported SRS outcomes in 112 (22%). In the surgical cohort, facial nerve function improved in 23% (95% CI 15%–32%), stabilized in 41% (95% CI 32%–50%), and worsened in 30% (95% CI 21%–40%). In the SRS cohort, facial nerve function was improved in 20% (95% CI 9%–34%), stable in 66% (95% CI 54%–78%), and worsened in 9% (95% CI 3%–16%). Compared with SRS, microsurgery was associated with a significantly lower incidence of stable facial nerve function (p < 0.01) and a significantly higher incidence of wors- ened facial nerve function (p < 0.01). Tumor progression and complication rates were comparable. Outcome certainty assessments were very low to moderate for all parameters.

CONCLUSIONS Unfavorable facial nerve function outcomes are associated with surgical treatment of intracranial FNS, whereas stable facial nerve function outcomes are associated with SRS. Therefore, SRS should be recommended to patients with FNS who require treatment, and surgery should be reserved for patients with another indication, such as decompression of the brainstem. Further study is required to definitively optimize and validate management strategies for these rare skull base tumors.

Tumor Growth Rate as a New Predictor of Progression-Free Survival After Chordoma Surgery

Neurosurgery 89:291–299, 2021

Currently, different postoperative predictors of chordoma recurrence have been identified. Tumor growth rate (TGR) is an image-based calculation that provides quantitative information of tumor’s volume changing over time and has been shown to predict progression-free survival (PFS) in other tumor types.

OBJECTIVE: To explore the usefulness of TGR as a new preoperative radiological marker for chordoma recurrence.

METHODS: A retrospective single-institution study was carried out including patients reflecting these criteria: confirmed diagnosis of chordoma on pathological analysis, no history of previous radiation, and at least 2 preoperative thin-slice magnetic resonance images available to measure TGR. TGR was calculated for all patients, showing the percentage change in tumor size over 1 mo.

RESULTS: A total of 32 patients were retained for analysis. Patients with a TGR ≥ 10.12%/m had a statistically significantly lower mean PFS (P<.0001). TGR≥10.12%/m (odds ratio=26, P=.001) was observed more frequently in recurrent chordoma. In a subgroup analysis, we found that the association of Ki-67 labeling index≥6% and TGR≥10.12%/m was correlated with recurrence (P = .0008).

CONCLUSION: TGR may be considered as a preoperative radiological indicator of tumor proliferation and seems to preoperatively identify more aggressive tumors with a higher tendency to recur. Our findings suggest that the therapeutic strategy and clinical radiological follow-up of patients with chordoma can be adapted also according to this new parameter.

Impact of vestibular nerve preservation on facial and hearing outcomes in small vestibular schwannoma surgery

Acta Neurochirurgica (2021) 163:2219–2224

Management of small vestibular schwannomas (VSs) remains controversial. When surgery is chosen, the preservation of facial and cochlear nerve function is a priority. In this report, we introduce and evaluate a technique to anatomically preserve the vestibular nerves to minimize manipulation and preserve the function of the facial and cochlear nerves.

Methods The vestibular nerve preservation technique was prospectively applied to resect small VS tumors in patients with serviceable preoperative hearing (American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) class A or B). Clinical and radiological data were recorded and analyzed.

Results Ten patients met the inclusion criteria. The mean (SD) age was 40.4 (12.5) years. Follow-up ranged from 6 weeks to 2 years. The maximum tumor diameter parallel to the internal auditory canal ranged from 10 to 20 mm (mean, 14.9 (3.1) mm). There were three Koos grade 3 and seven Koos grade 2 tumors. Gross total resection was achieved in all cases. Both the facial and cochlear nerves were anatomically preserved in all cases. Postoperatively, 7 patients (70%) remained in the AAO-HNS class A or B hearing category. None of the patients had new vestibular symptoms, and all had House–Brackmann grade 1 facial function. Nervus intermedius dysfunction was observed in 1 patient preoperatively, which worsened postoperatively. Two patients had new nervus intermedius symptoms postoperatively.

Conclusion Improvement of facial nerve and hearing outcomes is feasible through the intentional preservation of the vestibular nerves in the resection of small VSs. Longer follow-up is required to rule out tumor recurrence.

Large and small vestibular schwannomas: same, yet different tumors

Acta Neurochirurgica (2021) 163:2199–2207

Vestibular schwannomas (VS) present at variable size with heterogeneous symptomatology. Modern treatment paradigms for large VS include gross total resection, subtotal resection (STR) in combination with observation, and/or radiation to achieve optimal function preservation, whereas treatment is felt to be both easier and safer for small VS. The objective is to better characterize the presentation and surgical outcomes of large and small VS.

Methods We collected data of patients who had surgically treated VS with a posterior fossa diameter of 4.0 cm or larger (large tumor group, LTG) and smaller than 1.0 cm in cisternal diameter (small tumor group, STG). Statistical significance was defined as p < 0.05.

Results LTG included 48 patients (average tumor size: 44.9 mm) and STG 38 (7.9 mm). Patients in STG presented more frequently with tinnitus and sudden hearing loss. Patients in LTG underwent more STR than STG (50.0% vs. 2.6%, p < 0.0001). LTG had more complications (31.3% vs. 13.2%, p = 0.049). Postoperative facial nerve function in STG was significantly better than LTG. STG had better hearing preoperatively (p < 0.0001) and postoperatively than LTG (p = 0.0002). Postoperative headache was more common in STG (13.2% vs. 2.1%, p = 0.045). The rate of recurrence/progression needing treatment was not statistically different between the groups (12.5% in LTG vs. 7.9% in STG, p = 0.49). Those patients who required periprocedural cerebrospinal fluid diversion had higher risk of infection (20.8% vs 4.8%, p = 0.022).

Conclusion Large and small VS present differently. LTG showed more unsatisfactory outcomes in facial nerve function and postoperative hearing despite maximal efforts undertaken toward function-preservation strategy; however, similar tumor control was achieved.

Assessment and validation of proposed classification tools for brainstem cavernous malformations

J Neurosurg 135:410–416, 2021

Treatment indications for patients with brainstem cavernous malformations (BSCMs) remain difficult and controversial. Some authors have tried to establish classification tools to identify eligible candidates for surgery. Authors of this study aimed to validate the performance and replicability of two proposed BSCM grading systems, the Lawton- Garcia (LG) and the Dammann-Sure (DS) systems.

METHODS For this cross-sectional study, a database was screened for patients with BSCM treated surgically between 2003 and 2019 in the authors’ department. Complete clinical records, preoperative contrast-enhanced MRI, and a postoperative follow-up ≥ 6 months were mandatory for study inclusion. The modified Rankin Scale (mRS) score was determined to quantify neurological function and outcome. Three observers independently determined the LG and the DS score for each patient.

RESULTS A total of 67 patients met selection criteria. Univariate and multivariate analyses identified multiple bleedings (p = 0.02, OR 5.59), lesion diameter (> 20 mm, p = 0.007, OR 5.43), and patient age (> 50 years, p = 0.019, OR 4.26) as predictors of an unfavorable postoperative functional outcome. Both the LG (AUC = 0.72, p = 0.01) and the DS (AUC = 0.78, p < 0.01) scores were robust tools to estimate patient outcome. Subgroup analyses confirmed this observation for both grading systems (LG: p = 0.005, OR 6; DS: p = 0.026, OR 4.5), but the combined use of the two scales enhanced the test performance significantly (p = 0.001, OR 22.5).

CONCLUSIONS Currently available classification systems are appropriate tools to estimate the neurological outcome after BSCM surgery. Future studies are needed to design an advanced scoring system, incorporating items from the LG and the DS score systems.

 

Observation Versus Intervention for Low-Grade Intracranial Dural Arteriovenous Fistulas

Neurosurgery 88:1111–1120, 2021

Low-grade intracranial dural arteriovenous fistulas (dAVF) have a benign natural history in the majority of cases. The benefit from treatment of these lesions is controversial.

OBJECTIVE: To compare the outcomes of observation versus intervention for low-grade dAVFs.

METHODS: We retrospectively reviewed dAVF patients from institutions participating in the CONsortium for Dural arteriovenous fistula Outcomes Research (CONDOR). Patients with low-grade (Borden type I) dAVFs were included and categorized into intervention or observation cohorts. The intervention and observation cohorts were matched in a 1:1 ratio using propensity scores. Primary outcome was modified Rankin Scale (mRS) at final follow-up. Secondary outcomes were excellent (mRS 0-1) and good (mRS 0-2) outcomes, symptomatic improvement, mortality, and obliteration at final follow-up.

RESULTS: The intervention and observation cohorts comprised 230 and 125 patients, respectively. We found no differences in primary or secondary outcomes between the 2 unmatched cohorts at last follow-up (mean duration 36 mo), except obliteration rate was higher in the intervention cohort (78.5% vs 24.1%, P < .001). The matched intervention and observation cohorts each comprised 78 patients. We also found no differences in primary or secondary outcomes between the matched cohorts except obliteration was also more likely in the matched intervention cohort (P < .001). Procedural complication rates in the unmatched and matched intervention cohorts were 15.4% and 19.2%, respectively.

CONCLUSION: Intervention for low-grade intracranial dAVFs achieves superior obliteration rates compared to conservative management, but it fails to improve neurological or functional outcomes. Our findings do not support the routine treatment of low-grade dAVFs.

Spetzler-Martin Grade III Arteriovenous Malformations: A Comparison of Modified and Supplemented Spetzler-Martin Grading Systems

Neurosurgery 88:1103–1110, 2021

The modified Spetzler-Martin (SM) grading system proposes that grade III arteriovenous malformation (AVM) subtypes are associated with variable microsurgical risks, with small AVMs (III−) having lower risk and medium/eloquent AVMs (III+) having higher risk. Adding patient age and AVM bleeding status and compactness to the SM grade produces a score – the supplemented SM (Supp-SM) grade – to more accurately assess preoperative risk.

OBJECTIVE: To compare the predictive power of the modified SMand Supp-SM grades for risk assessment in patients with grade III AVMs.

METHODS: Patients with SM grade III AVMs treated between 2011 and 2018were retrospectively reviewed. Good outcomes were defined as modified Rankin Scale (mRS) scores ≤ 2 or unchanged/improved mRS scores (pre- vs postsurgery).

RESULTS: Of 102 patients with SM grade III AVMs, 59% had grade III− and 24% had grade III+ AVMs. Supp SM grade 6 and grade 7 AVMs accounted for 44% and 24%, respectively. Overall, 33% of patients worsened but outcomes did not significantly differ by SM III subtype. Neurological outcomes were associated with Supp-SM grade, with proportions of patients with worsening increasing from 0% with Supp-SM grade 4 AVMs to 54% with Supp-SM grade 7 AVMs. Analyses of factors associated with neurological worsening identified age > 60 yr and Supp-SM grade 7 as significant.

CONCLUSION: Supp-SM grades were more predictive of microsurgical outcomes than modified SM grades for grade III AVMs, with a hard cutoff for acceptable surgical risk at Supp-SM grade 6. Supp-SM grading is a better decision-making tool than subtyping with the modified SM scale.

 

Predictors of visual functional outcome following treatment for cavernous sinus meningioma

J Neurosurg 134:1435–1446, 2021

Cavernous sinus meningioma (CSM) can affect visual function and require expeditious treatment to prevent permanent visual loss. Authors of this retrospective study sought to determine the factors associated with visual functional outcomes in CSM patients treated with surgery, stereotactic radiosurgery (SRS), or stereotactic radiation therapy (SRT), alone or in combination.

METHODS Consecutive patients with CSM who had presented at an academic tertiary care hospital from 2000 to 2018 were identified through retrospective chart review. Visual function—visual eye deficit (VED), optic disc (OD) appearance, intraocular pressure (IOP), and extraocular movement (EOM)—was assessed before and after treatment for CSM. VED with visual acuity (VA) ≤ 20/200 and visual field defect ≥ −11 dB, pale OD appearance in the ipsilateral or contralateral eye, increased ipsilateral IOP, and/or EOM restriction were defined as a poor visual functional outcome. Multivariable logistic regression was used to evaluate the associations between pretreatment visual functional assessment and posttreatment visual outcomes.

RESULTS The study cohort included 44 patients (73% female; median age 55 years), with a median clinical follow-up of 14 months. Ipsilateral VED improved, remained stable, or worsened, respectively, in 0%, 33.4%, and 66.6% of the patients after subtotal resection (STR) alone; in 52.6%, 31.6%, and 15.8% after STR plus radiation treatment; in 28.5%, 43.0%, and 28.5% after gross-total resection (GTR) alone; and in 56.3%, 43.7%, and 0% after radiation treatment (SRS or SRT) alone. Contralateral VED remained intact in all the patients after STR alone and those with radiation treatment (SRS or SRT) alone; however, it improved, remained stable, or worsened in 10.5%, 84.2%, and 5.3% after STR plus radiation treatment and in 43.0%, 28.5%, and 28.5% after GTR alone. EOM remained intact, fully recovered, remained stable, and worsened, respectively, in 0%, 50%, 50%, and 0% of the patients after STR alone; in 36.8%, 47.4%, 15.8%, and 0% of the patients after STR with radiation treatment; in 57.1%, 0%, 28.6%, and 14.3% of the patients after GTR alone; and in 56.2%, 37.5%, 6.3%, and 0% of the patients after radiation treatment (SRS or SRT) alone. In multivariable analyses adjusted for age, tumor volume, and treatment modality, initial ipsilateral poor VED (OR 10.1, 95% CI 1.05–97.2, p = 0.04) and initial ipsilateral pale OD appearance (OR 21.1, 95% CI 1.6–270.5, p = 0.02) were associated with poor ipsilateral VED posttreatment. Similarly, an initial pale OD appearance (OR 15.7, 95% CI 1.3–199.0, p = 0.03), initial poor VED (OR 21.7, 95% CI 1.2–398.6, p = 0.03), and a higher IOP in the ipsilateral eye (OR 55.3, 95% CI 1.7–173.9, p = 0.02) were associated with an ipsilateral pale OD appearance posttreatment. Furthermore, a higher initial ipsilateral IOP (OR 35.9, 95% CI 3.3–400.5, p = 0.004) was indicative of a higher IOP in the ipsilateral eye posttreatment. Finally, initial restricted EOM was indicative of restricted EOM posttreatment (OR 20.6, 95% CI 18.7–77.0, p = 0.02).

CONCLUSIONS Pretreatment visual functional assessment predicts visual outcomes in patients with CSM and can be used to identify patients at greater risk for vision loss.

How safe are elective craniotomies in elderly patients in neurosurgery today?

J Neurosurg 134:1113–1121, 2021

With global aging, elective craniotomies are increasingly being performed in elderly patients. There is a paucity of prospective studies evaluating the impact of these procedures on the geriatric population. The goal of this study was to assess the safety of elective craniotomies for elderly patients in modern neurosurgery.

METHODS For this cohort study, adult patients, who underwent elective craniotomies between November 1, 2011, and October 31, 2018, were allocated to 3 age groups (group 1, < 65 years [n = 1008], group 2, ≥ 65 to < 75 [n = 315], and group 3, ≥ 75 [n = 129]). Primary outcome was the 30-day mortality after craniotomy. Secondary outcomes included rate of delayed extubation (> 1 hour), need for emergency head CT scan and reoperation within 48 hours after surgery, length of postoperative intensive or intermediate care unit stay, hospital length of stay (LOS), and rate of discharge to home. Adjustment for American Society of Anesthesiologists Physical Status (ASA PS) class, estimated blood loss, and duration of surgery were analyzed as a comparison using multiple logistic regression. For significant differences a post hoc analysis was performed.

RESULTS In total, 1452 patients (mean age 55.4 ± 14.7 years) were included. The overall mortality rate was 0.55% (n = 8), with no significant differences between groups (group 1: 0.5% [95% binominal CI 0.2%, 1.2%]; group 2: 0.3% [95% binominal CI 0.0%, 1.7%]; group 3: 1.6% [95% binominal CI 0.2%, 5.5%]). Deceased patients had a significantly higher ASA PS class (2.88 ± 0.35 vs 2.42 ± 0.62; difference 0.46 [95% CI 0.03, 0.89]; p = 0.036) and increased estimated blood loss (1444 ± 1973 ml vs 436 ± 545 ml [95% CI 618, 1398]; p <0.001). Significant differences were found in the rate of postoperative head CT scans (group 1: 6.65% [n = 67], group 2: 7.30% [n = 23], group 3: 15.50% [n = 20]; p = 0.006), LOS (group 1: median 5 days [IQR 4; 7 days], group 2: 5 days [IQR 4; 7 days], and group 3: 7 days [5; 9 days]; p = 0.001), and rate of discharge to home (group 1: 79.0% [n = 796], group 2: 72.0% [n = 227], and group 3: 44.2% [n = 57]; p < 0.001).

CONCLUSIONS Mortality following elective craniotomy was low in all age groups. Today, elective craniotomy for well selected patients is safe, and for elderly patients, too. Elderly patients are more dependent on discharge to other hospitals and postacute care facilities after elective craniotomy. Clinical trial registration no.: NCT01987648 (clinicaltrials.gov).

Preoperative embolization versus no embolization for WHO grade I intracranial meningioma

J Neurosurg 134:693–700, 2021

The controversy continues over the clinical utility of preoperative embolization for reducing tumor vascularity of intracranial meningiomas prior to resection. Previous studies comparing embolization and nonembolization patients have not controlled for detailed tumor parameters before assessing outcomes.

METHODS The authors reviewed the cases of all patients who underwent resection of a WHO grade I intracranial meningioma at their institution from 2008 to 2016. Propensity score matching was used to generate embolization and nonembolization cohorts of 52 patients each, and a retrospective review of clinical and radiological outcomes was performed.

RESULTS In total, 52 consecutive patients who underwent embolization (mean follow-up 34.8 ± 31.5 months) were compared to 52 patients who did not undergo embolization (mean follow-up 32.8 ± 28.7 months; p = 0.63). Variables controlled for included patient age (p = 0.82), tumor laterality (p > 0.99), tumor location (p > 0.99), tumor diameter (p = 0.07), tumor invasion into a major dural sinus (p > 0.99), and tumor encasement around the internal carotid artery or middle cerebral artery (p > 0.99). The embolization and nonembolization cohorts did not differ in terms of estimated blood loss during surgery (660.4 ± 637.1 ml vs 509.2 ± 422.0 ml; p = 0.17), Simpson grade IV resection (32.7% vs 25.0%; p = 0.39), perioperative procedural complications (26.9% vs 19.2%; p = 0.35), development of permanent new neurological deficits (5.8% vs 7.7%; p = 0.70), or favorable modified Rankin Scale (mRS) score (a score of 0–2) at last follow-up (96.0% vs 92.3%; p = 0.43), respectively. When comparing the final mRS score to the preoperative mRS score, patients in the embolization group were more likely than patients in the nonembolization group to have an improvement in mRS score (50.0% vs 28.8%; p = 0.03).

CONCLUSIONS After controlling for patient age, tumor size, tumor laterality, tumor location, tumor invasion into a major dural sinus, and tumor encasement of the internal carotid artery or middle cerebral artery, preoperative meningioma embolization intended to decrease tumor vascularity did not improve the surgical outcomes of patients with WHO grade I intracranial meningiomas, but it did lead to a greater chance of clinical improvement compared to patients not treated with embolization.

 

 

Mild and Severe Obesity Reduce the Effectiveness of Lumbar Fusions

Neurosurgery 88 (2) 2021: 285–294

Elevated body mass index (BMI) is a well-known risk factor for surgical complications in lumbar surgery. However, its effect on surgical effectiveness independent of surgical complications is unclear.

OBJECTIVE: To determine increasing BMI’s effect on functional outcomes following lumbar fusion surgery, independent of surgical complications.

METHODS:We retrospectively analyzed a prospectively built, patient-reported, quality of life registry representing 75 hospital systems. We evaluated 1- to 3-level elective lumbar fusions. Patients who experienced surgical complicationswere excluded. A stepwisemultivariate regression model assessed factors independently associated with 1-yr Oswestry Disability Index (ODI), preop to 1-yr ODI change, and achievement of minimal clinically important difference (MCID).

RESULTS: A total of 8171 patients met inclusion criteria: 2435 with class I obesity (BMI 30- 35 kg/m2), 1328 with class II (35-40 kg/m2), and 760 with class III (≥40 kg/m2). Increasing BMI was independently associated with worse 12-mo ODI (t = 8.005, P < .001) and decreased likelihood of achieving MCID (odds ratio [OR] = 0.977, P < .001). One year after surgery, mean ODI, ODI change, and percentage achieving MCID worsened with class I, class II, and class III vs nonobese cohorts (P < .001) in stepwise fashion.

CONCLUSION: Increasing BMI is associated with decreased effectiveness of 1- to 3-level elective lumbar fusion, despite absence of surgical complications. BMI ≥ 30 kg/m2 is, therefore, a risk factor for both surgical complication and reduced benefit from lumbar fusion.

Survival, Dependency, and Health-Related Quality of Life in Patients With Ruptured Intracranial Aneurysm

Neurosurgery 88:252–260, 2021

Previous analyses of the International Subarachnoid Aneurysm Trial (ISAT) cohort have reported on clinical outcomes after treatment of a ruptured intracranial aneurysm with either neurosurgical clipping or endovascular coiling.

OBJECTIVE: To evaluate the long-term quality-adjusted life years (QALYs) gained of endovascular coiling compare to neurosurgical clipping in the UK cohort of ISAT.

METHODS: Between September 12, 1994 and May 1, 2002, patients with ruptured intracranial aneurysms who were assumed treatment equipoise were randomly allocated to either neurosurgical clipping or endovascular coiling. We followed-up 1644 patients in 22 UK neurosurgical centers for a minimum of 10 yr. Health-related quality of life (HRQoL) was collected through yearly questionnaires,measured by utilities calculated from the EQ- 5D-3L. We compared HRQoL between the 2 treatment groups over a period of 10 yr. In all, 1-yr, 5-yr, and 10-yr QALYs were estimated by combining utility and survival information.

RESULTS: Higher average utility values were found in the endovascular group throughout the follow-up period, with mean differences between groups statistically significant in most years. The 10-yr QALYs were estimated to be 6.68 (95% CI: 6.45-6.90) in the coiling group and 6.32 (95% CI: 6.10-6.55) in the clipping group, respectively, a significant mean difference of 0.36 (95% CI: 0.04-0.66). A third of this mean QALYs gain was estimated to derive solely from HRQoL differences.

CONCLUSION: HRQoL after treatment of a ruptured intracranial aneurysm was better after endovascular coiling compared to neurosurgical clipping, which contributed significantly to the QALYs gained over a 10-yr period.

Giant Fusiform and Dolichoectatic Aneurysms of the Basilar Trunk and Vertebrobasilar Junction

Neurosurgery 88:82–95, 2021

Giant fusiform and dolichoectatic aneurysms of the basilar trunk and vertebrobasilar junction (BTVBJ-GFDA) are extremely difficult to treat. OBJECTIVE: To evaluate factors influencing survival and outcome of BTVBJ-GFDA by performing a retrospective multicenter cohort study.

METHODS: A total of 32 patients with BTVBJ-GFDA were included in this study. Clinicopathological characteristics, treatment measures, and outcomes were collected from medical records and imaging studies. Autopsy and histological findings of the aneurysm and adjacent brain tissue were also obtained in 9 cases.

RESULTS: A total of 11 patients did not undergo surgery, of whom 10 died; 3 from progressive brainstem compression, 4 from subarachnoid hemorrhage, 2 from brainstem infarction, and 1 from associated atherosclerotic disease. The remaining 21 patients underwent a surgical treatment, consisting of immediately proximal parent artery occlusion, remotely proximal parent artery occlusion, clip reconstruction, and distal bypass and achieved significantly longer overall survival compared with those who received conservative therapy (adjusted hazard ratio 1.508, 95% CI 1.058-2.148, P = .02). Histological examination of the aneurysms demonstrated staged clots, open lumen, and intrathrombotic channels with endothelial lining. The patients younger than 45 yr of age showed statistically longer survival than those equal and older than 45 yr (P = .03).

CONCLUSION: Surgical intervention achieved greater survival than conservative management in BTVBJ-GFDA. Narrow ideal treatment window of the blood flow within the aneurysm to maintain sufficient but not excess supply should be targeted based on the hemodynamics of both the posterior communicating arteries and perforating vessel collaterals.

KEYWORDS: Basilar trunk, Dolichoectasia, Dolichoectatic aneurysms, Fusiform aneurysms, Megadolichobasilar anomaly, Vertebrobasilar

Impact of Intraoperative Magnetic Resonance Imaging and Other Factors on Surgical Outcomes for Newly Diagnosed Grade II Astrocytomas and Oligodendrogliomas: A Multicenter Study

Neurosurgery 88 (1) 2021: 63–73,

Few studies use large, multi-institutional patient cohorts to examine the role of intraoperative magnetic resonance imaging (iMRI) in the resection of grade II gliomas.

OBJECTIVE: To assess the impact of iMRI and other factors on overall survival (OS) and progression-free survival (PFS) for newly diagnosed grade II astrocytomas and oligodendrogliomas.

METHODS: Retrospective analyses of a multicenter database assessed the impact of patient-, treatment-, and tumor-related factors on OS and PFS.

RESULTS: A total of 232 resections (112 astrocytomas and 120 oligodendrogliomas) were analyzed. Oligodendrogliomas had longer OS (P < .001) and PFS (P = .01) than astrocytomas. Multivariate analyses demonstrated improved OS for gross total resection (GTR) vs subtotal resection (STR; P = .006, hazard ratio [HR]: .23) and near total resection (NTR; P = .02, HR: .64). GTR vs STR (P = .02, HR: .54), GTR vs NTR (P = .04, HR: .49), and iMRI use (P = .02, HR: .54) were associated with longer PFS. Frontal (P = .048, HR: 2.11) and occipital/parietal (P = .003, HR: 3.59) locations were associated with shorter PFS (vs temporal). Kaplan-Meier analyses showed longer OS with increasing extent of surgical resection (EOR) (P=.03) and 1p/19q gene deletions (P=.02). PFS improved with increasing EOR (P = .01), GTR vs NTR (P = .02), and resections above STR (P = .04). Factors influencing adjuvant treatment (35.3% of patients) included age (P=.002, odds ratio [OR]: 1.04) and EOR (P=.003,OR: .39) but not glioma subtype or location. Additional tumor resection after iMRI was performed in 105/159 (66%) iMRI cases, yielding GTR in 54.5% of these instances.

CONCLUSION: EOR is a major determinant of OS and PFS for patients with grade II astrocytomas and oligodendrogliomas. Intraoperative MRI may improve EOR and was associated with increased PFS.

Eyebrow supraorbital keyhole craniotomy for olfactory groove meningiomas with endoscope assistance

Acta Neurochirurgica (2021) 163:101–112

Olfactory groove meningiomas (OGMs) are commonly treated with open craniotomy. Endonasal approaches have also been described. Objective To present clinical and radiographic outcomes for the minimally invasive eyebrow incision supraorbital keyhole approach with endoscopic assistance for OGMs.

Methods We performed a retrospective single-center cohort study and a systematic literature review.

Results Fifteen patients were identified, all with Grade I meningiomas. Radiographic gross total resection of enhancing tumor was achieved in all patients. Mean frontal lobe fluid-attenuated inversion recovery volume decreased from 11.1 ± 18.3 cm3 preoperatively to 9.9 ± 11.4 cm3 immediately postoperatively, and there was minimal new restricted diffusion (3.2 ± 2.2 cm3; max 7.5 cm3). Median length of stay was 3 days (range 2–8). Vision was improved in 4 (80%) and stable in 1 (20%) of 5 patients with a preoperative deficit. New postoperative anosmia occurred in 3 (23%) of 13 patients with any preoperative olfaction. All patients were satisfied with their cosmetic result at 3 months. After a median follow-up of 32.2 months, there were 2 (13.3%) asymptomatic radiographic recurrences, 1 treated with radiosurgery and the other with endoscopic endonasal approach (EEA). No patients required further craniotomy. Systematic review revealed the present series to be the largest to date reporting disaggregated outcomes for the eyebrow approach to OGM.

Conclusion The eyebrow incision supraorbital keyhole craniotomy with endoscopic assistance is a safe and effective approach to OGM with tumor control rates similar to more invasive open approaches and better than the endonasal approach.Rates of frontal lobe injury, CSF leak and anosmia are comparatively low.