Author: cba

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Anterior transpetrosal approach: experiences in 274 cases over 33 years. Technical variations, operated patients, and approach-related complications

J Neurosurg 136:413–421, 2022

The anterior transpetrosal approach (ATPA) was initially reported in 1985. The authors’ institution has 274 case records of surgery performed with the ATPA during the period from 1984 to 2017. Although many technical advances and modifications in the ATPA have occurred over those 33 years, to the authors’ knowledge no articles to date have reported a detailed analysis of variations and complications of the ATPA. In this study, the authors analyzed their patient series to elucidate improvements over time in ATPA methodology while highlighting unresolved problems and evaluating how to avoid surgical complications.

METHODS All surgical cases (274 patients) using the ATPA at the authors’ institution during the period from 1984 to 2017 were analyzed retrospectively using charts, clinical summaries, operative records, and operative videos. Obtained parameters were patient age and sex, diagnosis, size of tumors, location of disease, operative date, neurological symptoms before and after surgery, radiographically identified brain injury, and other surgical complications. The most common diagnosis was petroclival meningioma (n = 158), followed by trigeminal schwannoma (n = 32), chordoma (n = 25), epidermoid tumor (n = 21), other tumor (n = 27), aneurysm (n = 6), and other (n = 5).

RESULTS The original ATPA was performed in 239 cases. In an additional 35 cases, a modified ATPA was performed. Zygomatic osteotomy with ATPA was a common modification that was used in 19 of the 35 cases to decrease retraction damage to the temporal lobe for high-positioned tumors. Brain injury by temporal lobe retraction without venous hemorrhage still occurred in 8 of the 19 cases (3.1%) with surgical death in 1 of these cases (0.4%) of reoperation with sacrifice of the petrosal vein. Symptomatic CSF leak was the most frequent complication noted and was observed in 35 cases (13.5%). In most of these cases the patients were cured by observation or lumbar drain, but in 6 cases (17.1%) reoperation was needed. Facial nerve damage related to surgical approach decreased from 6.2% to 3.5% after 2010; however, the incidence of CSF leaks (13.5%) has not improved.

CONCLUSIONS There have been several modifications and advancements made in the ATPA to increase tumor removal and decrease surgical complications. However, complications related to surgical approach occurred, such as venous occlusion–related brain injury and facial nerve damage at pyramid resection. CSF leak remained an unsolved problem related to the ATPA procedures. Preoperative assessment of venous variation of the middle fossa, pneumatization of the temporal bone, and intraoperative monitoring of cranial nerves are important procedures to decrease these complications.

 

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Insular epilepsy surgery: lessons learned from institutional review and patient-level meta-analysis

J Neurosurg 136:523–535, 2022

Insular lobe epilepsy is a challenging condition to diagnose and treat. Due to anatomical intricacy and proximity to eloquent brain regions, resection of epileptic foci in that region can be associated with significant postoperative morbidity. The aim of this study was to review available evidence on postoperative outcomes following insular epilepsy surgery.

METHODS A comprehensive literature search (PubMed/MEDLINE, Scopus, Cochrane) was conducted for studies investigating the postoperative outcomes for seizures originating in the insula. Seizure freedom at last follow-up (at least 12 months) comprised the primary endpoint. The authors also present their institutional experience with 8 patients (4 pediatric, 4 adult).

RESULTS A total of 19 studies with 204 cases (90 pediatric, 114 adult) were identified. The median age at surgery was 23 years, and 48% were males. The median epilepsy duration was 8 years, and 17% of patients had undergone prior epilepsy surgery. Epilepsy was lesional in 67%. The most common approach was transsylvian (60%). The most commonly resected area was the anterior insular region (n = 42, 21%), whereas radical insulectomy was performed in 13% of cases (n = 27). The most common pathology was cortical dysplasia (n = 68, 51%), followed by low-grade neoplasm (n = 16, 12%). In the literature, seizure freedom was noted in 60% of pediatric and 69% of adult patients at a median follow-up of 29 months (75% and 50%, respectively, in the current series). A neurological deficit occurred in 43% of cases (10% permanent), with extremity paresis comprising the most common deficit (n = 35, 21%), followed by facial paresis (n = 32, 19%). Language deficits were more common in left-sided approaches (24% vs 2%, p < 0.001). Univariate analysis for seizure freedom revealed a significantly higher proportion of patients with lesional epilepsy among those with at least 12 months of follow-up (77% vs 59%, p = 0.032).

CONCLUSIONS These findings may serve as a benchmark when tailoring decision-making for insular epilepsy, and may assist surgeons in their preoperative discussions with patients. Although seizure freedom rates are quite high with insular epilepsy treatment, the associated morbidity needs to be weighed against the potential for seizure freedom.

 

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Fluorescein-guided resection of cerebral metastases is associated with greater tumor resection

Acta Neurochirurgica (2022) 164:451–457

Sodium fluorescein (fluorescein) crosses a disrupted blood-brain barrier similarly to gadolinium contrast in contrast-enhancing cerebral tumors. When exposed to light with 560 nm wavelength during surgery, fluorescein emits a yellow-green fluorescent light that can be visualized through an operating microscope equipped with an appropriate emission filter. The distribution of the fluorescence correlates with the contrast on a gadolinium contrast-enhanced MRI.

Objective The objective of this single-center retrospective study was to investigate if the use of fluorescein would increase the extent of resection and to examine if fluorescein guided resection influences postoperative neurological status.

Methods During the study period from August 2014 to August 2018, 117 patients were operated for cerebral metastases. Of these, 56 operations were guided by fluorescein and 61 by traditional white light. All patients had an early postoperative MRI within 72 h after surgery.

Results The use of fluorescein increased the extent of resection in patients with cerebral metastases. The use of fluorescein was not associated with increased postoperative sequelae or neurological damage regardless of underlying primary cancer.

Conclusion Fluorescein is a helpful supplement in the neurosurgical treatment of cerebral metastases.

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Patient outcomes after circumferential minimally invasive surgery compared with those of open correction for adult spinal deformity

J Neurosurg Spine 36:203–214, 2022

Circumferential minimally invasive spine surgery (cMIS) for adult scoliosis has become more advanced and powerful, but direct comparison with traditional open correction using prospectively collected data is limited. The authors performed a retrospective review of prospectively collected, multicenter adult spinal deformity data. The authors directly compared cMIS for adult scoliosis with open correction in propensity-matched cohorts using health-related quality-of-life (HRQOL) measures and surgical parameters.

METHODS Data from a prospective, multicenter adult spinal deformity database were retrospectively reviewed. Inclusion criteria were age > 18 years, minimum 1-year follow-up, and one of the following characteristics: pelvic tilt (PT) > 25 , pelvic incidence minus lumbar lordosis (PI-LL) > 10 , Cobb angle > 20 , or sagittal vertical axis (SVA) > 5 cm. Patients were categorized as undergoing cMIS (percutaneous screws with minimally invasive anterior interbody fusion) or open correction (traditional open deformity correction). Propensity matching was used to create two equal groups and to control for age, BMI, preoperative PI-LL, pelvic incidence (PI), T1 pelvic angle (T1PA), SVA, PT, and number of posterior levels fused.

RESULTS A total of 154 patients (77 underwent open procedures and 77 underwent cMIS) were included after matching for age, BMI, PI-LL (mean 15  vs 17 , respectively), PI (54  vs 54 ), T1PA (21  vs 22 ), and mean number of levels fused (6.3 vs 6). Patients who underwent three-column osteotomy were excluded. Follow-up was 1 year for all patients. Postoperative Oswestry Disability Index (ODI) (p = 0.50), Scoliosis Research Society–total (p = 0.45), and EQ-5D (p = 0.33) scores were not different between cMIS and open patients. Maximum Cobb angles were similar for open and cMIS basepatients at baseline (25.9  vs 26.3 , p = 0.85) and at 1 year postoperation (15.0  vs 17.5 , p = 0.17). In total, 58.3% of open patients and 64.4% of cMIS patients (p = 0.31) reached the minimal clinically important difference (MCID) in ODI at 1 year. At 1 year, no differences were observed in terms of PI-LL (p = 0.71), SVA (p = 0.46), PT (p = 0.9), or Cobb angle (p = 0.20). Open patients had greater estimated blood loss compared with cMIS patients (1.36 L vs 0.524 L, p < 0.05) and fewer levels of interbody fusion (1.87 vs 3.46, p < 0.05), but shorter operative times (356 minutes vs 452 minutes, p = 0.003). Revision surgery rates between the two cohorts were similar (p = 0.97).

CONCLUSIONS When cMIS was compared with open adult scoliosis correction with propensity matching, HRQOL improvement, spinopelvic parameters, revision surgery rates, and proportions of patients who reached MCID were similar between cohorts. However, well-selected cMIS patients had less blood loss, comparable results, and longer operative times in comparison with open patients.

 

 

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Impact of awake mapping on overall survival and extent of resection in patients with adult diffuse gliomas within or near eloquent areas

Acta Neurochirurgica (2022) 164:395–404

Awake craniotomy (AC) with intraoperative mapping is the best approach to preserve neurological function for glioma surgery in eloquent or near eloquent areas, but whether AC improves the extent of resection (EOR) and overall survival (OS) is controversial. This study aimed to compare the long-term clinical outcomes of glioma resection under AC with those under general anesthesia (GA).

Methods Data of 335 patients who underwent surgery with intraoperative magnetic resonance imaging for newly diagnosed gliomas of World Health Organization (WHO) grades II-IV between 2000 and 2013 were reviewed. EOR and OS were quantitatively compared between the AC and GA groups after 1:1 propensity score matching. The two groups were matched for age, preoperative Karnofsky performance status (KPS), tumor location, and pathology.

Results After propensity score matching, 91 pairs were obtained. The median EOR was 96.1% (interquartile range [IQR] 7.3) and 97.4% (IQR 14.4) in the AC and GA groups, respectively (p = 0.31). Median KPS score 3 months after surgery was 90 (IQR 20) in both groups (p = 0.384). The median survival times were 163.3 months (95% confidence interval [CI] 77.9–248.7) and 143.5 months (95% CI 94.4–192.7) in the AC and GA groups, respectively (p = 0.585).

Conclusion Even if the glioma was within or close to the eloquent area, AC was comparable with GA in terms of EOR and OS. In case of difficulties in randomizing patients with eloquent or near eloquent glioma, our propensity score-matched analysis provides retrospective evidence that AC can obtain EOR and OS equivalent to removing glioma under GA.

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Outcome of glioblastoma resection in patients 80 years of age and older

Acta Neurochirurgica (2022) 164:373–383

Objective To evaluate the role and possible complications of tumor resection in the management of glioblastoma (GBM) in a series of patients 80 years of age and older with review of literature.

Methods The authors retrospectively analyzed cases involving patients 80 years or older who underwent biopsy or initial resection of GBM at their hospital between 2007 and 2018. A total of 117 patients (mean age 82 years) met the inclusion criteria; 57 had resection (group A) and 60 had biopsy (group B). Functional outcomes and survival at follow-up were analyzed.

Results Group A differed significantly from group B at baseline in having betterWHO performance status, better ASA scores, more right-sided tumors, and no basal ganglia or “butterfly” gliomas. Nevertheless, 56% of group A patients had an ASA score of 3. Median survival was 9.5 months (95% CI 8–17 months) in group A, 4 months (95% CI 3.5–6 months) in group B, and 17.5 months (95% CI 12–24 months) in the 56% of group A patients treated with resection and Stupp protocol. Rates of postoperative neurologic and medical complications were almost identical in the 2 groups, but the rate of surgical site complications was substantially greater in group A (12% vs 5%). There was no significant difference in mean preoperative and postoperative KPS scores (group A).

Conclusions In selected patients 80 years or older, radical removal of GBM was associated with acceptable survival and a low perioperative complication rate which is comparable to that of a biopsy. Although the median survival of the whole group was lower than reported for younger patients, a subgroup amenable to radical surgery and Stupp protocol achieved a median survival of 17.5 months.

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Complications after 1002 endoscopic endonasal approach procedures at a single center: lessons learned, 2010–2018

https://doi.org/10.3171/2020.11.JNS202494

The endoscopic endonasal approach (EEA) has evolved into a mainstay of skull base surgery over the last two decades, but publications examining the intraoperative and perioperative complications of this technique remain scarce. A prior landmark series of 800 patients reported complications during the first era of EEA (1998–2007), parallel to the development of many now-routine techniques and technologies. The authors examined a single-institution series of more than 1000 consecutive EEA neurosurgical procedures performed since 2010, to elucidate the safety and risk factors associated with surgical and postoperative complications in this modern era.

METHODS
After obtaining institutional review board approval, the authors retrospectively reviewed intraoperative and postoperative complications and their outcomes in patients who underwent EEA between July 2010 and June 2018 at a single institution.

RESULTS
The authors identified 1002 EEA operations that met the inclusion criteria. Pituitary adenoma was the most common pathology (n = 392 [39%]), followed by meningioma (n = 109 [11%]). No patients died intraoperatively. Two (0.2%) patients had an intraoperative carotid artery injury: 1 had no neurological sequelae, and 1 had permanent hemiplegia. Sixty-one (6.1%) cases of postoperative cerebrospinal fluid leak occurred, of which 45 occurred during the original surgical hospitalization. Transient postoperative sodium dysregulation was noted after 87 (8.7%) operations. Six (0.6%) patients were treated for meningitis, and 1 (0.1%) patient died of a fungal skull base infection. Three (0.3%) patients died of medical complications, thereby yielding a perioperative 90-day mortality rate of 0.4% (4 deaths). High-grade (Clavien-Dindo grade III–V) complications were identified after 103 (10%) EEA procedures, and multivariate analysis was performed to determine the associations between factors and these more serious complications. Extradural EEA was significantly associated with decreased rates of these high-grade complications (OR [95% CI] 0.323 [0.153–0.698], p = 0.0039), whereas meningioma pathology (OR [95% CI] 2.39 [1.30–4.40], p = 0.0053), expanded-approach intradural surgery (OR [95% CI] 2.54 [1.46–4.42], p = 0.0009), and chordoma pathology (OR [95% CI] 9.31 [3.87–22.4], p < 0.0001) were independently associated with significantly increased rates of high-grade complications.

CONCLUSIONS
The authors have reported a large 1002-operation cohort of EEA procedures and associated complications. Modern EEA surgery for skull base pathologies has an acceptable safety profile with low morbidity and mortality rates. Nevertheless, significant intraoperative and postoperative complications were correlated with complex intradural procedures and meningioma and chordoma pathologies.

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Morphometric Study of the Posterior Fossa: Identification of Practical Parameters for Tailored Selection of Surgical Routes to the Petroclival Region

J Neurol Surg B Skull Base 2022;83:37–43

The petroclival region is an integral part of the skull base. It can harbor different pathologies and provides access to the petroclival junction and cerebellopontine angle. We present the results of the morphometric analysis of the posterior fossa and a prediction model to enable skull base surgeons to choose an optimal surgical corridor considering patient’s bony anatomy.

Methods Ninety patients (14 to assess interobserver reliability) with temporal bone computed tomography were selected. Exclusion criteria included patients <18 years of age, radiographic evidence of trauma, infection, or previous surgery. The images were analyzed using OsiriX MD (Bernex, Switzerland). We recorded clival length, vertical angle, and surface area, and petroclival angle, petrous apex, and translabyrinthine corridors volume.

Results The average age was 49.5 years (55%) for males. The mean clival length and surface areas were 44.2mm (standard deviation [SD]   4.1) and 8.1 cm2 (SD   1.3). The mean petrous apex and translabyrinthine corridors volumes were 2.2 cm3 (SD   0.6) and 10.1 cm3 (SD   3.7). The mean petroclival angle at the internal auditory canal (IAC) was 154.9 degrees (SD   9). The clival length correlated positively with clival surface area (rho   0.6, p <0.05), petrous apex volume (rho   0.3, p < 0.05), and translabyrinthine volume (rho   0.3, p < 0.05).

Conclusion The petroclival region is complex and with high variability of surgical significance. The use of preoperative measurements of the clival length and petroclival angle as part of surgical planning that could help the surgeon to choose an optimal surgical corridor by overcoming the anatomical variability elements.

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A Systematic Review of Repeat Microvascular Decompression for Recurrent or Persistent Trigeminal Neuralgia

World Neurosurg. (2022) 158:226-233

When conservative therapy fails, microvascular decompression (MVD) has been the preferred treatment of primary trigeminal neuralgia (TN). However, the management of recurrent or persistent TN after MVD can often be difficult. The purpose of the present systematic review was to objectively analyze and summarize the reported literature regarding the feasibility of repeat MVD.

METHODS: We conducted a database search using the MEDLINE and PubMed databases until July 2020. The search terms used for title and abstract screening were as follows: “recurrent trigeminal neuralgia,” “persistent trigeminal neuralgia,” “repeat microvascular decompression,” and “reexploration.” The inclusion criteria for the systematic review were as follows: clinical studies (excluding case studies), repeat MVD treatment of TN, and studies that had recorded the pain relief outcomes, operative findings, and complications (if any).

RESULTS: Of the 1771 initial results obtained, we performed a full text screening of 43 studies, and, ultimately, 19 were deemed eligible. A total of 2247 patients had undergone MVD for TN, of whom, 311 had experienced recurrence (13.84%). Of the 311 patients, 178 had undergone repeat MVD. The average painfree interval was 27.75 months after the first MVD. The effective rate of repeat MVD was 91.66%, and 71.48% of the patients had had obvious compression found at repeat MVD. The postoperative complication rate after repeat MVD was 37.31% and was due to postoperative adhesions around the nerve and nerve injury caused by partial sensory rhizotomy. The most common complication after repeat MVD was facial numbness (21.89%), although the incidence of other complications was <5%.

CONCLUSIONS: For patients with recurrent or persistent pain after MVD, the findings from our systematic review support that repeat MVD remains a feasible treatment for recurrent or persistent TN.

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Adult Posterior Fossa Anaplastic Ependymoma

World Neurosurg. (2022) 158:205-209

Ependymomas are rare central nervous system tumors. The current treatment strategy is gross total tumor removal. Whether adjuvant therapy will be beneficial is controversial. We retrospectively analyzed 3 cases of World Health Organization (WHO) grade III posterior fossa anaplastic ependymomas treated with different treatment modalities. We aimed to identify possible treatment options for infratentorial WHO grade III anaplastic ependymoma in adults.

METHODS: We performed a retrospective analysis of 3 patients diagnosed with infratentorial anaplastic ependymomas in our institution from 2016 to 2020. The demographic data were documented. This case series of 3 patients does not meet the Department of Health and Human Services definition of research and does not need Institutional Review Board approval. All patients’ informed consents have been obtained.

RESULTS: One patient underwent subtotal tumor resection combined with adjuvant radiotherapy and Gamma Knife radiosurgery while the other 2 patients underwent gross total tumor removal combined with Gamma Knife radiosurgery or adjuvant radiotherapy. Tumors recurred in the first patient 20 months later, while the other 2 patents did not develop recurrence. The modified Rankin scale scores of these patients were 1, 0, and 0. All patients are followed up with regular magnetic resonance imaging at our facility.

CONCLUSIONS: The strategy for treating WHO grade III anaplastic ependymomas is controversial, but gross total tumor resection remains the key element. Adjuvant stereotactic radiosurgery after tumor removal might be considered if radiotherapy is not an option. The role of chemotherapy is unclear, and the use of chemotherapy should be tailored to individual patients

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The immunology of low-grade gliomas

Neurosurg Focus 52 (2):E2, 2022

Low-grade gliomas (LGGs), which harbor an isocitrate dehydrogenase (IDH) mutation, have a better prognosis than their high-grade counterparts; nonetheless, they remain incurable and impart significant negative impacts on patients’ quality of life.

Although immunotherapies represent a novel avenue of treatment for patients with LGGs, they have not yet been successful. Accurately selecting and evaluating immunotherapies requires a detailed understanding of LGG tumor immunology and the underlying tumor immune phenotype.

A growing body of literature suggests that LGGs significantly differ in their immunology from high-grade gliomas, highlighting the importance of investigation into LGG immunology specifically.

In this review, the authors aimed to discuss relevant research surrounding the LGG tumor immune microenvironment, including immune cell infiltration, tumor immunogenicity, checkpoint molecule expression, the impact of an IDH mutation, and implications for immunotherapies, while also briefly touching on current immunotherapy trials and future directions for LGG immunology research.

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Ventriculoatrial Shunts: Review of Technical Aspects and Complications

World Neurosurg. (2022) 158:158-164.

Diversion of cerebrospinal fluid is required in many neurosurgical conditions. When a standard ventriculoperitoneal shunt and endoscopic third ventriculostomy are not appropriate options, placement of a ventriculoatrial shunt is a safe, relatively familiar second-line shunting procedure.

Herein we reviewed the technical aspects of ventriculoatrial shunt placement using an illustrative case. We focused on the different modalities for inserting and confirming the location of the distal catheter tip. We discussed how to overcome typical difficulties and significant concerns, such as cardiac arrhythmias and venous thrombosis. In addition, we reviewed the current literature for the different complications associated with ventriculoatrial shunt placement

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Blood Biomarkers and Structural Imaging Correlations Post-Traumatic Brain Injury: A Systematic Review

Neurosurgery 90:170–179, 2022

Blood biomarkers are of increasing importance in the diagnosis and assessment of traumatic brain injury (TBI). However, the relationship between them and lesions seen on imaging remains unclear.

OBJECTIVE: To perform a systematic review of the relationship between blood biomarkers and intracranial lesion types, intracranial lesion injury patterns, volume/number of intracranial lesions, and imaging classification systems.

METHODS: We searched Medical Literature Analysis and Retrieval System Online, Excerpta Medica dataBASE, and Cumulative Index to Nursing and Allied Health Literature from inception to May 2021, and the references of included studies were also screened. Heterogeneity in study design, biomarker types, imaging modalities, and analyses inhibited quantitative analysis, with a qualitative synthesis presented.

RESULTS: Fifty-nine papers were included assessing one or more biomarker to imaging comparisons per paper: 30 assessed imaging classifications or injury patterns, 28 assessed lesion type, and 11 assessed lesion volume or number. Biomarker concentrations were associated with the burden of brain injury, as assessed by increasing intracranial lesion volume, increasing numbers of traumatic intracranial lesions, and positive correlations with imaging classification scores. There were inconsistent findings associating different biomarkers with specific imaging phenotypes including diffuse axonal injury, cerebral edema, and intracranial hemorrhage.

CONCLUSION: Blood-based biomarker concentrations after TBI are consistently demonstrated to correlate burden of intracranial disease. The relation with specific injury types is unclear suggesting a lack of diagnostic specificity and/or is the result of the complex and heterogeneous nature of TBI.

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Neurosurgical Causes of Pulsatile Tinnitus

Neurosurgery 90:161–169, 2022

Traditionally in the domain of the otolaryngologist, pulsatile tinnitus (PT) has become increasingly relevant to neurosurgeons.

PT may prove to be a harbinger of life-threatening pathology; however, often, it is a marker of a more benign process.

Irrespectively, the neurosurgeon should be familiar with the many potential etiologies of this unique and challenging patient population.

In this review, we discuss the myriad causes of PT, categorized by pulse-phase rhythmicity.

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Steroid in Chronic Subdural Hematoma: An Updated Systematic Review and Meta- Analysis Post DEX-CSDH Trial

World Neurosurg. (2022) 158:84-99

Chronic subdural hematoma (CSDH) is a neurologic condition characterized as a hematoma in the subdural space with a period >3 weeks that primarily affects the elderly. Glucocorticoid, especially dexamethasone, either alone or combined with surgery, has been used to manage CSDH. We aimed to perform an updated systematic review and meta-analysis of the literature regarding the role of steroids in CSDH.

METHODS: We searched the electronic databases PubMed, PubMed Central, Scopus, and Embase for relevant articles until December 2020. Study characteristics, quality, and end points were extracted, and analysis was performed by RevMan 5.4.

RESULTS: The odds for subdural hematoma recurrence were decreased by 61% in the steroid group (odds ratio [OR], 0.39; confidence interval [CI], 0.19e 0.79) compared with the control group. There was no significant difference in mortality during the study period (OR, 0.66; CI, 0.20e2.18), modified Rankin Scale score 0e3 (OR, 0.87; CI, 0.31e2.40), and modified Rankin Scale score 4e6 (OR, 1.15; CI, 0.42e3.18) between the 2 groups. However, pooling data from 3 studies showed 2.7 times higher odds of occurring adverse effects in steroid groups using the fixed-effect model (OR, 2.70; CI, 1.71e4.28). The treatment success was similar between the steroid and control groups (OR, 2.39; CI, 0.94e6.04).

CONCLUSIONS: Treatment with steroids was associated with a lesser recurrence of CSDH. However, there was no benefit of steroid treatment in CSDH compared with nonsteroid treatment in terms of mortality and treatment success and some but significantly increased risk of adverse events.

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Recurrent Low-Grade Gliomas: Does Reoperation Affect Neurocognitive Functioning?

Neurosurgery 90:221–232, 2022

Reoperations in patients with recurrent low-grade gliomas (RLGG) were proposed to control tumor residual and delay the risk of malignant transformation over time.

OBJECTIVE: To investigate neurocognitive outcomes in patients with RLGG who underwent a second surgery with awake monitoring.

METHODS: In this retrospective study, patients who underwent a second awake surgery for RLGG were included. Patients had presurgical and 3-mo postsurgical neuropsychological assessments. Data were converted into Z-scores and combined by the cognitive domain. Number of patients with cognitive deficits (Z-score <À1.65), variations of Z-scores, and extent of resection (EOR) were analyzed.

RESULTS: Sixty-two patients were included (mean age: 41.2 ± 10.0 yr). None had permanent neurological deficits postoperatively. Eight patients (12.9%) had a cognitive deficit preoperatively. Four additional patients (6.5%) had a cognitive deficit 3 mo after reoperation. Among other patients, 13 (21.0%) had a mild decline without cognitive deficits while 29 (46.8%) had no change of their performances and 8 (12.9%) improved. Overall, 94.2% of the patients returned to work. There were no correlations between EOR and Z-scores. Total/ subtotal resections were achieved in 91.9% of the patients (mean residual: 3.1 cm3 ). Fiftyeight patients (93.5%) were still alive after an overall follow-up of 8.3 yr.

CONCLUSION: Reoperation with awake monitoring in patients with RLGG was compatible with an early recovery of neuropsychological abilities. Four patients (6.5%) presented a new cognitive deficit at 3 mo postoperatively. Total/subtotal resections were achieved in most patients. Based on these favorable outcomes, reoperation should be considered in a more systematic way.

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Robotic-Assisted vs Nonrobotic-Assisted Minimally Invasive Transforaminal Lumbar Interbody Fusion: A Cost-Utility Analysis

Neurosurgery 90:192–198, 2022

Management of degenerative disease of the spine has evolved to favor minimally invasive techniques, including nonrobotic-assisted and robotic-assisted minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF). Value-based spending is being increasingly implemented to control rising costs in the US healthcare system. With an aging population, it is fundamental to understand which procedure(s) may be most cost-effective.

OBJECTIVE: To compare robotic and nonrobotic MIS-TLIF through a cost-utility analysis.

METHODS: We considered direct medical costs related to surgical intervention and to the hospital stay, as well as 1-yr utilities. We estimated costs by assessing all cases involving adults undergoing robotic surgery at a single institution and an equal number of patients undergoing nonrobotic surgery, matched by demographic and clinical characteristics. We adopted a willingness to pay of $50 000/quality-adjusted life year (QALY). Uncertainty was addressed by deterministic and probabilistic sensitivity analyses.

RESULTS: Costs were estimated based on a total of 76 patients, including 38 undergoing robot-assisted and 38 matched patients undergoing nonrobot MIS-TLIF. Using point estimates, robotic surgery was projected to cost $21 546.80 and to be associated with 0.68 QALY, and nonrobotic surgery was projected to cost $22 398.98 and to be associated with 0.67 QALY. Robotic surgery was found to be more cost-effective strategy, with costeffectiveness being sensitive operating room/materials and room costs. Probabilistic sensitivity analysis identified robotic surgery as cost-effective in 63% of simulations.

CONCLUSION: Our results suggest that at a willingness to pay of $50 000/QALY, robotic assisted MIS-TLIF was cost-effective in 63% of simulations. Cost-effectiveness depends on operating room and room (admission) costs, with potentially different results under distinct neurosurgical practices.

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Distinct approaches to language pathway tractography

J Neurosurg 136:589–600, 2022

Visualization of subcortical language pathways by means of diffusion tensor imaging–fiber tracking (DTIFT) is evolving as an important tool for surgical planning and decision making in patients with language-suspect brain tumors. Repetitive navigated transcranial magnetic stimulation (rTMS) cortical language mapping noninvasively provides additional functional information. Efforts to incorporate rTMS data into DTI-FT are promising, but the lack of established protocols makes it hard to assess clinical utility. The authors performed DTI-FT of important language pathways by using five distinct approaches in an effort to evaluate the respective clinical usefulness of each approach.

METHODS Thirty patients with left-hemispheric perisylvian lesions underwent preoperative rTMS language mapping and DTI. FT of the principal language tracts was conducted according to different strategies: Ia, anatomical landmark based; Ib, lesion-focused landmark based; IIa, rTMS based; IIb, rTMS based with postprocessing; and III, rTMS enhanced (based on a combination of structural and functional data). The authors analyzed the respective success of each method in revealing streamlines and conducted a multinational survey with expert clinicians to evaluate aspects of clinical utility.

RESULTS The authors observed high usefulness and accuracy ratings for anatomy-based approaches (Ia and Ib). Postprocessing of rTMS-based tractograms (IIb) led to more balanced perceived information content but did not improve the usefulness for surgical planning and risk assessment. Landmark-based tractography (Ia and Ib) was most successful in delineating major language tracts (98% success), whereas rTMS-based tractography (IIa and IIb) frequently failed to reveal streamlines and provided less complete tractograms than the landmark-based approach (p < 0.001). The lesionfocused landmark-based (Ib) and the rTMS-enhanced (III) approaches were the most preferred methods.

CONCLUSIONS The lesion-focused landmark-based approach (Ib) achieved the best ratings and enabled visualization of the principal language tracts in almost all cases. The rTMS-enhanced approach (III) was positively evaluated by the experts because it can reveal cortico-subcortical connections, but the functional relevance of these connections is still unclear. The use of regions of interest derived solely from cortical rTMS mapping (IIa and IIb) leads to cluttered images that are of limited use in clinical practice.

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Preoperative Duration of Symptoms Does Not Affect Outcomes of Anterior Lumbar Interbody Fusion

Neurosurgery 90:215–220, 2022

Previous studies have examined the impact of preoperative duration of symptoms (DOS) on lumbar spinal surgery outcomes although this has not been explored for anterior lumbar interbody fusion (ALIF).

OBJECTIVE: To assess the impact of preoperative DOS on patient-reported outcome measures (PROMs) of ALIF with posterior instrumentation.

METHODS: A database was retrospectively reviewed for ALIFs with posterior instrumentation. PROMs recorded at preoperative, 6-wk, 12-wk, 6-mo, and 1-yr postoperative timepoints in- cluded Visual Analog Scale back and leg, Oswestry Disability Index, 12-Item Short-Form Physical Component Score (SF-12 PCS), and PROM Information System physical function. Achievement of minimum clinically important difference (MCID) was determined by com- paring differences in postoperative PROMs from baseline to established values. Patients were grouped based on preoperative DOS into <1-yr and ≥1-yr groups. Differences in PROMs were compared using a t-test, whereas MCID achievement used a χ2 test.

RESULTS: Fifty-three patients were included, with 20 in the <1-yrgroup and 33 in the ≥1-yr group. The most common diagnosis was isthmic spondylolisthesis. No significant preoperative differences were observed in any PROM. DOS groups demonstrated significantly different scores for SF-12 PCS at 6 wk (P = .049). No significant differences in MCID achievement were observed between groups for any PROM.

CONCLUSION: ALIF patients demonstrated similar levels of pain, disability, and physical function regardless of preoperative DOS, except for back pain and physical function at intermittent timepoints. MCID achievement did not differ based on DOS for all outcome measures.

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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.

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