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Predictive factors for post operative seizures following meningioma resection in patients without preoperative seizures: a multicenter retrospective analysis

Acta Neurochirurgica (2023) 165:1333–1343

Meningiomas are the most common primary brain tumor and represent 35% of all intracranial neoplasms. However, in the early post-operative period approximate 3–5% of patients experience an acute symptomatic seizure. Establishing risk factors for postoperative seizures will identify those patients without preoperative seizures at greatest risk of postoperative seizures and may guide antiseizure medications (ASMs) management.

Methods Adult seizure naïve patients who underwent primary resection of a World Health Organization (WHO) Grade 1–3 meningioma at the three Mayo Clinic Campuses between 2012–2022 were retrospectively reviewed. Multivariate regression analyses were used to identify radiological, surgical, and management features with the development of new-onset seizures in patients undergoing meningioma resection.

Results Of 113 seizure naïve patients undergoing meningioma resection 11 (9.7%) experienced a new-onset post-operative seizure. Tumor volume ≥ 25 cm 3 (Odds Ratio (OR) 5.223, 95% Confidence Interval (CI) 1.546 – 17.650, p = 0.008) and cerebral convexity meningiomas (OR 4.742, 95% CI 1.255 – 14.336, p = 0.016) were most associated with new onset postoperative seizures in multivariate analysis. ASMs and corticosteroid therapies did not display a significant difference among those with and without a new onset postoperative seizure.

Conclusion In the current study, a larger tumor volume (≥ 25 cm3 ) and/or convexity meningiomas predicted the development of new onset post-operative seizures. Those who present with these factors should be counseled for their increased risk of new onset post-operative seizures and may benefit from prophylactic ASMs therapy.

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Microsurgical anatomy of the auditory radiations: revealing the enigmatic acoustic pathway from a surgical viewpoint

J Neurosurg 138:1443–1456, 2023

The thalamocortical projections of the auditory system have not been detailed via microanatomical fiber dissections from a surgical viewpoint. The aim of this study was to delineate the course of the auditory radiations (ARs) from the medial geniculate body to their final destination in the auditory cortex. The authors’ additional purpose was to display the relevant neural structures in relation to their course en route to Heschl’s gyrus.

METHODS White matter fibers were dissected layer by layer in a lateral-to-medial, inferolateral-to-superomedial, and inferior-to-superior fashion.

RESULTS The origin of ARs just distal to the medial geniculate body was revealed following the removal of the parahippocampal gyrus, cingulum bundle, and mesial temporal structures, in addition to the lateral geniculate body. Removing the fimbria, stria terminalis, and the tail of the caudate nucleus along the roof of the temporal horn in an inferior-to-superior direction exposed the lateral compartment of the sublenticular segment of the internal capsule as the predominant obstacle that prevents access to the ARs. The ARs were initially obscured by the inferolaterally located temporopulvinar tract of Arnold, and their initial course passed posterolateral to the temporopontine fascicle of Türck. The ARs subsequently traversed above the temporopulvinar fibers in a perpendicular manner and coursed in between the optic radiations at the sensory intersection region deep to the inferior limiting sulcus of insula. The distal part of the ARs intermingled with the fibers of the anterior commissure and inferior fronto-occipital fasciculus during its ascent toward Heschl’s gyrus. The ARs finally projected to a large area over the superior temporal gyrus, extending well beyond the anteroposterior boundaries of the transverse temporal gyri.

CONCLUSIONS The ARs can be appreciated as a distinct fiber bundle ascending between the fibers of the sublenticular segment of the internal capsule and traversing superiorly along the roof of the temporal horn by spanning between the optic radiations. Our novel findings suggest potential disruption of the ARs’ integrity during transsylvian and transtemporal approaches along the roof of the temporal horn toward the mesial temporal lobe. The detailed 3D understanding of the ARs’ relations and awareness of their course may prove helpful to secure surgical interventions to the region.

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Pediatric Vagus Nerve Stimulation: Case Series Outcomes and Future Directions

Neurosurgery 92:1043–1051, 2023

Vagus nerve stimulation (VNS) is a neuromodulatory procedure most extensively studied as an adjunct to medically refractory epilepsy. Despite widespread adoption and decades of clinical experience, clinical predictors of response to VNS remain unclear. OBJECTIVE: To evaluate a retrospective cohort of pediatric patients undergoing VNS at our institution to better understand who may benefit from VNS and identify factors which may predict response to VNS.

METHODS: We conducted a retrospective cohort study examining pediatric patients undergoing VNS over nearly a 20-year span at a single institution. Presurgical evaluation, including demographics, clinical history, and diagnostic electroencephalogram, and imaging findings were examined. Primary outcomes included VNS response.

RESULTS: Two hundred ninety-seven subjects were studied. The mean age at surgery was 10.1 (SD = 4.9, range = 0.8-25.3) years; length of follow-up was a mean of 4.6 years (SD = 3.5, median = 3.9 years, range 1 day-16.1 years). There was no association between demographic factors, epilepsy etiology, or genetic basis and VNS outcomes. There was an association between reduction in main seizure type with positive MRI finding. Of all MRI findings analyzed, brain atrophy was significantly associated with worse VNS outcomes, whereas dysplastic hippocampus and chronic periventricular leukomalacia findings were found to be associated with improved outcomes. Increased seizure semiology variability and seizure type were also associated with improved seizure outcomes.

CONCLUSION: Predicting response to VNS remains difficult, leading to incompletely realized benefits and suboptimal resource utilization. Specific MRI findings and increased seizure semiology variability and type can help guide clinical decision making and patient counseling.

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Mechanical complications and patient-reported outcome measures associated with high pelvic incidence and persistent pelvic retroversion: the Roussouly “false type 2” profile

J Neurosurg Spine May 12, 2023

OBJECTIVE The objective of this paper was to report mechanical complications and patient-reported outcome measures (PROMs) for adult spinal deformity (ASD) patients with a Roussouly “false type 2” (FT2) profile.

METHODS ASD patients treated from 2004 to 2014 at a single center were identified. Inclusion criteria were pelvic incidence ≥ 60° and a minimum 2-year follow-up. FT2 was defined as a high postoperative pelvic tilt (PT), as defined by the Global Alignment and Proportion target, and thoracic kyphosis < 30°. Mechanical complications, defined as proximal junctional kyphosis (PJK) and/or instrumentation failure, were determined and compared. Scoliosis Research Society22r (SRS-22r) scores were compared between groups.

RESULTS Ninety-five patients (normal PT [NPT] group 49, FT2 group 46) who met the inclusion criteria were identified and studied. Most surgeries were revisions (NPT group 30 [61%], FT2 group 30 [65%]), and most were performed via a posterior-only approach (86%) (mean ± SD 9.6 ± 5 levels). Proximal junctional angles increased after surgery in both groups, without differences between groups. Neither rates of radiographic PJK (p = 0.10), revision for PJK (p = 0.45), nor revision for pseudarthrosis (p = 0.66) were different between groups. There were no differences between groups for SRS-22r domain scores or subscores.

CONCLUSIONS In this single-center experience, patients with high pelvic incidence fixed with persistent lumbopelvic parameter mismatch and engaged compensatory mechanisms (Roussouly FT2) had mechanical complications and PROMs not different from those with normalized alignment parameters. Compensatory PT may be acceptable in some cases of ASD surgery.

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Middle Meningeal Artery Embolization for Chronic Subdural Hematoma: A Review

Operative Neurosurgery 24:469–475, 2023

Middle meningeal artery embolization (MMAE) for chronic subdural hematomas (cSDHs) has evolved as a potential treatment alternative for these lesions. The indications for using this treatment modality and the pathophysiology of cSDHs are an area of considerable interest.

A retrospective review was performed including all major papers addressing this topic. Although considered a relatively new treatment option, MMAE for cSDHs is gaining widespread popularity. There are many questions that need to be addressed regarding its indications, some of which are the subject of ongoing clinical trials. The efficacy of this treatment modality in carefully selected patients has also provided new insights into the potential pathophysiology of cSDHs.

This concise review will focus on the current evidence supporting the use of embolization in the treatment of this disease and highlight unanswered relevant clinical questions regarding MMAE indications and technique.

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Presigmoid approach preserving the superior petrosal sinus in a pontine cavernous malformation associated to abnormal venous drainage of the brainstem

Acta Neurochirurgica (2023) 165:1233–1240

The presigmoid approach classically includes the ligature and section of the superior petrosal sinus to get a wider visibility window to the antero-lateral brainstem surface. In some cases, the separation of this venous structure should not be performed.

Method We present our experience getting safely to a pontine cavernous malformation through a conventional mastoidectomy presigmoid approach preserving an ingurgitated superior petrosal sinus because the association with an abnormal venous drainage of the brainstem.

Conclusions When sectioning the superior petrosal sinus in classical presigmoid approaches is contraindicated, its preservation could also offer good surgical corridors to get to small-medium anterior and lateral brainstem cavernous malformations.

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Internal Ventricular Cerebrospinal Fluid Shunt for Adult Hydrocephalus: A Systematic Review and Meta-Analysis of the Infection Rate

Hydrocephalus is a common neurological condition that usually requires internal ventricular cerebrospinal fluid shunt (IVCSFS). The reported infection rate (IR) varies greatly from below 1% up to over 50%, but no meta-analysis to assess the overall IR has ever been performed.

OBJECTIVE: To determine the IVCSFS overall IR in the adult population and search for associated factors.

METHODS: Six databases were searched from January 1990 to July 2022. Only original articles reporting on adult IVCSFS IR were included. Random-effects meta-analysis with generalized linear mixed model method and logit transformation was used to assess the overall IR. RESULTS: Of 1703 identified articles, 44 were selected, reporting on 57259 patients who had IVCSFS implantation and 2546 infections. The pooled IR value and its 95% CI were 4.75%, 95% CI (3.8 to 5.92). Ninety-five percent prediction interval ranged from 1.19% to 17.1%. The patients who had IVCSFS after intracranial hemorrhage showed a higher IR (7.65%, 95% CI [5.82 to 10], P-value = .002). A meta-regression by year of publication found a decreasing IR (À0.031, 95% CI [À0.06 to 0.003], P-value = .032) over the past 32 years.

CONCLUSION: IVCSF is a procedure that every neurosurgeon should be well trained to perform. However, the complication rate remains high, with an estimated overall IR of 4.75%. The IR is especially elevated for hydrocephalic patients who require IVCSFS after intracranial hemorrhage. However, decades of surgical advances may have succeeded in reducing IR over the past 32 years.

Neurosurgery 92:894–904, 2023

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Multiple Vessel Compression of the Trigeminal Nerve Is Associated With Worse Outcomes in Trigeminal Neuralgia After Microvascular Decompression

Neurosurgery 92:1029–1034, 2023

Whether the total number of compressive vessels in trigeminal neuralgia (TN) affects outcomes after microvascular decompression (MVD) is unknown.

OBJECTIVE: To investigate whether the number of compressive vessels is associated with outcomes after MVD.

METHODS: We retrospectively reviewed all patients with TN who underwent MVDs at our institution from 2007 to 2020. The number and identity of compressive vessels on the trigeminal nerve were recorded. Preoperative and postoperative pain and numbness Barrow Neurological Institute scores were compared. Factors associated with pain recurrence were assessed using survival analyses and multivariate regressions.

RESULTS: We identified 496 patients with a single vessel and 381 patients with multiple vessels compressing the trigeminal nerve. Compared with patients with a single compressive vessel, patients with multiple sources of compression exhibited increased Barrow Neurological Institute pain scores preoperatively (P = .01). In addition, pain recurrence was more frequent (P < .001) and occurred after a significantly shorter pain-free duration (P < .001) for the multiple compression group. Using multivariate ordinal regression, a greater number of arteries (P = .03) and veins (P = .03) were both significantly associated with higher pain scores at final follow-up. Furthermore, the number of arteries (P = .01) and of veins (P = .01) was significantly associated with a higher risk for pain recurrence.

CONCLUSION: TN patients with a single compressive vessel exhibited better pain outcomes after an MVD. Patients with multiple compressive vessels exhibited higher pain scores preoperatively and incurred a higher risk for pain recurrence, which occurred after a shorter pain-free interval compared with the single compression cohort.

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Surgical Resection of Deep-Seated Arteriovenous Malformations Through Stereotactically Guided Tubular Retractor Systems

Operative Neurosurgery 24:499–506, 2023

Arteriovenous malformations (AVMs) in the subcortical and/or periventricular regions can cause significant intraventricular and intracranial hemorrhage. These AVMs can pose a unique surgical challenge because traditional, open approaches to the periventricular region require significant cortical/white matter retraction to establish sufficient operative corridors, which may result in risk of neurological injury. Minimally invasive tubular retractor systems represent a novel, feasible surgical option for treating deep-seated AVMs.

OBJECTIVE: To explore 5 cases of NICO BrainPath-assisted resection of subcortical/ periventricular AVMs.

METHODS: Five patients from a single institution were operated on for deep-seated AVMs using tubular retractor systems. Collected data included demographics, AVM specifications, preoperative neurological status, postoperative neurological status, and postoperative/intraoperative angiogram results.

RESULTS: Five patients, ranging from age 10 to 45 years, underwent mini-craniotomy for stereotactically guided tubular retractor-assisted AVM resection using neuronavigation for selecting a safe operative corridor. No preoperative embolization was necessary. Mean maximum AVM nidal diameter was 8.2 mm. All deep-seated AVMs were completely resected without complications. All AVMs demonstrated complete obliteration on intraoperative angiogram and on 6-month follow-up angiogram.

CONCLUSION: Minimally invasive tubular retractors are safe and present a promising surgical option for well-selected deep-seated AVMs. Furthermore, study may elucidate whether tubular retractors improve outcomes after microsurgical AVM resection secondary to mitigation of iatrogenic retraction injury risk.

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Comparison of Single-Session, Neoadjuvant, and Adjuvant Embolization Gamma Knife Radiosurgery for Arteriovenous Malformation

Neurosurgery 92:986–997, 2023

The purpose of intracranial arteriovenous malformations (AVMs) treatment is to prevent bleeding or subsequent hemorrhage with complete obliteration. For large, difficult-to-treat AVMs, multimodal approaches including surgery, endovascular embolization, and gamma knife radiosurgery (GKRS) are frequently used.

OBJECTIVE: To analyze the outcomes of AVMs treated with single-session, neoadjuvant, and adjuvant embolization GKRS.

METHODS: We retrospectively reviewed a database of 453 patients with AVMs who underwent GKRS between January 2007 and December 2017 at our facility. The obliteration rate, incidence of latent period bleeding, cyst formation, and radiation-induced changes were compared among the 3 groups, neoadjuvant-embolized, adjuvant-embolized, nonembolized group. In addition, the variables predicting AVM obliteration and complications were investigated.

RESULTS: A total of 228 patients were enrolled in this study. The neoadjuvant-embolized, adjuvant-embolized, and nonembolized groups comprised 29 (12.7%), 19 (8.3%), and 180 (78.9%) patients, respectively. Significant differences were detected among the 3 groups in the history of previous hemorrhage and the presence of aneurysms (P < .0001). Multivariate Cox regression analyses revealed a significant inverse correlation between neoadjuvant embolization and obliteration occurring 36 months after GKRS (hazard ratio, 0.326; P = .006).

CONCLUSION: GKRS with either neoadjuvant or adjuvant embolization is a beneficial approach for the treatment of AVMs with highly complex angioarchitectures that are at risk for hemorrhage during the latency period. Embolization before GKRS may be a negative predictive factor for late-stage obliteration (>36 months). To confirm our conclusions, further studies involving a larger number of patients and continuous follow-up are necessary.

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Reappraisal of Intracerebral Hemorrhages and Intracerebral Hemorrhage Grading Scale Score in Surgically and Medically Managed Cerebellar Intracerebral Hemorrhage

 

Neurosurgery 92:1021–1028, 2023

As compared with supratentorial intracerebral hemorrhages (ICH), bleeds that occur within the cerebellum require special consideration given the nature of the posterior fossa.

OBJECTIVE: To validate ICH and ICH grading scale (ICH-GS) scores in patients with cerebellar hemorrhage and examine the outcomes of patients managed surgically as compared with those who underwent conservative treatment.

METHODS: This observational multicenter study included 475 patients with cerebellar hemorrhage from 9 different neurosurgical departments in Germany between 2005 and 2021. The prognostic accuracy of ICH and ICH-GS scores were calculated by the area under the curve of the receiver operating characteristic curves. Analyzed outcomes were the inhospital mortality, mortality at 6 months, in-hospital outcome, and outcome at 6 months.

RESULTS: Of 403 patients, 252 patients (62.5%) underwent surgical treatment and 151 patients (37.5%) conservative treatment. Both ICH and ICH-GS scores demonstrated good prognostic accuracy regarding both overall mortality and functional outcomes. In those patients presenting with severe cerebellar hemorrhages, ie, ICH score >3 and ICH-GS score >11, overall mortality was significantly lower in surgically treated patients. Mortality was significantly higher in those patients managed surgically who presented with ICH scores ≤3; in such patients, improved outcomes were noted when the hematoma was treated conservatively.

CONCLUSION: ICH and ICH scores are useful tools for prediction of survival and outcome in patients with cerebellar ICH. Surgical management may be beneficial for those who present with severe cerebellar ICH as reflected by ICH scores >3, while conservative management seems reasonable in patients with lower ICH scores.

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Endoscopic clipping of an anterior communicating artery aneurysm

Acta Neurochirurgica (2023) 165:1227–1231

Anterior communicating artery aneurysms are most prone to rupture. Surgically, they are conventionally being managed by a pterional approach. Some neurosurgeons prefer a supraorbital keyhole approach in select cases. Fully endoscopic clipping of such aneurysms is seldom described.

Method We clipped an antero-inferiorly directed anterior communicating artery aneurysm endoscopically via a supraorbital keyhole approach. The intraoperative aneurysmal rupture was also managed endoscopically. The patient made an excellent postoperative recovery without any neurological deficits.

Conclusion Select cases of anterior communicating artery aneurysms can be clipped endoscopically using standard instruments and adhering to the basic principles of aneurysm clipping.

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Endovascular treatment of brain arteriovenous malformations: clinical outcomes of patients included in the registry of a pragmatic randomized trial

J Neurosurg 138:1393–1402, 2023

The role of endovascular treatment in the management of patients with brain arteriovenous malformations (AVMs) remains uncertain. AVM embolization can be offered as stand-alone curative therapy or prior to surgery or stereotactic radiosurgery (SRS) (pre-embolization). The Treatment of Brain AVMs Study (TOBAS) is an all-inclusive pragmatic study that comprises two randomized trials and multiple registries.

METHODS Results from the TOBAS curative and pre-embolization registries are reported. The primary outcome for this report is death or dependency (modified Rankin Scale [mRS] score > 2) at last follow-up. Secondary outcomes include angiographic results, perioperative serious adverse events (SAEs), and permanent treatment-related complications leading to an mRS score > 2.

RESULTS From June 2014 to May 2021, 1010 patients were recruited in TOBAS. Embolization was chosen as the primary curative treatment for 116 patients and pre-embolization prior to surgery or SRS for 92 patients. Clinical and angiographic outcomes were available in 106 (91%) of 116 and 77 (84%) of 92 patients, respectively. In the curative embolization registry, 70% of AVMs were ruptured, and 62% were low-grade AVMs (Spetzler-Martin grade I or II), while the pre-embolization registry had 70% ruptured AVMs and 58% low-grade AVMs. The primary outcome of death or disability (mRS score > 2) occurred in 15 (14%, 95% CI 8%–22%) of the 106 patients in the curative embolization registry (4 [12%, 95% CI 5%–28%] of 32 unruptured AVMs and 11 [15%, 95% CI 8%–25%] of 74 ruptured AVMs) and 9 (12%, 95% CI 6%–21%) of the 77 patients in the pre-embolization registry (4 [17%, 95% CI 7%–37%] of 23 unruptured AVMs and 5 [9%, 95% CI 4%–20%] of 54 ruptured AVMs) at 2 years. Embolization alone was confirmed to occlude the AVM in 32 (30%, 95% CI 21%–40%) of the 106 curative attempts and in 9 (12%, 95% CI 6%–21%) of 77 patients in the pre-embolization registry. SAEs occurred in 28 of the 106 attempted curative patients (26%, 95% CI 18%–35%, including 21 new symptomatic hemorrhages [20%, 95% CI 13%–29%]). Five of the new hemorrhages were in previously unruptured AVMs (n = 32; 16%, 95% CI 5%–33%). Of the 77 pre-embolization patients, 18 had SAEs (23%, 95% CI 15%–34%), including 12 new symptomatic hemorrhages [16%, 95% CI 9%–26%]). Three of the hemorrhages were in previously unruptured AVMs (3/23; 13%, 95% CI 3%–34%).

CONCLUSIONS Embolization as a curative treatment for brain AVMs was often incomplete. Hemorrhagic complications were frequent, even when the specified intent was pre-embolization before surgery or SRS. Because the role of endovascular treatment remains uncertain, it should preferably, when possible, be offered in the context of a randomized trial.

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The longitudinal volumetric response of vestibular schwannomas after Gamma Knife radiosurgery

J Neurosurg 138:1273–1280, 2023

Gamma Knife radiosurgery (GKRS) is an effective treatment for vestibular schwannomas (VSs) and has been used in > 100,000 cases worldwide. In the present study the authors sought to define the serial volumetric tumor response of Koos grade I–IV VS after radiosurgery.

METHODS A total of 201 consecutive VS patients underwent GKRS at a single institution between 2015 and 2019. All patients had a minimum follow-up of 18 months and at least 2 interval postprocedure MRI scans. The contrast-enhanced tumor volumes were contoured manually and compared between pre- and post-GKRS imaging. The percentages of tumor volume change at 18 months (short-term follow-up) and up to 5 years after GKRS (long-term follow-up) were compared with the baseline tumor volume. An increase of 20% was considered a significant increase of tumor volume. Trends of tumor volume over time were assessed with linear models using time as a continuous variable. A test for linear trend was evaluated according to the initial Koos tumor classification.

RESULTS Koos grade II VS was the most frequently occurring tumor (n = 74, 36.8%), followed by grade III (n = 57, 28.4%), grade I (n = 41, 20.4%), and grade IV (n = 29, 14.4%). The mean tumor volume at the time of GKRS was 2.12 ±2.82 cm 3 (range 0.12–18.77 cm 3 ) and the median margin dose was 12 Gy. Short-term follow-up revealed that tumor volumes transiently increased in 34.2% and 28.4% of patients at 6 and 18 months, respectively, regardless of Koos grade. Linear regression analysis of Koos grade II, III, and IV tumors showed a significant longitudinal volume decrease on long-term follow-up. At last follow-up (median 30 months, range 18–54 months), 19 patients (9.4%) showed a persistent increase of tumor volume. Five patients received additional management after GKRS.

CONCLUSIONS Although selected VS patients demonstrate an early and measurable transient volumetric increase after GKRS, > 90% have stable or reduced tumor volumes over an observed period of up to 5 years. Volumetric regression is most pronounced in Koos grade II, III, and IV tumors and may not be fully detectable until 3 years after GKRS.

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Recurrent insular low-grade gliomas: factors guiding the decision to reoperate

J Neurosurg 138:1216–1226, 2023

Reoperation has been established as an effective therapeutic strategy in recurrent diffuse low-grade gliomas (LGGs). Insular gliomas represent a specific surgical challenge because of the surrounding vascular and functional structures. The aim of this study was to investigate the main clinicoradiological factors guiding the decision to reoperate on recurrent insular LGGs (ILGGs).

METHODS In this retrospective consecutive series, the authors screened all patients operated on for an ILGG in their institution who further presented with a tumor regrowth without the development of contrast enhancement. They compared patients who were subsequently offered a reoperation under awake mapping at recurrence or who underwent reoperation after adjuvant treatment had reduced the volume of the initial tumor recurrence (with a proven pathological diagnosis of LGG after the second surgery) to patients who were not selected for a reoperation. The first group (reoperated group; n = 20) included all recurrent ILGG patients who underwent second resection, and the second group (nonreoperated group; n = 60) included patients who did not undergo reoperation but underwent adjuvant oncological treatment.

RESULTS Factors significantly associated with reoperation were extent of resection (EOR) at first surgery (91.9% vs 89.7%, p = 0.014), residual tumor volume (9.5 ± 7.1 mL [range 0–30 mL] vs 6.3 ± 7.3 mL [range 0–30 mL], p = 0.02) at first surgery and left temporopolar infiltration at the time of tumor recurrence (Liebermeister statistical analysis, 4293 voxels survived false discovery rate correction with p < 0.05; maximal z-statistic = 6.50). Infiltration of the anterior perforated substance at tumor recurrence was significantly anticorrelated to reoperation (179 voxels survived false discovery rate correction with p < 0.05; minimal z-statistic = −4.33). The mean EOR was 83.7% at reoperation with a 90% survival rate at last follow-up (9.3 ± 3.8 years), low postsurgical morbidity (Karnofsky Performance Status score ≥ 80 in 95% of patients), a high rate of postoperative professional resumption (95%), and seizure control in 57.1% of patients.

CONCLUSIONS In selected patients with recurrent ILGG without radiographic evidence of malignant transformation, reoperation with intraoperative awake mapping is associated with favorable oncological outcomes and a low postsurgical morbidity. A greater EOR and a lower residual tumor volume at first surgery were significantly associated with reoperation. Patients who benefited from a second surgery typically had a recurrent pattern within cortical areas (such as the temporopolar region), while other patients typically presented with a deeper infiltrative pattern within the anterior perforated substance and the surrounding white matter pathways. Such original findings may be helpful to select the optimal indications of reoperation in recurrent ILGG.

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Burr hole microsurgical subtemporal selective amygdalohippocampectomy

Acta Neurochirurgica (2023) 165:1215–1226

At present, selective amygdalohippocampectomy (SAH) has become popular in the treatment of drug-resistant mesial temporal lobe epilepsy (TLE). However, there is still an ongoing discussion about the advantages and disadvantages of this approach.

Methods The study included a consecutive series of 43 adult patients with drug-resistant TLE, involving 24 women and 19 men (1.8/1). Surgeries were performed at the Burdenko Neurosurgery Center from 2016 to 2019. To perform subtemporal SAH through the burr hole with the diameter of 14 mm, we used two types of approaches: preauricular, 25 cases, and supra-auricular, 18 cases. The follow-up ranged from 36 to 78 months (median 59 months). One patient died 16 months after surgery (accident).

Results By the third year after surgery, Engel I outcome was achieved in 80.9% (34 cases) of cases and Engel II in 4 (9.5%) and Engel III and Engel IV in 4 (9.6%) cases. Among the patients with Engel I outcomes, anticonvulsant therapy was completed in 15 (44.1%), and doses were reduced in 17 (50%) cases. Verbal and delayed verbal memory decreased after surgery in 38.5% and 46.1%, respectively. Verbal memory was mainly affected by preauricular approach in comparison with supraauricular (p = 0.041). In 15 (51.7%) cases, minimal visual field defects were detected in the upper quadrant. At the same time, visual field defects did not extend into the lower quadrant and inside the 20° of the upper affected quadrant in any case.

Conclusions Burr hole microsurgical subtemporal SAH is an effective surgical procedure for drug-resistant TLE. It involves minimal risks of loss of visual field within the 20° of the upper quadrant. Supra-auricular approach, compared to preauricular, results in a reduction in the incidence of upper quadrant hemianopia and is associated with a lower risk of verbal memory impairment.

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Lumbar Synovial Cysts—Should You Fuse or Not?

Neurosurgery 92:1013–1020, 2023

Spinal synovial cysts are lesions that most commonly occur in the lumbar region. The need for an instrumented spinal fusion in addition to lumbar decompression with removal of the synovial cyst is unknown.

OBJECTIVE: To test the hypothesis that select patients who underwent decompression with instrumented fusion for lumbar synovial cysts would be less likely to have subsequent surgery (SS) in a 2-year period than patients treated with laminectomy alone.

METHODS: This retrospective cohort study was performed using IBM MarketScan Commercial Claims and Encounters Database. Patients who had a lumbar synovial cyst diagnosis and laminectomy surgery with or without fusion surgery were included in this study. Patients were tracked for SS 2 years after surgery. Laminectomy patients were propensity score–matched to laminectomy with fusion (LF) patients using a 2:1 ratio. The log-rank test and Cox regression were used to compare the cumulative incidence of SS between groups.

RESULTS: There were 7664 and 1631 patients treated with laminectomy and LF before matching. After matching, there were 2212 laminectomy and 1631 LF patients and patient characteristics were balanced. The 2-year incidence of recurrent SS was 3.1% ([CI]: 2.2%, 4.0%) and 1.7% (95% CI: 0.9%, 2.5%) laminectomy and LF, respectively. Compared with laminectomy, LF had a statistically significant lower risk of recurrent SS (hazard ratio: 0.56 [95% CI: 0.32-0.97]; P-value: .04).

CONCLUSION: All patients who had concomitant lumbar fusion showed decreased chance of having a cyst- or noncyst-related recurrence SS when compared with all patients undergoing laminectomy alone, regardless of diagnosis at the time of SS.

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Presence of a fundal fluid cap on preoperative magnetic resonance imaging may predict long-term facial nerve function after resection of vestibular schwannoma via the retrosigmoid approach

J Neurosurg 138:972–980, 2023

Preservation of neurological function is a priority when performing a resection of a vestibular schwannoma (VS). Few studies have examined the radiographic value of a fundal fluid cap—i.e., cerebrospinal fluid in the lateral end of a VS within the internal auditory canal—for prediction of postoperative neurological function. The aim of this study was to clarify whether the presence of a fundal fluid cap on preoperative magnetic resonance images has a clinical impact on facial nerve function after resection of VSs.

METHODS The presence of a fundal fluid cap and its prognostic impact on long-term postoperative facial nerve function were analyzed.

RESULTS A fundal fluid cap was present in 102 of 143 patients who underwent resection of sporadic VSs via the retrosigmoid approach. Facial nerve function was acceptable (House-Brackmann grade I–II) immediately after surgery in 82 (80.4%) patients with a fundal fluid cap and in 26 (63.4%) of those without this sign. The preservation rate of facial nerve function increased in a time-dependent manner after surgery in patients with a fundal fluid cap but plateaued by 3 months postoperatively in those without a fundal fluid cap; the difference was statistically significant at 12 months (96.1% vs 82.9%, p = 0.013) and 24 months (97.1% vs 82.9%, p = 0.006) after surgery. The presence of a fundal fluid cap had a significantly positive effect on long-term facial nerve function at 24 months after surgery when tumor size and intraoperative neuromonitoring response were taken into account (OR 5.55, 95% CI 1.12–27.5, p = 0.034).

CONCLUSIONS Neuromonitoring-guided microsurgery for total resection of VSs is more likely to be successful in terms of preservation of facial nerve function if a fundal fluid cap is present. This preoperative radiographic sign could be helpful when counseling patients and deciding the treatment strategy.

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Volumetric Growth and Growth Curve Analysis of Residual Intracranial Meningioma

Neurosurgery 92:734–744, 2023

After meningioma surgery, approximately 1 in 3 patients will have residual tumor that requires ongoing imaging surveillance. The precise volumetric growth rates of these tumors are unknown.

OBJECTIVE: To identify the volumetric growth rates of residual meningioma, growth trajectory, and factors associated with progression.

METHODS: Patients with residual meningioma identified at a tertiary neurosurgery center between 2004 and 2020 were retrospectively reviewed. Tumor volumewas measured using manual segmentation, after surgery and at every follow-up MRI scan. Growth rates were ascertained using a linear mixed-effects model and nonlinear regression analysis of growth trajectories. Progression was defined according to the Response Assessment in Neuro- Oncology (RANO) criteria (40% volume increase).

RESULTS: There were 236 patients with residual meningioma. One hundred and thirtytwo patients (56.0%) progressed according to the RANO criteria, with 86 patients being conservatively managed (65.2%) after progression. Thirteen patients (5.5%) developed clinical progression. Over a median follow-up of 5.3 years (interquartile range, 3.5–8.6 years), the absolute growth rate was 0.11 cm3 per year and the relative growth rate 4.3% per year. Factors associated with residual meningioma progression in multivariable Cox regression analysis were skull base location (hazard ratio [HR] 1.60, 95% CI 1.02–2.50) and increasing Ki-67 index (HR 3.43, 95% CI 1.19–9.90). Most meningioma exhibited exponential and logistic growth patterns (median R2 value 0.84, 95% CI 0.60–0.90).

CONCLUSION: Absolute and relative growth rates of residual meningioma are low, but most meet the RANO criteria for progression. Location and Ki-67 index can be used to stratify adjuvant treatment and surveillance paradigms.

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Nomogram for predicting an individual prospective hemorrhage risk in untreated brainstem cavernous malformations

J Neurosurg 138:910–921, 2023

In this study, the authors aimed to create a nomogram for precisely predicting the 5-year prospective hemorrhage risk in brainstem cavernous malformations (BSCMs).

METHODS Patients with confirmed BSCMs in a single-center prospective observational series from January 2012 to December 2016 were included in the present study for nomogram building and validation. The concordance index (C-index), calibration curves, and decision curve analysis were used to evaluate the predictive accuracy, discriminative ability, and clinical usefulness of the nomogram. Then, a nomogram-based risk stratification model for untreated BSCMs was developed.

RESULTS In total, 600 patients were included in the study; 417 patients who had been enrolled before July 2015 were divided into the training and validation cohorts, and 183 subsequently enrolled patients were used as the external validation cohort. By applying a backward stepwise procedure in the multivariable Cox model, variables, including prior hemorrhage (HR 1.69), hemorrhage on admission (HR 3.33), lesion size > 1.5 cm (HR 1.84), lesion depth (HR 2.35), crossing the axial midpoint (HR 1.94), and developmental venous anomaly (HR 2.62), were incorporated to develop a nomogram. The Harrell C-index values for a 5-year prospective hemorrhage were 0.752 (95% CI 0.687–0.816), 0.801 (95% CI 0.665–0.936), and 0.758 (95% CI 0.674–0.842) in the training, internal validation, and external validation cohorts, respectively. The nomogram performed well in terms of consistency between prediction and actual observation according to the calibration curve. The patients could be classified into three distinct (low, medium, and high) risk groups using the final score of this nomogram.

CONCLUSIONS Independent predictors of the 5-year hemorrhage risk in untreated BSCMs were selected to create the first nomogram for predicting individual prospective hemorrhage. The nomogram was able to stratify patients into different risk groups and assist in clinical decision-making.

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