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Alexandra Lauric, Luke Silveira, Emal Lesha, Jeffrey M. Breton, and Adel M. Malek

OBJECTIVE

Vessel tapering results in blood flow acceleration at downstream bifurcations (firehose nozzle effect), induces hemodynamics predisposing to aneurysm initiation, and has been associated with middle cerebral artery (MCA) aneurysm presence and rupture status. The authors sought to determine if vessel caliber tapering is a generalizable predisposing factor by evaluating upstream A1 segment profiles in association with aneurysm presence in the anterior communicating artery (ACoA) complex, the most prevalent cerebral aneurysm location associated with a high rupture risk.

METHODS

Three-dimensional rotational angiographic studies were analyzed for 68 patients with ACoA aneurysms, 37 nonaneurysmal contralaterals, and 53 healthy bilateral controls (211 samples total). A1 segments were determined to be dominant, codominant, or nondominant based on flow and size. Equidistant cross-sectional orthogonal cuts were generated along the A1 centerline, and cross-sectional area (CSA) was evaluated proximally and distally, using intensity-invariant edge detection filtering. The relative tapering of the A1 segment was evaluated as the tapering ratio (distal/proximal CSA). Computational fluid dynamics was simulated on ACoA parametric models with and without tapering.

RESULTS

Aneurysms occurred predominantly on dominant (79%) and codominant (17%) A1 segments. A1 segments leading to unruptured ACoA aneurysms had significantly greater tapering compared to nonaneurysmal contralaterals (0.69 ± 0.13 vs 0.80 ± 0.17, p = 0.001) and healthy controls (0.69 ± 0.13 vs 0.83 ± 0.16, p < 0.001), regardless of dominance labeling. There was no statistically significant difference in tapering values between contralateral A1 and healthy A1 controls (0.80 ± 0.17 vs 0.83 ± 0.16, p = 0.56). Hemodynamically, A1 segment tapering induces high focal pressure, high wall shear stress, and high velocity at the ACoA bifurcation.

CONCLUSIONS

Aneurysmal, but not contralateral or healthy control, A1 segments demonstrated significant progressive vascular tapering, which is associated with aneurysmogenic hemodynamic conditions at the ACoA complex. Demonstration of the upstream tapering effect in the communicating ACoA segment is consistent with its prior detection in the noncommunicating MCA bifurcation, which together form more than 50% of intracranial aneurysms. The mechanistic characterization of this upstream vascular tapering phenomenon is warranted to understand its clinical relevance and devise potential therapeutic strategies.

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Yifei Duan, Berje Shammassian, Shaarada Srivatsa, Kerrin Sunshine, Arunit Chugh, Jonathan Pace, Amanda Opaskar, and Nicholas C. Bambakidis

OBJECTIVE

Endovascular mechanical thrombectomy is safe and effective for the treatment of acute ischemic stroke (AIS) due to large-vessel occlusion (LVO). Still, despite high rates of procedural success, it is routine practice to uniformly admit postthrombectomy patients to an intensive care unit (ICU) for postoperative observation. Predictors of ICU criteria and care requirements in the postmechanical thrombectomy ischemic stroke patient population are lacking. The goal of the present study is to identify risk factors associated with requiring ICU-level intervention following mechanical thrombectomy.

METHODS

The authors retrospectively analyzed data from 245 patients undergoing thrombectomy for AIS from anterior circulation LVO at a comprehensive stroke and tertiary care center from January 2015 to March 2020. Clinical variables that predicted the need for critical care intervention were identified and compared. The performance of a binary classification test constructed from these predictive variables was also evaluated using a validation cohort.

RESULTS

Seventy-six patients (31%) required critical care interventions. A recanalization grade lower than modified Thrombolysis in Cerebral Infarction (mTICI) scale grade 2B (odds ratio [OR] 3.625, p = 0.001), Alberta Stroke Program Early Computed Tomography Score (ASPECTS) < 8 (OR 3.643, p < 0.001), and presence of hyperdensity on postprocedure cone-beam CT (OR 2.485, p = 0.005) were significantly associated with the need for postthrombectomy critical care intervention. When applied to a validation cohort, a clearance classification scheme using these three variables demonstrated high positive predictive value (0.88).

CONCLUSIONS

A recanalization grade lower than mTICI 2B, ASPECTS < 8, and postprocedure hyperdensity on cone-beam CT were shown to be independent predictors of requiring ICU-level care. Routine admission to ICU-level care can be costly and confer increased risk for hospital-acquired conditions. Safely and reliably identifying low-risk patients has the potential for cost savings, value-based care, and decreasing hospital-acquired conditions.

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Nicolò Marchesini, Nicola Tommasi, Franco Faccioli, Giampietro Pinna, and Francesco Sala

OBJECTIVE

Cauda equina ependymoma (CEE) is a rare tumor for which little information is available on the oncological and clinical outcomes of patients. In this study the authors aimed to address functional, oncological, and quality-of-life (QOL) outcomes in a large series of consecutive patients operated on at their institution during the past 20 years.

METHODS

The records of 125 patients who underwent surgery between January 1998 and September 2018 were reviewed. Analyzed variables included demographic, clinical, radiological, surgical, and histopathological features. Neurological outcomes were graded according to the McCormick and Kesselring scales. The QOL at follow-up was evaluated by administering the EQ-5DL questionnaire.

RESULTS

On admission, 84% of patients had a McCormick grade of I and 76.8% had a Kesselring score of 0. At follow-up (clinical 8.13 years; radiological 5.87 years) most scores were unchanged. Sacral level involvement (p = 0.029) and tumor size (p = 0.002) were predictors of poor functional outcome at discharge. Tumor size (p = 0.019) and repeated surgery (p < 0.001) were predictors of poor outcome. A preoperative McCormick grade ≥ III and Kesselring grade ≥ 2 were associated with worse outcomes (p = 0.035 and p = 0.002, respectively). Myxopapillary ependymoma (MPE) was more frequent than grade II ependymoma (EII). The overall rate of gross-total resection (GTR) was 91.2% and rates were significantly higher for patients with EII (98%) than for those with MPE (84%) (p = 0.0074). On multivariate analysis, the only factor associated with GTR was the presence of a capsule (p = 0.011). Seventeen patients (13.7%) had recurrences (13 MPE, 4 EII; 76.4% vs 23.6%; p = 0.032). The extent of resection was the only factor associated with recurrence (p = 0.0023) and number of surgeries (p = 0.006). Differences in progression-free survival (PFS) were seen depending on the extent of resection at first operation (p < 0.001), subarachnoid seeding (p = 0.041), piecemeal resection (p = 0.004), and number of spine levels involved (3 [p = 0.016], 4 [p = 0.011], or ≥ 5 [p = 0.013]). At follow-up a higher proportion of EII than MPE patients were disease free (94.7% vs 77.7%; p = 0.007). The QOL results were inferior in almost all areas compared to a control group of subjects from the Italian general population. A McCormick grade ≥ 3 and repeated surgeries were associated with a worse QOL (p = 0.006 and p = 0.017).

CONCLUSIONS

An early diagnosis of CEE is important because larger tumors are associated with recurrences and worse functional neurological outcomes. Surgery should be performed with the aim of achieving an en bloc GTR. The histological subtype was not directly associated with recurrences, but some of the features more commonly encountered in MPEs were. The outcomes are in most cases favorable, but the mean QOL perception is inferior to that of the general population.

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Heiko Koller, Alexandre Ansorge, Isabel C. Hostettler, Juliane Koller, Wolfgang Hitzl, Axel Hempfing, and Dezsoe Jeszenszky

OBJECTIVE

Three-column osteotomy (3CO) is used for severe spinal deformities. Associated complications include sagittal translation (ST), which can lead to neurological symptoms. Mismatch between the surgical center of rotation (COR) and the concept of the ideal COR is a potential cause of ST. Matching surgical with conceptual COR is difficult with pedicle subtraction osteotomy (PSO) and vertebral column resection (VCR). This mismatch influences correction geometry, which can prevent maximum possible correction. The authors’ objective was to examine the sagittal correction geometry and surgical COR of thoracic and lumbar 3CO.

METHODS

In a retrospective study of patients with PSO or VCR for severe sagittal plane deformity, analysis of surgical COR was performed using pre- and postoperative CT scans in the PSO group and digital radiographs in the VCR group. Radiographic analysis included standard deformity measurements and regional kyphosis angle (RKA). All patients had 2-year follow-up, including neurological outcome. Preoperative CT scans were studied for rigid osteotomy sites versus mobile osteotomy sites. Additional radiographic analysis of surgical COR was based on established techniques superimposing pre- and postoperative images. Position of the COR was defined in a rectangular net layered onto the osteotomy vertebrae (OVs).

RESULTS

The study included 34 patients undergoing PSO and 35 undergoing VCR, with mean ages of 57 and 29 years and mean RKA corrections of 31° and 49°, respectively. In the PSO group, COR was mainly in the anterior column, and surgical and conceptual COR matched in 22 patients (65%). Smaller RKA correction (27° vs 32°, p = 0.09) was seen in patients with anterior eccentric COR. Patients with rigid osteotomy sites were more likely to have an anterior eccentric COR (41% vs 11%, p = 0.05). In the VCR group, 20 patients (57%) had single-level VCR and 15 (43%) had multilevel VCR. COR was mainly located in the anterior or middle column. Mismatch between surgical and conceptual COR occurred in 24 (69%) patients. Larger RKA correction (63° vs 45°, p = 0.03) was seen in patients with anterior column COR. Patients with any posterior COR had a smaller RKA correction compared to the rest of the patients (42° vs 61°, p = 0.007).

CONCLUSIONS

Matching the surgical with the conceptual COR is difficult and in this study failed in one- to two-thirds of all patients. In order to avoid ST during correction of severe deformities, temporary rods, tracking rods, or special instruments should be used for correction maneuvers.

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Joshua S. Catapano, Stefan W. Koester, Visish M. Srinivasan, Mohamed A. Labib, Neil Majmundar, Candice L. Nguyen, Caleb Rutledge, Tyler S. Cole, Jacob F. Baranoski, Andrew F. Ducruet, Felipe C. Albuquerque, Robert F. Spetzler, and Michael T. Lawton

OBJECTIVE

Ophthalmic artery (OA) aneurysms are surgically challenging lesions that are now mostly treated using endovascular procedures. However, in specialized tertiary care centers with experienced neurosurgeons, controversy remains regarding the optimal treatment of these lesions. This study used propensity adjustment to compare microsurgical and endovascular treatment of unruptured OA aneurysms in experienced tertiary and quaternary settings.

METHODS

The authors retrospectively reviewed the medical records of all patients who underwent microsurgical treatment of an unruptured OA aneurysm at the University of California, San Francisco, from 1997 to 2017 and either microsurgical or endovascular treatment at Barrow Neurological Institute from 2011 to 2019. Patients were categorized into two cohorts for comparison: those who underwent open microsurgical clipping, and those who underwent endovascular flow diversion or coil embolization. Outcomes included neurological or visual outcomes, residual or recurrent aneurysms, retreatment, and severe complications.

RESULTS

A total of 345 procedures were analyzed: 247 open microsurgical clipping procedures (72%) and 98 endovascular procedures (28%). Of the 98 endovascular procedures, 16 (16%) were treated with primary coil embolization and 82 (84%) with flow diversion. After propensity adjustment, microsurgical treatment was associated with higher odds of a visual deficit (OR 8.5, 95% CI 1.1–64.9, p = 0.04) but lower odds of residual aneurysm (OR 0.06, 95% CI 0.01–0.28, p < 0.001) or retreatment (OR 0.12, 95% CI 0.02–0.58, p = 0.008) than endovascular therapy. No difference was found between the two cohorts with regard to worse modified Rankin Scale score, modified Rankin Scale score greater than 2, or severe complications.

CONCLUSIONS

Compared with endovascular therapy, microsurgical clipping of unruptured OA aneurysms is associated with a higher rate of visual deficits but a lower rate of residual and recurrent aneurysms. In centers experienced with both open microsurgical and endovascular treatment of these lesions, the treatment choice should be based on patient preference and aneurysm morphology.

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Robert J. Macielak, Katherine P. Wallerius, Skye K. Lawlor, Christine M. Lohse, John P. Marinelli, Brian A. Neff, Jamie J. Van Gompel, Colin L. W. Driscoll, Michael J. Link, and Matthew L. Carlson

OBJECTIVE

Detection of vestibular schwannoma (VS) growth during observation leads to definitive treatment at most centers globally. Although ≥ 2 mm represents an established benchmark of tumor growth on serial MRI studies, 2 mm of linear tumor growth is unlikely to significantly alter microsurgical outcomes. The objective of the current work was to ascertain where the magnitude of change in clinical outcome is the greatest based on size.

METHODS

A single-institution retrospective review of a consecutive series of patients with sporadic VS who underwent microsurgical resection between January 2000 and May 2020 was performed. Preoperative tumor size cutpoints were defined in 1-mm increments and used to identify optimal size thresholds for three primary outcomes: 1) the ability to achieve gross-total resection (GTR); 2) maintenance of normal House-Brackmann (HB) grade I facial nerve function; and 3) preservation of serviceable hearing (American Academy of Otolaryngology–Head and Neck Surgery class A/B). Optimal size thresholds were obtained by maximizing c-indices from logistic regression models.

RESULTS

Of 603 patients meeting inclusion criteria, 502 (83%) had tumors with cerebellopontine angle (CPA) extension. CPA tumor size was significantly associated with achieving GTR, postoperative HB grade I facial nerve function, and maintenance of serviceable hearing (all p < 0.001). The optimal tumor size threshold to distinguish between GTR and less than GTR was 17 mm of CPA extension (c-index 0.73). In the immediate postoperative period, the size threshold between HB grade I and HB grade > I was 17 mm of CPA extension (c-index 0.65). At the most recent evaluation, the size threshold between HB grade I and HB grade > I was 23 mm (c-index 0.68) and between class A/B and C/D hearing was 18 mm (c-index 0.68). Tumors within 3 mm of the 17-mm CPA threshold displayed similarly strong c-indices. Among purely intracanalicular tumors, linear size was not found to portend worse outcomes for all measures.

CONCLUSIONS

The probability of incurring less optimal microsurgical outcomes begins to significantly increase at 14–20 mm of CPA extension. Although many factors ultimately influence decision-making, when considering timing of microsurgical resection, using a size threshold range as depicted in this study offers an evidence-based approach that moves beyond reflexively recommending treatment for all tumors after detecting ≥ 2 mm of tumor growth on serial MRI studies.

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Mengchun Sun, Benzhang Tao, Gan Gao, Hui Wang, and Aijia Shang

OBJECTIVE

This study aimed to explore the migration process of the conus medullaris (CM) in early infancy using infant MRI and to evaluate the application of MRI for locating the infant CM level.

METHODS

The authors retrospectively analyzed the CM level on the lumbosacral MR images of 26 term infants aged < 3 months who were classified into three groups according to age. The authors numbered the CM level in each patient and analyzed the range and average of the CM level of the cohort. The authors studied the linear correlation between CM level and postnatal days with linear regression analysis, 1-way ANOVA, and the least significant difference test.

RESULTS

The CM level ranged from the superior border of the L1 vertebra to the top third of the L3 vertebra. About 96.2% of infants had CM higher than the superior border of the L3 vertebra. On average, CM was located between the L1–2 intervertebral disc and the inferior border of the L2 vertebra (mean ± SD score 1.64 ± 1.14). The three groups had no significant statistical difference in CM level (F = 1.071 and p = 0.359; groups 1 and 2, p = 0.408; groups 1 and 3, p = 0.170; groups 2 and 3, p = 0.755). CM level had no linear regression correlation with postnatal days within the first month (r = 0.061, F = 0.654, p = 0.438) or within the first 3 months (r = 0.002, F = 0.056, p = 0.816).

CONCLUSIONS

The CM level reaches the normal adult level by birth in term infants and does not ascend during childhood. On average, the CM was between the L1–2 intervertebral disc and the inferior border of the L2 vertebra in term infants. Considering the possibility of physiologically low-lying CM, the authors agree that normal CM is located above the L3 level in term infants and CM at the L3 level could be equivocal and should be investigated with other clinical data. The study data suggest that MRI is an accurate and valuable method for determining the CM level in term infants.

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Mounica Paturu, Regina L. Triplett, Siddhant Thukral, Dimitrios Alexopoulos, Christopher D. Smyser, David D. Limbrick Jr., and Jennifer M. Strahle

OBJECTIVE

Posthemorrhagic hydrocephalus (PHH) is associated with significant morbidity, smaller hippocampal volumes, and impaired neurodevelopment in preterm infants. The timing of temporary CSF (tCSF) diversion has been studied; however, the optimal time for permanent CSF (pCSF) diversion is unknown. The objective of this study was to determine whether cumulative ventricle size or timing of pCSF diversion is associated with neurodevelopmental outcome and hippocampal size in preterm infants with PHH.

METHODS

Twenty-five very preterm neonates (born at ≤ 32 weeks’ gestational age) with high-grade intraventricular hemorrhage (IVH), subsequent PHH, and pCSF diversion with a ventriculoperitoneal shunt (n = 20) or endoscopic third ventriculostomy (n = 5) were followed until 2 years of age. Infants underwent serial cranial ultrasounds from birth until 1 year after pCSF diversion, brain MRI at term-equivalent age, and assessment based on the Bayley Scales of Infant and Toddler Development, Third Edition, at 2 years of age. Frontooccipital horn ratio (FOHR) measurements were derived from cranial ultrasounds and term-equivalent brain MRI. Hippocampal volumes were segmented and calculated from term-equivalent brain MRI. Cumulative ventricle size until the time of pCSF diversion was estimated using FOHR measurements from each cranial ultrasound performed prior to permanent intervention.

RESULTS

The average gestational ages at tCSF and pCSF diversion were 28.9 and 39.0 weeks, respectively. An earlier chronological age at the time of pCSF diversion was associated with larger right hippocampal volumes on term-equivalent MRI (Pearson’s r = −0.403, p = 0.046) and improved cognitive (r = −0.554, p = 0.047), motor (r = −0.487, p = 0.048), and language (r = −0.414, p = 0.021) outcomes at 2 years of age. Additionally, a smaller cumulative ventricle size from birth to pCSF diversion was associated with larger right hippocampal volumes (r = −0.483, p = 0.014) and improved cognitive (r = −0.711, p = 0.001), motor (r = −0.675, p = 0.003), and language (r = −0.618, p = 0.011) outcomes. There was no relationship between time to tCSF diversion or cumulative ventricle size prior to tCSF diversion and neurodevelopmental outcome or hippocampal size. Finally, a smaller cumulative ventricular size prior to either tCSF diversion or pCSF diversion was associated with a smaller ventricular size 1 year after pCSF diversion (r = 0.422, p = 0.040, R2 = 0.178 and r = 0.519, p = 0.009, R2 = 0.269, respectively).

CONCLUSIONS

In infants with PHH, a smaller cumulative ventricular size and shorter time to pCSF diversion were associated with larger right hippocampal volumes, improved neurocognitive outcomes, and reduced long-term ventriculomegaly. Future prospective randomized studies are needed to confirm these findings.

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Andrew P. Carlson and C. William Shuttleworth