Publications by authors named "Simon G Ammanuel"

12 Publications

  • Page 1 of 1

Factors associated with seizures at initial presentation in pediatric patients with cerebral arteriovenous malformations.

J Neurosurg Pediatr 2021 Sep 24:1-6. Epub 2021 Sep 24.

1Department of Neurological Surgery, University of California San Francisco, San Francisco.

Objective: Children with cerebral arteriovenous malformations (AVMs) can present with seizures, potentially increasing morbidity and impacting clinical management. However, the factors that lead to seizures as a presenting sign are not well defined. While AVM-related seizures have been described in case series, most studies have focused on adults and have included patients who developed seizures after an AVM rupture. To address this, the authors sought to analyze demographic and morphological characteristics of AVMs in a large cohort of children.

Methods: The demographic, clinical, and AVM morphological characteristics of 189 pediatric patients from a single-center database were studied. Univariate and multivariate logistic regression models were used to test the effect of these characteristics on seizures as an initial presenting symptom in patients with unruptured brain AVMs.

Results: Overall, 28 of 189 patients initially presented with seizures (14.8%). By univariate comparison, frontal lobe location (p = 0.02), larger AVM size (p = 0.003), older patient age (p = 0.04), and the Supplemented Spetzler-Martin (Supp-SM) grade (0.0006) were associated with seizure presentation. Multivariate analysis confirmed an independent effect of frontal lobe AVM location and higher Supp-SM grade. All patients presenting with seizures had AVMs in the cortex or subcortical white matter.

Conclusions: While children and adults share some risk factors for seizure presentation, their risk factor profiles do not entirely overlap. Pediatric patients with cortical AVMs in the frontal lobe were more likely to present with seizures. Additionally, the Supp-SM grade was highly associated with seizure presentation. Future clinical research should focus on the effect of therapeutic interventions targeting AVMs on seizure control in these patients.
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http://dx.doi.org/10.3171/2021.6.PEDS21126DOI Listing
September 2021

Correlation of natural language assessment results with health-related quality of life in adult glioma patients.

J Neurosurg 2021 Jul 30:1-7. Epub 2021 Jul 30.

1Department of Neurological Surgery and.

Objective: Impairments of speech are common in patients with glioma and negatively impact health-related quality of life (HRQoL). The benchmark for clinical assessments is task-based measures, which are not always feasible to administer and may miss essential components of HRQoL. In this study, the authors tested the hypothesis that variations in natural language (NL) correlate with HRQoL in a pattern distinct from task-based measures of language performance.

Methods: NL use was assessed using audio samples collected unobtrusively from 18 patients with newly diagnosed low- and high-grade glioma. NL measures were calculated using manual segmentation and correlated with Quality of Life in Neurological Disorders (Neuro-QoL) outcomes. Spearman's rank-order correlation was used to determine relationships between Neuro-QoL scores and NL measures.

Results: The distribution of NL measures across the entire patient cohort included a mean ± SD total time speaking of 11.5 ± 2.20 seconds, total number of words of 27.2 ± 4.44, number of function words of 10.9 ± 1.68, number of content words of 16.3 ± 2.91, and speech rate of 2.61 ± 0.20 words/second. Speech rate was negatively correlated with functional domains (rho = -0.62 and p = 0.007 for satisfaction with social roles; rho = -0.74 and p < 0.001 for participation in social roles) but positively correlated with impairment domains (rho = 0.58 and p = 0.009 for fatigue) of Neuro-QoL.

Conclusions: Assessment of NL at the time of diagnosis may be a useful measure in the context of treatment planning and monitoring outcomes for adult patients with glioma.
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http://dx.doi.org/10.3171/2021.1.JNS203387DOI Listing
July 2021

COVID-19 Radiology Preparedness, Challenges & Opportunities: Responses From 18 Countries.

Curr Probl Diagn Radiol 2021 Apr 24. Epub 2021 Apr 24.

Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA.

Purpose: Radiology departments around the world have been faced with the challenge to adapt, and recover to the COVID-19 pandemic. This study is part of a worldwide survey of radiologists' responses to COVID-19 in 18 different countries in Africa, Asia, Europe, and Latin America. The purpose of this study is to analyze the changes made in international radiology departments and practices in response to the pandemic.

Methods: The 18-item survey was sent via email from April to May 2020 to radiologists in Africa, Asia, Europe, and Latin America to assess their response to COVID-19. Our survey included questions regarding imaging, workforce adjustments, testing availability, staff and patient safety, research and education, and infrastructure availability.

Results: Twenty-eight survey responses were reviewed. Of the 28 respondents, 42.9% have shortages of infrastructure and 78.6% responded that COVID-19 testing was available. Regarding the use of Chest CT in COVID-19 patients, 28.6% respondents used Chest CT as screening for COVID-19. For staff safety, interventions included encouraging use of masks in patient encounters, social distancing and PPE training. To cope with their education and research mission, radiology departments are doing online lectures, reducing the number of residents in rotations, and postponing any non-urgent activities.

Conclusion: In conclusion, there are disparities in infrastructure, research, and educational initiatives during COVID-19 which also provides opportunity for the global radiology community to work together on these issues.
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http://dx.doi.org/10.1067/j.cpradiol.2021.03.017DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8064895PMC
April 2021

Are preoperative chlorhexidine gluconate showers associated with a reduction in surgical site infection following craniotomy? A retrospective cohort analysis of 3126 surgical procedures.

J Neurosurg 2021 Apr 30:1-9. Epub 2021 Apr 30.

Departments of1Neurological Surgery.

Objective: Surgical site infection (SSI) is a complication linked to increased costs and length of hospital stay. Prevention of SSI is important to reduce its burden on individual patients and the healthcare system. The authors aimed to assess the efficacy of preoperative chlorhexidine gluconate (CHG) showers on SSI rates following cranial surgery.

Methods: In November 2013, a preoperative CHG shower protocol was implemented at the authors' institution. A total of 3126 surgical procedures were analyzed, encompassing a time frame from April 2012 to April 2016. Cohorts before and after implementation of the CHG shower protocol were evaluated for differences in SSI rates.

Results: The overall SSI rate was 0.6%. No significant differences (p = 0.11) were observed between the rate of SSI of the 892 patients in the preimplementation cohort (0.2%) and that of the 2234 patients in the postimplementation cohort (0.8%). Following multivariable analysis, implementation of preoperative CHG showers was not associated with decreased SSI (adjusted OR 2.96, 95% CI 0.67-13.1; p = 0.15).

Conclusions: This is the largest study, according to sample size, to examine the association between CHG showers and SSI following craniotomy. CHG showers did not significantly alter the risk of SSI after a cranial procedure.
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http://dx.doi.org/10.3171/2020.10.JNS201255DOI Listing
April 2021

Accuracy of omni-planar and surface casting of epileptiform activity for intracranial seizure localization.

Epilepsia 2021 04 26;62(4):947-959. Epub 2021 Feb 26.

Department of Neurology and Weill Institute for Neurosciences, University of California, San Francisco, California, USA.

Objective: Intracranial electroencephalography (ICEEG) recordings are performed for seizure localization in medically refractory epilepsy. Signal quantifications such as frequency power can be projected as heatmaps on personalized three-dimensional (3D) reconstructed cortical surfaces to distill these complex recordings into intuitive cinematic visualizations. However, simultaneously reconciling deep recording locations and reliably tracking evolving ictal patterns remain significant challenges.

Methods: We fused oblique magnetic resonance imaging (MRI) slices along depth probe trajectories with cortical surface reconstructions and projected dynamic heatmaps using a simple mathematical metric of epileptiform activity (line-length). This omni-planar and surface casting of epileptiform activity approach (OPSCEA) thus illustrated seizure onset and spread among both deep and superficial locations simultaneously with minimal need for signal processing supervision. We utilized the approach on 41 patients at our center implanted with grid, strip, and/or depth electrodes for localizing medically refractory seizures. Peri-ictal data were converted into OPSCEA videos with multiple 3D brain views illustrating all electrode locations. Five people of varying expertise in epilepsy (medical student through epilepsy attending level) attempted to localize the seizure-onset zones.

Results: We retrospectively compared this approach with the original ICEEG study reports for validation. Accuracy ranged from 73.2% to 97.6% for complete or overlapping onset lobe(s), respectively, and ~56.1% to 95.1% for the specific focus (or foci). Higher answer certainty for a given case predicted better accuracy, and scorers had similar accuracy across different training levels.

Significance: In an era of increasing stereo-EEG use, cinematic visualizations fusing omni-planar and surface functional projections appear to provide a useful adjunct for interpreting complex intracranial recordings and subsequent surgery planning.
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http://dx.doi.org/10.1111/epi.16841DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8276628PMC
April 2021

Assessing the Readability of Online Patient Education Resources Related to Gynecomastia.

Ann Plast Surg 2021 08;87(2):123-125

Division of Plastic and Reconstructive Surgery, Department of Surgery, University of California, San Francisco, San Francisco, CA.

Background: The Internet has a plethora of online patient education resources for many symptoms and diseases. National medical governing bodies recommend that patient education materials are written at or below the eighth-grade level, and the literature suggests that health literacy has been linked to increased adherence to treatment regimens and improved outcomes. The primary aim of the study is to assess the readability of online patient materials relating to gynecomastia and ascertain the availability of patient materials in non-English languages.

Methods: The readability of patient education materials relating to gynecomastia for academic-based websites and nonacademic websites was assessed using the Flesch Reading Ease (FRE), Flesch-Kincaid Grade Level (FKGL), and Simple Measure of Gobbledygook (SMOG). The prevalence of non-English patient education materials was assessed for both academic-based and nonacademic websites.

Results: Fifty-eight documents were collected across academic websites. Overall median values were 10.7 for the FKGL, 47.0 for the FRE, and 11.4 for the SMOG. For the 10 nonacademic institutions, the overall median values were 10.6 for the FKGL, 45.2 for the FRE, and 10.8 for the SMOG. No appreciable differences were observed for readability when stratified by region or source. The prevalence of non-English patient materials was 19.1% across institutions. None of the noninstitutional materials had information in non-English languages.

Conclusions: The readability of patient education materials related to gynecomastia is at higher levels than recommended by national organizations. There are limited non-English patient education materials. Future efforts should focus on improving the readability and accessibility of patient materials.
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http://dx.doi.org/10.1097/SAP.0000000000002620DOI Listing
August 2021

Bringing high-grade arteriovenous malformations under control: clinical outcomes following multimodality treatment in children.

J Neurosurg Pediatr 2020 Apr 10:1-10. Epub 2020 Apr 10.

Departments of1Neurological Surgery.

Objective: Brain arteriovenous malformations (AVMs) consist of dysplastic blood vessels with direct arteriovenous shunts that can hemorrhage spontaneously. In children, a higher lifetime hemorrhage risk must be balanced with treatment-related morbidity. The authors describe a collaborative, multimodal strategy resulting in effective and safe treatment of pediatric AVMs.

Methods: A retrospective analysis of a prospectively maintained database was performed in children with treated and nontreated pediatric AVMs at the University of California, San Francisco, from 1998 to 2017. Inclusion criteria were age ≤ 18 years at time of diagnosis and an AVM confirmed by a catheter angiogram.

Results: The authors evaluated 189 pediatric patients with AVMs over the study period, including 119 ruptured (63%) and 70 unruptured (37%) AVMs. The mean age at diagnosis was 11.6 ± 4.3 years. With respect to Spetzler-Martin (SM) grade, there were 38 (20.1%) grade I, 40 (21.2%) grade II, 62 (32.8%) grade III, 40 (21.2%) grade IV, and 9 (4.8%) grade V lesions. Six patients were managed conservatively, and 183 patients underwent treatment, including 120 resections, 82 stereotactic radiosurgery (SRS), and 37 endovascular embolizations. Forty-four of 49 (89.8%) high-grade AVMs (SM grade IV or V) were treated. Multiple treatment modalities were used in 29.5% of low-grade and 27.3% of high-grade AVMs. Complete angiographic obliteration was obtained in 73.4% of low-grade lesions (SM grade I-III) and in 45.2% of high-grade lesions. A periprocedural stroke occurred in a single patient (0.5%), and there was 1 treatment-related death. The mean clinical follow-up for the cohort was 4.1 ± 4.6 years, and 96.6% and 84.3% of patients neurologically improved or remained unchanged in the ruptured and unruptured AVM groups following treatment, respectively. There were 16 bleeding events following initiation of AVM treatment (annual rate: 0.02 events per person-year).

Conclusions: Coordinated multidisciplinary evaluation and individualized planning can result in safe and effective treatment of children with AVMs. In particular, it is possible to treat the majority of high-grade AVMs with an acceptable safety profile. Judicious use of multimodality therapy should be limited to appropriately selected patients after thorough team-based discussions to avoid additive morbidity. Future multicenter studies are required to better design predictive models to aid with patient selection for multimodal pediatric care, especially with high-grade AVMs.
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http://dx.doi.org/10.3171/2020.1.PEDS19487DOI Listing
April 2020

Interictal Epileptiform Discharges and the Quality of Human Intracranial Neurophysiology Data.

Front Hum Neurosci 2020 3;14:44. Epub 2020 Mar 3.

Department of Neurological Surgery, University of California, San Francisco, San Francisco, CA, United States.

Intracranial electroencephalography (IEEG) involves recording from electrodes placed directly onto the cortical surface or deep brain locations. It is performed on patients with medically refractory epilepsy, undergoing pre-surgical seizure localization. IEEG recordings, combined with advancements in computational capacity and analysis tools, have accelerated cognitive neuroscience. This Perspective describes a potential pitfall latent in many of these recordings by virtue of the subject population-namely interictal epileptiform discharges (IEDs), which can cause spurious results due to the contamination of normal neurophysiological signals by pathological waveforms related to epilepsy. We first discuss the nature of IED hazards, and why they deserve the attention of neurophysiology researchers. We then describe four general strategies used when handling IEDs (manual identification, automated identification, manual-automated hybrids, and ignoring by leaving them in the data), and discuss their pros, cons, and contextual factors. Finally, we describe current practices of human neurophysiology researchers worldwide based on a cross-sectional literature review and a voluntary survey. We put these results in the context of the listed strategies and make suggestions on improving awareness and clarity of reporting to enrich both data quality and communication in the field.
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http://dx.doi.org/10.3389/fnhum.2020.00044DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7062638PMC
March 2020

Perioperative Anesthesia Lean Implementation Is Associated With Increased Operative Efficiency in Posterior Cervical Surgeries at a HighVolume Spine Center.

Neurospine 2020 Jun 5;17(2):390-397. Epub 2020 Feb 5.

Department of Neurosurgery, University of California San Francisco, San Francisco, CA, USA.

Objective: Lean management strategies aim to increase efficiency by eliminating waste or by improving processes to optimize value. The operating room (OR) is an arena where these strategies can be implemented. We assessed changes in OR efficiency after the application of lean methodology on perioperative anesthesia associated with posterior cervical spine surgeries.

Methods: We utilized pre- and post-lean study design to identify inefficiencies during the perioperative anesthesia process and implemented strategies to improve the process. Patient characteristics were recorded to assess for differences between the 2 groups (group 1, prelean; group 2, post-lean). In the pre-lean period, key steps in the perioperative anesthesia process were identified that were amenable to lean implementation. The time required for each identified key step was recorded by an independent study coordinator. The times for each step were then compared between the groups utilizing univariate analyses.

Results: After lean implementation, there was a significant decrease in overall perioperative anesthesia process time (88.4 ± 4.7 minutes vs. 76.2 ± 3.2 minutes, p = 0.04). This was driven by significant decreases in the steps: transport and setup (10.4 ± 0.8 minutes vs. 8.0 ± 0.7 minutes, p = 0.03) and positioning (20.8 ± 2.1 minutes vs. 15.7 ± 1.3 minutes, p = 0.046). Of note, the total time spent in the OR was lower for group 2 (270.1 ± 14.6 minutes vs. 252.8 ± 14.1 minutes) but the result was not statistically significant, even when adjusting for number of operated levels.

Conclusion: Lean methodology may be successfully applied to posterior cervical spine surgery whereby improvements in the perioperative anesthetic process are associated with significantly increased OR efficiency.
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http://dx.doi.org/10.14245/ns.1938318.159DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7338954PMC
June 2020

A New Era of Extended Time Window Acute Stroke Interventions Guided by Imaging.

Neurohospitalist 2020 Jan 19;10(1):29-37. Epub 2019 Aug 19.

Department of Radiology and Biomedical Imaging, University of California San Francisco, CA, USA.

Ischemic stroke is one of the most debilitating and deadliest conditions worldwide. Intravenous t-PA is the current standard treatment within 4 hours after onset of symptoms. Recent randomized controlled trials have demonstrated the efficacy of neurointerventional intra-arterial treatment in acute ischemic stroke. About 20% of acute ischemic stroke are classified as wake-up strokes, which falls out of the conventional treatment time window. New evidence suggests that some patients with longer time from symptom onset (up to 24 hours) may benefit from thrombectomy, probably in part due to variations in collateral circulation among individual patients. Advanced imaging can play a crucial role in identifying patients who could benefit from endovascular intervention presenting within extended treatment time windows. In this article, we review the advanced imaging algorithm for ischemic stroke workup in the multiple studies published to date and summarize the results of the clinical trials for late ischemic stroke that can be clinically useful.
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http://dx.doi.org/10.1177/1941874419870701DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6900647PMC
January 2020

Readability of Online Neuro-Oncology-Related Patient Education Materials from Tertiary-Care Academic Centers.

World Neurosurg 2020 Feb 27;134:e1108-e1114. Epub 2019 Nov 27.

Department of Neurological Surgery, University of California, San Francisco, California, USA. Electronic address:

Background: The Internet has become a popular resource for patients to research diagnosed or suspected medical diseases. Medical institutions provide comprehensive online education resources about various conditions to the general public. The U.S. National Institutes of Health and American Medical Association recommend that patient education materials aimed at the general population should be written at or below eighth-grade reading level. The goal of this study is to assess the readability of patient education materials for central nervous system tumors across tertiary-care institutions.

Methods: Patient education materials were collected from National Cancer Institute designated cancer centers in October 2019. Materials were analyzed by Flesch-Kincaid Grade Level (FKGL) and Flesch Reading Ease (FRE) score using Microsoft Office Word software. Subgroups were formed based on regions in the United States (Northeast, Southeast, Midwest, Southwest, and West) as well as diagnostic and treatment information.

Results: A total of 180 documents were collected across 50 institutions. Overall median FKGL was 12.5, and median FRE was 38.2. Median FKGL for diagnostic information was 11.6 and FRE was 43.0, whereas median FKGL for treatment information was 12.9 and median FRE was 34.3. No statistically significant differences were seen for both FKGL and FRE among geographic regions (P > 0.05).

Conclusions: Online neuro-oncology patient education materials from tertiary institutions are written above recommended reading levels. Future efforts should be taken to improve the readability of brain tumor-specific patient education materials, particularly with information relating to treatment.
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http://dx.doi.org/10.1016/j.wneu.2019.11.109DOI Listing
February 2020

Chlorhexidine Showers are Associated With a Reduction in Surgical Site Infection Following Spine Surgery: An Analysis of 4266 Consecutive Surgeries.

Neurosurgery 2019 12;85(6):817-826

Department of Neurosurgery, University of California, San Francisco, San Francisco, California.

Background: Surgical site infection (SSI) is a common complication following spinal surgery. Prevention is critical to maintaining safe patient care and reducing additional costs associated with treatment.

Objective: To determine the efficacy of preoperative chlorhexidine (CHG) showers on SSI rates following fusion and nonfusion spine surgery.

Methods: A mandatory preoperative CHG shower protocol was implemented at our institution in November 2013. A cohort comparison of 4266 consecutive patients assessed differences in SSI rates for the pre- and postimplementation periods. Subgroup analysis was performed on the type of spinal surgery (eg, fusion vs nonfusion). Data represent all spine surgeries performed between April 2012 and April 2016.

Results: The overall mean SSI rate was 0.4%. There was no significant difference between the pre- (0.7%) and postimplementation periods (0.2%; P = .08). Subgroup analysis stratified by procedure type showed that the SSI rate for the nonfusion patients was significantly lower in the post- (0.1%) than the preimplementation group (0.7%; P = .02). There was no significant difference between SSI rates for the pre- (0.8%) and postimplementation groups (0.3%) for the fusion cohort (P = .21). In multivariate analysis, the implementation of preoperative CHG showers were associated with significantly decreased odds of SSI (odds ratio = 0.15, 95% confidence interval [0.03-0.55], P < .01).

Conclusion: This is the largest study investigating the efficacy of preoperative CHG showers on SSI following spinal surgery. In adjusted multivariate analysis, CHG showering was associated with a significant decrease in SSI following spinal surgery.
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http://dx.doi.org/10.1093/neuros/nyy568DOI Listing
December 2019
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