Aerosol Generation During High Intensity Exercise-Implications for COVID-19 Transmission.

BACKGROUND AND AIM: COVID-19 can be transmitted through aerosolised respiratory particles. The degree to which exercise enhances aerosol production has not been previously assessed. We aimed to quantify the size and concentration of aerosol particles and evaluate the impact of physical distance and surgical mask wearing during high intensity exercise (HIE). METHODS: Using a prospective observational crossover study, three healthy volunteers performed high intensity cardiopulmonary exercise testing at 80% of peak capacity in repeated 5-minute bouts on a cycle ergometer. Aerosol size and concentration was measured at 35, 150 and 300 cm from the participants in an anterior and lateral direction, with and without a surgical face mask, using an Aerodynamic Particle Sizer (APS) and a Mini Wide Range Aerosol Spectrometer (MiniWRAS), with over 10,000 sample points. RESULTS: High intensity exercise generates aerosol in the 0.2-1 micrometre range. Increasing distance from the rider reduces aerosol concentrations measured by both MiniWRAS (p=0.003 for interaction) and APS (p=0.041). However, aerosol concentrations remained significantly increased above baseline measures at 300 cm from the rider. A surgical face mask reduced submicron aerosol concentrations measured anteriorly to the rider (p=0.031 for interaction) but not when measured laterally (p=0.64 for interaction). CONCLUSIONS: High intensity exercise is an aerosol generating activity. Significant concentrations of aerosol particles are measurable well beyond the commonly recommended 150 cm of physical distancing. A surgical face mask reduces aerosol concentration anteriorly but not laterally to an exercising individual. Measures for safer exercise should emphasise distance and airflow and not rely solely on mask wearing.

Aerosolisation in endonasal endoscopic pituitary surgery.

PURPOSE: To determine the particle size, concentration, airborne duration and spread during endoscopic endonasal pituitary surgery in actual patients in a theatre setting. METHODS: This observational study recruited a convenience sample of three patients. Procedures were performed in a positive pressure operating room. Particle image velocimetry and spectrometry with air sampling were used for aerosol detection. RESULTS: Intubation and extubation generated small particles (< 5 µm) in mean concentrations 12 times greater than background noise (p < 0.001). The mean particle concentrations during endonasal access were 4.5 times greater than background (p = 0.01). Particles were typically large (> 75 µm), remained airborne for up to 10 s and travelled up to 1.1 m. Use of a microdebrider generated mean aerosol concentrations 18 times above baseline (p = 0.005). High-speed drilling did not produce aerosols greater than baseline. Pituitary tumour resection generated mean aerosol concentrations less than background (p = 0.18). Surgical drape removal generated small and large particles in mean concentrations 6.4 times greater than background (p < 0.001). CONCLUSION: Intubation and extubation generate large amounts of small particles that remain suspended in air for long durations and disperse through theatre. Endonasal access and pituitary tumour resection generate smaller concentrations of larger particles which are airborne for shorter periods and travel shorter distances.

A New Framework for Investigating the Biological Basis of Degenerative Cervical Myelopathy [AO Spine RECODE-DCM Research Priority Number 5]: Mechanical Stress, Vulnerability and Time.

STUDY DESIGN: Literature Review (Narrative). OBJECTIVE: To propose a new framework, to support the investigation and understanding of the pathobiology of DCM, AO Spine RECODE-DCM research priority number 5. METHODS: Degenerative cervical myelopathy is a common and disabling spinal cord disorder. In this perspective, we review key knowledge gaps between the clinical phenotype and our biological models. We then propose a reappraisal of the key driving forces behind DCM and an individual's susceptibility, including the proposal of a new framework. RESULTS: Present pathobiological and mechanistic knowledge does not adequately explain the disease phenotype; why only a subset of patients with visualized cord compression show clinical myelopathy, and the amount of cord compression only weakly correlates with disability. We propose that DCM is better represented as a function of several interacting mechanical forces, such as shear, tension and compression, alongside an individual's vulnerability to spinal cord injury, influenced by factors such as age, genetics, their cardiovascular, gastrointestinal and nervous system status, and time. CONCLUSION: Understanding the disease pathobiology is a fundamental research priority. We believe a framework of mechanical stress, vulnerability, and time may better represent the disease as a whole. Whilst this remains theoretical, we hope that at the very least it will inspire new avenues of research that better encapsulate the full spectrum of disease.

Quality of Literature Searches Published in Leading Neurosurgical Journals: A Review of Reviews.

BACKGROUND: There is mounting evidence that the search strategies upon which systematic reviews (SRs) are based frequently contain errors are incompletely reported or insensitive. OBJECTIVE: To appraise the quality of search strategies in the 10 leading specialty neurosurgical journals and identify factors associated with superior searches. METHODS: This research-on-research study systematically surveyed SRs published in the 10 leading neurosurgical journals between 01/10/2017 and 31/10/2019. All SRs were eligible for assessment using a predefined coding manual that was adapted from the preferred reporting items for systematic reviews and meta-analyses (PRISMA), a measurement tool to assess systematic reviews (AMSTAR), and Cochrane Collaboration guidelines. The PubMed interface was used to search the MEDLINE database, which was supplemented by individual journal searches. Descriptive statistics were utilized to identify factors associated with improved search strategies. RESULTS: A total of 633 articles were included and contained a median of 19.00 (2.00-1654.00) studies. Less than half (45.97%) of included search strategies were considered to be reproducible. Aggregated reporting score was positively associated with in-text reference to reporting guideline adherence (τb = 0.156, P < .01). The number of articles retrieved by a search (τb = 0.11, P < .01) was also associated with the reporting of a reproducible search strategy. CONCLUSION: This study demonstrates that the search strategies used in neurosurgical SRs require improvement. In addition to increasing awareness of reporting standards, we propose that this be achieved by the incorporation of PRISMA and other guidelines into article submission and peer-review processes. This may lead to the conduct of more informative SRs, which may result in improved clinician decision-making and patient outcomes.

The Relative Merits of Posterior Surgical Treatments for Multi-Level Degenerative Cervical Myelopathy Remain Uncertain: Findings from a Systematic Review.

OBJECTIVES: To assess the reporting of study design and characteristics in multi-level degenerative cervical myelopathy (DCM) treated by posterior surgical approaches, and perform a comparison of clinical and radiographic outcomes between different approaches. METHODS: A literature search was performed in Embase and MEDLINE between 1995-2019 using a sensitive search string combination. Studies were selected by predefined selection criteria: Full text articles in English, with >10 patients (prospective) or >50 patients (retrospective), reporting outcomes of multi-level DCM treated by posterior surgical approach. RESULTS: A total of 75 studies involving 19,510 patients, conducted worldwide, were identified. Laminoplasty was described in 56 studies (75%), followed by laminectomy with (36%) and without fusion (16%). The majority of studies were conducted in Asia (84%), in the period of 2016-2019 (51%), of which laminoplasty was studied predominantly. Twelve (16%) prospective studies and 63 (84%) retrospective studies were identified. The vast majority of studies were conducted in a single centre (95%) with clear inclusion/exclusion criteria and explicit cause of DCM. Eleven studies (15%) included patients with ossification of the posterior longitudinal ligament exclusively with cohorts of 57 to 252. The clinical and radiographic outcomes were reported with heterogeneity when comparing laminoplasty, laminectomy with and without fusion. CONCLUSIONS: Heterogeneity in the reporting of study and sample characteristics exists, as well as in clinical and radiographic outcomes, with a paucity of studies with a higher level of evidence. Future studies are needed to elucidate the clinical effectiveness of posterior surgical treatments.

Endoscopic Fenestration of a Symptomatic Porencephalic Cyst in an Adult.

A porencephalic cyst is an aberrant accumulation of cerebrospinal fluid within the brain parenchyma. Its occurrence is rare, with an incidence of 3.5 per 100,000 live births. Etiology is considered the result of perinatal cerebral ischemia or hemorrhage, leading to parenchymal loss. Porencephalic cysts are diagnosed radiologically, and management depends on the clinical manifestation. Our case depicts a porencephalic cyst presenting with nondominant parietal lobe symptoms in adulthood. We hypothesize that a membrane between the cyst and ventricle allowed formation of a 1-way valve that led to slowly progressive cyst enlargement, eventually causing mass effect and nondominant parietal lobe symptoms. Endoscopic fenestration of the cyst membrane into the lateral ventricle was successful in reducing cyst volume and improving mass effect.

Cervical Laminectomy With or Without Lateral Mass Instrumentation: A Comparison of Outcomes.

STUDY DESIGN: Narrative review. BACKGROUND: Cervical decompressive laminectomy is a common posterior approach for addressing multilevel cervical spondylotic myelopathy. However, there is a concern that cervical laminectomy can lead to kyphotic deformity with subsequent neurological decline. In this context, cervical laminectomy with fusion using lateral mass instrumentation has become increasingly utilized with the aim of reducing the risk of developing postoperative kyphotic deformity, which is thought to predispose to poorer neurological outcomes in the long term. OBJECTIVE: To compare the evidence for stand-alone cervical laminectomy with laminectomy with posterior fusion in terms of clinical outcomes and the incidence of adverse events, particularly the development of postoperative cervical kyphosis. MATERIAL AND METHODS: Initial Medline search using MeSH terms yielded 226 articles, 23 of which were selected. An additional PubMed search and the reference list of individual papers were utilized to identify the remaining papers of relevance. RESULTS: Cervical laminectomy both with and without fusion offers effective decompression for symptomatic multilevel cervical spondylotic myelopathy. The incidence of postlaminectomy kyphosis is lower following posterior fusion; however, there seems to be no clinical-radiologic correlation given that patients who develop postoperative kyphosis often do not progress to clinical myelopathy. Furthermore, there are specific additional risks of posterior instrumentation that need to be considered. CONCLUSION: In carefully selected patients with normal preoperative cervical sagittal alignment, stand-alone cervical laminectomy may offer acceptably low rates of postoperative kyphosis. In patients with preoperative loss of cervical lordosis and/or kyphosis, posterior fusion is recommended to reduce the risk of progression to postoperative kyphotic deformity, bearing in mind that radiologic evidence of kyphosis may not necessarily correlate with poorer clinical outcomes. Furthermore, the specific risks associated with posterior fusion (instrumentation failure, pseudarthrosis, infection, C5 nerve root palsy, and vertebral artery injury) need to be considered and weighed up against potential benefits.

Reporting Quality of Systematic Review Abstracts Published in Leading Neurosurgical Journals: A Research on Research Study.

BACKGROUND: Systematic review (SR) abstracts are frequently relied upon to guide clinical decision-making. However, there is mounting evidence that the quality of abstract reporting in the medical literature is suboptimal. OBJECTIVE: To appraise SR abstract reporting quality in neurosurgical journals and identify factors associated with improved reporting. METHODS: This study systematically surveyed SR abstracts published in 8 leading neurosurgical journals between 8 April 2007 and 21 August 2017. Abstracts were identified through a search of the MEDLINE database and their reporting quality was determined in duplicate using a tool derived from the Preferred Reporting Items for Systematic Reviews and Meta-analyses for Abstracts (PRISMA-A) statement. All SR abstracts that provided comparison between treatment strategies were eligible for inclusion. Descriptive statistics were utilized to identify factors associated with improved reporting. RESULTS: A total of 257 abstracts were included in the analysis, with a mean of 22.8 (±25.3) included studies. The overall quality of reporting in included abstracts was suboptimal, with a mean score of 53.05% (±11.18). Reporting scores were higher among abstracts published after the release of the PRISMA-A guidelines (M = 56.52; 21.74-73.91) compared with those published beforehand (M = 47.83; 8.70-69.57; U = 4346.00, z = -4.61, P < .001). Similarly, both word count (r = 0.338, P < .001) and journal impact factor (r = 0.199, P = .001) were associated with an improved reporting score. CONCLUSION: This study demonstrates that the overall reporting quality of abstracts in leading neurosurgical journals requires improvement. Strengths include the large number abstracts assessed, and its weaknesses include the fact that only neurosurgery-specific journals were surveyed. We recommend that attention be turned toward strengthening abstract submission and peer-review processes.

Diskogenic Reactivation of Herpes Zoster.

Varicella zoster virus remains dormant in the dorsal root ganglia after childhood exposure to chickenpox. Its reactivation results in herpes zoster, otherwise known as shingles, which is a painful vesicular rash in a dermatomal distribution. We present a case of foraminal disk extrusion that resulted in radicular pain in a dermatomal distribution. The resultant inflammatory response around the dorsal root ganglion triggered an episode of shingles, which elegantly highlights the pathophysiology of this condition at a gross anatomic level.

Synoptic reporting of pituitary magnetic resonance imaging.

BACKGROUND: Pituitary adenomas are common, often asymptomatic tumours that are diagnosed incidentally by magnetic resonance imaging (MRI) of the brain. There is considerable variation in the reporting of pituitary MRI, in part because there is no consensus as to what information should be included in such reports. Synoptic reporting consists of using structured checklists to standardize communication. It has been adopted in the surgical pathology literature and more recently in the breast imaging field. The purpose of this study was to assess what parameters of a pituitary MRI report were useful to surgeons and in doing so, to propose a synoptic reporting template. METHODS: We used the Delphi technique to obtain group consensus between three neuroradiologists, three otolaryngologists and three anterior skull base neurosurgeons across three tertiary Melbourne hospitals. Answers from the three speciality groups were then converted into numerical scores for analysis. RESULTS: There was statistically significant consensus between specialties over which characteristics were deemed most important. These were T1 pre- and post-contrast sequences in the coronal and sagittal planes, the degree of displacement of the optic chiasm, invasion of the medial wall of the cavernous sinus, the size and pneumatization pattern of the sphenoid sinus and the differential diagnosis of aneurysm. There were also significant differences between groups. CONCLUSIONS: There are similarities and differences between what radiologists, otolaryngologists and neurosurgeons deem as important features when reporting pituitary MRI. A synoptic reporting system template is proposed to improve consistency in pituitary imaging reports.

Interobserver Reliability of Spinal Adverse Events Severity System - Neuro (SAVES-N): A Prospective Adverse Event Reporting System for Neurosurgical Cases.

BACKGROUND: The reporting of adverse events (AEs) in neurosurgery uses inconsistent definitions and subjective grading systems. A standardized system for recording and describing AEs would allow valid comparisons to be drawn between different institutions, using different technologies, at different times. The Spinal Adverse Events Severity System - Neuro (SAVES-N) system is a modification of the well-validated SAVES-V2 system that encompasses complications from both cranial and spinal surgery. The objective of this study was to assess the interobserver reliability of SAVES-N in spinal and cranial neurosurgery. METHODS: Ten vignettes, including cranial and spinal neurosurgical cases, were assessed by groups of consultant neurosurgeons (n = 5) and neurosurgical registrars (n = 5) using the SAVES-N system. Interobserver reliability for the presence of AEs, the type of AE, and the SAVES severity grade of the AE were calculated using Gwet's AC2 and Fleiss' kappa and were interpreted using the thresholds described by Landis and Koch. RESULTS: Neurosurgeons had almost-perfect agreement (Gwet AC2 = 0.93), whereas registrars had substantial agreement (Gwet's AC2 = 0.74) in determining the presence or absence of AEs. Both neurosurgeons (Fleiss' kappa = 0.78) and registrars (Fleiss' kappa = 0.70) demonstrated substantial agreement within their groups as to the type of AE. Similarly, neurosurgeons (Gwet's AC2 = 0.94) and registrars (Gwet's AC2 = 0.81) both graded the severity of the AE with almost perfect agreement. CONCLUSIONS: The results of this study demonstrate that the scope of the well-validated SAVES-V2 system may be broadened to cranial neurosurgical cases by SAVES-N with substantial to almost-perfect interobserver reliability.

Axonal plasticity underpins the functional recovery following surgical decompression in a rat model of cervical spondylotic myelopathy.

Cervical spondylotic myelopathy (CSM) is the most common spinal cord disorder and a major cause of disability in adults. Improvements following surgical decompression are limited and patients often remain severely disabled. Post mortem studies indicate that CSM is associated with profound axonal loss. However, our understanding of the pathophysiology of CSM remains limited.To investigate the hypothesis that axonal plasticity plays a role in the recovery following surgical decompression, we adopted a novel preclinical model of mild to moderate CSM. Spinal cord compression resulted in significant locomotor deterioration, increased expression of the axonal injury marker APP, and loss of serotonergic fibres. Surgical decompression partially reversed the deficits and attenuated APP expression. Decompression was also associated with axonal sprouting, reflected in the restoration of serotonergic fibres and an increase of GAP43 expression. The re-expression of synaptophysin indicated the restoration of functional synapses following decompression. Promoting axonal plasticity may therefore be a therapeutic strategy for promoting neurological recovery in CSM.

Progression of choroid plexus papilloma.

Choroid plexus papillomas are rare neoplasms that arise from choroid plexus epithelium. The World Health Organization classification describes three histological grades. Grade I is choroid plexus papilloma, grade II is atypical choroid plexus papilloma and grade III is choroid plexus carcinoma. Progression between grades is rare but documented. We present two adult cases, a 53-year-old female and a 70-year-old male, who demonstrated clear interval histological progression from grade I choroid plexus papilloma to higher grades.

Predictors of creatinine rise post-endovascular abdominal aortic aneurysm repair.

BACKGROUND: Endovascular abdominal aortic aneurysm repair involves manipulation of the aorta around the renal arteries. Fenestrated grafts involve the direct cannulation, stenting and injecting of contrast into the renal arteries. These procedures may be associated with an acute post-operative creatinine rise. METHODS: We retrospectively examined data from all endovascular aortic repairs at our institution from 2005 to 2009, where contrast dosage had been recorded. Renal impairment was defined as a 25% increase in creatinine during the 5-day postoperative period. Univariable analysis was undertaken for a number of likely predictors, including: age, contrast dosage, preoperative creatinine, graft type (fenestrated or standard), diabetes mellitus, hypertension, hypercholesterolaemia, ischaemic heart disease, aspirin therapy, statins therapy, non-steroidal anti-inflammatory drug use, preoperative N-acetyl-cysteine and intravenous pre-hydration. Multivariable analysis was then applied to variables with a univariable P-value of < 0.05. RESULTS: We identified 106 consecutive cases, with complete data for 102. Twenty per cent of patients developed renal impairment (22/102). Contrast dose (P = 0.043) and fenestrated grafts (P = 0.006) were identified as significant risk factors for post-operative creatinine increase (P = 0.043). Multivariable analysis demonstrated that fenestrated grafts were a risk factor independent of contrast dosage (P < 0.05). CONCLUSIONS: Patients who received a fenestration graft (P < 0.01) and increased contrast dose (P < 0.05) were at a significant increased risk of a 25% post-operative creatinine rise. The risk of fenestration grafts persisted when multivariable regression was performed to control for contrast dosage (P < 0.05). Other variables investigated were not found to be significant in this study.

Resources for the management of ocular emergencies in Australia.

The aim of the present paper is to assess the practical utility of the most common print resources used by practitioners in the management of ocular emergencies. Ten print resources were identified for review (three specialty eye texts, six general emergency medicine texts and one general practice text). The main outcome measures used were the extent a text matched crucial skills criteria in clinical assessment and treatment, and usability. No single print resource addressed all criteria. Red flag systems for clinical assessment and ease of navigation were the best match areas. Only one text inadequately stressed red flag conditions and one text was not ranked as easy to navigate. All texts made assumptions regarding the knowledge/skill level of practitioners, particularly in relation to eye examination procedures and treatment. Photographs ranged in number from 8 to 1500; 3/10 texts provided no photographs. Five texts included detailed instructions on the indications and urgency of referral and follow up for all conditions covered. The remainder lacked details. Only one text used the Australasian Triage Scale. Three texts included photographs/diagrams and instructions for the slit lamp and ophthalmoscope. None covered all procedures specified in the criteria. Only two reflected drug current practice in Australia and provided adequate details on usage. A single comprehensive reference (print and/or web-based) for dealing with ocular emergencies in Australia is clearly needed. Additionally, training and confidence levels of eye care providers must be addressed so that the risk of misdiagnosis and mismanagement of eye emergencies is reduced.