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The COVID-19 outbreak has led to fundamental disruptions of health care and its delivery with sweeping implications for patients and physicians of all specialties, including neurosurgery. In an effort to conserve hospital resources, neurosurgical procedures were classified into tiers to determine which procedures have to be performed in a timely fashion and which ones can be temporarily suspended to aid in the hospital's reallocation of resources when equipment is scarce. These guidelines were created quickly based on little existing evidence, and thus were initially variable and required refinement. As the early wave can now be assessed in retrospect, the authors describe the lessons learned and the protocols established based on published global evidence to continue to practice neurosurgery sensibly and minimize disruptions. These operational protocols can be applied in a surge of COVID-19 or another airborne pandemic.

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BACKGROUND: Although anesthesia providers may plan for moderate sedation, the depth of sedation is rarely quantified. Using processed electroencephalography (EEG) to assess the depth of sedation, this study investigates the incidence of general anesthesia with variable burst suppression in patients receiving propofol for outpatient colonoscopy. The lessons learned from neuromonitoring can then be used to guide institutional best sedation practice. METHODS: This was a prospective observational study of 119 outpatients undergoing colonoscopy at Thomas Jefferson University Hospital (TJUH). Propofol was administered by CRNAs under anesthesiologists' supervision. The Patient State Index (PSi™) generated by the Masimo SedLine® Brain Root Function monitor (Masimo Corp., Irvine, CA) was used to assess the depth of sedation. PSi data correlating to general anesthesia with variable burst suppression were confirmed by neuroelectrophysiologists' interpretation of unprocessed EEG. RESULTS: PSi values of <50 consistent with general anesthesia were attained in 118/119 (99.1%) patients. Of these patients, 33 (27.7%) attained PSi values <25 consistent with variable burst suppression. The 118 patients that reached PSi <50 spent a significantly greater percentage (53.1% vs. 42%) of their case at PSi levels <50 compared to PSi levels >50 (p=0.001). Mean total propofol dose was significantly correlated to patient PSi during periods of PSi <25 (R=0.406, p=0.021). CONCLUSION: Although providers planned for moderate to deep sedation, processed EEG showed patients were under general anesthesia, often with burst suppression. Anesthesiologists and endoscopists may utilize processed EEG to recognize their institutional practice patterns of procedural sedation with propofol and improve upon it.

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Some patients require emergent, urgent, or elective surgery in the time period immediately following diagnosis of concussion. However, changes in brain homeostatic mechanisms following a concussion and concern for secondary brain injury can complicate the decision as to whether or not a surgery should proceed or be postponed. Given the paucity of available evidence, further evaluation of the use of anesthesia in a patient with concussion is warranted. This article summarizes what is currently known about the relevant pathophysiology of concussion, intraoperative anesthesia considerations, and effects of anesthesia on concussion outcomes in an attempt to help providers understand the risks that may accompany surgery and anesthesia in this patient population. While most contraindications to the use of anesthesia in concussed patients are relative, there are nonetheless pathophysiologic changes associated with a concussion that can increase risk of its use. Understanding these changes and anesthetic implications can help providers optimize outcomes in this patient population.

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BACKGROUND: The Accreditation Council for Graduate Medical Education (ACGME) has introduced competency-based assessments (milestones) for resident education. However, the existing milestones for Anesthesiology are not specific to Neuroanesthesiology. The Society for Neuroscience in Anesthesiology & Critical Care (SNACC) commissioned a task force to adapt the ACGME anesthesiology milestones for use in Neuroanesthesiology training, and to provide recommendations for implementing milestones. METHODS: A 7-member expert task force supported by an advisory committee developed the initial milestones by consensus. Written permission was given by the ACGME. The milestones were refined following 3-month pilot use in 14 departments across the United States and inputs from SNACC members. Final milestones were approved by the SNACC Board of Directors. RESULTS: Twelve Neuroanesthesiology-specific milestones in 5 major ACGME domains are recommended; these were identified as most pertinent to this subspecialty rotation. These pertain to patient care (7 milestones), medical knowledge (2 milestones), practice-based learning and improvement (1 milestone), and interpersonal and communication skills (2 milestones). Each milestone was described in detail, with clear outline of expectations at various levels of training. CONCLUSIONS: The SNACC Neuroanesthesiology milestones provide a framework for reviewing resident performance and are expected to facilitate improved use of ACGME milestones during Neuroanesthesiology subspecialty training. The task force recommends that the target should be to accomplish level 4 or higher milestones by the end of residency training. Individual programs should decide the implications of a resident not meeting the expected milestones.

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This report displays a rare presentation of lactic acidosis in the setting of status epilepticus (SE). The differential diagnosis of lactic acidosis is broad and typically originates from states of shock; however, this report highlights an alternative and rare etiology, SE, due to chronic skull base erosion from temporomandibular joint (TMJ) disease. Lactic acidosis is defined by a pH below 7.35 in the setting of lactate values greater than 5 mmol/L. Two broad classifications of lactic acidosis exist: a type A lactic acidosis which stems from global or localized tissue hypoxia or a type B lactic acidosis which occurs once mitochondrial oxidative capacity is unable to match glucose metabolism. SE is an example of a type A lactic acidosis in which oxygen delivery is unable to meet increased cellular energy requirements. This report is consistent with a prior case series that consists of five patients experiencing generalized tonic-clonic (GTC) seizures and lactic acidosis. These patients presented with a pH range of 6.8-7.41 and lactate range of 3.8-22.4 mmol/L. Although severe lactic acidosis following GTC has been described, this is the first report in the literature of chronic skull base erosion from TMJ disease causing SE.

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BACKGROUND: Processed electroencephalogram (EEG) monitors help assess the hypnotic state during general anesthesia or sedation. Maintaining the bispectral index (BIS) or state entropy (SE) between 40 and 60 has been recommended to mitigate anesthesia awareness. Nonetheless, SEs > 70 were frequently observed at end-tidal sevoflurane concentrations unlikely to allow awareness. We sought to determine the prevalence of elevated discordant measurements during BIS and SE monitoring. METHODS: Electronic data collected over 11 months at two academic hospitals were retrospectively reviewed. At the hospital using SE, all cases were included with patients ≥ 18 yr and sevoflurane administered for at least 30 min during surgery. A cohort of cases propensity matched by age and American Society of Anesthesiologist Physical Status were selected from the hospital using BIS. Elevated discordant EEG indices were defined as values > 70 occurring during stable end-tidal sevoflurane concentrations > 1.5%. The odds ratio (OR) based on the probability of a case having at least one elevated discordant SE or BIS lasting ≥ two minutes (primary endpoint) was calculated. RESULTS: At each hospital, 3,690 cases were studied. The mean (95% confidence interval [CI]) incidence of cases with at least one interval of an elevated discordant EEG index lasting at least two minutes was 3.6% (2.8% to 4.4%) for SE compared with 0.24% (0.17% to 0.27%) for BIS (pooled OR, 17.0; 95% CI, 8.3 to 34.7; P < 0.001). CONCLUSIONS: The prevalence of an elevated discordant EEG index is much greater with SE than with BIS. Elevated index values occurring at anesthetic concentrations well above the awareness threshold need to be assessed to determine if they indicate an inadequate depth of anesthesia requiring treatment or if they simply reflect the underlying monitoring algorithm.

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Klippel-Feil syndrome (KFS) is a congenital anomaly characterized by a defect in the formation or segmentation of the cervical vertebrae, resulting in their fusion. The clinical triad of the syndrome consists of short neck, low posterior hairline, and limited neck movement, although fewer than 50 percent of patients demonstrate all three clinical features. The short neck and its immobility and instability present a significant challenge for endotracheal intubation. The purpose of this paper is to describe the management of a 13-year-old patient with KFS, extensive dental caries, and restricted mouth opening using a deep sedation technique in the operating room, which allowed successful completion of dental treatment.

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BACKGROUND: In the United States, anesthesia information management systems (AIMS) are well established, especially within academic practices. Many hospitals are replacing their stand-alone AIMS during migration to an enterprise-wide electronic health record. This presents an opportunity to review choices made during the original implementation, based on actual usage. One area amenable to this informatics approach is the configuration in the AIMS of quick buttons for typical drug doses. The use of such short cuts, as opposed to manual typing of doses, simplifies and may improve the accuracy of drug documentation within the AIMS. We analyzed administration data from 3 different institutions, 2 of which had empirically configured default doses, and one in which defaults had not been set up. Our first hypothesis was that most (ie, >50%) of drugs would need at least one change to the existing defaults. Our second hypothesis was that for most (>50%) drugs, the 4 most common doses at the site lacking defaults would be included among the most common doses at the 2 sites with defaults. If true, this would suggest that having default doses did not affect the typical administration behavior of providers. METHODS: The frequency distribution of doses for all drugs was determined, and the 4 most common doses representing at least 5% of total administrations for each drug were identified. The appropriateness of the current defaults was determined by the number of changes (0-4) required to match actual usage at the 2 hospitals with defaults. At the institution without defaults, the most frequent doses for the 20 most commonly administered drugs were compared with the default doses at the other institutions. RESULTS: At the 2 institutions with defaults, 84.7% and 77.5% of drugs required at least 1 change in the default drug doses (P < 10 for both compared with 50%), confirming our first hypothesis. At the institution lacking the default drug doses, 100% of the 20 most commonly administered doses (representing ≥5% of use for that drug) were included in the most commonly administered doses at the other 2 institutions (P < 10), confirming our second hypothesis. CONCLUSIONS: We recommend that default drug doses should be analyzed when switching to a new AIMS because most drugs needed at least one change. Such analysis is also recommended periodically so that defaults continue to reflect current practice. The use of default dose buttons does not appear to modify the selection of drug doses in clinical practice.

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Intubating laryngeal mask airways can be used to provide continuous ventilation throughout intubation. This is a case of a morbidly obese (body mass index = 58) 65-year-old woman with T10 and T11 compression fractures. Optimal positioning for airway management was hindered by her unstable spine, minimal neck range of motion, and extreme pain with any movement. An intubating laryngeal mask airway was placed in the awake, topically anesthetized patient, and the laryngeal mask airway and endotracheal tube combination was left in place throughout surgery.

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Papaverine has been associated with transient cranial nerve dysfunction after topical application during craniotomy. The authors report similar dysfunction after the use of papaverine affected brainstem structures. Two patients undergoing craniotomy for clipping of an aneurysm experienced bilateral depression of cortical somatosensory evoked potentials to both median and tibial nerve stimulation after administration of papaverine. Arterial blood gas analysis, hemodynamic parameters, and anesthetic levels remained constant throughout these somatosensory evoked potential changes. In addition, intraoperative angiography and immediate postoperative CT imaging showed intact blood flow with complete exclusion of the aneurysm. Both patients recovered within 1-2 hours and had normal neurological examination findings after extubation. Topical papaverine use may be associated with direct effects on brainstem structures. The transient nature of those changes suggests that aggressive intervention may not be needed. Maneuvers to limit the spread of papaverine to basal cisterns should be considered.

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PURPOSE: Interference on pulse oximetry can come from many sources. We found an additional source of interference from the Stealth Station. This article gives an overview of sources of pulse oximeter interference so that clinicians can better prevent them. Technical features: This article discusses the infrared disturbances caused by the Stealth Station. The Stealth Station is a frameless stereotactic positioning system that utilizes a three dimensional location system to measure the position of the patient and the surgical tools, and to relate those positions to previously recorded imaging. To understand the disturbance caused by the Stealth Station, we discuss its operation and that of pulse oximeter monitors. Pulse oximeter interference can come from volume artifacts, electrical and light noise, and can be caused by issues related to the patient. Because the passive Stealth Station contains a strong infrared light source, interference caused by light is a likely reason for the interference we noted. Pulse oximeters rely on the time-variant light signal modulated by arterial volume variations in the finger. Although relatively immune to static light sources, pulse oximeters are extremely sensitive to time-varying light sources. The light emitted by the passive Stealth Station is time-varying at 4 Hz and this is causing the pulse oximeter to provide invalid results. Shielding can generally be used to stop the light from the Stealth Station from being picked up by the pulse oximeter sensor. CONCLUSION: Infrared light interference can be very common, but is easily dealt with if one is aware of it.

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Visual loss is a rare, but catastrophic, complication of surgery in the prone position. The prone position increases intraocular pressure (IOP), which may lead to visual loss by decreasing perfusion of the anterior optic nerve. We tested whether the reverse Trendelenburg position ameliorates the increase in IOP caused by prone positioning. Furthermore, we compared two prone positioning set ups. The IOP of 10 healthy awake volunteers was measured in the prone position at 3 different degrees of inclination (horizontal, 10 degrees reverse Trendelenburg, and 10 degrees Trendelenburg) and in the sitting and supine positions in a randomized crossover study comparing the Jackson table and the Wilson frame. In a given eye, all prone IOP values (median [25th-75th percentile] exceeded those of the sitting (15.0 mm Hg [12.8-16.3 mm Hg]) and supine (16.8mm Hg [14.0-18.3 mm Hg]) positions. IOPs in the reverse Trendelenburg, horizontal, and Trendelenburg positions were 20.3 mm Hg (16.3-22.5 mm Hg), 22.5 mm Hg (19.8-25.3 mm Hg), and 23.8 mm Hg (21.5-26.3 mm Hg), respectively (P < 0.001 versus reverse Trendelenburg; dagger P < 0.001 versus horizontal). The reverse Trendelenburg position ameliorated the increase in IOP caused by the prone position. Furthermore, the reverse Trendelenburg position decreased the number of grossly abnormal IOP values (>23 mm Hg) by 50% and 75% compared with the prone horizontal and Trendelenburg positions, respectively. The prone positioning setups did not differ in their effect on IOP. The increase in IOP caused by prone positioning was ameliorated by the reverse Trendelenburg position and was aggravated by the Trendelenburg position. The short time period between changes in position and changes in IOP suggests an important role for ocular venous pressures in determining IOP. Therefore, IOP can be beneficially manipulated by operating table inclination in the prone position.

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