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.

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. Keywords: Brain concussion; Brain ischemia; General anesthesia; Intracranial hypotension; Post-concussion syndrome.

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.

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.

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.

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.

Neurologic monitoring in the intensive care unit (ICU) is used either in a general sense as part of a system-based approach to assess one of the major bodily systems or with the specific intent to guide therapy and/or assess prognosis. Imaging studies of the central nervous system (CNS)—while not considered “monitoring” in the strict sense—play a central role in this assessment by establishing diagnoses and quantifying the extent of pathology. Important constraints for typical neuroradiologic imaging are presented in the first section below. Many interventions in the ICU aimed at restoring or maintaining conditions that are favorable for recovery of the patient target the normal brain and, by extension, affect the results of neurologic monitoring. Therefore, an understanding of the parameters that affect the state of the brain is necessary as the context for interpreting the results of neurologic monitoring. These are presented in the second section, followed by a detailed discussion of available modalities for serial assessment or monitoring of the nervous system.

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.

University of Florida College of Medicine, Gainesville, Florida. mahla@ufl.eduEdited by Anton Koht, M.D., Tod B. Sloan, M.D., M.B.A., Ph.D., J. Richard Toleikis, Ph.D. New York, Springer, 2012. ISBN-10: 1461403073. ISBN-13: 978-1-4614-0307-4. eISBN: 978-1-4614-0308-1. Pages: 846. Price: $89.95.Although there are many texts and peer-reviewed publications that address intraoperative monitoring of various aspects of the nervous system, few are directed specifically at healthcare providers not actually performing or interpreting the monitoring. Unless a clinician has specific education in neurophysiology, neuropharmacology, neuroanatomy, and technical aspects of recording neurophysiologic signals, most available texts will be very difficult reading. This text was written specifically to provide needed information to healthcare providers, especially anesthesiologists, who have a key role in optimizing conditions for monitoring to provide useful and interpretable information.The tone for the text is set nicely by forewords written by three individuals (Clyde Nash, M.D., orthopedic spine surgeon; Maurice Albin, M.D., neuroanesthesiologist; and H. Hunt Batjer, M.D., neurosurgeon), some of whom have been actively involved in neuromonitoring since its functional beginning a half century ago.The book is divided into four major sections addressing techniques of monitoring, anesthetic considerations, case-based presentations, and monitoring in the intensive care unit. The first section provides a succinct, well-referenced review of each of the important methods of monitoring the nervous system encountered in the operating room or in the intensive care unit. The techniques discussed are separated logically into those that monitor neurologic function (sensory and motor evoked potentials, spinal cord stimulation techniques, electroencephalography, and electromyography), adequacy of blood flow (near-infrared spectroscopy, transcranial Doppler ultrasound, and jugular venous oxygen saturation), structural localization techniques (deep brain stimulation and cortical mapping), and intracranial pressure monitoring. For each monitoring modality, an anatomic basis for monitoring is provided that demonstrates why monitoring a particular pathway would logically provide information about a particular portion of the nervous system. This discussion also provides the clinician with an understanding of the anatomically based limitations of each type of monitoring. Next, methods and technical considerations are described. This description is complete enough to provide a good understanding of what monitoring technologists must do in preparation for and during monitoring but not so comprehensive as to be difficult to understand for those who are not neurologists or neurophysiologists. Third, nonsurgical factors that may make monitoring difficult to interpret, including but not limited to anesthetic drugs and temperature, are reviewed. Finally, the most important applications of each monitoring modality and some evidence-based literature are reviewed. These discussions are limited in scope by design because the entire third section of the book addresses applications of monitoring in specific cases.The second major section of the book has three chapters that focus on the anesthesia provider. Because cortical functional mapping and surgery for placement of deep brain stimulating electrodes usually require an awake, cooperative patient, there is an excellent discussion about anesthesia for awake neurosurgical procedures. This chapter covers the important aspects of management, including preoperative evaluation and patient selection, sedation techniques that do not significantly impair the neurologic examination, regional anesthetic techniques that may be useful adjuncts, and complications related to surgery and anesthetics that may occur during surgery. The second chapter provides a succinct review of the interpretative difficulties general anesthesia introduces for each monitoring technique and suggests ways anesthesia providers may facilitate neurologic monitoring. The final chapter of this section, “Monitoring Anesthetic Effect,” not only reviews how the electroencephalogram can be used for monitoring drug effects in both the operating room and intensive care unit but also discusses how the electroencephalogram can be used to monitor metabolic suppression and detect ischemia. Computer processing and display simplification of the electroencephalogram are addressed, demonstrating how the anesthesiologist, who is also responsible for monitoring other organ systems, may efficiently gain information about central nervous system drug effects and cerebral ischemia.The third and largest section of the text is what really distinguishes this work from other texts covering the same topic. Although it is well and good to provide theoretical background and outcome data for each monitoring modality, the anesthesiologist will not really learn how to optimize his or her practice for use during monitoring and will not really understand just how important this monitoring can be to the patient's well-being until real clinical experience is gained with monitoring. The anesthesiologist will be convinced of the importance of controlling for confounding factors during critical monitoring periods upon actually seeing a surgeon place an aneurysm clip (which appears by all assessments to be well placed) cause a loss of cortical somatosensory evoked response that returns after the clip is adjusted. Each chapter focuses on neurologic monitoring during cases the practicing neuroanesthesiologist is likely to encounter. Considering this section as a whole, nearly all common applications of the monitoring techniques described in the first section of the book are reviewed in an easy-to-read, case discussion format. The cases were selected to demonstrate the utility, limitations, and confounding factors during surgery that may make interpretation difficult and often involve multiple modalities simultaneously. Real patient examples, with all identification removed, show how vitally important the information provided by neurologic monitoring can be to all personnel taking care of the patient and effectively demonstrate how the real-time information provided by monitoring enables the surgeon and anesthesiologist to work together to restore function to nervous tissue identified to be at risk. Some cases were clearly selected to demonstrate the effects of poor control of the anesthetic technique, technical factors that may cause evoked potential changes, positioning effects, and limitations of monitoring techniques (false negatives). By selecting these cases, the editors provide an appropriate balance between demonstrated efficacy and limitations of each monitoring technique.The final section of the book provides a brief glimpse into the potential uses of neurologic monitoring in the intensive care unit, focusing on cerebral blood flow measurement modalities. This text emphasizes the far more commonly used and more extensively studied intraoperative applications of neurologic monitoring. This choice of emphasis is understandable because, relatively speaking, intensive care unit neuromonitoring is still in its infancy. Most intensive care unit applications of neuromonitoring are really not monitoring, but rather diagnostic snapshots. If there is any weakness to this text, it is in this area. Intensive care unit applications are covered to some extent in the first section of the book, and this section almost appears to be an afterthought.In summary, Monitoring the Nervous System for Anesthesiologists and Other Health Care Professionals is a must read for trainees undertaking a fellowship in neuroanesthesia and for neuroanesthesiologists who are not themselves directing a neurologic monitoring service or who have limited experience with neurologic monitoring. This book would also be a useful adjunct for trainees in clinical neurophysiology who intend to focus a significant portion of their professional effort on intraoperative neurologic monitoring.

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.

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.

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.

Thromboelastography to assess coagulation in the thrombocytopenic parturientTo the Editor: We present two cases in which pregnant women received a neuraxial block despite having a platelet count in the thrombocytopenic range.In our current practice, patients with platelet counts less that 100,000•mm -3 are not eligible for a neuraxial block.However, based on the normal thromboelastogram (TEG) tracing (Figure ), the decision was made to proceed with neuraxial anesthesia.

Background. We developed a problem-based learning exercise with a full-scale human patient simulator to teach residents the emergency management and differential diagnosis of acute intraoperative hypotension. Methods.We developed the exercise through the following steps: clear definition of learning objectives, preparation of an appropriate case stem, development of clinically realistic scenarios to illustrate objectives, and an interactive instructor to stimulate discussion. Results. The exercise focused on the differential diagnosis of intraoperative hypotension, and the acute treatment of hypovolemia, cardiac tamponade, tension pneumothorax, and anaphylaxis. Conclusions. Exercises on a full-scale patient simulator are a natural extension of problem-based learning. Recent research in learning theory provides the rationale for this teaching modality's potential as a learning tool.