Intraoperative Neurophysiological Monitoring

Abstract: Minimally invasive parathyroidectomy is an accepted treatment option for primary hyperparathyroidism. The need for intraoperative parathyroid hormone assays (iPTH) to confirm adenoma removal remains controversial. We studied minimally invasive radio-...

The anaesthetist plays a key role in the management of high-risk pregnancies, and must be a member of the multidisciplinary team that is required to care for the critically ill obstetric patient. Anaesthetists are trained in advanced life support and resuscitation. They are experienced in the management of the critically ill, and provide anaesthesia, sedation and pain management. The obstetric anaesthetist should undertake education of medical and midwifery staff in the early recognition, monitoring and treatment of the sick mother, resuscitation training, running 'skills drills' for emergency simulations, risk management and audit of maternal morbidity on the labour ward. To date, there is little evidence to inform the anaesthetic management of the critically ill obstetric patient; most recommendations and guidelines are based on the management of non-obstetric, critically ill patients. Management must be adapted to encompass the physiological changes of pregnancy. Evidence-based guidelines on management of the critically ill woman with specific obstetric conditions are also lacking.

Anticoagulation therapy for cardiopulmonary bypass in patients with recently diagnosed heparin-induced thrombocytopenia can be particularly challenging. Although heparin is the standard of care, in these situations anticoagulation is achieved with alternative agents such as direct thrombin inhibitors. Therapeutic concentrations are difficult to assess with direct thrombin inhibitors, and their use is riddled with bleeding and thrombotic complications. We report the successful use of a specific chromogenic antifactor IIa assay in a patient with heparin-induced thrombocytopenia who received anticoagulation therapy with bivalirudin during cardiopulmonary bypass for coronary artery bypass graft surgery.

Cerebral state monitor (CSM) is a recently developed anaesthesia depth monitor based on EEG measurement. Medline search confi rmed that the accuracy of this monitor has already been compared with BIS monitoring; however, we did not fi nd any studies comparing CSM monitor with AEP monitoring. Therefore, the aim of our study was to investigate the correlation between AAI using AEP monitor and CSI (cerebral state index) using CSM monitor. Methods: Prospective, observational study involving 39 ASA I-III patients undergoing lumbar discus hernia operation. Simultaneous registration of CSI and AAI was performed during general anaesthesia. The identical values were off-line analysed. Additionally in 20 patients parallel registration of CSI and AAI was undertaken while anaesthesia was guided based on routine clinical signs. Results: While analysing the data in the superfi cial, ideal and deep anaesthesia zones, we found that a relationship between CSI and AAI is weak. Our patients spent roughly the half of the clinical anaesthesia in the ideal zone based on the AAI index and less than 50% based on CSI. Almost one fi fth of clinical anaesthesia based on AAI and nearly 40% based on CSI was spent in the deep anaesthesia zones. A superfi cial anaesthesia has been detected in 27% of time based on AAI and 17% based on CSI. Conclusions: CSI and AAI weakly correlated to each other. Depth of anaesthesia monitors may be useful in detecting patients who spend valuable time within the deep anaesthetic zone.

Amidst controversy about methodology and safety, intraoperative neurophysiology has entered a new era of increasingly routine transcranial and direct electrical brain stimulation for motor evoked potential (MEP) monitoring. Based on literature review and illustrative clinical experience, this tutorial aims to present a balanced overview for experienced practitioners, surgeons and anesthesiologists as well as those new to the field. It details the physiologic basis, indications and methodology of current MEP monitoring techniques, evaluates their safety, explores interpretive controversies and outlines some applications and results, including aortic aneurysm, intramedullary spinal cord tumor, spinal deformity, posterior fossa tumor, intracranial aneurysm and peri-rolandic brain surgeries. The many advances in motor system assessment achieved in the last two decades undoubtedly improve monitoring efficacy without unduly compromising safety. Future studies and experience will likely clarify existing controversies and bring further advances.

Surgical repair of the mitral valve is being increasingly performed to treat severe mitral regurgitation. Transesophageal echocardiography is an essential tool for assessing valvular function and guiding surgical decision making during the perioperative period. A careful and systematic transesophageal echocardiographic examination is necessary to ensure that appropriate information is obtained and that the correct diagnoses are obtained before and after repair. The purpose of this article is to provide a practical guide for perioperative echocardiographers caring for patients undergoing surgical repair of mitral regurgitation. A guide to performing a systematic transesophageal echocardiographic examination of the mitral valve is provided, along with an approach to prerepair and postrepair assessment. Additionally, the anatomy and function of normal and regurgitant mitral valves are reviewed.

A comparison was made of arterial pressures measured invasively from a radial arterial cannula and non-invasively from the middle finger using the 2300 Finapres (Ohmeda) during induction and maintenance of anaesthesia. Digital outputs of both pressures were captured directly onto computer hard disk; data recorded during flushing of the arterial line were excluded from analysis. We studied 53 patients undergoing cardiac, major vascular and neurosurgical procedures; 17705 comparisons of systolic, diasto/ic and mean pressure were analysed. Overall correlations between Finapres and invasive pressures were poor (r = 0.82, 0.68 and 0.78 for systolic, diastolic and mean pressures, respectively). The Finapres exhibited a high level of accuracy and precision in some recordings. However, patient data sets showed marked variability in average pressure differences (invasive minus Finapres) when examined individually or grouped by operation type. Unexplained variations in pressure difference with time and absolute pressure were observed also. Whilst providing useful beat-to-beat information on arterial pressure trends, the Finapres cannot be recommended as a universal substitute for invasive arterial pressure monitoring.

Amidst controversy about methodology and safety, intraoperative neurophysiology has entered a new era of increasingly routine transcranial and direct electrical brain stimulation for motor evoked potential (MEP) monitoring. Based on literature review and illustrative clinical experience, this tutorial aims to present a balanced overview for experienced practitioners, surgeons and anesthesiologists as well as those new to the field. It details the physiologic basis, indications and methodology of current MEP monitoring techniques, evaluates their safety, explores interpretive controversies and outlines some applications and results, including aortic aneurysm, intramedullary spinal cord tumor, spinal deformity, posterior fossa tumor, intracranial aneurysm and peri-rolandic brain surgeries. The many advances in motor system assessment achieved in the last two decades undoubtedly improve monitoring efficacy without unduly compromising safety. Future studies and experience will likely clarify existing controversies and bring further advances.

Monitoring of oxygen uptake during general anesthesia would have several benefits, but unfortunately, this is usually not available in the clinical routine situation. The herein proposed formula to calculate oxygen uptake (.VO2) necessitates only the accurate measurement of FIO2 as well as fresh gas flow and composition. Additionally, this method is not affected by the presence of anesthetic gases. The calculation uses the difference in oxygen content between the delivered fresh gas and the resulting FIO2 in the anesthesia circle system. This gap originates from oxygen uptake (that is mainly caused by metabolic oxygen consumption) and is more pronounced if low fresh gas flows are administered. In order to obtain representative results, calculation of .VO2 should be performed only after achievement of respiratory steady state conditions. Due to its simplicity and wide availability, it has the potential to become a valuable extension in anesthesia monitoring during the performance of ...

Neurosurgical, orthopedic and vascular interventions may be associated with an inherent risk of ischemia and structural
damage to the central nervous system. Along with other modalities used to monitor the intraoperative nervous function, registration of evoked responses is intended to provide real-time feedback about the functional integrity of the central nervous system and help to prevent avoidable trauma during surgery. In this review, the principal indications and limitations of monitoring various evoked responses during surgery on the brain and spinal cord are discussed. Current approaches, recent advances and problems associated with intraoperative rhomboid fossa mapping, cranial nerve stimulation and electrooculographic monitoring are presented as well. The authors discuss the effects of general anesthesia on evoked responses and possible ways to avoid signal variability during registration. It is emphasized that only with close cooperation between neurosurgeons, anesthesiologists and neurophysiologists it will be possible to maximize the benefits of intraoperative monitoring of evoked responses and avoid misinterpretation of the results.
Keywords: Neurophysiological Monitoring; Evoked Potentials; Electrooculography; Rhomboid Fossa Mapping; Cranial
Nerve Stimulation.
Abbreviations: AEP: Auditory evoked potential(s); AVM: Arterio-venous malformation; BAEP: Brainstem acoustic
evoked potential(s); CBF: Cerebral blood flow; CMAP: Compound muscle action potential(s); CN: Cranial nerve(s); CNAP: Compound nerve action potential(s); CNS: Central Nervous System; CPA: Cerebellopontine angle; EEG: Electroencephalography; EMG: Electromyography; EOG: Electrooculography; EP: Evoked Potentials; HFS: Hemifacial spasm; ICP:
Intracranial pressure; INM: Intraoperative neuromonitoring; IPL: Interpeak latency; MAC: Minimal alveolar concentration;
MEP: Motor evoked potential(s); MLAEP: Mid-latency auditory evoked potential(s); MR: magnetic resonance; MVD:
Microvascular decompression; SEP: Sensory evoked potential(s); SHA: Superior hypophyseal artery; SSEP: Somatosensory evoked potential(s); TcMEP: Transcranial motor evoked potential(s); VEP: Visual evoked potential(s); TES: Transcranial electrical stimulation; TMS : Transcranial magnetic stimulation.

Objectives: Despite previous lesional and functional neuroimaging studies, the actual role of the left ventral premotor cortex (vPMC), i.e., the lateral part of the precentral gyrus, is still poorly known. Experimental design:We report a series of eight patients with a glioma involving the left vPMC, who underwent awake surgery with intraoperative cortical and subcortical language mapping. The function of the vPMC, its subcortical connections, and its reorganization potential are investigated in the light of surgical findings and language outcome after resection. Principal observations: Electrostimulation of both the vPMC and subcortical white matter tract underneath the vPMC, that is, the anterior segment of the lateral part of the superior longitudinal fascicle (SLF), induced speech production disturbances with anarthria in all cases. Moreover, although some degrees of redistribution of the vPMC have been found in four patients, allowing its partial resection with no permanent speech disorders, this area was nonetheless still detected more medially in the precentral gyrus in the eight patients, despite its invasion by the glioma. Moreover, a direct connection of the vPMC with the SLF was preserved in all cases. Conclusions: Our original data suggest that the vPMC plays a crucial role in the speech production network and that its plastic potential is limited. We propose that this limitation is due to an anatomical constraint, namely the necessity for the left vPMC to remain connected to the lateral SLF. Beyond fundamental implications, such knowledge may have clinical applications, especially in surgery for tumors involving this cortico-subcortical circuit. Hum Brain Mapp 00:000-000,

A variety of technologies have been developed to assist decision-making during the management of patients with acute brain injury who require intensive care. A large body of research has been generated describing these various technologies. The Neurocritical Care Society (NCS) in collaboration with the European Society of Intensive Care Medicine (ESICM), the Society for Critical Care Medicine (SCCM), and the Latin America Brain The Neurocritical Care Society affirms the value of this consensus statement as an educational tool for clinicians.

Object The incidence of postoperative C-5 spinal nerve root palsy following decompressive cervical spinal surgery has been reported to be as high as 12% for anterior procedures and 30% for posterior procedures. The present study was conducted to document the prevalence of iatrogenic C-5 nerve root deficit during anterior cervical spinal surgery, as well as to evaluate the sensitivity and specificity of intraoperative transcranial electrical stimulation (TES)–induced motor evoked potentials (MEPs) and spontaneous electromyographic (EMG) activity for identifying evolving C-5 nerve root impairment. Methods The authors conducted a retrospective study of 238 consecutive anterior cervical spinal procedures performed by a single surgeon at Christiana Care Hospital within a 48-month period. Techniques used to monitor spinal nerve root function included TES-induced MEPs and spontaneous EMG activity from deltoid, biceps, triceps, wrist extensor, and hand intrinsic muscles innervated by the C5...

Significant detrimental intra-operative hemodynamic and respiratory changes occur in the morbidly obese during laparoscopic gastric bypass. Design: Case series. Setting: Tertiary care university hospital. Patients: Thirteen patients, 10 women and 3 men, undergoing uncomplicated laparoscopic gastric bypass for morbid obesity. Interventions: Using a pulmonary artery catheter and an arterial line, we intraoperatively monitored hemodynamic and respiratory parameters. Parameter values were recorded at set points of the procedure, and the changes were statistically analyzed. Results: Significant hemodynamic and respiratory changes, mostly unfavorable, occur in the morbidly obese

To describe accurate, standardized 1h-multimodal neurophysiological monitoring (1h-MNM), while simultaneously recording VEEG, aEEG, and SEP-C bilaterally from median nerves, and to collect neonatal normative SEP-C data related to behavioural states. Twenty healthy, term newborn infants (13 males, 7 females; gestational age 37-42wks; mean 39.6wks, standard deviation [SD] 1.3wks) underwent 1h-MNM within 2 days of life, with focus on recording of the SEP-C (band-pass setting 1-100 Hz, rate of stimulation 1.1 Hz, 50 alternate stimuli). 1h-MNM was easily obtained with identification of cervical (N13) and cortical (N1, P1) SEP-C responses in all infants. SEP-C minimal and maximum N1 latencies/N1-P1 amplitudes were identified, bilaterally, during periods of spontaneous sleep active-quiet-active (AS-QS-AS) and quiet-wakefulness. Minimal latencies and amplitudes occurred in 60% of active sleep/quiet-wakefulness, with the maximums in 70% of quiet sleep. The SEP-C mean values were latencies of...

Background: Common bile duct injuries occur in 0.2% to 0.8% of laparoscopic cholecystectomies (LC). Intraoperative cholangiograms (IOCG) are a useful means of detecting common bile duct injuries in the operating room. Methods: Data were retrospectively reviewed for patients referred for management of common duct injuries from 1996 to 2000. Cost data were obtained from hospital records. Legal settlements were obtained from published sources. Results: Twenty-one patients (0.133%) were found to have bile duct injuries and incurred median hospital stays of 11.5 days at an average cost of $587,491. The average cost of those requiring reoperation was $669,134. The 21 cases in our sample had total charges of $10,819,767. Performing IOCG during each LC in Orange County would have cost $10,669,725. If extrapolated to state and nationwide levels, the savings is far greater. Conclusions: IOCG during LC is a cost-effective means of preventing the costs of delayed recognition of bile duct injuries.

Monitoring depth of anesthesia using the Electroencephalogram (EEG) is a major ongoing challenge for anesthetists. The EEG is the recording of brain electrical activity and it contains valuable information related to the different physiological states of the brain. This paper proposes a novel automated method for assessing the anesthesia depth level which consists of two steps. Initially, the sample entropy and permutation entropy features are extracted from the EEG signal. As EEG derived parameters represent different aspects of EEG features, it would be reasonable to use multiple parameters to assess the effect of anesthetic. These features quantify the amount of complexity or irregularity in EEG data and are conceptually simple, computationally efficient and artifact resistant. Then, the extracted features are used as input to an artificial neural network that is a data processing system based on the structure of a biological nervous system. The experimental results indicate that an overall accuracy of 88% can be obtained during sevoflurane in 17 patients to classify the EEG into awake, light, general and deep anesthetised states. Also this method yields a classification accuracy of 92.4% to distinguish between awake and general anesthesia in an independent database of propofol and desflurane in 129 patients. Considering the high accuracy of this method, a new EEG monitoring system could be developed to assist the anesthesiologist to estimate depth of anesthesia quickly and accurately.

Neurosurgery aims to achieve maximal tumor resection while preserving neurological function. Tools such as neuronavigation, high-field intraoperative magnetic resonance imaging (iMRI), and intraoperative neurophysiological monitoring (IOM) have consistently helped to achieve this goal, but integration has often been difficult. Surgery of eloquent areas requires IOM, which in an operating theater equipped with high-field (1.5-T) iMRI could present several issues. To identify the electrodes types more suitable for IOM in a high-field iMRI operating theater by performing an experimental study on phantoms, to report our experience with platinum-iridium (Pt/Ir) electrodes during surgery, and to prove that integration between IOM with Pt/Ir electrodes and high-field iMRI is safe and reliable. Electrodes of different materials (gold, Pt/Ir, and stainless steel) were tested on jelly phantom and apples to evaluate their safety and compatibility. Subsequently, electrodes were tested on 5 heal...

The modalities examined in previous simultaneity judgment (SJ) were limited to vision, audition, and touch. By contrast, olfaction and gustation have not been addressed to date in SJ. In this study, we constructed a measurement system for performing SJ with three cross-modal, combinations of odor, taste, and light stimuli. Odor and taste stimulators were able to stimulate to only the receptors corresponding to the modalities of each stimulus, without inducing tactile sensation. Furthermore, in order to precisely calculate the time points at which stimulus reached receptors in each trial, we monitored the presented stimuli in real time. After we calculated the actual values of stimulus onset asynchrony (SOA) between standard and comparison stimuli on the basis of the records of real-time monitoring, we evaluated the temporal distributions of simultaneous response rates in each cross-modal combination. When we fitted a Gaussian distribution to these temporal distributions, we observed low error rates in all cross-modal combinations, as demonstrated in SJ using visual, audio, and tactile stimuli. SJ using chemical stimuli and SJ using physical stimuli exhibit the same degree of measurement accuracy. We succeeded in development a high accurate measurement system for SJ using chemical stimuli. We attribute this success to the use of strict real-time monitoring of stimulus presentation.

Individualizing mean arterial blood pressure (MAP) based on cerebral blood flow (CBF) autoregulation monitoring during cardiopulmonary bypass (CPB) holds promise as a strategy to optimize organ perfusion. The purpose of this study was to evaluate the accuracy of cerebral autoregulation monitoring using microcirculatory flow measured with innovative ultrasound-tagged near-infrared spectroscopy (UT-NIRS) noninvasive technology compared with transcranial Doppler (TCD). Sixty-four patients undergoing CPB were monitored with TCD and UT-NIRS (CerOx™). The mean velocity index (Mx) was calculated as a moving, linear correlation coefficient between slow waves of TCD-measured CBF velocity and MAP. The cerebral flow velocity index (CFVx) was calculated as a similar coefficient between slow waves of cerebral flow index measured using UT-NIRS and MAP. When MAP is outside the autoregulation range, Mx is progressively more positive. Optimal blood pressure was defined as the MAP with the lowest Mx ...

Purpose We examined the hypothesis that remifentanil decreases the bispectral index (BIS) as well as blunts cardiovascular responses to tracheal intubation during anesthesia with midazolam. Methods Sixty patients were randomly allocated to three groups according to the dose of remifentanil-0.1 (S), 0.2 (M), or 0.5 (L) lg kg-1 min-1 , respectively. Infusion of remifentanil was started 5 min before the induction of general anesthesia with midazolam 0.2 mg/kg in all groups. Following the administration of vecuronium 0.1 mg/kg, the trachea was intubated 5 min after induction, and the infusion rate of remifentanil was then reduced to 0.05 lg kg-1 min-1 in all groups. Mean arterial blood pressure (MAP), heart rate (HR), BIS, and 95% spectral edge frequency (SEF95) were measured until 10 min after tracheal intubation. Results Infusion of remifentanil alone before the induction of anesthesia did not affect the hemodynamic or electroencephalographic parameters. MAP was significantly decreased after induction in all groups of patients (P \ 0.01), with no differences among the three groups, while it was significantly increased after tracheal intubation in the patients of groups S and M, but not in those of group L. The HR did not change after induction in any of the groups, but it was also significantly increased after tracheal intubation of group S and M patients, although not in those of group L. The BIS decreased after induction, and both the BIS and SEF95 were significantly lower in group L patients than in those of group S (P \ 0.01). All patients were unconscious after induction, and none complained of intraoperative awareness. Conclusion In our patient cohort, remifentanil 0.5 lg kg-1 min-1 effectively decreased the BIS after the induction of general anesthesia with midazolam 0.2 mg/kg and suppressed the increase of MAP and HR in response to subsequent laryngoscopy and tracheal intubation.

Objective Thyroidectomy may be performed for clinical indications that include malignancy, benign nodules or cysts, suspicious findings on fine needle aspiration biopsy, dysphagia from cervical esophageal compression, or dyspnea from airway compression. About 1 in 10 patients experience temporary laryngeal nerve injury after surgery, with longer lasting voice problems in up to 1 in 25. Reduced quality of life after thyroid surgery is multifactorial and may include the need for lifelong medication, thyroid suppression, radioactive scanning/treatment, temporary and permanent hypoparathyroidism, temporary or permanent dysphonia postoperatively, and dysphagia. This clinical practice guideline provides evidence-based recommendations for management of the patient’s voice when undergoing thyroid surgery during the preoperative, intraoperative, and postoperative period. Purpose The purpose of this guideline is to optimize voice outcomes for adult patients aged 18 years or older after thyroi...

Object Transcranial motor evoked potential (TcMEP) monitoring is frequently used in complex spinal surgeries to prevent neurological injury. Anesthesia, however, can significantly affect the reliability of TcMEP monitoring. Understanding the impact of various anesthetic agents on neurophysiological monitoring is therefore essential. Methods A literature search of the National Library of Medicine database was conducted to identify articles pertaining to anesthesia and TcMEP monitoring during spine surgery. Twenty studies were selected and reviewed. Results Inhalational anesthetics and neuromuscular blockade have been shown to limit the ability of TcMEP monitoring to detect significant changes. Hypothermia can also negatively affect monitoring. Opioids, however, have little influence on TcMEPs. Total intravenous anesthesia regimens can minimize the need for inhalational anesthetics. Conclusions In general, selecting the appropriate anesthetic regimen with maintenance of a stable conce...

Perioperative optimalization of haemodynamics is associated with improved post-operative development, as presented in most published studies. This study has confirmed that intra-operative correction of cardiac output back to it's physiological level is associated with improved post-operative course in the group of patients undergoing major elective intraabdominal surgery. Statistically significant decreasing of post-operative complications (4.7% vs 17.7%), decreased length of stay (LOS) in the ICU by 33% and decreased LOS in the hospital by 24% was recorded. Interpretation of the study could be limited by using non-indexed cardiac output values and higher female presentation in the group of patients (although statistically not significant).

Background: Repetitive navigated transcranial magnetic stimulation (rTMS) was recently described for mapping of human language areas. However, its capability of detecting language plasticity in brain tumor patients was not proven up to now. Thus, this study was designed to evaluate such data in order to compare rTMS language mapping to language mapping during repeated awake surgery during follow-up in patients suffering from language-eloquent gliomas. Methods: Three right-handed patients with left-sided gliomas (2 opercular glioblastomas, 1 astrocytoma WHO grade III of the angular gyrus) underwent preoperative language mapping by rTMS as well as intraoperative language mapping provided via direct cortical stimulation (DCS) for initial as well as for repeated Resection 7, 10, and 15 months later.

Objective: This "real-world" study was designed to assess the patterns of regional cerebral oxygen saturation (rSO 2) change during adult cardiac surgery. A secondary objective was to determine any relation between perioperative rSO 2 (baseline and during surgery) and patient characteristics or intraoperative variables. Design: Prospective, observational, multicenter, nonrandomized clinical study. Setting: Cardiac operating rooms at 3 academic medical centers. Participants: Ninety consecutive adult patients presenting for cardiac surgery with or without cardiopulmonary bypass. Interventions: Patients received standard care at each institution plus bilateral forehead recordings of cerebral oxygen saturation with the 7600 Regional Oximeter System (Nonin Medical, Plymouth, MN). Measurements and Main Results: The average baseline (before induction) rSO 2 was 63.9 ؎ 8.8% (range 41%-95%); preoperative hematocrit correlated with baseline rSO 2 (0.48% increase for each 1% increase in hematocrit, p ‫؍‬ 0.008). The average nadir (lowest recorded rSO 2 for any given patient) was 54.9 ؎ 6.6% and was correlated with on-pump surgery, baseline rSO 2 , and height. Baseline rSO 2 was found to be an independent predictor of length of stay (hazard ratio 1.044, confidence interval 1.02-1.07, for each percentage of baseline rSO 2). Conclusions: In cardiac surgical patients, lower baseline rSO 2 value, on-pump surgery, and height were significant predictors of nadir rSO 2 , whereas only baseline rSO 2 was a predictor of postoperative length of stay. These findings support previous research on the predictive value of baseline rSO 2 on length of stay and emphasize the need for further research regarding the clinical relevance of baseline rSO 2 and intraoperative changes.

Spreading depression (SD), a slow propagating depolarization wave, plays an important role in pathophysiology of different neurological disorders. Yet, research into SD-related disorders has been hampered by the lack of non-invasive recording techniques of SD. Here we compared the manifestations of SD in continuous non-invasive electroencephalogram (EEG) recordings to invasive electrocorticographic (ECoG) recordings in order to obtain further insights into generator structures and electrogenic mechanisms of surface recording of SD. SD was induced by KCl application and simultaneous SD recordings were performed by scalp EEG as well as ECoG electrodes of somatosensory neocortex of rats using a novel homemade EEG amplifier, AgCl recording electrodes, and high chloride conductive gel. Different methods were used to analyze the data; including the spectrogram, bi-spectrogram, pattern distribution, relative spectrum power, and multivariable Gaussian fit analysis. The negative DC shifts recorded by scalp electrodes exhibited a high homogeneity to those recorded by ECoG electrodes. Furthermore, this novel method of recording and analysis was able to separate SD recorded by scalp electrodes from non-neuronal DC shifts induced by other potential generators, such as the skin, muscles, arteries, dura, etc. These data suggest a novel application for continuous non-invasive monitoring of DC potential changes, such as SD. Non-invasive monitoring of SD would allow early intervention and improve outcome in SDrelated neurological disorders.

OBJECTIVE Intraoperative overestimation of resection volume in epilepsy surgery is a well-known problem that can lead to an unfavorable seizure outcome. Intraoperative MRI (iMRI) combined with neuronavigation may help surgeons avoid this pitfall and facilitate visualization and targeting of sometimes ill-defined heterogeneous lesions or epileptogenic zones and may increase the number of complete resections and improve seizure outcome. METHODS To investigate this hypothesis, the authors conducted a retrospective clinical study of consecutive surgical procedures performed during a 10-year period for epilepsy in which they used neuronavigation combined with iMRI and functional imaging (functional MRI for speech and motor areas; diffusion tensor imaging for pyramidal, speech, and visual tracts; and magnetoencephalography and electrocorticography for spike detection). Altogether, there were 415 patients (192 female and 223 male, mean age 37.2 years; 41% left-sided lesions and 84.9% tempo...

Maintaining the depth of hypnosis (DOH) during surgery is one of the major objectives of anesthesia infusion system. Continuous administration of Propofol infusion during surgical procedures is essential but increases the undue load of an anesthetist in operating room working in a multitasking setup. Manual and target controlled infusion (TCI) systems are not good at handling instabilities like blood pressure changes and heart rate variability arising due to interpatient variability. Patient safety, large interindividual variability, and less postoperative effects are the main factors to motivate automation in anesthesia. The idea of automated system for Propofol infusion excites the control engineers to come up with a more sophisticated and safe system that handles optimum delivery of drug during surgery and avoids postoperative effects. In contrast to most of the investigations with linear control strategies, the originality of this research work lies in employing a nonlinear cont...

Many different robotic systems have been developed for invasive medical procedures. In this article we will focus on robotic systems for image-guided interventions such as biopsy of suspicious lesions, interstitial tumor treatment, or needle placement for spinal blocks and neurolysis. Medical robotics is a young and evolving field and the ultimate role of these systems has yet to be determined. This paper presents four interventional robotics systems designed to work with MRI, CT, fluoroscopy, and ultrasound imaging devices. The details of each system are given along with any phantom, animal, or human trials. The systems include the AcuBot for active needle insertion under CT or fluoroscopy, the B-Rob systems for needle placement using CT or ultrasound, the INNOMOTION for MRI and CT interventions, and the MRBot for MRI procedures. Following these descriptions, the technology issues of image compatibility, registration, patient movement and respiration, force feedback, and control mode are briefly discussed. It is our belief that robotic systems will be an important part of future interventions, but more research and clinical trials are needed. The possibility of performing new clinical procedures that the human cannot achieve remains an ultimate goal for medical robotics. Engineers and physicians should work together to create and validate these systems for the benefits of patients everywhere.

Electroencephalography (EEG) has been widely utilized to measure the depth of anaesthesia (DOA) during operation. However, the EEG signals are usually contaminated by artifacts which have a consequence on the measured DOA accuracy. In this study, an effective and useful filtering algorithm based on multivariate empirical mode decomposition and multiscale entropy (MSE) is proposed to measure DOA. Mean entropy of MSE is used as an index to find artifacts-free intrinsic mode functions. The effect of different levels of artifacts on the performances of the proposed filtering is analysed using simulated data. Furthermore, 21 patients' EEG signals are collected and analysed using sample entropy to calculate the complexity for monitoring DOA. The correlation coefficients of entropy and bispectral index (BIS) results show 0.14 ± 0.30 and 0.63 ± 0.09 before and after filtering, respectively. Artificial neural network (ANN) model is used for range mapping in order to correlate the measure...

A variety of optical techniques utilizing nearinfrared (NIR) light are being proposed for intraoperative breast tumor margin assessment. However, immediately following a lumpectomy excision, the margins are inked, which preserves the orientation of the specimen but prevents optical interrogation of the tissue margins. Here, a workflow is proposed that allows for both NIR optical assessment following full specimen marking using molecular dyes which have negligible absorption and scattering in the NIR. The effect of standard surgical inks in contrast to molecular dyes for an NIR signal is shown. Further, the proposed workflow is demonstrated with full specimen intraoperative imaging on all margins directly after the lumpectomy has been excised and completely marked. This work is an important step in the path to clinical feasibility of intraoperative breast tumor margin assessment using NIR optical methods without having to compromise on the current clinical practice of inking resected specimens for margin orientation. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

Objective. To determine the physiologic effectiveness of multi-site, multi-depth sacral lateral branch injections. Design. Double-blind, randomized, placebo-controlled study. Setting. Outpatient pain management center. Patients. Twenty asymptomatic volunteers. Background. The dorsal innervation to the sacroiliac joint (SIJ) is from the L5 dorsal ramus and the S1-3 lateral branches. Multi-site, multi-depth lateral branch blocks were developed to compensate for the complex regional anatomy that limited the effectiveness of single-site, single-depth lateral branch injections. Interventions. Bilateral multi-site, multi-depth lateral branch green dye injections and subsequent dissection on two cadavers revealed a 91% accuracy with this technique. Session 1: 20 asymptomatic subjects had a 25-g spinal needle probe their interosseous (IO) and dorsal sacroiliac (DSI) ligaments. The inferior dorsal SIJ was entered and capsular distension with contrast medium was performed. Discomfort had to occur with each provocation maneuver and a contained arthrogram was necessary to continue in the study. Session 2: 1 week later; computer randomized, double-blind multi-site, multi-depth lateral branch blocks injections were performed. Ten subjects received active (bupivicaine 0.75%) and 10 subjects received sham (normal saline) multi-site, multi-depth lateral branch injections. Thirty minutes later, provocation testing was repeated with identical methodology used in session 1. Outcome measures. Presence or absence of pain for ligamentous probing and SIJ capsular distension. Results. Seventy percent of the active group had an insensate IO and DSI ligaments, and inferior dorsal SIJ vs 0-10% of the sham group. Twenty percent of the active vs 10% of the sham group did not feel repeat capsular distension. Six of seven subjects (86%) retained the ability to feel repeat capsular distension despite an insensate dorsal SIJ complex. Conclusion. Multi-site, multi-depth lateral branch blocks are physiologically effective at a rate of 70%. Multi-site, multi-depth lateral branch blocks do not effectively block the intra-articular portion of the SIJ. There is physiological evidence that the intra-articular portion of the SIJ is

The authors illustrate some relevant emerging topics in pediatric anesthesia. Endotracheal cuffed tubes have entered into routine clinical practice in younger patients. Concerns about tracheal stenosis were overcome when manufactures began to produce a new class of high volume, low pressure endotracheal tubes. Ultrasound-guided central venous cannulation helped anesthesiologists and intensivists to more efficaciously and safely perform the invasive monitoring required by ever more invasive surgical procedures. The utility of ultrasonography in peripheral nervous blocking has also been demonstrated. Better knowledge of the pathophysiology of both hypovolemic shock and coagulation dysfunction helped made it possible to face and successfully perform even major surgical procedures and treat more dramatic trauma. The introduction of devices to monitor anesthesia depth helped clinicians to better understand the pharmacodynamic effects of anesthetics, resulting in the maintenance of a more...

Continuous infusion of intravenous anesthetics can be achieved either by a manually controlled infusion (MCI) pump, or by a computer-assisted continuous infusion (CACI) pharmacokinetic model-driven infusion system. Randomized double-blind comparisons of the two infusion systems for general anesthesia were performed in 24 patients undergoing coronary artery bypass grafting. Patients were allocated to receive continuous infusions of midazolam and fentanyl by either a MCI device or CACI. Midazolam and fentanyl infusions were independently titrated to maintain hemodynamic stability, defined as mean arterial pressure (MAP) and heart rate (HR) within 20% of baseline values. As directed by the study design, comparable hemodynamic controi was achieved in both groups. Mean plasma fentanyl concentrations measured at specific timepoints were similar between groups. The plasma midazolam level for induction was 196 + 139 ng/mL in the CACI group and 300 * 128 ng/mL in the MCI group, and the fentanyl level was similar in both groups, 6.7 ? 1.9 ng/mL in CACI and 6.3 +: 4.6 ng/mL in the MCI group. The drug levels were lower (P 5 .05) for midazolam during maintenance of anesthesia and similar for fentanyl during the maintenance of anesthesia. In the MCI group, the il"(?rlo(? duration of anesthesia was 246:5 2 35:O minutes;