Intraoperative Monitoring System Research Articles

Developing a piezoresistive sensor based bionic neurological intraoperative monitoring system for spine surgery skill training.

This research aims to tackle the limitations faced in surgical education nowadays, particularly in the complex field of spinal cord tumor removal surgery. An innovative flexible piezoresistive sensor designed to mimic a motor nerve was developed and integrated into a bionic spine surgery simulation system, allowing for the intraoperative nerve monitoring possible during simulated tumor removal surgeries. The motor nerve, fabricated using a combination of carbon nanotubes and silicone rubber, exhibited a strong correlation between applied force and resultant changes in resistance, as confirmed by experimental results. This creative system can play an important role in providing valuable feedback for training doctors, facilitating the assessment of surgical precision and success, and enabling doctors to take necessary precautions to minimize the risk of nerve damage in real surgical scenarios. Ultimately, this proposed system has the potential to elevate the standard of surgical education, foster skill development among doctors, and significantly contribute to enhanced patient care and recovery.

Electroencephalographic monitoring of anesthesia during surgical procedures in mice using a modified clinical monitoring system

Monitoring brain activity and associated physiology during the administration of general anesthesia (GA) in mice is pivotal to guarantee postanesthetic health. Clinically, electroencephalogram (EEG) monitoring is a well-established method to guide GA. There are no established methods available for monitoring EEG in mice (Mus musculus) during surgery. In this study, a minimally invasive rodent intraoperative EEG monitoring system was implemented using subdermal needle electrodes and a modified EEG-based commercial patient monitor. EEG recordings were acquired at three different isoflurane concentrations revealing that surgical concentrations of isoflurane anesthesia predominantly contained burst suppression patterns in mice. EEG suppression ratios and suppression durations showed strong positive correlations with the isoflurane concentrations. The electroencephalographic indices provided by the monitor did not support online monitoring of the anesthetic status. The online available suppression duration in the raw EEG signals during isoflurane anesthesia is a straight forward and reliable marker to assure safe, adequate and reproducible anesthesia protocols.

Cerebral oximetry monitoring by means of INVOS-4100 as a predictor of ischemic events during carotid endarterectomy.

Several methods have been proposed to monitor cerebral perfusion during carotid endarterectomy (CEA), with the purpose of minimizing the risk of perioperative stroke. The INVOS-4100 is able to detect cerebral oxygen saturation providing an intraoperative real-time monitoring system of cerebral oximetry. The aim of this study was to evaluate the performance of the INVOS-4100 in predicting cerebral ischemia during CEA. Between January 2020 and May 2022, 68 consecutive patients were scheduled for CEA either under general anesthesia or regional anesthesia with deep and superficial cervical block. Vascular oxygen saturation was recorded continually through INVOS before and during clamping of the ICA. Awake testing was performed in the group of patients undergoing CEA under regional anesthesia. Sixty-eight patients were included; 43 were males (63.2%). Severe stenosis of the artery was present in 92%. Forty-one (60.3%) patients were monitored by INVOS, while 22 (39.7%) underwent awake testing. Mean clamping time was 20 ± 6.6 min. Patients undergoing awake testing had a lower hospital stay and ICU stay during admission (p = 0.011 and p = 0.007 respectively). Comorbidities correlated with a higher ICU stay (p < 0.05). The INVOS monitoring was able to predict ischemic events with a sensitivity of 98% (AUC = 0.976). The present study demonstrates that cerebral oximetry monitoring was a strong predictor of cerebral ischemia, although it was not possible to determine the non-inferiority of cerebral oximetry compared to awake testing. Nonetheless, the use of cerebral oximetry evaluates only perfusion in the superficial brain tissue and an absolute rSO2 value corresponding to significant cerebral ischemia has not been established. Therefore, larger prospective studies that correlate cerebral oximetry with neurologic outcomes are needed.

A simple marking system for accurate intraoperative monitoring and adjustment of cyclotorsion strabismus surgery.

Ocular cyclotorsion is treatable only with surgery. The surgical procedure must be tailored individually to the specific etiologies causing the horizontal and vertical strabismus and its torsional components. An adjustable surgical approach is often used for postoperative or intraoperative adjustments. However, the methods currently used have some limitations. In this study, we propose a simple intraoperative marking system for all cyclotorsion correction surgery. The proposed marking system used three sets of surface markers: external horizontal markings, ocular horizontal markings, and surgical torsion markings, drawn in sequence. We retrospectively analyzed the surgical results using this novel marking system in this single-center, single-surgeon study. Fifteen patients with cyclotorsion who underwent treatment using the proposed marking system as an intraoperative aid between August 2019 and August 2021 were included. The medical charts were thoroughly reviewed, and the pre-and postoperative subjective and objective cyclotorsion were analyzed. Among the study subjects (10 males, 5 females; age range: 6-89 years), 13 had excyclotorsion and 2 incyclotorsion. Preoperative mean net subjective cyclotorsion measured by the double Maddox rod (DMR) test was 6.0° (standard deviation: 10.8°) and mean net disc-to-fovea angle (DFA) was 20.23° (13.21°). The postoperative net DMR and DFA were 0.2° (2.1°) and 14.09° (5.97°), respectively. The mean absolute net DMR and DFA being treated were 9.8° (4.8°) and 9.76° (4.61°). Overall, the proposed intraoperative marking system is a simple and quantitative method to assess, monitor, and adjust the torsional aspect for all strabismus surgeries.

Performance of the Hypotension Prediction Index May Be Overestimated Due to Selection Bias.

The Hypotension Prediction Index is a proprietary prediction model incorporated into a commercially available intraoperative hemodynamic monitoring system. The Hypotension Prediction Index uses multiple features of the arterial blood pressure waveform to predict hypotension. The index publication introducing the Hypotension Prediction Index describes the selection of training and validation data. Although precise details of the Hypotension Prediction Index algorithm are proprietary, the authors describe a selection process whereby a mean arterial pressure (MAP) less than 75 mmHg will always predict hypotension. We hypothesize that the data selection process introduced a systematic bias that resulted in an overestimation of the current MAP value's ability to predict future hypotension. Since current MAP is a predictive variable contributing to Hypotension Prediction Index, this exaggerated predictive performance likely also applies to the corresponding Hypotension Prediction Index value. Other existing validation studies appear similarly problematic, suggesting that additional validation work and, potentially, updates to the Hypotension Prediction Index model may be necessary.

Thyroidectomy in Australia 2022: lessons from 21,000 consecutive cases.

In this article, we aim to describe our modern-day approach to total thyroidectomy, detailing the subtle refinements of our technique, as it has evolved over three decades and 21 000 cases. Since Delbridge's seminal paper in 2003, the major changes to our approach include a retrograde approach to the recurrent laryngeal nerve that allows dissection of the distal RLN from fascial bands within the ligament of Berry before medialisation of the thyroid lobe. Routine use of intraoperative nerve monitoring systems has increased our awareness of temporary neuropraxia, facilitated a reduction in the risk of bilateral RLN palsy and improved our identification and preservation of the external branch of the superior laryngeal nerve. The increasing use of advanced energy devices has been associated with a reduction in post-operative haematoma rates. We adopt a low threshold to parathyroid auto-transplantation, unless all glands are assessed to be clearly not at risk, and routinely supplement patients with Caltrate in the immediate post-operative period to minimize the risk of symptomatic hypocalcaemia. Ultimately, when we reflect on the subtle refinements that have contributed to improved outcomes, the fundamental principles of exposure and dissection that have evolved over decades remain the basis of our surgical approach and must continue to do so.

Understanding the Molecular Mechanism of Vestibular Schwannoma for Hearing Preservation Surgery: Otologists’ Perspective from Bedside to Bench

Vestibular schwannoma is a clinically benign schwannoma that arises from the vestibulocochlear nerve that causes sensorineural hearing loss. This tumor is clinically and oncologically regarded as a benign tumor as it does not metastasize or invade surrounding tissues. Despite being a benign tumor, its management is difficult and controversial due to the potential serious complications, such as irreversible sensorineural hearing loss, of current interventions. Therefore, preventing hearing loss due to the natural course of the disease and complications of surgery is a challenging issue for an otologist. Improvements have been reported recently in the treatment of vestibular schwannomas. These include advances in intraoperative monitoring systems for vestibular schwannoma surgery where the risk of hearing loss as a complication is decreased. Precise genomic analysis of the tumor would be helpful in determining the characteristics of the tumor for each patient, leading to a better hearing prognosis. These procedures are expected to help improve the treatment of vestibular schwannomas. This review summarizes recent advances in vestibular schwannoma management and treatment, especially in hearing preservation. In addition, recent advances in the understanding of the molecular mechanisms underlying vestibular schwannomas and how these advances can be applied in clinical practice are outlined and discussed, respectively. Moreover, the future directions from the bedside to the bench side are presented from the perspective of otologists.

Separation of cardiogenic oscillations from airflow waveforms using singular spectrum analysis

Background and ObjectiveAirflow fluctuations caused by cardiac contraction can trigger inappropriate ventilator pressure support in anesthesia machines and intensive care unit mechanical ventilators. Removal of this cardiogenic artifact from the airflow signal would improve ventilator function. The application of singular spectrum analysis (SSA) to remove cardiogenic oscillations from ventilator airflow signals recorded from intubated, mechanically ventilated patients under general anesthesia was evaluated in this study. MethodsAirflow (liters/minute) and CO2 (mmHg) data were collected at a sampling rate of 125 Hz from the intraoperative monitoring systems using special-purpose software. Simultaneous electrocardiogram signals (mV) were also collected at a sampling rate of 250 Hz. One-dimensional SSA was performed offline on normalized airflow signals using a window length sufficient to span one period of typical respiratory variation. The main components of the airflow waveform are respiratory excursions and cardiogenic oscillations, with respiratory excursions more slowly varying and of higher magnitude. The smooth respiratory waveform was formed from elementary reconstructed series corresponding to the highest singular values obtained with SSA analysis. The quality of respiratory waveform extraction with SSA was determined by calculating the weighted correlation between the selected elementary reconstructed series. ResultsAirflow data was recorded from 6 patients. The respiratory component of the airflow signal without cardiogenic oscillations was reconstructed from elementary series corresponding to singular values of highest magnitude. The weighted correlations obtained were greater than 0.96 in the majority of patients studied. Cardiogenic oscillations were reconstructed from elementary reconstructed series corresponding to singular values of lower magnitude. ConclusionsSSA is effective in extracting higher amplitude respiratory excursions while excluding lower amplitude cardiogenic oscillations and noise from the airflow signal. This study demonstrates that suppression of the cardiogenic artefact with SSA is computationally feasible to augment ventilator performance.

Augmented vertical rectus transpositions: Intraoperative measurement of torsion following sequential muscle detachment.

After vertical recti transposition surgery, a torsional change may occur. We hypothesized that step-by-step monitoring of the intraoperative torsional position of the eye can avoid any unexpected complications and identify critical moments of surgery that may have adverse effects. Nine patients with sixth nerve palsy that underwent complete transposition of the superior (SR) and inferior rectus (IR) muscles to the lateral rectus muscle by means of the technique of augmented vertical recti transposition were prospectively included. The torsional position of the eye was recorded at eight stages of the procedure. We observed two distinct patterns of induced torsional deviation during partial disinsertion of a vertical rectus muscle depending on whether disinsertion began medially or laterally, after cutting about 3/4 of the muscle fibers: ¾ nasal disinsertion of the SR and ¾ temporal disinserton of the IR caused intorsion, ¾ temporal disinsertion of the SR and ¾ nasal disinsertion of the IR caused extorsion. Torsion improved after the vertical rectus was attached temporally to the sclera along the spiral of Tillaux with tying of the augmentation suture to the LR. The greatest change in torsion was from ¾ temporal disinsertion of the SR (5°extorsion), to reattachment along the spiral of Tillaux temporally (5°intorsion). The SR and IR have different torsional effects, which only appears when more than half of the fibers are detached. Augmented transposition does not cause any additional torsional effects. This intraoperative monitoring system can be used to detect unintended torsional complications, especially during transposition surgery.

The usefulness of intraoperative neurological monitoring for esophageal cancer with double aortic arch; a case report

BackgroundDouble aortic arch (DAA) is a congenital anomaly of the aorta. Esophageal cancer with DAA is rare, and consequently, the appropriate surgical approach has not been standardized. Herein, we report the utilization of intraoperative neurological monitoring (IONM) system to preserve the function of the recurrent laryngeal nerve.Case presentationA 79-year-old man with esophageal cancer was diagnosed with DAA incidentally. The descending aorta was located on the right side of the thoracic vertebrae. Safe dissection of the mediastinal lymph nodes was difficult using the right transthoracic approach because of the anatomical abnormalities. During surgery, we used cervical mediastinoscopy combined with the IONM system to preserve the bilateral recurrent laryngeal nerves. Severe complications, including recurrent nerve palsy, were not observed postoperatively.ConclusionIONM may be useful for evaluation of the function of the recurrent laryngeal nerve, and it would be suitable for atypical cases of esophageal cancer.

Killian-Jamieson diverticulum safely resected using a manual intraoperative neural monitoring system: a case report

BackgroundKillian-Jamieson diverticulum is a rare pharyngoesophageal diverticulum. The risk of intraoperative injury of the recurrent laryngeal nerve (RLN) is high during surgical resection of Killian-Jamieson diverticulum because the RLN usually runs next to the base of the diverticulum. We present a case of Killian-Jamieson diverticulum that was safely resected with effective use of an intraoperative nerve monitoring (IONM) system with a handheld stimulating probe to prevent RLN injury.Case presentationA 69-year-old man complaining of dysphagia was diagnosed with Killian-Jamieson diverticulum and underwent open transcervical diverticulectomy. Because the anterior aspect of the diverticulum was expected to be close to the RLN, the accurate location of the RLN was checked during dissection by intermittent stimulation using a handheld probe of the IONM system to avoid mechanical and thermal injury. The diverticulum was transected longitudinally using a linear stapler, and the staple line was buried using absorbable sutures from the distal end. During its closure, RLN was identified very close to the diverticulum stump by IONM, and the upper side of the stump was left unburied to avoid RLN injury. The postoperative course was uneventful and the patient was discharged on postoperative day 7. Postoperative evaluation showed no vocal cord paralysis.ConclusionIONM may be beneficial during open surgery for Killian-Jamieson diverticulum, which usually protrudes just lateral to the RLN.

A Novel Passive Method for the Assessment of Skin-Electrode Contact Impedance in Intraoperative Neurophysiological Monitoring Systems

Intraoperative Neurophysiological Monitoring is a set of monitoring techniques consisting of reading electrical activity generated by the nervous system structures during surgeries. In order to guarantee signal quality, contact impedance between the sensing electrodes and the patient’s skin needs to be as low as possible. Hence, monitoring this impedance while signals are measured is an important feature of current medical devices. The most commonly used technique involves injection of a known current and measurement of the voltage drop in the contact interface. This method poses several problems, such as power consumption (critical in battery-powered systems), frequency dependency and regulation issues, which are overcome by using a passive method. The fundamentals of the method proposed in this paper are based on the utilization of the variation suffered by the input random signal when a known resistance is connected in parallel to the input terminals of the low-noise amplifier (LNA) of the analog front-end of the acquisition system. Controlling the connection of the resistors and computing the root mean square of the LNA output voltage has been proved to be a useful tool to assess that the contact impedance is suitably low, allowing the user to know if the neural measurements obtained are valid.

Monitoring hip posture in total hip arthroplasty using an inertial measurement unit-based hip smart trial system: An in vitro validation experiment using a fixed pelvis model

Intraoperative measurement of hip posture is the basis for assessing hip range of motion (ROM) and predicting postoperative functional limits allowable for activities of daily living. Although computer navigation for total hip arthroplasty (THA) has improved the accuracy of intraoperative ROM evaluation, it has not gained widespread popularity due to its complex and time-consuming protocol. We therefore developed an inertial measurement unit-based hip smart trial system (IMUHST) for intraoperative monitoring of hip posture. An in vitro validation experiment was conducted using bone models with a three-dimensional measurement model as the reference standard. The absolute mean error, Bland – Altman analysis and intra-class correlation coefficient demonstrated that the validity and reliability of this system meets the requirement for clinical application. Given that monitoring posture is the basis for evaluating the direction(s) of potential impingement, subluxation and dislocation, the IMUHST is a promising development direction of computer assisted surgery in THA.

Novel method of intraoperative ocular movement monitoring using a piezoelectric device: experimental study of ocular motor nerve activating piezoelectric potentials (OMNAPP) and clinical application for skull base surgeries.

Intraoperative monitoring systems that utilize various evoked potentials for the detection and/or preservation of cranial nerves have become increasingly common due to recent technical and commercial developments, particularly during skull base surgeries. We established a novel system for the intraoperative monitoring of the extraocular motor nerves (eOMNs) using a piezoelectric device capable of detecting imperceptible vibrations induced by ocular movement, with sensors placed on the eyelids alone. We first evaluated the efficacy and reliability of this device for the intraoperative monitoring of eOMNs in two Beagle dogs. Based on the results, we then determined the appropriate stimulation parameters for use in human surgical cases involving removal of various skull base tumors. Animal experiments revealed that a 0.4mA monopolar electrical stimulation was required to elicit significant responses and that these responses were not inferior to those obtained via the electrooculogram/electromyogram. Significant responses were also detected in preliminary clinical investigations in human patients, following both direct and indirect monopolar electrical stimulation of the oculomotor and abducens nerves, although obtaining responses from the trochlear nerve was difficult. Intraoperative monitoring using a piezoelectric device provides a simple and reliable method for detecting eOMNs, especially the oculomotor and abducens nerves. This monitoring system can be adapted to various surgeries for skull base tumor.

PS01.189: A STUDY ON THE UTILITY OF INTRAOPERATIVE NEUROSTIMULATION MONITORING SYSTEM FOR RECURRENT LARYNGEAL NERVE IN ESOPHAGECTOMY

Abstract Background Recurrent laryngeal nerve paralysis in esophagectomy is one of the most concerned complications. In recent years, intraoperative neurostimulation monitoring system (IONM) in thyroid surgery have been widespread for identification of recurrent laryngeal nerve and assessment of soundness. Therefore, IONM is often used during esophagectomy in Japan. In this study, we examined the efficacy of IONM in the patients undergoing esophagectomy. Methods Of 66 patients underwent esophagectomy since April 2015 until December 2017, IONM used in 27 patients in the surgery for the examination of recurrent nerve paralysis. We retrospectively reviewed these cases for intraoperative findings, neurostimulation monitoring findings and their outcomes. Results Of 27 patients, 25 were male and two were female, and the median age at operation was 66 years old. Although IONM was used in cervical lymph node dissection, there were no vocal cord responses in 5 patients (left side in 4 and right side in 1) with stimulation of the vagus nerve. Because all patients had no vocal cord paralysis due to stimulation of the cervical recurrent laryngeal nerve, it was diagnosed that there was the recurrent laryngeal nerve injury due to thoracic para recurrent nerve lymph node dissection. IONM was able to facilitate the identification and preservation of cervical recurrent nerve in all patients. Three out of 5 patients with no vocal cord response by IONM were confirmed recurrent laryngeal nerve paralysis in postoperative endoscope. In patients with vocal cord paralysis by IONM, it was possible to carefully performed postoperative management. On the other hand, in patients without paralysis, extubation on the operation day seemed possible without the concern for aspiration. Conclusion By using IONM in esophagectomy, we were able to evaluate the damage of the recurrent laryngeal nerve in real-time. Confirming the intraoperative recurrent nerve injuries is important for postoperative management or prediction of postoperative aspiration pneumonia. IONM in esophagectomy was useful not only in terms of surgical procedures but also in the evaluation of postoperative management. Disclosure All authors have declared no conflicts of interest.

O177 Novel method of intraoperative ocular movement monitoring using a piezoelectric device: Experimental study of OMNAPP (ocular motor nerve activating piezoelectric potentials) and clinical application for skull base surgeries

Objectives Intraoperative monitoring for the extraocular motor nerves (eOMNs) using electromyograms are not widely accepted due to their inherent invasiveness. We established a novel system for the intraoperative monitoring of eOMNs using a piezoelectric device capable of detecting imperceptible vibrations induced by ocular movement, with sensors placed on the eyelids alone. Methods We first evaluated the efficacy and reliability of this system for the intraoperative monitoring of eOMNs in two Beagle dogs. The oculomotor nerve of each dog was detected under general anesthesia, following which the detection of ocular movement was evaluated by providing varying levels of stimulation to the nerve. Based on the results of these animal experiments, we then determined the appropriate stimulation parameters for use in some surgical cases of various skull base tumors. Results Animal experiments revealed that 0.4–0.6 mA of monopolar electrical stimulation was required to elicit significant responses, which were not inferior to those obtained via the electrooculogram/electromyogram. Significant responses were also detected in preliminary clinical investigations in human patients following both direct and indirect monopolar electrical stimulation of the oculomotor and abducens nerves, although it was difficult to obtain responses from the trochlear nerve. Conclusions Our findings indicate that intraoperative monitoring system using a piezoelectric device represents a simple and reliable method that can be adapted to various skull base surgeries. Further studies are required to investigate functional outcomes in patientstreated using this intraoperative monitoring system. Significance This intraoperative monitoring system (We call as OMNAPP system) for the eOMNs is useful for skull base surgeries including various transcranial approaches.

Intraoperative correction of hemodynamic instability in patients with pheochromocytoma

Aim. Development, clinical evaluation and implementation of intraoperative hemodynamic monitoring system to ensure the modern anesthetic management of laparoscopic adrenalectomy in patients with pheochromocytoma in a specialized endocrinology center based on the algorithm of staged perioperative hemodynamic management (SPOHM).Materials and methods. We performed the analysis and comparison of hemodynamic parameters at the stage of selection of the tumor of the adrenal gland, after the clip overlay and intersection v. Centralis in 33 women operated for pheochromocytomas during 2013-2016 in the department of endocrine surgery of Ukrainian Scientific and Practical Center of Endocrine Surgery, Transplantation of Endocrine Organs and Tissues of Public of the Ministry of Health of Ukraine. Adrenal pheochromocytoma was removed by minimally invasive technologies — video-assisted laparoscopic adrenalectomy.Results and discussion. All patients had significantly (p &lt;0.001) increased levels of daily urine metanephrines to 1831.6±337.9 mg/24 h (control – 169.3±12.7 mg/24 h). In accordance to the SPOHM algorithm we used doxazosin 10.0±1.0 mg or urapidil 144.0±11.2 mg in 2 divided doses in the first stage. In a second step we performed hemodilution using 10% solution of HES (200/0.5) and controlled antihypertensive therapy by infusion of urapidil with an average speed 9.7±1.9 mg/hr. In the third stage intraoperative infusion rate of urapidil was 1.25±0.08 mg/min (at the moment of surgical separation of adrenal pheochromocytoma optional bolus of urapidil 25-50 mg was administered if even the slightest increase in blood pressure appears). After removal of the tumor we observed stabilization of hemodynamic parameters in the absence of significant hypotension. Sympathomimetics were not used. In the fourth stage prevention of adrenal insufficiency and hypovolemia was performed.Conclusions. The introduction of anesthetic management of patients with pheochromocytoma in the specialized endocrinology center provided high efficiency and safety of hemodynamic monitoring in laparoscopic adrenalectomy. The SPOHM algorithm in preparation for surgery and during surgery is an effective, easy to manage and secure method of hemodynamic parameters stabilization.

A New Intraoperative Real-time Monitoring System for Reconstructive Middle Ear Surgery: An Experimental and Clinical Feasibility Study.

Electromagnetical excitation of ossicular vibration is suitable for middle ear transmission measurements in the experimental and clinical setting. Thereby, it can be used as a real-time monitoring system for quality control in ossiculoplasty. Positioning and coupling of middle ear prosthesis are a precondition for good postoperative hearing results, but at the same time completely dependent upon the surgeon's subjective judgment during surgery. We evaluated an electromagnetically driven measurement system that enables for in vitro and in vivo transmission measurements and thus can be used as a real-time monitoring tool in ossicular reconstruction. For electromagnetical excitation a magnet was placed on the umbo of the malleus handle and driven by a magnetic field. The induced stapes displacement was picked up by laser Doppler vibrometry on the footplate. Measurements were performed on the intact ossicular chain in five cadaveric temporal bones and during five cochlear implant surgeries. Additionally, two ossiculoplasties were performed under real-time transmission feedback with the monitoring system. Experimentally, the equivalent sound pressure level of the electromagnetic excitation was about 70 to 80 dB which is 10 to 20 dB less than the acoustic stimulation. In the intraoperative setup the generated stapes displacements were about 5 to 20 dB smaller compared with the temporal bone experiments. Applied as real-time feedback system, an improvement in the middle ear transfer function of 4.5 dB in total and 20 dB in partial ossicular reconstruction were achieved. The electromagnetical excitation and measurement system is comparable to the gold standard with acoustical stimulation in both, the experimental setup in temporal bones as well as in vivo. The technical feasibility of the electromagnetical excitation method has been proven and it is shown that it can be used as a real-time monitoring system for ossiculoplasty in the operation room.

Surgeon-driven neurophysiologic monitoring in a spinal surgery population.

This is a prospective observational study examining the use of a surgeon-driven intraoperative neurophysiologic monitoring system. Intraoperative neurophysiologic monitoring is becoming the standard of care for spinal surgeries with potential post-operative neurologic deficits. This standard applies to both adult and pediatric spinal surgery, but a shortage of appropriately trained and certified technologists and physiologists can compromise monitoring capabilities in some centers. A surgeon-driven, intra-operative monitoring system in the absence of a technologist or physiologist was examined for safety and efficacy. One hundred thirty-five patients undergoing a variety of spinal procedures were monitored intra-operatively using a surgeon-driven neuro-monitoring system over a period of 80 months. Intraoperative monitoring included serial motor evoked potentials via an automated system that provided visual and audible feedback directly to the operative surgeon. Changes in monitoring and any corresponding surgical responses were evaluated and compared with postoperative neurological status. Of the 135 patients studied, intraoperative adjustments based on neuro-monitoring took place in four patients (3.0%): following reduction in spondylolisthesis, during instrumentation and fusion for a large kyphoscoliosis deformity, due to low hemoglobin, and because of traction. In all cases, surgical and/or anaesthetic modification restored MEPs toward baseline values. The accuracy of the neuro-monitoring results was sensitive to narcotics, benzodiazepines and changes in haemoglobin concentrations. No new postoperative deficits were observed in any patients in the cohort. The authors concluded that surgeon-driven neuro-monitoring was a safe and effective means of intraoperative neuro-monitoring during spinal surgery. It reliably detected intraoperative insults, which could potentially have resulted in postoperative neurologic compromise, and was not associated with any false-negative results in this cohort. Utility of surgeon-driven monitoring, using validated algorithms, may provide an option for this added safety measure even in cases where monitoring personnel are unavailable.

55. Intraoperative monitoring system (IOM). Its application in lumbo-sacral lesions

Objective Clinical and neurophysiological evaluation in patients with lumbo-sacral lesions, and intraoperative (IOM) and postsurgical assessment. Material and methods We studied 44 patients clinically and electrophysiologically, complaining spine lumbosacral lesions (tumors, lumbar canal stenosis, tethered cord). IOM was performed using SEP, MEP, continuous and triggered EMG, using Neuronic 5 (SA) equipment, and IMO specially designed software for intraoperative monitoring (EMG WORKPLACE AND MNIO 1.0). Results Electrophysiological signals changes after surgery were correlated with clinical scale scores showing dysfunction or functional improvement. IOM showed in 9.4% of patients, signs of alarm indicating a neural damage. In 3.7% of cases after surgical decompression, P40 cortical response reappeared (P40), with increments of amplitude and latency decrement. In 87% of cases, no changes were demonstrated (signs of good prognosis). Conclusions Multimodal IOM allows assessing somatic and motor pathways, showing signs of alarms during the neurosurgical procedures. Significance The development of a specially designed IOM software is an effective tool for an early detection of functional abnormalities during spine surgery.