Intraoperative Monitoring Modalities Research Articles

Integrated multi-modality image-guided navigation for neurosurgery: open-source software platform using state-of-the-art clinical hardware

PurposeImage-guided surgery (IGS) is an integral part of modern neuro-oncology surgery. Navigated ultrasound provides the surgeon with reconstructed views of ultrasound data, but no commercial system presently permits its integration with other essential non-imaging-based intraoperative monitoring modalities such as intraoperative neuromonitoring. Such a system would be particularly useful in skull base neurosurgery.MethodsWe established functional and technical requirements of an integrated multi-modality IGS system tailored for skull base surgery with the ability to incorporate: (1) preoperative MRI data and associated 3D volume reconstructions, (2) real-time intraoperative neurophysiological data and (3) live reconstructed 3D ultrasound. We created an open-source software platform to integrate with readily available commercial hardware. We tested the accuracy of the system’s ultrasound navigation and reconstruction using a polyvinyl alcohol phantom model and simulated the use of the complete navigation system in a clinical operating room using a patient-specific phantom model.ResultsExperimental validation of the system’s navigated ultrasound component demonstrated accuracy of <4.5,hbox {mm} and a frame rate of 25 frames per second. Clinical simulation confirmed that system assembly was straightforward, could be achieved in a clinically acceptable time of <15,hbox {min} and performed with a clinically acceptable level of accuracy.ConclusionWe present an integrated open-source research platform for multi-modality IGS. The present prototype system was tailored for neurosurgery and met all minimum design requirements focused on skull base surgery. Future work aims to optimise the system further by addressing the remaining target requirements.

P.118 An experience with combined cerebral oximetry and stump pressure measurement to guide shunt insertion during carotid endarterectomy

Background: Cross-clamp ischemia during carotid endarterectomy (CEA) can cause perioperative stroke. Selectively shunting patients based on intraoperative monitoring modalities that assess risk for ischemia can reduce the occurrence of immediate stroke. An experience with combined cerebral oximetry and stump pressure measurement to direct selective shunting is presented here. Methods: Study comparing intraoperative monitoring data, the decision to shunt, and presence of immediate post-operative deficits. Patients were shunted if either cerebral oxygen saturation dropped by more than 10% by cerebral oximetry, or stump pressure during cross-clamping was less than 40 mmHg. Cross-clamp ischemia was determined by the presence of ipsilateral neurological deficit upon awakening. Results: 245 patients were included in this study. 22% were shunted. Patients who were not shunted were significantly more likely to have collateral blood flow detected on angiography. Immediate post-operative stroke was not encountered in any of the patients included in the study. One patient who met shunting criteria but was excluded since he could not have a shunt inserted due to difficult anatomy did suffer stroke. Conclusions: With the dual-monitoring criteria presented here, 22% of patients were shunted. With the exception of one patient who could not have a shunt placed, no immediate post-operative stroke was encountered.

Intra-operative use of Bispectral Index Monitoring and Time to Extubation and Patients Length of Stay after Cardio Pulmonary Bypass Surgery, at An-Najah National University Hospital / Nablus /Palestine. A Randomized Control Study

Background: The primary goal of cardiac surgery is not just a minimally acceptable outcome where the patient survives without life threatening complications, but a healthy productive long term survivor. There is no universally accepted technique for anesthesia management during cardiac surgery,Anesthetic protocols in cardiac surgery are investigated and analyzed in terms of their effect on post-operative mortality and incidence of myocardial infarction following cardiac surgery, needs for inotropic support, time to extubation, time on mechanical ventilation, and hospital length of stay. Fast–track tracheal extubation (within 6 hours after the surgery) after cardiac surgery has become a methods which is believed to facilitate this must be validated. One of these methods, is the use of intra-operative monitoring Modalities, such as (BIS) which is a value derived from electroencephalogram, and had been used as a measure of anesthesia effect. We performed this study in An-najah National University Hospital / Palestine to investigate the role of BIS monitoring on time to extubate and CCU length of stay after cardiopulmonary bypass surgery. Methods: In a randomized control study we used the bispectral index monitoring during cardiopulmonary bypass between 40-50 and in the CCU between 60-70 until extubation. 100 patients between the age of 30 and 75 years undergoing elective cardiopulmonary bypass surgery and patients undergoing elective valve replacement or repair, from 01/10/2015 to 01/04/2016 were assigned for this study, randomized to 50 patients each in the BIS group and the conventional group. Results: Extubation time data were available for 100 patients. The median time to extubate (320) minutes in the BIS group and (365) minutes in conventional group. The median CCU length of stay (24.1) hours in BIS group and (24.3) hours in conventional group. Regarding hospital length of stay, there was no difference in between the two groups, with median time of (5 days) in both groups. Conclusions: Data from this study suggested that the use of the BIS monitor during cardio pulmonary bypass does not confer an advantage in reducing time to extubation, CCU length of stay, or overall hospital length of stay.

The use of bilateral blink reflexes in intraoperative monitoring of facial-trigeminal nerves in cerebello-pontine angle operations

Background and Objective: Intraoperative monitoring (IOM) of facial nerve is routinely recommended in CerebelloPontine Angle (CP Angle) operations. Middle cranial nerves: V, VII, VIII are mainly involved since these nerves are sometimes separated by the tumor mass causing an inadvertent section of the facial nerve. Blink reflex could be elicited by stimulation of supraorbital branch of Trigeminal nerve which elicits EMG responses in facial muscles. Threshold, amplitude, latencies, pre-post surgery are strong predictors of postoperative facial function. Methods: In 17 cases of CP angle tumors (24-43 mm, by MRI) approached suboccipitally, we performed bilateral blink reflexes pre/intra/post surgery. The setup consisted of a Nicolet Endeavor IOM system( VIASYS Healthcare, 2005, USA) with the ability to perform several voltage/current stimulations and recordingsup to 20 Evoked Potentials and Electromyography (EMG) simultaneously. Bilateral blink reflexes were evoked by stimulation of bilateral supraorbital nerves. Stimulating pulses of 0.1 ms duration and 5-20 mA intensity were applied percutaneously at the intervals of 10-20 s. The orbicularis oculi muscle responses were recorded using surface electrodes. Early EMG responses (R1) and later reflex activities (R2) were elicited ipsi/contra laterally (R1/2-i/c). Every five successive trials were superimposed and the lowest latencies were used for comparison. Blink reflexes of each subject considered pathologic if: 1- Loss of R1-i,c to the operation side, latencies are more than 15 ms or side differences are 3 ms or more; 2- Loss of R2-i, latencies are more than 50 ms or side differences are 10 ms or more. 3- Loss of R2-c, latencies are more than 55 ms or side differences are 10 ms or more. Recordings were performed 2-3 days before operaration, intraoperative and 21 days after operation. Results: Before surgery, in 15 subjects, the amplitudes of R1-i responses were significantly lower than the R1-c. However, in 2 cases with tumor size of 39 and 43 mm, the R1-i s were absent while R2-c of opposite side of the tumor were weakly present. Intraoperative recordings were continuously jugged according to patient previous results. Post operation records of all subjects showed improved amplitudes in R1-i, R1-c and R2-c with significant reduction of latencies. Propofol or Propofol/Ketamine mixture plus narcotic is suitable to record stable reproducible blink responses. Atracurium or other non-depolarizing muscle relaxant should be avoided prior to EMG recordings. Conclusion: Direct facial nerve stimulation by surgeon is often difficult in large tumors until substantial tumor mass debulked and without knowledge of the location of the nerve it sometimes, could be too late. Saving facial nerve in CP angle operations has been widely studied but optimum predictive variables have yet to be determined. The main limitation of the study method was our inability to record the reflex during electrocautery which creates large artifacts that obliterate EMG signals at the times when the risk of thermal injury caused by cautery is high. To acquire IOM modalities, close collaboration of the anesthesiologist is necessary.

Predictive value of intraoperative neurophysiological monitoring during cervical spine surgery: a prospective analysis of 1055 consecutive patients

Despite the growing use of multimodal intraoperative monitoring (IOM) in cervical spinal surgery, limited data exist regarding the sensitivity, specificity, and predictive values of such a technique in detecting new neurological deficits in this setting. The authors sought to define the incidence of significant intraoperative electrophysiological changes and new postoperative neurological deficits in a cohort of patients undergoing cervical surgery. The authors conducted a prospective analysis of a consecutive series of patients who had undergone cervical surgery during a 5-year period at a university-based neurosurgical unit, in which multimodal IOM was recorded. Sensitivity, specificity, positive predictive values (PPVs), and negative predictive values (NPVs) were determined using standard Bayesian techniques. The study population included 1055 patients (614 male and 441 female) with a mean age of 55 years. The IOM modalities performed included somatosensory evoked potential (SSEP) recording in 1055 patients, motor evoked potential (MEP) recording in 26, and electromyography (EMG) in 427. Twenty-six patients (2.5%) had significant SSEP changes. Electromyographic activity was transient in 212 patients (49.6%), and 115 patients (26.9%) had sustained burst or train activity. New postoperative neurological deficits occurred in 34 patients (3.2%): 6 had combined sensory and motor deficits, 7 had new sensory deficits, 9 had increased motor weakness, and 12 had new root deficits. Of these 34 patients, 12 had spinal tumors, of which 7 were intramedullary. Overall, of the 34 new postoperative deficits, 21 completely resolved, 9 partially resolved, and 4 had no improvement. The deficits that completely resolved did so on average 3.3 months after surgery. Patients with deficits that did not fully resolve (partial or no improvement) were followed up for an average of 1.8 years after surgery. Somatosensory evoked potentials had a sensitivity of 52%, a specificity of 100%, a PPV of 100%, and an NPV of 97%. Motor evoked potential sensitivity was 100%, specificity 96%, PPV 96%, and NPV 100%. Electromyography had a sensitivity of 46%, specificity of 73%, PPV of 3%, and an NPV of 97%. Combined neurophysiological IOM with EMG and SSEP recording and the selective use of MEPs is helpful for predicting and possibly preventing neurological injury during cervical spine surgery.