Value of multimodality monitoring using brainstem auditory evoked potentials and somatosensory evoked potentials in endoscopic endonasal surgery
Parthasarathy D. ThirumalaHemasree S KodavatigantiMiguel HabeychKelley WichmanYue‐Fang ChangPaul A. GardnerCarl H. SnydermanDonald J. CrammondJeffrey Balzer
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Abstract:
To evaluate the value of intraoperative neurophysiological monitoring (IONM) using brainstem auditory evoked potential (BAEP) and somatosensory evoked potential (SSEP) monitoring to predict and/or prevent postoperative neurological deficits during endoscopic endonasal surgery (EES).We retrospectively identified 138 consecutive patients who had BAEP monitoring in addition to SSEP monitoring during EES at our institution. We reviewed the postoperative clinical outcomes and neurophysiological changes independently.The total of number of patients with any IONM changes was 10. The incidence of BAEP changes was 3.62%. The incidence of SSEP changes was 3.62% as well. One patient had changes in both BAEPs and SSEPs. Majority of the changes were observed during changes in mean arterial pressure (MAP) without any postoperative neurological deficits. There were two postoperative neurological deficits.BAEPs and SSEPs provide unique information about integrity of brainstem function during EES procedures involving tumors in the and around clival region. We advocate a comprehensive multimodality approach to IONM during EESs including BAEPs and SSEPs depending on the location of the neural structures at risk.Keywords:
Somatosensory evoked potential
Intraoperative neurophysiological monitoring
Evoked potential
Monitoring the brain function of comatose patients caused by brain injury can predict clinic outcome and direct therapy. Combined brainstem auditory evoked potential(BAEP) and Somatosensory evoked potential (SSEP) can explain the function from brainstem to cerebral cortex. The studies aimed to conclude the clinic use of BAEP and SSEP.
Key words:
Brain injury; Brainstem auditory evoked potential; Somatosensory evoked potential; Coma
Somatosensory evoked potential
Coma (optics)
Evoked potential
Brain Function
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The primary objective of neurophysiologic monitoring during surgery is to prevent permanent neurological sequelae. We prospectively evaluated whether the combined use of somatosensory- and motor-evoked potential (SEP/MEP) for intramedullary spinal cord tumor (IMSCT) surgery may be beneficial. Combined SEP/MEP monitoring was attempted in 20 consecutive procedures for IMSCT operations. Trains of transcranial electric stimulation over the motor cortex were used to elicit MEPs from limb target muscles. The tibial and median nerves were stimulated to record SEP. The operation was paused or the surgical strategy was modified in every case of significant SEP/MEP changes. Combined SEP/MEP recording was successfully achieved in 17 of 20 (85%) operations. In 3 of 17 operations, SEP and MEP were stable, and all patients remained neurologically intact after surgery. Significant MEP changes were recorded in 12 operations (70%). In 7 of these 12 operations, MEP recovered to some extent after surgical intervention, and these patients showed no neurological changes. In the remaining 5 operations, MEP did not recover and the patients had a transient (n = 2) or a permanent (n = 1) motor deficit. Significant SEP changes with stable MEP were related to a transient hypesthesia. Combined SEP/MEP monitoring provided higher sensitivity, and higher positive and negative predictive value than single-modality techniques. Detection of MEP changes and adjustment of surgical strategy may prevent irreversible pyramidal tract damage.
Somatosensory evoked potential
Evoked potential
Intraoperative neurophysiological monitoring
Tibial nerve
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Introduction. From findings in the neurophysiological tests, especially with the recordings of the Evoked Potentials (EPs) it is possible to characterize the functional state of the Nervous System (NS) structures,in the course of diseases, in the Clinical Neurophysiologicaly Laboratory, and also can be performed during surgery and at Intensive Care Unit (ICU). Objective. To describe neurophysiological immediate and short-term changes that occur, in the NS structures in patients assessed in three different contexts of work: Intraoperative Neurophysiologic Monitoring (IONM), ICU, and in the Clinical Neurophysiological Laboratory. Methods. Here are presented the results of the neurophysiological evaluation in a case-study of patients during their admission at ICU, IONM. In addition, we provide evidences of the value of EPs in assessing neuroplasticity in deaf and deaf-blind subjects. In each section Auditory Brainstem Responses (ABR), Visual Evoked Potentials (VEP) and Somatosensory Evoked Potentials (SSEP) were used according to their pathology. In addition, other neurophysiological tests such as Electromyography (EMG), Nerve Conduction Study (NCS), and Motor Evoked Potentials (MEPs) were performed according to the clinical situation of patients. Results. It was possible to illustrate the practical utility of EPs in IONM and ICU. The neurophysiological changes are summarized using graphics showing the main findings obtained with EPs and other EDX tests. Electrophysiological responses change over time, being possible to provide evidences of the disease course through the measured parameters of each electrophysiological signal. On the other hand, the expansion of the SSEP cortical response to the left temporal region in subjects with sensory loss was interpreted as evidence of Cross-Modal-Plasticity. Conclusions. EPs associated with other neurophysiological tests provide means to noninvasively brain functional assessment in patients at ICU and IONM. EPs are largely used for supplement information obtained from clinics, neuroimage methods, and other laboratory tests. Nowadays, SSEP and ABR are the most important EPs used, and show interesting findings in the patient's assessment at IONM and ICU, while a characterization of the topographic distribution pattern of peaks in cortical evoked responses yields a complementary value to EPs assessment and interpretation for clinic and research.
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Neurophysiology
Clinical neurophysiology
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Abstract Background: Evoked potential monitoring such as somatosensory-evoked potential (SSEP) or motor-evoked potential (MEP) monitoring during surgical procedures in proximity to the spinal cord requires minimising the minimum alveolar concentrations (MACs) below the anaesthetic concentrations normally required (1 MAC) to prevent interference in amplitude and latency of evoked potentials. This could result in awareness. Our primary objective was to determine the incidence of awareness while administering low MAC inhalational anaesthetics for these unique procedures. The secondary objective was to assess the adequacy of our anaesthetic technique from neurophysiologist’s perspective. Methods: In this prospective observational pilot study, 61 American Society of Anesthesiologists 1 and 2 patients undergoing spinal surgery for whom intraoperative evoked potential monitoring was performed were included; during the maintenance phase, 0.7–0.8 MAC of isoflurane was targeted. We evaluated the intraoperative depth of anaesthesia using a bispectral (BIS) index monitor as well as the patients response to surgical stimulus (PRST) scoring system. Post-operatively, a modified Bruce questionnaire was used to verify awareness. The adequacy of evoked potential readings was also assessed. Results: Of the 61 patients, no patient had explicit awareness. Intraoperatively, 19 of 61 patients had a BIS value of above sixty at least once, during surgery. There was no correlation with PRST scoring and BIS during surgery. Fifty-four out of 61 patient’s evoked potential readings were deemed ‘good’ or ‘fair’ for the conduct of electrophysiological monitoring. Conclusions: This pilot study demonstrates that administering low MAC inhalational anaesthetics to facilitate evoked potential monitoring does not result in explicit awareness. However, larger studies are needed to verify this. The conduct of SSEP electrophysiological monitoring was satisfactory with the use of this anaesthetic technique. However, the conduct of MEP monitoring was satisfactory, only in patients with Nurick Grade 1 and 2. The MEP response was poor in patients with Nurick Grade 4 and 5.
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Evoked potential
Intraoperative neurophysiological monitoring
Desflurane
Intraoperative Awareness
Bispectral index
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To evaluate the value of intraoperative neurophysiological monitoring (IONM) using brainstem auditory evoked potential (BAEP) and somatosensory evoked potential (SSEP) monitoring to predict and/or prevent postoperative neurological deficits during endoscopic endonasal surgery (EES).We retrospectively identified 138 consecutive patients who had BAEP monitoring in addition to SSEP monitoring during EES at our institution. We reviewed the postoperative clinical outcomes and neurophysiological changes independently.The total of number of patients with any IONM changes was 10. The incidence of BAEP changes was 3.62%. The incidence of SSEP changes was 3.62% as well. One patient had changes in both BAEPs and SSEPs. Majority of the changes were observed during changes in mean arterial pressure (MAP) without any postoperative neurological deficits. There were two postoperative neurological deficits.BAEPs and SSEPs provide unique information about integrity of brainstem function during EES procedures involving tumors in the and around clival region. We advocate a comprehensive multimodality approach to IONM during EESs including BAEPs and SSEPs depending on the location of the neural structures at risk.
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BACKGROUND:This study aimed to evaluate the effects of different combined evoked potentials monitoring modes for non-osteotomy and osteotomy surgery of spinal deformity, and to select individualized modes for various surgeries. MATERIAL AND METHODS:We retrospectively reviewed a total of 188 consecutive cases undergoing spinal deformity correction. All patients were classified into 2 cohorts: non-osteotomy (Group A) and osteotomy (Group B). According to intraoperative evoked potential monitoring mode, Group A was divided into 2 sub-groups: A1 [spinal somatosensory evoked potential (SSEP)/motor evoked potential (MEP), n=67)] and A2 [SSEP/MEP/descending neurogenic evoked potential (DNEP), n=52]. Group B was classified as B1 (SSEP/MEP, n=27) and B2 (SSEP/MEP/DNEP, n=42). The demographics, surgical parameters, and evoked potential events of different combined monitoring modes were analyzed within each group. RESULTS:The baselines of SSEP/MEP/DNEP in all cases were elicited successfully. Three cases with evoked potential (EP) events (2 with MEP changes and 1 with SSEP/MEP change) were noted in Group A1 and 1 with SSEP change in Group A2, with no neurological complications. Thirteen cases in Group B1 were positive for MEP intraoperatively, including 16 EP events (13 with MEP change and 3 with both SSEP+MEP changes), with no neural complications. In Group B2, 15 cases had 21 EP events, including 12 with MEP change and 2 with SSEP+MEP changes, with no complications. Postoperative neurological complications were observed in 5 of the 7 cases with SS4EP/DNEP changes. CONCLUSIONS:Intraoperative simultaneous SSEP/MEP can effectively reflect neurological function in non-osteotomy spinal surgery patients. Simultaneous SSEP/MEP/DNEP can effectively avoid the unnecessary interference by false-positive results of MEP during osteotomy.
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Objective To evaluate whether stent could improve the recovery of subclinical symptom of patients with vertebrobasilar transient ischemia attack.Methods A series of 11 patients who underwent stenting for vertebrobasilar transient ischemia attack patients with symptomatic vertebrobasilar artery stenosis was investigated in this study.All patients were evaluated with somatosensory evoked potential,brainstem auditory evoked potential,as well as visual evoked potential both before and after stent placement.Latency and wave amplitude of evoked potentials before and after stent placement were analysed for significance.Results We found abnormal evoked potential before the stenting,especially prolonged latency of N20 and P40 in somatosensory evoked potential(SEP),of wave I,Ⅲ and V in brainstem auditory evoked potential(BAEP),and of P100 in visual evoked potential(VEP).While after the procedure evoked potential showed that in BAEP the latency of I-Ⅲ wave significantly decreased(P=0.046) and the amplitude of wave Ⅲ increased significantly(P=0.05);In SEP the latency of N20 was shortened(P=0.012) and the intervals of N13-N20(P=0.013) and P14-N20(P=0.005) were both decreased;In VEP the latency of P100 was shortened significantly(P=0.022).Conclusion somatosensory evoked potential,brainstem auditory evoked potential,and visual evoked potential of patients with vertebrobasilar transient ischemia attack were improved after stenting.Stenting is may be helpful to the recovery of subclinical symptom.
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Vertebrobasilar insufficiency
Subclinical infection
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Introduction Intraoperative neurophysiological monitoring (IONM) is a method which uses different kinds of electrophysiological methods to monitor the function of neural structures during the operation. The methods are motor evoked potentials (MEP), somatosensory evoked potentials (SSEP), brainstem auditory evoked potentials (BAEP), visual evoked potentials (VEP), electroencephalography (EEG), and electromyography (EMG). There are a large number of indications for using IONM in neurosurgery, as well as in other fields of surgery.
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Intraoperative neurophysiological monitoring
Neurophysiology
Evoked potential
Visual evoked potentials
Clinical neurophysiology
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It is more than 60 years since averaged somatosensory evoked potentials (SEPs) were devised. During this period, other evoked potentials including spinal cord evoked potentials and motor evoked potentials (MEPs) were developed. In cases needing identification of the pathologic level of myelopathy and monitoring the function of the spinal cord, these evoked potentials are now indispensable. The combination of these evoked potentials (multimodality monitoring) has been demonstrated to be sensitive and specific for detecting intraoperative neurologic injury during spine surgery. Although there is still a low level of evidence that intraoperative evoked potentials reduce the rate of new or worsened perioperative neurologic deficits, it is recommended to monitor MEP for thoracoabdominal aortic surgery and multimodal evoked potentials including at least spinal cord evoked potentials and MEP for spine surgery, when the spinal cord is considered to be at risk.
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N intraoperative neurophysiological monitoring (IONM) is routinely carried out during various surgeries on spinal cord, vertebral column, and aortic/cerebral aneurysms. Critical neurological structures may easily be damaged by operative manipulations during these procedures. The aim of such monitoring is to identify changes in neuronal function prior to irreversible damage. The technology used is relatively sophisticated and requires neurophysiologists to interpret the signals and convey it to the operative team. However, the evoked potentials are rather simple in concept with regard to their clinical application for diagnostic testing and intra-operative monitoring.1 Evoked potential monitoring includes somatosensory evoked potentials (SSEP), brainstem auditory evoked potentials (BAEP), motor evoked potentials (MEP), and visual evoked potentials (VEP). SSEPs reflect conduction in dorsal columns whereas transcranial MEPs represent anterior horn motor neuron function. Electrophysiological monitoring in the operative milieu may pose several specific challenges. These include 1) presence of electromagnetic interference from use of various equipments in the operating room (OR); and 2) use of anesthetic agents that can alter recordings. Anesthetics exert their effects on the brain by depressing cerebral metabolism which may result in alteration of signals of evoked potentials in the form of decreased amplitude and increased latency. In the article published on this issue of Minerva Anestesiologica, Fudickar et al.2 highlighted on electrophysiologic neuromonitoring during repair of thoracoabdominal aorta by anesthesiologists. This article brings out two relevant points to the forefront. Important one being the fact that neurophysiological monitoring is essential to prevent spinal cord ischemia resulting in paraparesis or paraplegia.3 Twenty consecutive patients undergoing thoracic/thoracoabdominal aortic aneurysm repair were monitored successfully with SSEP and MEP during the cardiopulmonary bypass (CPB) phase by certified anesthesiologists. One patient who was not monitored with MEP developed postoperative paraplegia. The result was consistent with the results of a survey on practice of evoked potential monitoring by Legatt.4 Timely corrective action by the surgical team in reperfusing the spinal cord, when alerted to by the anesthesiologist monitoring the combined SSEP and MEP signals, prevented any long-term damage potential to these patients. Secondly, the anesthesiologist has taken over the role of neurophysiologists who are traditionally involved with such monitoring, in the OR apart from carrying out the primary role. This becomes a necessity where neurophysiologists are not available either due to a resource crunch or lack of adequate number of neurophsyiologists. The need to train anesthesiologists for interpretation of electrophysiologic neuromonitoring methods has been carried out by the German Society of Anaesthesiology and Intensive Medicine (DGAI) proIntraoperative neurophysiological monitoring by anesthesiologists
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Intraoperative neurophysiological monitoring
Evoked potential
Neurophysiology
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