The lateral supracerebellar infratentorial, translateral mesencephalic sulcus approach to the mesencephalopontine junction

2019 ◽  
Vol 1 (2) ◽  
pp. V14
Author(s):  
M. Yashar S. Kalani ◽  
Kaan Yağmurlu ◽  
Nikolay L. Martirosyan ◽  
Robert F. Spetzler
Keyword(s):  
Patient Outcomes ◽  
Evoked Potential ◽  
Cavernous Malformation ◽  
Motor Evoked Potential ◽  
Pial Surface ◽  
Sensory Changes ◽  
Selection For ◽  
Evoked Potential Monitoring ◽  
Neurologically Intact

The lateral supracerebellar infratentorial (SCIT) approach provides advantageous access to lesions located in the lateral mesencephalon and mesencephalopontine junction. For lesions that abut the pial surface, a direct approach is ideal and well tolerated. For deep-seated lesions, the lateral mesencephalic sulcus (LMS) can be used to access lesions with minimal morbidity to the patient. This video demonstrates the use of the SCIT approach via the LMS to remove a cavernous malformation at the level of the mesencephalopontine junction. The use of somatosensory and motor evoked potential monitoring and intraoperative neuronavigation is essential for optimizing patient outcomes. Meticulous, multilayered closure is critical for optimal results in the posterior fossa. For optimal patient outcomes, approach selection for deep-seated lesions should combine the two-point method with safe entry zones. At follow-up, the patient had persistent sensory changes but was otherwise neurologically intact.The video can be found here: https://youtu.be/bHFEZhG8dHw.

scholarly journals Impact of Motor-Evoked Potential Monitoring on Facial Nerve Outcomes after Vestibular Schwannoma Resection

2018 ◽  
Vol 128 (1) ◽  
pp. 56-61 ◽  
Author(s):  
Kareem O. Tawfik ◽  
Zoe A. Walters ◽  
Gavriel D. Kohlberg ◽  
Noga Lipschitz ◽  
Joseph T. Breen ◽  
...  
Keyword(s):  
Facial Nerve ◽  
Vestibular Schwannoma ◽  
Predictive Value ◽  
Evoked Potential ◽  
Amplitude Ratio ◽  
Motor Evoked Potential ◽  
Level Of Evidence ◽  
Facial Function

Objectives: Assess the utility of intraoperative transcranial facial motor-evoked potential (FMEP) monitoring in predicting and improving facial function after vestibular schwannoma (VS) resection. Study Design: Retrospective chart review. Methods: Data were obtained from 82 consecutive VS resections meeting inclusion criteria. Sixty-two cases were performed without FMEP and 20 with FMEP. Degradation of FMEP response was defined as a final-to-baseline amplitude ratio of 0.5 or less. House-Brackmann (HB) grade was assessed preoperatively, postoperatively, at follow-up assessments, and it was compared between pre- and post-FMEP cohorts. Positive predictive value (PPV) and negative predictive value (NPV), sensitivity, and specificity of FMEP degradation in predicting facial weakness were calculated. Results: In the pre-FMEP group, at length of follow-up (LOF) ⩾9 months, 83.9% (52/62) of patients exhibited HB 1-2 outcome. In the post-FMEP cohort, 75.0% (15/20) exhibited HB 1-2 function at LOF ⩾9 months. There was no difference in rates of HB 1-2 outcomes between groups in the immediate postoperative period ( P = .35) or at long-term follow-up ( P = 1.0). With respect to predicting immediate postoperative facial function, FMEP demonstrated high specificity (88.9%) and moderate sensitivity (54.5%). The PPV and NPV for immediate postoperative facial function were 85.7% and 61.5%, respectively. With respect to long-term (⩾9 months LOF) facial function, intraoperative FMEP was moderately sensitive (71.4%) and highly specific (84.6%); PPV was moderate (71.4%), and NPV was high (84.6%). Conclusions: Intraoperative FMEP is highly specific and moderately sensitive in predicting postoperative facial function for patients undergoing VS resection, but its use may not be associated with improved facial nerve outcomes. Level of Evidence: 4

scholarly journals Awareness during anaesthesia for surgery requiring evoked potential monitoring: A pilot study

2017 ◽  
Vol 04 (01) ◽  
pp. 036-041
Author(s):  
Pritish Korula ◽  
Ramamani Mariappan ◽  
Justin James ◽  
Prashant Kumar ◽  
Grace Korula
Keyword(s):  
Pilot Study ◽  
Evoked Potential ◽  
Motor Evoked Potential ◽  
Maintenance Phase ◽  
Primary Objective ◽  
Anaesthetic Technique ◽  
Depth Of Anaesthesia ◽  
Electrophysiological Monitoring ◽  
Evoked Potential Monitoring ◽  
Potential Monitoring

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.

scholarly journals Somatosensory and transcranial motor evoked potential monitoring in a porcine model for experimental procedures

PLoS ONE ◽  
2018 ◽  
Vol 13 (10) ◽  
pp. e0205410 ◽  
Author(s):  
Sven Maier ◽  
Ulrich Goebel ◽  
Sonja Krause ◽  
Christoph Benk ◽  
Martin A. Schick ◽  
...  
Keyword(s):  
Evoked Potential ◽  
Porcine Model ◽  
Motor Evoked Potential ◽  
Transcranial Motor Evoked Potential ◽  
Evoked Potential Monitoring ◽  
Potential Monitoring

scholarly journals Feasibility of adjunct facial motor evoked potential monitoring to reduce the number of false-positive results during cervical spine surgery

2020 ◽  
Vol 32 (4) ◽  
pp. 570-577
Author(s):  
Ryuta Matsuoka ◽  
Yasuhiro Takeshima ◽  
Hironobu Hayashi ◽  
Tsunenori Takatani ◽  
Fumihiko Nishimura ◽  
...  
Keyword(s):  
Cervical Spine ◽  
Spine Surgery ◽  
False Positive ◽  
Evoked Potential ◽  
Motor Evoked Potential ◽  
Unaffected Side ◽  
Cervical Spine Surgery ◽  
Supramaximal Stimulation ◽  
Evoked Potential Monitoring ◽  
Positive Results

OBJECTIVEFalse-positive intraoperative muscle motor evoked potential (mMEP) monitoring results due to systemic effects of anesthetics and physiological changes continue to be a challenging issue. Although control MEPs recorded from the unaffected side are useful for identifying a true-positive signal, there are no muscles on the upper or lower extremities to induce control MEPs in cervical spine surgery. Therefore, this study was conducted to clarify if additional MEPs derived from facial muscles can feasibly serve as controls to reduce false-positive mMEP monitoring results in cervical spine surgery.METHODSPatients who underwent cervical spine surgery at the authors’ institution who did not experience postoperative neurological deterioration were retrospectively studied. mMEPs were induced with transcranial supramaximal stimulation. Facial MEPs (fMEPs) were subsequently induced with suprathreshold stimulation. The mMEP and subsequently recorded fMEP waveforms were paired during each moment during surgery. The initial pair was regarded as the baseline. A significant decline in mMEP and fMEP amplitude was defined as > 80% and > 50% decline compared with baseline, respectively. All mMEP alarms were considered false positives. Based on 2 different alarm criteria, either mMEP alone or both mMEP and fMEP, rates of false-positive mMEP monitoring results were calculated.RESULTSTwenty-three patients were included in this study, corresponding to 102 pairs of mMEPs and fMEPs. This included 23 initial and 79 subsequent pairs. Based on the alarm criterion of mMEP alone, 17 false-positive results (21.5%) were observed. Based on the alarm criterion of both mMEP and fMEP, 5 false-positive results (6.3%) were observed, which was significantly different compared to mMEP alone (difference 15.2%; 95% CI 7.2%–23.1%; p < 0.01).CONCLUSIONSfMEPs might be used as controls to reduce false-positive mMEP monitoring results in cervical spine surgery.

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