Cutoff Points, Sensitivities, and Specificities of Intraoperative Motor-Evoked Potential Monitoring Determined Using Receiver Operating Characteristic Analysis

Background Although intraoperative motor-evoked potential (MEP) monitoring is widely performed during neurosurgical operations, evaluating its results is controversial. Study Aims The cutoff point of MEP monitoring should be determined not only to predict but also to prevent postoperative neurologic deficits. Material and Methods MEP monitoring was performed during 484 neurosurgical operations for patients without definitive preoperative motor palsy including 325 spinal operations, 102 cerebral aneurysmal operations, and 57 brain tumor operations, all monitored by transcranial stimulation, and 34 brain tumor operations monitored under direct cortical stimulation. To exclude the effects of muscle relaxants on MEP, the compound muscle action potential (CMAP), measured immediately after transcranial stimulation or direct cortical stimulation at supramaximal stimulation of the peripheral nerve, was used for normalization. The cutoff points, sensitivity, and specificity of MEP recorded during neurosurgery were examined by receiver operating characteristic (ROC) analyses and categorized according to the type of operation and stimulation. Results In spinal operations under transcranial stimulation, amplitude reduction of 77.9% and 80.6% as cutoff points for motor palsy with and without CMAP normalization, respectively, provided a sensitivity of 100% and specificity of 96.8% and 96.5%. In aneurysmal operations under transcranial stimulation, cutoff points of 70.7% and 69.6% offered specificities of 95.2% and 95.7% with and without CMAP normalization, respectively. The sensitivities for both were 100%. In brain tumor operations under direct stimulation, cutoff points were 83.5% and 86.3% with or without CMAP normalization, respectively, and the sensitivity and specificity for both were 100%. Conclusion An amplitude decrease of 80% in brain tumor operations, 75% in spinal operations, and 70% in aneurysmal operations should be used as the cutoff points.

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Direct cortical stimulation with cylindrical depth electrodes in the interhemispheric fissure for leg motor evoked potential monitoring

Clinical Neurophysiology ◽

10.1016/j.clinph.2019.10.014 ◽

2020 ◽

Vol 131 (1) ◽

pp. 127-132

Author(s):

Liberto Brage ◽

Pedro Javier Pérez-Lorensu ◽

Julio Plata-Bello ◽

Ángel Saponaro-González ◽

Luis Pérez-Orribo ◽

...

Keyword(s):

Evoked Potential ◽

Motor Evoked Potential ◽

Cortical Stimulation ◽

Direct Cortical Stimulation ◽

Depth Electrodes ◽

Interhemispheric Fissure ◽

Evoked Potential Monitoring ◽

Potential Monitoring

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S2-3. Intraoperative monitoring of lower extremity motor-evoked potential by direct cortical stimulation

Clinical Neurophysiology ◽

10.1016/j.clinph.2013.02.032 ◽

2013 ◽

Vol 124 (8) ◽

pp. e20

Author(s):

Masami Fujii ◽

Yuichi Maruta ◽

Hirochika Imoto ◽

Hisaharu Goto ◽

Michiyasu Suzuki

Keyword(s):

Lower Extremity ◽

Intraoperative Monitoring ◽

Evoked Potential ◽

Motor Evoked Potential ◽

Cortical Stimulation ◽

Direct Cortical Stimulation

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P31-9 Intraoperative monitoring of the motor evoked potential elicited by direct cortical stimulation of the lower extremities

Clinical Neurophysiology ◽

10.1016/s1388-2457(10)61176-5 ◽

2010 ◽

Vol 121 ◽

pp. S288

Author(s):

Y. Maruta ◽

M. Fujii ◽

H. Imoto ◽

S. Nomura ◽

F. Oka ◽

...

Keyword(s):

Intraoperative Monitoring ◽

Evoked Potential ◽

Motor Evoked Potential ◽

Lower Extremities ◽

Cortical Stimulation ◽

Direct Cortical Stimulation ◽

Stimulation Of

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Transcranial and direct cortical stimulation for motor evoked potential monitoring in intracerebral aneurysm surgery

Neurophysiologie Clinique ◽

10.1016/j.neucli.2007.09.006 ◽

2007 ◽

Vol 37 (6) ◽

pp. 391-398 ◽

Cited By ~ 54

Author(s):

A. Szelényi ◽

D. Langer ◽

J. Beck ◽

A. Raabe ◽

E.S. Flamm ◽

...

Keyword(s):

Evoked Potential ◽

Motor Evoked Potential ◽

Cortical Stimulation ◽

Aneurysm Surgery ◽

Direct Cortical Stimulation ◽

Evoked Potential Monitoring ◽

Intracerebral Aneurysm ◽

Potential Monitoring

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P31-10 Intraoperative monitoring of the lower extremity motor evoked potential (LE-MEP) elicited by direct cortical stimulation

Clinical Neurophysiology ◽

10.1016/s1388-2457(10)61177-7 ◽

2010 ◽

Vol 121 ◽

pp. S288

Author(s):

Y. Maruta ◽

M. Fujii ◽

H. Imoto ◽

S. Nomura ◽

F. Oka ◽

...

Keyword(s):

Lower Extremity ◽

Intraoperative Monitoring ◽

Evoked Potential ◽

Motor Evoked Potential ◽

Cortical Stimulation ◽

Direct Cortical Stimulation

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The warning-sign hierarchy between quantitative subcortical motor mapping and continuous motor evoked potential monitoring during resection of supratentorial brain tumors

Journal of Neurosurgery ◽

10.3171/2012.10.jns12895 ◽

2013 ◽

Vol 118 (2) ◽

pp. 287-296 ◽

Cited By ~ 78

Author(s):

Kathleen Seidel ◽

Jürgen Beck ◽

Lennart Stieglitz ◽

Philippe Schucht ◽

Andreas Raabe

Keyword(s):

Evoked Potential ◽

Tumor Resection ◽

Motor Evoked Potential ◽

Cortical Stimulation ◽

Motor Deficits ◽

Warning Sign ◽

Motor Mapping ◽

Direct Cortical Stimulation ◽

Monopolar Stimulation ◽

Signal Changes

Object Mapping and monitoring are believed to provide an early warning sign to determine when to stop tumor removal to avoid mechanical damage to the corticospinal tract (CST). The objective of this study was to systematically compare subcortical monopolar stimulation thresholds (1–20 mA) with direct cortical stimulation (DCS)–motor evoked potential (MEP) monitoring signal abnormalities and to correlate both with new postoperative motor deficits. The authors sought to define a mapping threshold and DCS-MEP monitoring signal changes indicating a minimal safe distance from the CST. Methods A consecutive cohort of 100 patients underwent tumor surgery adjacent to the CST while simultaneous subcortical motor mapping and DCS-MEP monitoring was used. Evaluation was done regarding the lowest subcortical mapping threshold (monopolar stimulation, train of 5 stimuli, interstimulus interval 4.0 msec, pulse duration 500 μsec) and signal changes in DCS-MEPs (same parameters, 4 contact strip electrode). Motor function was assessed 1 day after surgery, at discharge, and at 3 months postoperatively. Results The lowest individual motor thresholds (MTs) were as follows (MT in mA, number of patients): > 20 mA, n = 12; 11–20 mA, n = 13; 6–10 mA, n = 20; 4–5 mA, n = 30; and 1–3 mA, n = 25. Direct cortical stimulation showed stable signals in 70 patients, unspecific changes in 18, irreversible alterations in 8, and irreversible loss in 4 patients. At 3 months, 5 patients had a postoperative new or worsened motor deficit (lowest mapping MT 20 mA, 13 mA, 6 mA, 3 mA, and 1 mA). In all 5 patients DCS-MEP monitoring alterations were documented (2 sudden irreversible threshold increases and 3 sudden irreversible MEP losses). Of these 5 patients, 2 had vascular ischemic lesions (MT 20 mA, 13 mA) and 3 had mechanical CST damage (MT 1 mA, 3 mA, and 6 mA; in the latter 2 cases the resection continued after mapping and severe DCS-MEP alterations occurred thereafter). In 80% of patients with a mapping MT of 1–3 mA and in 75% of patients with a mapping MT of 1 mA, DCS-MEPs were stable or showed unspecific reversible changes, and none had a permanent motor worsening at 3 months. In contrast, 25% of patients with irreversible DCS-MEP changes and 75% of patients with irreversible DCS-MEP loss had permanent motor deficits. Conclusions Mapping should primarily guide tumor resection adjacent to the CST. DCS-MEP is a useful predictor of deficits, but its value as a warning sign is limited because signal alterations were reversible in only approximately 60% of the present cases and irreversibility is a post hoc definition. The true safe mapping MT is lower than previously thought. The authors postulate a mapping MT of 1 mA or less where irreversible DCS-MEP changes and motor deficits regularly occur. Therefore, they recommend stopping tumor resection at an MT of 2 mA at the latest. The limited spatial and temporal coverage of contemporary mapping may increase error and may contribute to false, higher MTs.

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S2-2. Intraoperative monitoring of motor evoked potential in aneurysm surgery: Transcranial or direct cortical stimulation?

Clinical Neurophysiology ◽

10.1016/j.clinph.2013.02.031 ◽

2013 ◽

Vol 124 (8) ◽

pp. e20

Author(s):

Tatsuya Sasaki ◽

Makoto Abe ◽

Mizuho Inoue ◽

Hiroki Uchida ◽

Atsushi Saito ◽

...

Keyword(s):

Intraoperative Monitoring ◽

Evoked Potential ◽

Motor Evoked Potential ◽

Cortical Stimulation ◽

Aneurysm Surgery ◽

Direct Cortical Stimulation

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Diagnostic performances of manual and automated reticulocyte parameters in anaemic cats

Journal of Feline Medicine and Surgery ◽

10.1177/1098612x17699067 ◽

2017 ◽

Vol 20 (2) ◽

pp. 122-127 ◽

Cited By ~ 2

Author(s):

Saverio Paltrinieri ◽

Marco Fossati ◽

Valentina Menaballi

Keyword(s):

Receiver Operating Characteristic ◽

Sensitivity And Specificity ◽

Operating Characteristic ◽

Positive Likelihood Ratio ◽

Roc Curves ◽

Blood Samples ◽

Production Index ◽

Instrumental Measurement ◽

Sensitivity Specificity ◽

Reticulocyte Production

Objectives The objective of this study was to evaluate the diagnostic performances of manual and instrumental measurement of reticulocyte percentage (Ret%), reticulocyte number (Ret#) and reticulocyte production index (RPI) to differentiate regenerative anaemia (RA) from non-regenerative anaemia (NRA) in cats. Methods Data from 106 blood samples from anaemic cats with manual counts (n = 74; 68 NRA, six RA) or instrumental counts of reticulocytes (n = 32; 25 NRA, seven RA) collected between 1995 and 2013 were retrospectively analysed. Sensitivity, specificity and positive likelihood ratio (LR+) were calculated using either cut-offs reported in the literature or cut-offs determined from receiver operating characteristic (ROC) curves. Results All the reticulocyte parameters were significantly higher in cats with RA than in cats with NRA. All the ROC curves were significantly different ( P <0.001) from the line of no discrimination, without significant differences between the three parameters. Using the cut-offs published in literature, the Ret% (cut-off: 0.5%) was sensitive (100%) but not specific (<75%), the RPI (cut-off: 1.0) was specific (>92%) but not sensitive (<15%), and the Ret# (cut-off: 50 × 10³/µl) had a sensitivity and specificity >80% and the highest LR+ (manual count: 14; instrumental count: 6). For all the parameters, sensitivity and specificity approached 100% using the cut-offs determined by the ROC curves. These cut-offs were higher than those reported in the literature for Ret% (manual: 1.70%; instrumental: 3.06%), lower for RPI (manual: 0.39; instrumental: 0.59) and variably different, depending on the method (manual: 41 × 10³/µl; instrumental: 57 × 10³/µl), for Ret#. Using these cut-offs, the RPI had the highest LR+ (manual: 22.7; instrumental: 12.5). Conclusions and relevance This study indicated that all the reticulocyte parameters may confirm regeneration when the pretest probability is high, while when this probability is moderate, RA should be identified using the RPI providing that cut-offs <1.0 are used.

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