Authors	Reason for Exclusion
After full-text review (n = 140)
Bidkar et al. (2021) [119]	Not a primary study
Keeble et al. (2021) [120]	No preoperatively defined MEP warning criteria
Lee et al. (2021) [121]	No MEP warning criteria
Simon et al. (2021) [122]	No MEP warning criteria
Wang et al. (2021) [123]	No motor outcome analysis
Bander et al. (2020) [124]	No MEP warning criteria
Brage et al. (2020) [125]	No sufficient motor outcome data in conjunction with MEP warning criteria
Fekete et al. (2020) [126]	Only spinal and brainstem lesions
Hayashi et al. (2020) [127]	No MEP warning criteria
Jahodová et al. (2020) [128]	No preoperatively defined cutoff value for MEP warning criteria
Kim et al. (2020) [129]	No MEP warning criteria
Lee et al. (2020) [130]	No MEP warning criteria
Porčnik et al. (2020) [131]	Motor outcome data of asleep patients cannot be distinguished from those of awake patients
Roth et al. (2020) [132]	No cutoff values for MEP warning criteria
Balaji et al. (2019) [133]	No MEP warning criteria
Chung et al. (2019) [134]	Only analysis of false-positive and false-negative cases
Hu et al. (2019) [135]	No MEP warning criteria
Kanaya et al. (2019) [136]	No MEP warning criteria
Rossi et al. (2019) [137]	No sufficient motor outcome data in conjunction with MEP warning criteria
Wang et al. (2019) [138]	No MEP warning criteria
Della Puppa et al. (2018) [139]	No MEP warning criteria
Han et al. (2018) [140]	No MEP warning criteria
Silverstein et al. (2018) [141]	No MEP warning criteria
Skrap et al. (2018) [142]	No clear MEP monitoring warning criteria and no sufficient motor outcome data in conjunction with MEPs-mixture with SSEP
Umemura et al. (2018) [143]	Motor outcome data of patients with supratentorial lesions were not clearly reported and could not be extracted
Wakui et al. (2018) [144]	No MEP warning criteria
Abboud et al. (2017) [100]	Predefined analysis of patients without a postoperative deficit and without MEP warning criteria to investigate pneumocephalus with MRI
Akiyama et al. (2017) [145]	No preoperatively defined MEP warning criteria
Lv X et al. (2017) [146]	No MEP monitoring
Pintea et al. (2017) [147]	No MEP warning criteria
Takagaki et al. (2017) [148]	No MEP monitoring
Carrabba et al. (2016) [149]	No MEP warning criteria
Gripp et al. (2016) [150]	No MEP warning criteria
Grossauer et al. (2016) [151]	No preoperatively defined MEP warning criteria
Ikedo et al. (2016) [152]	Evacuation of hematoma and control of the presence of MEPs after evacuation -not tumor, vascular or epileptogenic lesion
Imai et al. (2016) [153]	No motor outcome analysis
Isozaki et al. (2016) [154]	No MEP warning criteria
Koenig et al. (2016) [155]	No preoperatively defined MEP warning criteria
Nakagomi et al. (2016) [156]	No MEP warning criteria
Rossetto et al. (2016) [157]	No MEP warning criteria
Zhuang et al. (2016) [158]	Data for patients with supratentorial lesions cannot be extracted with certainty
Zhukov et al. (2016) [159]	No preoperatively defined MEP warning criteria
Wang et al. (2016) [160]	No MEP warning criteria
Eldin et al. (2015) [161]	No MEP warning criteria
Erdoğan et al. (2015) [162]	“Presence or absence” warning criterion but only the spinal and brainstem cases are adequately related to postoperative motor outcome
Jo et al. (2015) [163]	No MEP warning criteria
Joksimovic et al. (2015) [164]	No MEP warning criteria
Okamoto et al. (2015) [165]	No MEP warning criteria
Quan et al. (2015) [166]	No MEP warning criteria
Rashad et al. (2015) [167]	No MEP warning criteria
Shiban et al. (2015) [102]	No clear MEP warning criteria
Udaka et al. (2015) [168]	No MEP warning criteria
Raabe et al. (2014) [105]	Overlapping series from the same institution
Sahaya et al. (2014) [169]	Only 3 cases with MEP monitoring and no reporting of motor outcome for them
Schucht et al. (2014) [170]	No sufficient motor outcome data in conjunction with MEP warning criteria and mapping thresholds
Bulusu et al. (2013) [171]	No MEP warning criteria
Krieg et al. (2013) [172]	Overlapping series from the same institution
Krieg et al. (2013) [173]	No sufficient motor outcome data in conjunction with MEP warning criteria, data for asleep patients, and postoperative motor deficit cannot be extracted with certainty
Shah P.A. (2013) [174]	No clear MEP warning criteria
Vassal et al. (2013) [175]	No MEP warning criteria
Chen et al. (2012) [176]	No clear MEP warning criteria
Horton et al. (2012) [177]	No cutoff values for MEP warning criteria
Krieg et al. (2012) [96]	Overlapping series from the same institution
Ohue et al. (2012) [107]	No preoperatively defined MEP warning criteria
Ritzl EK. (2012) [178]	Not a primary study
Schucht et al. (2012) [179]	No sufficient motor outcome data in conjunction with MEP warning criteria
Seidel et al. (2012) [97]	No MEP monitoring warning criteria, only mapping warning criteria
Uchino et al. (2012) [180]	No sufficient motor outcome data in conjunction with MEP warning criteria
Zhu et al. (2012) [181]	No clear MEP warning criteria
Chang et al. (2011) [182]	No MEP warning criteria
Chen et al. (2011) [183]	No MEP monitoring
Fukaya et al. (2011) [184]	No MEP warning criteria
González-Darder(2011) [185]	No MEP warning criteria
Li et al. (2011) [186]	No sufficient motor outcome data in conjunction with MEP warning criteria
Lin et al. (2011) [187]	No cutoff values for MEP warning criteria
Nossek et al. (2011) [108]	No clear MEP monitoring warning criteria. No sufficient motor outcome data in conjunction with mapping warning criteria for the asleep patients.
Prabhu et al. (2011) [106]	No preoperatively defined MEP warning criteria
Szelényi et al. (2011) [103]	No MEP warning criteria
Tanaka et al. (2011) [188]	Numbers of MEP changes reported in percentages. Only motor palsy <2/5 MMRC and not postoperative motor deterioration is reported.
von Der Brelie et al. (2011) [189]	No MEP monitoring
Walter et al. (2011) [190]	No MEP warning criteria
Bello et al. (2010) [191]	No preoperatively defined MEP warning criteria
Bozzao et al. (2010) [192]	No MEP warning criteria
Feigl et al. (2010) [193]	No sufficient motor outcome data in conjunction with MEP warning criteria
Juretschke et al. (2010) [194]	No MEP warning criteria
Maesawa et al. (2010) [195]	No preoperatively defined MEP warning criteria
Sala et al. (2010) [196]	Not a primary study
Sanai et al. (2010) [197]	Not a primary study
Talacchi et al. (2010) [1]	No MEP monitoring warning criteria
Tanaka et al. (2010) [198]	Earlier series from the same institution
Yang et al. (2010) [199]	No MEP warning criteria
Gorji et al. (2009) [200]	No clear MEP warning criteria
Hattingen et al. (2009) [201]	Data for patients with supratentorial lesions cannot be extracted with certainty
Kamada et al. (2009) [109]	No preoperatively defined MEP warning criteria
Kombos et al. (2009) [202]	No sufficient motor outcome data in conjunction with MEP warning criteria
Krammer et al. (2009) [203]	Motor outcome data of patients with supratentorial lesions were not clearly reported and could not be extracted
Ozawa et al. (2009) [204]	No MEP warning criteria
Simon et al. (2009) [205]	No MEP warning criteria
Sugita et al. (2009) [206]	No MEP warning criteria
Von Lehe et al. (2009) [207]	No MEP warning criteria
Yamaguchi et al. (2009) [208]	No motor outcome analysis
Calancie et al. (2008) [209]	Only spinal cases
Berman et al. (2007) [210]	No MEP warning criteria
Mikuni et al. (2007) [211]	No MEP warning criteria
Neuloh et al. (2007) [212]	Overlapping series from the same institution
Szelényi et al. (2007) [6]	No MEP warning criteria
Yamaguchi et al. (2007) [213]	No motor outcome analysis
Fujiki et al. (2006) [214]	No clear preoperatively defined MEP warning criteria
Okada et al. (2006) [215]	No MEP warning criteria
Kamada et al. (2005) [216]	No MEP warning criteria
Szelényi et al. (2005) [101]	No motor outcome data in conjunction with MEP warning criteria
Keles et al. (2004) [217]	No MEP warning criteria
Kombos et al. (2004) [218]	No MEP warning criteria
Neuloh et al. (2004) [219]	No clear and preoperatively defined MEP warning criteria
Quiñones-Hinojosa et al. (2004) [220]	No sufficient motor outcome data in conjunction with MEP warning criteria
Sakuma et al. (2004) [221]	No MEP warning criteria
Signorelli et al. (2004) [222]	No MEP warning criteria
Yamamoto et al. (2004) [223]	Only D-wave recording
Duffau et al. (2003) [224]	No MEP monitoring warning criteria
Fukaya et al. (2003) [225]	Inclusion criterion in the study that the patient did not exhibit MEP amplitude decrease of >50% (warning criteria) intraoperatively
Sala et al. (2003) [111]	No sufficient motor outcome data in conjunction with MEP warning criteria
Suess et al. (2002) [226]	No MEP warning criteria
Kombos et al. (2000) [227]	No MEP warning criteria
Kofler et al. (1999) [228]	No MEP warning criteria
Kombos et al. (1999) [229]	No MEP warning criteria
Rohde et al. (1999) [230]	MEPs elicited through Transcranial Magnetic Stimulation(TMS)
Yingling et al. (1999) [231]	No MEP warning criteria
Krombach et al. (1998) [232]	No MEP warning criteria
Zentner et al. (1998) [233]	No correlation of MEPs with postoperative but with preoperative motor deficit
Zentner et al. (1996) [117]	No MEP warning criteria
Kawaguchi et al. (1996) [234]	No clear MEP warning criteria
Maertens et al. (1996) [235]	No clear MEP warning criteria
Pechstein et al. (1996) [236]	No MEP warning criteria
Rodi et al. (1996) [237]	No MEP warning criteria
Skirboll et al. (1996) [238]	No MEP warning criteria
Taniguchi et al. (1993) [5]	No MEP warning criteria
Ebeling et al. (1992) [239]	No MEP warning criteria
Schramm et al. (1990) [240]	Only SSEP monitoring
Zentner et al. (1988) [241]	No clear MEP warning criteria
After abstract screening (n = 73)
Chen et al. (2021) [242]	Τechnical report, presentation of a new technique
Machetanz et al. (2021) [243]	MEPs elicited through Transcranial Magnetic Stimulation(TMS)
Cattaneo et al. (2020) [244]	Use of MEPs to investigate brain connectivity
Kang et al. (2020) [245]	Not a primary study
Policicchio et al. (2020) [246]	Not a primary study
Shibata et al. (2020) [247]	Awake craniotomy
Wang et al. (2020) [248]	Only SSEP analysis
Zuo et al. (2020) [249]	Not a primary study
NCT04178395(2019) [250]	Protocol for clinical trial
Hiruta et al. (2019) [251]	Τechnical report (cortical and subcortical stimulation ratio), no motor outcome data
Zhu et al. (2019) [91]	Not a primary study
Rajan et al. (2018) [252]	Not a primary study
Valci et al. (2018) [253]	No MEP monitoring to avoid a postoperative deficit, no MEP warning criteria
Abdulrauf et al. (2017) [254]	Awake surgery
Benavides et al. (2017) [255]	Not a clinical study; study in pigs
Bharadwaj et al. (2017) [256]	Τechnical report, application, and feasibility of a new monitoring system
Calancie B. (2017) [257]	Not a primary study
Grasso et al. (2017) [258]	Not a primary study
Hemmer et al. (2017) [259]	Not a primary study
Journée et al. (2017) [20]	Not a primary study
Ku et al. (2017) [260]	Case report of a patient with vestibular schwannoma
Liu et al. (2017) [21]	Spinal surgery
MacDonald DB. (2017) [9]	Not a primary study
Moser et al. (2017) [261]	MEPs elicited through Transcranial Magnetic Stimulation (TMS)
Sanmillan et al. (2017) [98]	Not a primary study
Schucht et al. (2017) [104]	Not a primary study
Thomas et al. (2017) [89]	Not a primary study
Alimohamadi et al. (2016) [262]	Awake craniotomy
Coppola et al. (2016) [263]	Not a primary study
Holdefer et al. (2016) [28]	Not a primary study
König, R. (2016) [264]	Not a primary study
Raabe et al. (2016) [265]	Not a primary study
Yao et al. (2016) [266]	The term MEP referred to Meningiomas-en-plaque, no MEP monitoring
Holdefer et al. (2015) [92]	Not a primary study
Ottenhausen et al. (2015) [267]	Not a primary study
Sala et al. (2015) [87]	Not a primary study
Nakamura et al. (2014) [268]	Only abstract available
Suzuki et al. (2014) [269]	Awake aneurysm clipping
Yang et al. (2014) [270]	Intraoperative neuromonitoring used as a mapping technique to find the corticospinal projections
Landazuri et al. (2013) [271]	Not a primary study
MacDonald et al. (2013) [7]	Not a primary study
Rajapakse et al. (2013) [272]	Not a primary study
Yamashita et al. (2013) [273]	Only abstract available
Bacigaluppi et al. (2012) [274]	Not a primary study
De Witt Hamer et al. (2012) [275]	Not a primary study
Emerson et al. (2012) [276]	Not a primary study
Hotson et al. (2012) [277]	Electrocorticography analysis
Ito et al. (2012) [278]	Spinal surgery
Guo et al. (2011) [90]	Review/Not a primary study
Guo et al. (2011) [279]	Letter to the Editor/not a primary study
Li et al. (2011) [280]	Case report of a patient with high-grade brainstem glioma
Deiner S. (2010) [281]	Spinal surgery
Pabon et al. (2010) [282]	Only abstract available
Lefaucheur et al. (2009) [283]	Electrode placement for neuropathic pain treatment
Sun et al. (2009) [284]	MEPs elicited through Transcranial Magnetic Stimulation (TMS)
Duffau, H. (2008)-1 [285]	Not a primary study
Duffau, H. (2008)-2 [286]	Not a primary study
Takashima et al. (2008) [287]	Not a primary study
Duffau H. (2007) [288]	Not a primary study
Tharin et al. (2007) [289]	Not a primary study
Duffau, H. (2006) [290]	Not a primary study
Schramm et al. (2006) [291]	Only abstract available
Shinoura et al. (2006) [292]	Awake surgery
Kuzniecky et al. (2005) [293]	Not a primary study
Binder et al. (2004) [294]	Correlation of intraoperative neuromonitoring and imaging with Kernohan’s notch syndrome
Hashiguchi et al. (2004) [295]	Only abstract available
Kondo et al. (2004) [296]	Only abstract available
Neuloh et al. (2004) [297]	Not a primary study
Sala et al. (2002) [93]	Not a primary study
Di Lazzaro et al. (1999) [298]	Neurological and not neurosurgical patients
Calancie et al. (1998) [299]	Spinal lesions
Reinhardt et al. (1996) [300]	Τechnical report, presentation of an optical navigation system
Newlon et al. (1984) [301]	MEPs in diagnosis/prognosis/follow-up. Not intraoperatively.
After title screening: Duplicate or irrelevant records (n = 381)
** Additional clarifications -Not a primary study: review/meta-analysis/letter to the editor/technical report. -No MEP warning criteria: MEP monitoring may have been applied, but no MEP warning criteria were defined. -No clear MEP warning criteria: The authors reported that intraoperative MEP changes were considered, but it was not specified which criteria (amplitude, threshold, latency, and other) or which cut-off values were used. -No sufficient motor outcome data in conjunction with MEP warning criteria: The occurrence of MEP warning criteria and/or motor deficits were reported for the overall study population without specifying how many patients with intraoperative MEP alterations had postoperative motor deficits or vice versa, which was the outcome of interest for the scoping review. -No preoperatively defined MEP warning criteria: MEP warning criteria had to be determined a priori, namely before the operation. Postoperative reviews of monitoring datasets with post-hoc defined cut-off values as warning criteria, and analysis of motor outcomes were not eligible. A preoperatively determined warning criterion could be used to trigger intervention that may have altered the final results of the study. In the case of a postoperatively defined warning criterion, the intraoperative actions were not driven by alarm criteria, and the final results should not be regarded as comparable with those of studies with a priori defined alarm criteria. -No preoperatively defined cutoff value for MEP warning criteria: The cut-off values for MEP warning criteria (e.g., amplitude reduction >50%, threshold elevation >20 mA, latency increase >10%, etc.) had to be preoperatively defined. -No motor outcome analysis: Postoperative motor outcome was not reported. The study reported postoperative radiologic findings or sensory/cognitive/other deficits but no motor deficits. -Motor outcome data of anesthetized patients with supratentorial lesions were not clearly reported and could not be extracted: In studies with mixed populations (namely, anesthetized patients with supratentorial lesions and awake patients or infratentorial/spinal lesions). The data for supratentorial/anesthetized patients were not separately tabulated or reported in a way that they could be clearly distinguished from those with infratentorial/spinal/awake patients and extracted. -No MEP monitoring warning criteria, only mapping warning criteria: Our aim was to analyze MEP alarm criteria during continuous muscle MEP monitoring. Mapping criteria as complementary criteria were taken into consideration but only in studies that combined mapping with MEP monitoring. Studies with Penfield mapping without MEP monitoring were not included in the scoping review.