Why Does Threshold Level Change in Transcranial Motor-evoked Potentials During Surgery for Supratentorial Lesions?

Abboud, Tammam; Huckhagel, Torge; Stork, Jan; Hamel, Wolfgang; Schwarz, Cindy; Vettorazzi, Eik; Westphal, Manfred; Martens, Tobias

doi:10.1097/ana.0000000000000336

Cited by 11 publications

(8 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Furthermore, the significant MEP changes in our patients without postoperative motor deficits might have represented false-positive MEP findings. A recent study found that pneumocephalus was associated with an increase in the threshold stimulus intensity during intraoperative MEP monitoring when there was no damage to the motor pathway 22. In our study, postoperative CT or MRI scans revealed minimal pneumocephalus in 20% of patients with decreases in MEP.…”

Section: Discussionsupporting

confidence: 59%

Clinical Usefulness of Intraoperative Motor-Evoked Potential Monitoring during Temporal Lobe Epilepsy Surgery

et al. 2019

View full text Add to dashboard Cite

Background and Purpose We aimed to determine the effectiveness of intraoperative neurophysiological monitoring focused on the transcranial motor-evoked potential (MEP) in patients with medically refractory temporal lobe epilepsy (TLE). Methods We compared postoperative neurological deficits in patients who underwent TLE surgery with or without transcranial MEPs combined with somatosensory evoked potential (SSEP) monitoring between January 1995 and June 2018. Transcranial motor stimulation was performed using subdermal electrodes, and MEP responses were recorded in the four extremity muscles. A decrease of more than 50% in the MEP or the SSEP amplitudes compared with baseline was used as a warning criterion. Results In the TLE surgery group without MEP monitoring, postoperative permanent motor deficits newly developed in 7 of 613 patients. In contrast, no permanent motor deficit occurred in 279 patients who received transcranial MEP and SSEP monitoring. Ten patients who exhibited decreases of more than 50% in the MEP amplitude recovered completely, although two cases showed transient motor deficits that recovered within 3 months postoperatively. Conclusions Intraoperative transcranial MEP monitoring during TLE surgery allowed the prompt detection and appropriate correction of injuries to the motor nervous system or ischemic stroke. Intraoperative transcranial MEP monitoring is a reliable modality for minimizing motor deficits in TLE surgery.

show abstract

Section: Discussionsupporting

confidence: 59%

Clinical Usefulness of Intraoperative Motor-Evoked Potential Monitoring during Temporal Lobe Epilepsy Surgery

et al. 2019

View full text Add to dashboard Cite

show abstract

“…Even though this finding were not reproduced in the substudy 2, a possible explanation could be the small sample size of the study. As has been previously described, 38‐40 tcMEP amplitude and morphology vary from trace to trace due to the mechanism of MEP generation and, moreover, there is considerable inter‐ and intra‐individual variability in patients under general anaesthesia 8 . The generation of tcMEPs requires synaptic transmission at the anterior horn cell, which is facilitated by a train of stimulus pulses 41 .…”

Section: Discussionmentioning

confidence: 96%

Effect of dexmedetomidine on evoked‐potential monitoring in patients undergoing brain stem and supratentorial cranial surgery

Pacreu

Vilà

Moltó

et al. 2021

Acta Anaesthesiol Scand

View full text Add to dashboard Cite

Background Dexmedetomidine is used as adjuvant in total intravenous anaesthesia (TIVA), but there have been few studies concerning its effect on intraoperative neurophysiological monitoring (IONM) during cranial surgery. Our aim was to study the effect of dexmedetomidine on IONM in patients undergoing brain stem and supratentorial cranial surgery. Methods Two prospective, randomized, double‐blind substudies were conducted. In substudy 1, during TIVA with an infusion of propofol and remifentanil, 10 patients received saline solution (SS) (PR group) and another 10 (PRD group) received dexmedetomidine (0.5 mcg/kg/h). Total dosage of propofol and remifentanil, intensity, latency and amplitude of motor‐evoked potentials following transcranial electrical stimulation (tcMEPs) as well as somatosensory‐evoked potentials (SSEP) were recorded at baseline, 15, 30, 45 minutes, and at the end of surgery. In order to identify differences in the same patient after dexmedetomidine administration, we designed substudy 2 with 20 new patients randomized to two groups. After 30 minutes with TIVA, 10 patients received dexmedetomidine (0.5 mcg/kg/h) and 10 patients SS. The same variables were recorded. Results In substudy 1, propofol requirements were significantly lower (P = .004) and tcMEP intensity at the end of surgery was significantly higher in PRD group, but no statistically significant differences were observed for remifentanil requirements, SSEP and tcMEP latency or amplitude. In substudy 2, no differences in any of the variables were identified. Conclusions The administration of dexmedetomidine at a dosage of 0.5 mg/kg/h may reduce propofol requirements and adversely affect some neuromonitoring variables. However, it can be an alternative on IONM during cranial surgeries. REDEX EudraCT: 2014‐000962‐23

show abstract

“…That fact may interfere with the reliability and evaluation of TES-MEP warning criteria. Further, TES may cause a higher rate of patient movement [ 100 ]. Because of these drawbacks, many neurosurgeons opt for DCS, which needs lower stimulation intensities and allows a focal and superficial stimulation of corticospinal neurons [ 8 ].…”

Section: Discussionmentioning

confidence: 99%

Motor Evoked Potential Warning Criteria in Supratentorial Surgery: A Scoping Review

Asimakidou

Abut

Raabe

et al. 2021

Cancers

View full text Add to dashboard Cite

During intraoperative monitoring of motor evoked potentials (MEP), heterogeneity across studies in terms of study populations, intraoperative settings, applied warning criteria, and outcome reporting exists. A scoping review of MEP warning criteria in supratentorial surgery was conducted in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR). Sixty-eight studies fulfilled the eligibility criteria. The most commonly used alarm criteria were MEP signal loss, which was always a major warning sign, followed by amplitude reduction and threshold elevation. Irreversible MEP alterations were associated with a higher number of transient and persisting motor deficits compared with the reversible changes. In almost all studies, specificity and Negative Predictive Value (NPV) were high, while in most of them, sensitivity and Positive Predictive Value (PPV) were rather low or modest. Thus, the absence of an irreversible alteration may reassure the neurosurgeon that the patient will not suffer a motor deficit in the short-term and long-term follow-up. Further, MEPs perform well as surrogate markers, and reversible MEP deteriorations after successful intervention indicate motor function preservation postoperatively. However, in future studies, a consensus regarding the definitions of MEP alteration, critical duration of alterations, and outcome reporting should be determined.

show abstract

Why Does Threshold Level Change in Transcranial Motor-evoked Potentials During Surgery for Supratentorial Lesions?

Cited by 11 publications

References 17 publications

Clinical Usefulness of Intraoperative Motor-Evoked Potential Monitoring during Temporal Lobe Epilepsy Surgery

Clinical Usefulness of Intraoperative Motor-Evoked Potential Monitoring during Temporal Lobe Epilepsy Surgery

Effect of dexmedetomidine on evoked‐potential monitoring in patients undergoing brain stem and supratentorial cranial surgery

Motor Evoked Potential Warning Criteria in Supratentorial Surgery: A Scoping Review

Contact Info

Product

Resources

About