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Faro Viana F, Cotovio G, da Silva DR, Seybert C, Pereira P, Silva A, Carvalho F, Oliveira-Maia AJ. Reducing motor evoked potential amplitude variability through normalization. Front Psychiatry 2024; 15:1279072. [PMID: 38356910 PMCID: PMC10864444 DOI: 10.3389/fpsyt.2024.1279072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Accepted: 01/04/2024] [Indexed: 02/16/2024] Open
Abstract
BackgroundTranscranial Magnetic Stimulation (TMS) is used for in vivo assessment of human motor cortical excitability, with application of TMS pulses over the motor cortex resulting in muscle responses that can be recorded with electromyography (EMG) as Motor Evoked Potentials (MEPs). These have been widely explored as potential biomarkers for neuropsychiatric disorders but methodological heterogeneity in acquisition, and inherent high variability, have led to constraints in reproducibility. Normalization, consisting in scaling the signal of interest to a known and repeatable measurement, reduces variability and is standard practice for between-subject comparisons of EMG. The effect of normalization on variability of MEP amplitude has not yet been explored and was assessed here using several methods.MethodsThree maximal voluntary isometric contractions (MVICs) and 40 MEPs were collected from the right hand in healthy volunteers, with a retest session conducted 4 to 8 weeks later. MEP amplitude was normalized using either external references (MVICs) or internal references (extreme MEPs). Iterative re-sampling of 30 normalized MEPs per subject was repeated 5,000 times to define, for each normalization method, distributions for between-subject coefficients of variation (CV) of the mean MEP amplitude. Intra-class correlation coefficients (ICC) were used to assess the impact of normalization on test–retest stability of MEP amplitude measurements.ResultsIn the absence of normalization, MEPs collected from the right hand of 47 healthy volunteers were within reported values regarding between-subject variability (95% confidence intervals for the CV: [1.0567,1.0577]) and showed good temporal stability (ICC = 0.77). Internal reference normalization substantially reduced between-subject variability, by values of up to 64%, while external reference normalization had no impact or increased between-subject variability. Normalization with the smallest references reduced test–retest stability, with use of the largest references resulting in slight reduction or improvement of ICCs. Internal reference normalization using the largest MEPs was found to be robust to several sensitivity analyses.ConclusionInternal, but not external, reference normalization reduces between-subject variability of MEP amplitude, and has a minimal impact on within-subject variability when conducted with the largest references. Additional research is necessary to further validate these normalization methods toward potential use of MEPs as biomarkers of neuropsychiatric disorders.
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Affiliation(s)
- Francisco Faro Viana
- Champalimaud Research, Champalimaud Foundation, Lisbon, Portugal
- Champalimaud Clinical Centre, Champalimaud Foundation, Lisbon, Portugal
| | - Gonçalo Cotovio
- Champalimaud Research, Champalimaud Foundation, Lisbon, Portugal
- Champalimaud Clinical Centre, Champalimaud Foundation, Lisbon, Portugal
- NOVA Medical School, Faculdade de Ciências Médicas, NMS, FCM, Universidade NOVA de Lisboa, Lisbon, Portugal
- Department of Psychiatry and Mental Health, Centro Hospitalar de Lisboa Ocidental, Lisbon, Portugal
| | - Daniel Rodrigues da Silva
- Champalimaud Research, Champalimaud Foundation, Lisbon, Portugal
- Champalimaud Clinical Centre, Champalimaud Foundation, Lisbon, Portugal
| | - Carolina Seybert
- Champalimaud Research, Champalimaud Foundation, Lisbon, Portugal
- Champalimaud Clinical Centre, Champalimaud Foundation, Lisbon, Portugal
| | - Patrícia Pereira
- Champalimaud Research, Champalimaud Foundation, Lisbon, Portugal
- Champalimaud Clinical Centre, Champalimaud Foundation, Lisbon, Portugal
- Portuguese Red Cross Health School, Lisbon, Portugal
| | - Artur Silva
- Champalimaud Research, Champalimaud Foundation, Lisbon, Portugal
| | - Filipe Carvalho
- Champalimaud Research, Champalimaud Foundation, Lisbon, Portugal
| | - Albino J. Oliveira-Maia
- Champalimaud Research, Champalimaud Foundation, Lisbon, Portugal
- Champalimaud Clinical Centre, Champalimaud Foundation, Lisbon, Portugal
- NOVA Medical School, Faculdade de Ciências Médicas, NMS, FCM, Universidade NOVA de Lisboa, Lisbon, Portugal
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Low-dose Droperidol Reduces the Amplitude of Transcranial Electrical Motor-evoked Potential: A Randomized, Double-blind, Placebo-controlled Trial. J Neurosurg Anesthesiol 2021; 34:424-428. [PMID: 34411060 DOI: 10.1097/ana.0000000000000784] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2021] [Accepted: 05/03/2021] [Indexed: 11/27/2022]
Abstract
BACKGROUND Low-dose droperidol has been reported to suppress the amplitude of transcranial electrical motor-evoked potentials (TCE-MEPs), but no randomized controlled trials have been conducted to assess this. This randomized, double-blinded, placebo-controlled trial aimed to test the hypothesis that low-dose droperidol reduced TCE-MEP amplitudes. METHODS Twenty female patients with adolescent idiopathic scoliosis, aged between 12 and 20 years, and scheduled to undergo corrective surgery were randomly allocated to receive droperidol (20 µg/kg) or 0.9% saline. After recording baseline TCE-MEPs, the test drug was administered, following which TCE-MEP recordings were carried out every 2 minutes for up to 10 minutes. The primary outcome was the minimum relative TCE-MEP amplitude (peak-to-peak amplitude, percentage of baseline value) recorded in the left tibialis anterior muscle. Secondary outcomes included minimum relative MEP amplitudes recorded from all other muscle groups monitored in the study. Data are expressed as medians (interquartile range). RESULTS The TCE-MEP amplitude of the left tibialis anterior muscle was significantly reduced following droperidol administration compared with saline (37% [30% to 55%] vs. 76% [58% to 93%], respectively, P<0.01). In the other muscles, the amplitudes were reduced in the droperidol group, except for the bilateral abductor pollicis brevis and the left quadriceps femoris muscles. The relative amplitude of the bilateral F waves recorded from the gastrocnemius was decreased in the droperidol group. CONCLUSIONS Low-dose droperidol (20 µg/kg) reduced TCE-MEP amplitudes. Anesthesiologists should pay attention to the timing of droperidol administration during intraoperative TCE-MEP recordings, even if used in a low dose.
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Deguchi H, Furutani K, Mitsuma Y, Kamiya Y, Baba H. Propofol reduces the amplitude of transcranial electrical motor-evoked potential without affecting spinal motor neurons: a prospective, single-arm, interventional study. J Anesth 2021; 35:434-441. [PMID: 33825982 DOI: 10.1007/s00540-021-02927-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Accepted: 03/22/2021] [Indexed: 11/26/2022]
Abstract
PURPOSE Propofol inhibits the amplitudes of transcranial electrical motor-evoked potentials (TCE-MEP) in a dose-dependent manner. However, the mechanisms of this effect remain unknown. Hence, we investigated the spinal mechanisms of the inhibitory effect of propofol on TCE-MEP amplitudes by evaluating evoked electromyograms (H-reflex and F-wave) under general anesthesia. METHODS We conducted a prospective, single-arm, interventional study including 15 patients scheduled for spine surgery under general anesthesia. Evoked electromyograms of the soleus muscle and TCE-MEPs were measured at three propofol concentrations using target-controlled infusion (TCI: 2.0, 3.0, and 4.0 µg/mL). The primary outcome measure was the left H-reflex amplitude during TCI of 4.0- compared to 2.0-µg/mL propofol administration. RESULTS The median [interquartile range] amplitudes of the left H-reflex were 4.71 [3.42-6.60] and 5.6 [4.17-7.46] in the 4.0- and 2.0-μg/mL TCI groups (p = 0.4, Friedman test), respectively. There were no significant differences in the amplitudes of the right H-reflex and the bilateral F-wave among these groups. However, the TCE-MEP amplitudes significantly decreased with increased propofol concentrations (p < 0.001, Friedman test). CONCLUSION Propofol did not affect the amplitudes of the H-reflex and the F-wave, whereas TCE-MEP amplitudes were reduced at higher propofol concentrations. These results suggested that propofol can suppress the TCE-MEP amplitude by inhibiting the supraspinal motor pathways more strongly than the excitability of the motor neurons in the spinal cord.
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Affiliation(s)
- Hiroyuki Deguchi
- Department of Anesthesiology, Niigata University Medical and Dental Hospital, 1-754 Asahimachi-Dori, Chuo-ku, Niigata, 951-8520, Japan
| | - Kenta Furutani
- Department of Anesthesiology, Niigata University Medical and Dental Hospital, 1-754 Asahimachi-Dori, Chuo-ku, Niigata, 951-8520, Japan.
| | - Yusuke Mitsuma
- Department of Anesthesiology, Niigata University Medical and Dental Hospital, 1-754 Asahimachi-Dori, Chuo-ku, Niigata, 951-8520, Japan
| | - Yoshinori Kamiya
- Department of Anesthesiology, Niigata University Medical and Dental Hospital, 1-754 Asahimachi-Dori, Chuo-ku, Niigata, 951-8520, Japan
| | - Hiroshi Baba
- Department of Anesthesiology, Niigata University Medical and Dental Hospital, 1-754 Asahimachi-Dori, Chuo-ku, Niigata, 951-8520, Japan
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