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The Effect of Increasing Current or Pulse Duration on Patient Movement and Intraoperative Transcranial Electric Stimulation Motor Evoked Potential Amplitude

NCT05375669 · Status: COMPLETED · Phase: NA · Type: INTERVENTIONAL · Enrollment: 31

Last updated 2025-04-01

No results posted yet for this study

Summary

Transcranial electric stimulation (TES) motor evoked potential (MEP) monitoring is standard during surgery risking motor system injury. The stimuli are typically 5-pulse trains with a 4 ms interstimulus interval (ISI). The pulse duration (D) is often set to 50 or 500 µs. Both are effective, but setting D to the chronaxie would be physiologically optimal and limited data suggest that mean MEP chronaxie may be near 200 µs.

When necessary, one can obtain larger MEPs by increasing current (I) or D to increase stimulus charge (Q = I × D). However, this also increases patient movement that can interfere with surgery and reduce MEP acquisition frequency.

The main research question is whether increasing current or pulse duration when applying intraoperative neuromonitoring produces less patient movement during surgery. As such, the IOM ISIS System will be employed for neuromonitoring and an accelerometer will be used to quantify patient movement.

The constant-current TES stimulators will be used in this study with a high-precision oscilloscope. Total intravenous anesthesia (TIVA), surgery and TES MEP monitoring will proceed routinely without modification and normally involves acquiring many MEPs over several hours. The only departure from standard care will be the placement of two small accelerometers and a brief MEP sequence before skin incision to determine chronaxie and compare the effect of an equivalent increase of I or D on MEP amplitude and movement.

Conditions

  • Surgery

Interventions

DEVICE

ISIS IOM System

The constant-current TES stimulators will be used in this study with a high-precision oscilloscope. The calibration will assess 5-pulse trains with a 4 ms ISI and 100 mA output across a 1000 Ω resistor at 250, 500, and 1000 µs D. Measurements will include actual I and D of each pulse, and actual ISI. Total intravenous anesthesia (TIVA), surgery and TES MEP monitoring will proceed routinely without modification and normally involves acquiring many MEPs over several hours. The only departure from standard care will be the placement of two small accelerometers and a brief MEP sequence before skin incision to determine chronaxie and compare the effect of an equivalent increase of I or D on MEP amplitude and movement.

Sponsors & Collaborators

  • Insel Gruppe AG, University Hospital Bern

    lead OTHER

Principal Investigators

  • Kathleen Seidel, MMD · Inselspital Bern, Department of Neurosurgery

Study Design

Allocation
NA
Purpose
TREATMENT
Masking
NONE
Model
SINGLE_GROUP

Eligibility

Min Age
18 Years
Sex
ALL
Healthy Volunteers
No

Timeline & Regulatory

Start
2022-08-10
Primary Completion
2024-11-01
Completion
2024-11-01

Countries

  • Switzerland

Study Locations

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Read the full study record

This page highlights key information. For complete eligibility criteria, study locations, investigator contacts, and the full protocol, visit the original record on ClinicalTrials.gov.

View NCT05375669 on ClinicalTrials.gov