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

Sponsor
University Hospital Inselspital, Berne (Other)
Overall Status
Not yet recruiting
CT.gov ID
NCT05375669
Collaborator
(none)
31
Enrollment
1
Location
1
Arm
9
Anticipated Duration (Months)
3.5
Patients Per Site Per Month

Study Details

Study Description

Brief 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.

Condition or Disease Intervention/Treatment Phase
  • Device: ISIS IOM System
 N/A

Detailed Description

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. Anecdotal observations suggest that increasing D may produce larger MEPs with less movement than increasing I, but there is no published support. If true, then the optimal D for monitoring may be above the chronaxie because less movement could facilitate more frequent MEP acquisition.

Finally, there is ongoing controversy about constant-current or constant-voltage TES. However, with stable resistance (R) there is no fundamental reason to prefer one or the other since they are related by Ohm's law I = V/R. Also, since threshold current and voltage vary with D their maximum levels should also vary with selected D, which could be confusing. Instead, because the International Electrotechnical Commission 50 mJ safety limit is based on energy (E = I2 × D × R = V2 × D/R), it may be more logical to apply constant-energy TES that would provide a consistent 0-50 mJ selection range at any selected D.

The primary objective is to assess whether intraoperative neuromonitoring with constant current or constant voltage produces less patient movement during surgery. The secondary objectives are to compare MEP amplitudes with the different setups, to estimate the true mean or median chronaxie and to develop the concept of constant-energy TES.

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. 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.

Study Design

Study Type:
Interventional
Anticipated Enrollment :
31 participants
Allocation:
N/A
Intervention Model:
Single Group Assignment
Intervention Model Description:
Patients will be screened as part of the clinical routine and will be included if they satisfy the eligibility criteria and sign the informed consent. All the study subjects who are included are patients who undergo surgeryPatients will be screened as part of the clinical routine and will be included if they satisfy the eligibility criteria and sign the informed consent. All the study subjects who are included are patients who undergo surgery
Masking:
None (Open Label)
Primary Purpose:
Treatment
Official Title:
The Effect of Increasing Current or Pulse Duration on Patient Movement and Intraoperative Transcranial Electric Stimulation Motor Evoked Potential Amplitude
Anticipated Study Start Date :
Jul 1, 2022
Anticipated Primary Completion Date :
Jan 31, 2023
Anticipated Study Completion Date :
Mar 31, 2023

Arms and Interventions

Arm Intervention/Treatment
Experimental: ISIS IOM System

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.

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.

Outcome Measures

Primary Outcome Measures

  1. Comparison of the effect of a 2-fold increase of I or of D from threshold on patient movement [During surgery, estimated on average to be about 4 hours]

    Comparison of the effect of a 2-fold increase of I or of D from threshold on patient movement quantified by accelerometers on the patient's forehead and contralateral (non-affected) shoulder.

Secondary Outcome Measures

  1. Comparing the effect of a 2-fold increase of I or of D from threshold on MEP amplitude [During surgery, estimated on average to be about 4 hours]

    Compare the effect of a 2-fold increase of I or of D from threshold on MEP amplitude as measured by the ISIS IOM System

  2. Chronaxie [During surgery, estimated on average to be about 4 hours]

    The stimulation strength (in mA) necessary to elicit an MEP are measured with the different pulse durations (in μs)

Eligibility Criteria

Criteria

Ages Eligible for Study:
18 Years and Older
Sexes Eligible for Study:
All
Accepts Healthy Volunteers:
No
Inclusion Criteria:

  • Informed Consent signed by the subject

  • The patient has a supra- or infra-tentorial lesion requiring surgery

  • The patient is undergoing neurosurgery with the use of Intraoperative Monitoring (IOM) during surgery to protect functional tissue

  • The patient is older than 18 years

Exclusion Criteria:

  • No need for Intraoperative Monitoring (IOM)

  • Vulnerable subjects (pregnant women, pregnant, impaired consciousness)

  • People who do not want to participate in the study

  • Emergency procedures in which no consent was obtained before the operation

  • Multiple surgeries on the same patient

  • Preoperative non-affected arm motor deficit (MRC <5), that is to say, no motor deficit of the arm ipsilateral to the surgery

  • Inhalational anesthesia

  • Persisting neuromuscular blockade

Contacts and Locations

Locations

Site City State Country Postal Code
1 Dep. of Neurosurgery, Bern University Hospital Bern Switzerland 3010

Sponsors and Collaborators

  • University Hospital Inselspital, Berne

Investigators

  • Principal Investigator: Kathleen Seidel, MMD, Inselspital Bern, Department of Neurosurgery

Study Documents (Full-Text)

None provided.

More Information

Publications

Responsible Party:
University Hospital Inselspital, Berne
ClinicalTrials.gov Identifier:
NCT05375669
Other Study ID Numbers:
  • CCCV
First Posted:
May 17, 2022
Last Update Posted:
May 17, 2022
Last Verified:
May 1, 2022
Individual Participant Data (IPD) Sharing Statement:
No
Plan to Share IPD:
No
Studies a U.S. FDA-regulated Drug Product:
No
Studies a U.S. FDA-regulated Device Product:
No

Study Results

No Results Posted as of May 17, 2022