SurgeryCCCVNCT05375669
The Effect of Increasing Current or Pulse Duration on Patient Movement and Intraoperative Transcranial Electric Stimulation Motor Evoked Potential Amplitude
A study testing ISIS IOM System in people with Surgery, run by Insel Gruppe AG, University Hospital Bern at 1 site in Switzerland.
Trial 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. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Surgery
- What is being tested?
- ISIS IOM System
- Type of treatment
- Injection or infusion, Medical device
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 31 participants
- Where
- 1 siteSwitzerland
- Study dates
- 10 Aug 2022to 1 Nov 2024
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- 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
Who cannot join
- 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
Trial locations and contacts
1 site in 1 country.
Switzerland1 site
Dep. of Neurosurgery, Bern University Hospital
Bern, 3010
About this study
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.
Read more
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.
Read the 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.
- Conditions
- Surgery
- Being tested
- ISIS IOM System
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
ISIS IOM SystemDevice
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 group | Role | What they receive |
|---|---|---|
| ISIS IOM System | Experimental | 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. Receives: Device: ISIS IOM System |
What is being measured
The primary outcome is the main question the study is designed to answer.
Comparison of the effect of a 2-fold increase of I or of D from threshold on patient movement
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.
Measured: During surgery, estimated on average to be about 4 hours
Secondary outcomes (2)
Comparing the effect of a 2-fold increase of I or of D from threshold on MEP amplitude
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
Measured: During surgery, estimated on average to be about 4 hours
Chronaxie
The stimulation strength (in mA) necessary to elicit an MEP are measured with the different pulse durations (in μs)
Measured: During surgery, estimated on average to be about 4 hours
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted17 May 2022
- Study start10 Aug 2022
- Primary completion1 Nov 2024
- Study completion1 Nov 2024
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (5)Papers the sponsor has linked to this study.
- Other trials for SurgeryStudies of the same condition, open and under way.
- More trials run by Insel Gruppe AG, University Hospital BernThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Single group
- 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 surgery
- Masking
- None (open label)
- Enrolment
- 31 participants (actual)
Sponsor and investigators
- Lead sponsor
- Insel Gruppe AG, University Hospital Bern
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
- Investigators
- Kathleen Seidel, MMD, Principal investigator, Inselspital Bern, Department of Neurosurgery
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05375669
- Sponsor's protocol ID
- CCCV
- Acronym
- CCCV
- Status last verified
- Mar 2025
- First submitted
- 21 Apr 2022
- Last updated
- 1 Apr 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Publications
Szelenyi A, Kothbauer KF, Deletis V. Transcranial electric stimulation for intraoperative motor evoked potential monitoring: Stimulation parameters and electrode montages. Clin Neurophysiol. 2007 Jul;118(7):1586-95. doi: 10.1016/j.clinph.2007.04.008. Epub 2007 May 15.
PubMed 17507288Abalkhail TM, MacDonald DB, AlThubaiti I, AlOtaibi FA, Stigsby B, Mokeem AA, AlHamoud IA, Hassounah MI, Baz SM, AlSemari A, AlDhalaan HM, Khan S. Intraoperative direct cortical stimulation motor evoked potentials: Stimulus parameter recommendations based on rheobase and chronaxie. Clin Neurophysiol. 2017 Nov;128(11):2300-2308. doi: 10.1016/j.clinph.2017.09.005. Epub 2017 Sep 28.
PubMed 29035822Macdonald DB, Skinner S, Shils J, Yingling C; American Society of Neurophysiological Monitoring. Intraoperative motor evoked potential monitoring - a position statement by the American Society of Neurophysiological Monitoring. Clin Neurophysiol. 2013 Dec;124(12):2291-316. doi: 10.1016/j.clinph.2013.07.025. Epub 2013 Sep 18.
PubMed 24055297MacDonald DB. Safety of intraoperative transcranial electrical stimulation motor evoked potential monitoring. J Clin Neurophysiol. 2002 Oct;19(5):416-29. doi: 10.1097/00004691-200210000-00005.
PubMed 12477987Eng J. Sample size estimation: how many individuals should be studied? Radiology. 2003 May;227(2):309-13. doi: 10.1148/radiol.2272012051.
PubMed 12732691
Study at a glance
From the registry record, last updated by the sponsor on 1 Apr 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- The Effect of Increasing Current or Pulse Duration on Patient Movement and Intraoperative Transcranial Electric Stimulation Motor Evoked Potential Amplitude
- ClinicalTrials.gov ID
- NCT05375669
- Acronym / sponsor ID
- CCCV / CCCV
- Conditions
- Surgery
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 31 participants (actual)
- Lead sponsor
- Insel Gruppe AG, University Hospital BernUniversity, hospital or other
- Study start
- 10 Aug 2022 (actual)
- Primary completion
- 1 Nov 2024 (actual)
- Study completion
- 1 Nov 2024 (actual)
- First posted
- 17 May 2022 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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.
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
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
- 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 surgery
| Arm | Type | Receives |
|---|---|---|
| ISIS IOM System | Experimental | Device: ISIS IOM SystemTotal 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. |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (4 listed)
- 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
Key exclusion criteria (8 listed)
- 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
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| ISIS IOM SystemThe 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. | Device | ISIS IOM System |
Primary outcome
Comparison of the effect of a 2-fold increase of I or of D from threshold on patient movement
Time frame: 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.
2 secondary outcomes
Comparing the effect of a 2-fold increase of I or of D from threshold on MEP amplitude
Time frame: During surgery, estimated on average to be about 4 hours
Chronaxie
Time frame: During surgery, estimated on average to be about 4 hours
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 1 Apr 2025.
- Background: PubMed 17507288Szelenyi A, Kothbauer KF, Deletis V. Transcranial electric stimulation for intraoperative motor evoked potential monitoring: Stimulation parameters and electrode montages. Clin Neurophysiol. 2007 Jul;118(7):1586-95. doi: 10.1016/j.clinph.2007.04.008. Epub 2007 May 15.
- Background: PubMed 29035822Abalkhail TM, MacDonald DB, AlThubaiti I, AlOtaibi FA, Stigsby B, Mokeem AA, AlHamoud IA, Hassounah MI, Baz SM, AlSemari A, AlDhalaan HM, Khan S. Intraoperative direct cortical stimulation motor evoked potentials: Stimulus parameter recommendations based on rheobase and chronaxie. Clin Neurophysiol. 2017 Nov;128(11):2300-2308. doi: 10.1016/j.clinph.2017.09.005. Epub 2017 Sep 28.
- Background: PubMed 24055297Macdonald DB, Skinner S, Shils J, Yingling C; American Society of Neurophysiological Monitoring. Intraoperative motor evoked potential monitoring - a position statement by the American Society of Neurophysiological Monitoring. Clin Neurophysiol. 2013 Dec;124(12):2291-316. doi: 10.1016/j.clinph.2013.07.025. Epub 2013 Sep 18.
- Background: PubMed 12477987MacDonald DB. Safety of intraoperative transcranial electrical stimulation motor evoked potential monitoring. J Clin Neurophysiol. 2002 Oct;19(5):416-29. doi: 10.1097/00004691-200210000-00005.
- Background: PubMed 12732691Eng J. Sample size estimation: how many individuals should be studied? Radiology. 2003 May;227(2):309-13. doi: 10.1148/radiol.2272012051.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Kathleen Seidel, MMD principal investigator
Inselspital Bern, Department of Neurosurgery
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing ISIS IOM System in people with Surgery, run by Insel Gruppe AG, University Hospital Bern at 1 site in Switzerland.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 4 inclusion and 8 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 1 Apr 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Switzerland. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Comparison of the effect of a 2-fold increase of I or of D from threshold on patient movement (time frame: During surgery, estimated on average to be about 4 hours). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT05375669, which also lists 5 linked publications.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 1 Apr 2025.