Introduction

Non-invasive brain stimulation, such as transcranial Magnetic Stimulation (TMS) and transcranial current stimulation (tCS), is a common tool for both research and therapeutic uses and is generally regarded as safe. However, rare occurrences of brain stimulation induced loss of consciousness (LoC) have been reported. The fast majority of LoCs can be attributed to a vasodepressor (neurocardiogenic) syncope - a reaction to anxiety and psycho-physical discomfort - but in rare cases the induction of a seizure has occurred. Based on the number of studies, subjects, and patients involved with TMS research, the risk of seizure with non–invasive brain stimulation is considered very low (Rossi et al., 2010). Due to potential diagnostic problems differentiating a syncope and a seizure and because the initial measures for suspected seizures and syncope are identical we have one standard procedure for every loss of consciousness.

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Target group and scope

Target group

All investigators actively involved in non-invasive brain stimulation research projects at the MR-research section.

All medical doctors associated with non-invasive brain stimulation studies at the MR-research section. The “Mobilt Akut Team” (MAT) at Hvidovre Hospital.

Scope

Establishing a standard procedure for handling loss of consciousness in the course of a non-invasive brain stimulation experiment.

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Definitions

Loss of consciousness: the occurrence of a loss of the ability to perceive and respond.

Vasovagal syncope: Common cause of fainting and a reaction to anxiety and psycho-physical discomfort leading to sudden drop in heart rate and blood pressure. Recovery of consciousness after a vasovagal syncope is rapid (few seconds).

Pre-syncope: Some premonitory complaints like ‘‘I need to lie down”, or ‘‘I need air”, narrowing and blacking out of the visual field, sensations of heat, bradycardia, and decrease of peripheral pulse, are present but no loss of consciousness.

Seizure: Brief episodes of abnormal excessive or synchronous neuronal activity in the brain. The effect of a seizure can vary from wild thrashing movement (tonic-clonic seizure) to a brief loss of awareness (absence seizure). Recovery of consciousness after a seizure varies from 10 seconds to several minutes.

Most seizures after non-invasive brain stimulation were reported either in the presence of possible predisposing factors (medication, brain lesions or genetic susceptibility) or when the safety recommendations (Rossi et al., 2009, Wasserman et al., 1998) were not followed. The risk of developing additional seizure attacks after a brain stimulation induced seizure is not increased.

Primary Investigator: The researcher applying the brain stimulation and practically conducting the experiment.

Medical doctor associated with the project: A physician employed at the MR-research section who supervises patient and participant safety.

Research Group Leader: Scientific supervisor of the experiment - either at an MD or PhD level.

Responsible investigators in order of involvement:

Primary Investigator (direct responsibility). The primary investigator is responsible that the course of action, described in this document, is followed.
The medical doctor associated with the project is responsible for referring the participant to a neurological follow up examination in case of a suspected seizure.
RGL: Research Group Leader is responsible to ensure that the experiment complies with the international safety guidelines (Rossi S et al. 2021) and that all investigators directly involved in TMS/tDCS are familiar with these guidelines and have acquired the internal TMS-license.

Research subjects:

Any individual participating in TMS research projects at the MR-section.

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Course of Action

1.1 General Lab practice:

All investigators have to be familiar with the international TMS safety guidelines (Rossi S et al. 2021). All investigators are aware of the emergency procedure, which is visibly located in each laboratory. Additionally, investigators have acquired an internal TMS–license and successfully completed the obligatory resuscitation training.

All experiments are in compliance with the international TMS safety guidelines and all individuals taking part in brain stimulation studies are screened for risk factors prior to scanning (see Appendix 2 for questionnaire). If research participants with a known risk factors for a TMS induced seizure (e.g. epileptic patients, CNS-active medication) are taking part in transcranial brain stimulation studies a physician is present throughout the experiment and the inclusion of the risk-population has been cleared by the local ethics committee (a full list of TMS risk factors can be found in the safety guidelines and in our screening form.

1.2 In case of a loss of consciousness:

In case of a LoC investigators should follow these steps:

1. Stay calm / Stop stimulation

2. Bring participant in horizontal position

3. Try to make contact with participant

IF participant remains unconscious:

4. Check airways and breathing

5. Put patient in recovery position if possible

6. Call mobile acute team (nr: ###TELEFON###, your location: )

1. From Landline: ####TELEFON###, From cell: ####TELEFON###
2. And Report your location:
3. 1. 1. Contact TMS: ###DIVERSE###,
    2. NeurOne: ###DIVERSE###,
    3. Robot: ###DIVERSE###,
    4. 340-Lab: ###DIVERSE###

Once the situation is resolved:

Inform your research group leader

On suspicion of cardiac arrest: Call ###TELEFON### and thereafter start CPR.

These steps are described in the action card ‘Emergency Procedure TMS’ (Appendix 1). A copy of this document is visibly located in every brain stimulation laboratory.

1.3 Follow up

In the unlikely case of a loss of consciousness lasting more than 10 seconds, the emergency team decides the immediate further course of action. In case of a suspected seizure further neurological examination is necessary and the medical doctor associated with the brain stimulation study will refer the participant to a neurological follow up examination. Every loss of consciousness lasting more than 10 seconds is regarded as a serious unexpected adverse event and is immediately reported to the local ethical committee.

In case of a vasovagal syncope, that does not require further medical attention the research participant is monitored by the lead associative investigator for the next 30 minutes. The participant is recommended to take a taxi home and receives a taxi coupon. The lead associate investigator or RGL will make a follow up call to the participant 1-2 days after the incident. A vasovagal syncope is regarded as a minor unexpected adverse event and will be reported to the regional ethical committee in the yearly report.

1.4 In case of a pre-syncope:

Incase of a pre-syncope the experiment is discontinued. The research participant is offered to take a taxi home. Taxi coupons are located in each laboratory for that purpose. A presyncope is regarded as a minor adverse event and is reported to the local ethical committee in the yearly report.

1.5 Internal instructions for Hvidovre Hospital

A copy of the report by the emergency team and all other relevant documentation like a possible referral to a neurological examination is sent to the administrative office of the MR research section.

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Responsibility and Organization

The leadership of the MR research section is responsible for that all relevant employees are aware, and comply to these instructions.

All relevant departments, including the MR research section and the emergency department at Hvidovre Hospital, approve the present instructions

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References

Rossi, Simone, et al. "Safety and recommendations for TMS use in healthy subjects and patient populations, with updates on training, ethical and regulatory issues: expert guidelines." Clinical Neurophysiology 132.1 (2021): 269-306.

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