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Safety and emergencies

Read this page in full before your first session. It lists who cannot take part and what to do if a participant feels unwell, gets a headache or has a seizure. The rules for handling the equipment are on Lab and equipment.

Emergency: call +32 16 32 22 22

This is the internal KU Leuven emergency number; they help organise emergency assistance. Give your name and the reason for your call, and say where you are: Leuven, building PSI, floor 00, room 00.57. Then contact Matilda. The seizure procedure has the full steps.

Exclusion criteria

Screen everyone before every session, as described in Session procedure. Never stimulate anyone who meets one of these criteria.

You cannot conduct TMS on someone

  • who is pregnant or may possibly be pregnant
  • with epilepsy or history of seizures
  • who has a direct family history of seizure or epilepsy (parents and siblings)
  • with a history of traumatic brain injury or concussion
  • with a pacemaker!
  • with a cochlear implant, or any other implant in the head region

There are medications that are immediate exclusions for TMS because they decrease the seizure threshold (thus increasing the risk seizure). Participants taking these medications must be excluded from participating.

You cannot conduct TMS if you are pregnant or think you may be pregnant.

If something goes wrong

Whatever happens, stop stimulating first. Then follow the procedure for what you see: feeling unwell or fainting, headache or seizure.

Feeling unwell or fainting

In some cases, participants may feel unwell (nauseous), dizzy or feel as if they may pass out. This is almost always due to a vasovagal syncope; a common and usually harmless type of fainting that happens when the nervous system overreacts to a trigger, causing your heart rate and blood pressure to drop suddenly. Common triggers include; blood, medical instruments, needles, stress, anxiety or emotional upset, exhaustion, fatigue or dehydration, heat exposure, and standing for too long.

What to do if someone has a vasovagal syncope:

  1. Immediately cease stimulation
  2. Remove any equipment (i.e., neuronavigation glasses, EMG equipment)
  3. Help the participant to move towards the ground, and lie flat on their back with their legs raised onto their chair
    1. If they are unable to do this, have them lean forward and put their head between their knees. Clenching the hands into fists can also help with blood pressure
  4. If the participant is unconscious for more than 1 minute, immediately contact further medical attention (see Seizure Protocol for more info). This is a sign that this is a more serious medical episode.
  5. Provide comfort during the episode; syncopes can be frightening, especially if this is the first time someone has fainted or experienced this sort of phenomenon.
  6. Once the participant recovers, allow them to keep laying down
    1. Do not let them get up until dizziness, sweating, or lightheadedness completely goes away.
    2. Once ready, allow them to move to a sitting position first for a few minutes before standing up carefully.
    3. Once they are stable, if water is available provide it to them
    4. It is best to monitor the participant for at least 10-15 minutes post syncope before allowing them to leave
  7. Explain what a syncope is, and what causes it (the above information can be used as a guide).
  8. Discontinue the session.
  9. Contact Matilda and Hans to inform them of the event. They will carry out the required further steps, including contacting the participant later in the day to monitor their progress.
What is a vasovagal syncope? (Cleveland Clinic)

As per the Cleveland Clinic:

Vasovagal syncope is a reflex reaction to something going on around you. But the reflex is either too strong or happens at the wrong time. This all starts in the part of your nervous system that works without you having to think about it — your autonomic nervous system.

One of the key nerves in this system is the vagus nerve, which controls your heart rate and blood pressure. If your vagus nerve becomes too active, it can cause your heart rate and blood pressure to drop too much or too quickly (or both).

If your blood pressure drops too much, this causes vasovagal syncope. You pass out because your brain isn't getting enough blood flow.

Many people experience vasovagal syncope at least once in their life. It can happen to people of all age groups. In people under 40, most cases of fainting are vasovagal syncope.

Individuals are most likely to have symptoms 30 to 60 seconds right before a vasovagal syncope episode.

Symptoms before, during and after a syncope

Common symptoms include:

  • A sudden feeling of tiredness (fatigue)
  • A sudden warm feeling
  • Lightheadedness or dizziness
  • Loss of color in your skin (pallor)
  • Nausea
  • Heavy sweating
  • Slow pulse
  • Yawning
  • Tunnel vision

During a vasovagal syncope episode, someone may experience:

  • Brief disorientation or confusion
  • Eyes staying open but rolling up and back into your head
  • Falling when you lose consciousness
  • Loss of bladder control
  • Twitching movements, which people may mistake for a seizure

During a vasovagal syncope episode, those observing may notice

  • Jerky movements.
  • A slow, weak pulse.
  • Dilated pupils

Once conscious, people usually recover in about 20 to 30 seconds. Then, they may experience:

  • Anxiety or nervousness
  • Dizziness
  • Fatigue
  • Headache
  • Nausea
  • Pale skin (pallor)
  • Sweating

Headache

TMS should not hurt. What is normal is the possibility of developing a mild headache towards the end of the session or even hours later.

Stop the session if the participant feels sharp pain

If the participant experiences any form of intense, sharp or acute transient pain in their head when receiving stimulation, it is important to discontinue the session as this is not a normal sensation.

According to van der Velde et al., (2026) the most frequently reported physiological side effect of TMS is mild, transient headache. About a third of patients report headache and discomfort or pain on the scalp, jaw, eye, or neck regions during and shortly after stimulation This headache is usually rated at an intensity of 3 out of 10 and responds well to common analgesics within a few hours. If a participant mentions a headache, you can instruct them of this and recommend mild analgesics (e.g. paracetamol) if the participant deems it necessary.

Seizure or suspected seizure

The following information and guidelines are from the Epilepsy Foundation and are adapted for the context of TMS:

  1. STAY with the participant and start timing the seizure!
    • Immediately cease stimulation
    • Remain calm- speak calmly and reassuringly to the person during and after the seizure
    • Time from the beginning to the end of the active seizure
  2. Keep the person SAFE
    • Move the participant out of the chair and onto the ground if possible.
    • Make the participant as comfortable
      • Loosen tight clothes around the neck
      • Put something small and soft under their head
    • Turn them onto their side with their mouth pointing toward the ground. This prevents saliva from blocking their airway and helps the participant breathe more easily
    • During a convulsion, it may look like a person has stopped breathing. This happens when the chest muscles tighten during the tonic phase of a seizure. As this part of a seizure ends, the muscles will relax and breathing will resume normally
      • Rescue breathing is generally not needed during these seizure-induced changes in a person's breathing
    • DO NOT PUT ANY OBJECTS IN THEIR MOUTH
      • Don't worry- a person can't swallow their tongue during a seizure
      • Jaw and face muscles can tighten during a seizure, causing a person to bite down. If this happens when something is in the mouth, the person may break and swallow the object or break their teeth.
      • Do not give water, food or pills until the person is awake and alert. These may enter the lungs rather than the stomach or become a choking hazard
    • DO NOT RESTRAIN
      • Trying to stop movements or forcibly hold a person doesn't stop a seizure
      • Restraining a person can lead to injuries and make the person more confused, agitated or aggressive
  3. STAY with them until they are awake and alert after the seizure
    • Most seizures end in a few minutes
    • If a person appears to be choking, turn them off and call for help. If they are not able to cough and clear air passages on their own or having breathing difficulties, call for help immediately
  4. CALL for help
    • If the participant has no difficulties breathing or other high priority concerns, wait for the seizure to cease (unless it lasts for a prolonged period, 5 minutes or more) and then call for help.
    • Contact the internal KU Leuven emergency number, they will help to organise emergency assistance.
      • +32 16 32 22 22
      • Give your name and the reason for your call (specify that a research participant has had a seizure after receiving brain stimulation)
      • City: Leuven
      • Building: PSI
      • Floor: 00
      • Room Number: 00.57
    • If possible during this time, also contact Matilda (otherwise contact her as soon as possible)
    • Be sensitive and supportive as the participant recovers.
      • Seizures can be frightening. People may feel confused or embarrassed about what happened
      • Reassure the participant that they are safe
    • As per the ethical approval, if a seizure occurs during the session the participant must go to the relevant hospital service to be evaluated with a check-up
Signs of a seizure

Motor Signs

  • Rhythmic, uncontrollable jerking in the arms legs or face
  • Sudden stiffening of the muscles (tonus) which may cause the body to posture rigidly (tonic-clonic movements)
  • Upward rolling of the eyes
  • Frothing of the mouth

Behavioural or Cognitive Changes

  • Sudden blank stare or complete lack of responsiveness
  • Inability to speak, answer basic questions or follow basic commands
  • Sudden confusion or disorientation during the session

Autonomic Signs

  • Loss of consciousness or suddenly slumping in the chair
  • Irregular breathing or temporary pause in breathing
  • Frothing at the mouth

Post-Seizure (Postictal Signs)

  • Prolonged confusion or memory gaps regarding the last few minutes
  • Extreme fatigue, drowsiness or difficulty waking back up
  • A severe headache or muscle aches from voluntary contraction
Differences between syncope and seizure
  • If fainting (syncope), people will usually regain alertness almost immediately after waking up and will not exhibit prolonged confusion, tongue-biting or bowel or bladder incontinence. People will usually recover quickly after being placed in a position that allows for blood flow back to the head (like head between knees or flat on ground with legs raised). Syncope is frequently preceded by a prodrome (warning phase) which includes lightheadedness, nausea, tunnel vision, or a sense of warmth.
  • If it is a seizure, people will experience a "postictal" state leaving them confused, groggy, and disorientated for several minutes to hours post episode. Seizures can begin with an aura (an unusual smell, taste, or visceral feeling) or strike entirely without warning.
Why the risk of a seizure is very low

International safety guidelines limiting the intensity, duration and number of pulses that can be used were established in 1998. Following these guidelines, the risk of unexpected TMS-induced seizures in normal subjects is very low. In rare instances however, TMS has induced a seizure (or epileptic convulsion) even in participants without any predisposing illness. This risk is extremely low and is further minimised in our protocol because of our adherence to the international safety guidelines as described in the consensus conference in Sienna, 2008 (Rossi et al., 2009) and during the International Federation of Clinical Neurophysiology (IFCN), in Sienna, 2018 (Rossi et al., 2021), and our use of single- and dual-pulse TMS instead of repetitive TMS as commonly used in other KU Leuven research centres. It is therefore very important to respect certain safety measures. In addition, any TMS induced seizure would occur during stimulation or immediately after; it would not be expected to affect a participant hours or days after the TMS. Rossi et al. (2021) note an identifiable risk of 2/100 000 sessions (0.002%) of seizure in healthy participants who do not demonstrate risk factors during either single or paired pulse TMS.

Further reading

Safety guidelines

First aid and emergencies