TMS Screening Questions
Anyone who has actually run a TMS chair knows that some of the most important questions are the odd ones. The patient who shows up with dreadlocks, the intake form that says "titanium implant" with no other detail, or the childhood history of a febrile seizure. These are the moments where a technician or psychiatrist needs a clear answer and usually can't find one.
This post collects the edge cases that come up again and again. Before the specifics, two principles make almost all of them make sense.
First, TMS is a tiny but focused version of an MRI. People conflate the two constantly, including some clinicians. MRI uses a powerful, continuous static magnetic field across the whole body; TMS uses brief, pulsed magnetic fields focused over a small area of the scalp. An implant's MRI-safety status is a useful clue for TMS. If a patient has an implant and they’ve successfully had an MRI, it means that TMS will be a safe intervention for them.
Second, two things govern TMS screening: (1) conductive, ferromagnetic, or magnet-sensitive material near the coil — the commonly cited threshold is roughly within 30 cm of the treatment site — and (2) anything that meaningfully lowers the seizure threshold, since TMS carries a small inherent seizure risk. Nearly every question below is really one of those two questions in disguise.
A note on how to read this: the first group of items is practical — they affect comfort, positioning, or dose delivery, but not safety. The second group involves genuine safety screening and should always run through your clinical protocol and the relevant device manufacturer's guidance, not a blog post.
Practical questions: comfort, positioning, and dose
Can a patient do TMS with wet hair?
Not a contraindication. The practical issue is consistency: wet or heavily product-laden hair changes coil contact and can shift your scalp landmarks slightly, which matters when you're trying to reproduce the same treatment site day to day.
Can a patient with dreadlocks do TMS?
Safe, but a positioning challenge. Thick or locked hair can create distance between the coil and the scalp, and that gap reduces the effective field reaching the cortex. Thus, you may need a higher machine output to hit the same dose. Part the hair to improve contact where you can, document the setup so it's reproducible across sessions, and account for the contact distance when interpreting motor threshold.
Can a patient with wigs, extensions, and hairpieces with metal clips do TMS?
Removable wigs and clip-in extensions should come off before treatment, and any metal clips, combs, or weft attachments near the coil should be removed. Sewn-in or bonded extensions without metal hardware are generally not an issue beyond the positioning/contact considerations above. When in doubt, treat metal clips the same way you'd treat any small ferromagnetic object near the coil and remove it.
Can a patient with facial tattoos do TMS?
Generally not a concern for standard TMS, because the treatment site (typically over the prefrontal cortex) is on the scalp, not the face. The reason tattoos come up at all is an MRI carryover: some older or darker inks contain trace metallic pigments that can heat in an MRI's continuous field. With TMS's focused, pulsed field over a different region, facial tattoos are not a meaningful issue.
Can a patient with earrings and facial piercings do TMS?
Remove metal jewelry like earrings and facial piercing near the coil before treatment if easily removable; if not easily removable, use your best judgement and if in doubt, test with a single pulse. Jewelry well away from the scalp can stay.
Can a patient with dental implants do TMS?
Yes, dental implants are typically perfectly fine. Standard dental implants are titanium, which is non-ferromagnetic, and they sit below the treatment area. As with all implant questions, the safe move is to confirm the specific hardware rather than assume.
Safety-screening questions
Can a patient do TMS with titanium implants?
Titanium itself is non-ferromagnetic and is generally well tolerated in magnetic environments, which is why it's so widely used in surgical hardware. The complication is that "titanium" many patients don’t know what their implants are made out of. If a patient has had an MRI since their implant, consider that patient cleared for TMS from a safety perspective. However, if they don’t know what their implant is made out of, the screening task then becomes confirming the actual implant material and its location relative to the coil, ideally from surgical records and/or the manufacturer before treating.
Can patients do TMS with pacemakers and implanted cardiac devices (ICDs)?
These require careful screening and coordination, not a quick yes or no. A pacemaker or ICD sits in the chest, well away from a head-positioned coil, and while distance is protective, implanted electronic cardiac devices are sensitive to electromagnetic fields, and the appropriate course is to consult the patient's cardiologist before making any decision. Treat this as a documented multi-party clearance question.
Can patients do TMS with vagus nerve stimulators (VNS)?
VNS devices are under higher scrutiny than a chest-only device. A VNS is an implanted neurostimulator with a generator in the chest and a lead running up the neck toward the vagus nerve. That lead brings active, conductive hardware meaningfully closer to a head coil than a chest device alone. This is a clear case for the device manufacturer's guidance plus the supervising clinician's judgment before proceeding. Verify the device, its lead path, and the manufacturer's position on nearby magnetic fields. It is unlikely that
What to do when you don't know if the metal is MRI-safe
This is one of the most common real-world scenarios. The process should consist of the following:
Identify the implant. Pull surgical records, the implant card, or the manufacturer/model if the patient has it. The goal is the specific material and location.
Check the manufacturer's documentation. Look for MRI-conditional or MRI-safe labeling and any guidance on magnetic fields. Remember this informs but doesn't fully answer the TMS question.
Assess proximity to the coil. Material matters most when it's near the treatment site; the same implant in the hip is a very different question than one in the skull.
When it cannot be verified, defer to the supervising clinician. Unverifiable metal near the coil is a reason to pause and escalate, not to proceed and hope. "We couldn't confirm, so we waited and checked" is always the defensible position.
The principle: TMS screening tolerates uncertainty poorly near the coil and tolerates it well far from it. When you can't resolve the uncertainty, escalate.
Can patients do TMS with febrile seizures and/or a managed seizure disorder?
Because TMS carries a small inherent risk of inducing a seizure, any seizure history is part of screening–even though not all histories carry the same weight. Simple febrile seizures in early childhood are common and are generally regarded as low risk in the context of an overall seizure-threshold assessment; they are typically not treated as an absolute barrier on their own. A more complex seizure history, including a recent a well managed seizure disorder, require a clinician to thoroughly weigh the pros and cons of doing TMS safely vs the patient remaining untreated.
The bottom line
Most TMS edge cases resolve to one of two questions: is there ferromagnetic or electrically active material near the coil, and does anything lower this patient's seizure threshold. The cosmetic and positioning questions are about doing good technical work. The implant and seizure questions relate to screening discipline. The clinic that handles the odd cases calmly and correctly is the one that's been trained to think in principles rather than memorized lists.
This article is educational and intended for TMS clinicians and technicians. It does not constitute medical advice or establish eligibility for any individual patient. Screening and treatment decisions must be made by qualified clinicians in accordance with your clinic's protocols and the specific guidance of the relevant device manufacturers. Always consult the manufacturer's labeling for any implanted device and the supervising physician for any patient-specific question.
