Are Anticonvulsants Contraindicated in TMS?
No, anticonvulsants are not contraindicated in patients undergoing Transcranial Magnetic Stimulation (TMS), and in fact, they may provide protective benefit in patients with seizure history or other risk factors for TMS-induced seizures.
Safety Profile of TMS in Patients with Seizure Disorders
The evidence demonstrates that TMS can be safely administered to patients with epilepsy who are on anticonvulsant therapy:
TMS has been successfully used in patients with epilepsy without increased seizure risk when proper protocols are followed. A systematic review of 426 patients with epilepsy undergoing repetitive TMS (rTMS) found a crude per-subject seizure risk of only 2.9%, with only one atypical seizure reported that was directly attributable to the stimulation itself 1.
The overall seizure risk with TMS in individuals without risk factors is extremely low. A large survey of 318,560 TMS sessions between 2012-2016 found that TMS delivered within published guidelines to subjects without recognized risk factors caused fewer than 1 seizure per 60,000 sessions (<0.02 per 1000 sessions) 2.
Anticonvulsants do not need to be discontinued for TMS treatment. Current safety guidelines emphasize minimizing seizure risk through proper protocols rather than avoiding anticonvulsants 3, 4.
Risk Factors That Increase TMS-Related Seizure Risk
The following factors substantially increase seizure risk during TMS, making anticonvulsant coverage even more important:
Medications that lower seizure threshold: Cocaine use, alcohol withdrawal, benzodiazepine/barbiturate withdrawal, tramadol use, and bupropion (particularly relevant in nicotine cessation treatment) all theoretically increase brain sensitivity to TMS-induced seizures 3.
Structural brain lesions and active epilepsy: Subject risk factors including brain lesions and epilepsy increased seizure risk substantially in the survey data 2.
Exceeding published safety guidelines: Seizures appeared more common when TMS parameters exceeded established safety limits 2.
Protective Role of Anticonvulsants in TMS
Rather than being contraindicated, anticonvulsants serve a protective function:
Most TMS-related seizures occurred in patients receiving medications that lower seizure threshold or when guidelines were exceeded, often in patients NOT adequately covered with anticonvulsants 4.
Seizures are most likely to occur within the first few TMS exposures, suggesting that prophylactic anticonvulsant coverage may be particularly important during initial sessions 2.
In patients with known seizure disorders, maintaining anticonvulsant therapy is recommended as part of standard TMS safety protocols 1.
Clinical Recommendations for TMS in Patients on Anticonvulsants
For patients with controlled seizure disorders on anticonvulsants:
- Continue anticonvulsant therapy without interruption during TMS treatment 1, 4.
- Ensure therapeutic anticonvulsant levels are maintained throughout the TMS course 4.
- Monitor for any changes in seizure frequency or characteristics 1.
For patients without seizure history but on medications that lower seizure threshold:
- Consider prophylactic anticonvulsant coverage, particularly when using bupropion for smoking cessation or in patients with recent substance use (cocaine, alcohol) 3.
- Implement enhanced safety monitoring including assessment of substance use status 3.
For patients with epilepsy considering TMS:
- Achieve seizure control with anticonvulsants before initiating TMS when possible 1.
- Use conservative TMS parameters within established safety guidelines 4, 2.
- Recognize that TMS is being investigated as a therapeutic modality for seizure suppression itself, with evidence suggesting it may reduce epileptiform discharges 5.
Common Pitfalls to Avoid
Do not discontinue anticonvulsants in preparation for TMS. This misconception may arise from confusion with other procedures, but anticonvulsants provide protective benefit during TMS 1, 4.
Do not assume all repetitive TMS carries higher seizure risk than single-pulse TMS. High-frequency rTMS delivered within published guidelines to individuals without known risk factors was no more likely to cause seizures than low-frequency and single/paired-pulse TMS 2.
Do not overlook concurrent medications that lower seizure threshold. The combination of TMS with substances like bupropion, tramadol, or during alcohol/benzodiazepine withdrawal requires heightened vigilance 3, 4.
Why This Matters
The confusion may stem from the fact that TMS safety guidelines are "largely based around minimizing risk of seizures" 3, but this refers to protocol parameters (frequency, intensity, duration) rather than contraindication of anticonvulsants. In fact, the evidence supports that anticonvulsants reduce rather than increase risk during TMS, making them an important safety consideration rather than a contraindication 1, 4, 2.