The most serious risk involved in TMS therapy is that the procedure could trigger a grand mal seizure in the patient undergoing the process. However, the likelihood of suffering from this side effect is as little as 1 in 10,000. The risk increases substantially in patients who have a prior seizure disorder, raising the odds to 1 in 200. This is why it is important to discuss this disorder with the practicing physician; treatment must be applied much more carefully, if at all.
Our office has experience with treatment-resistant patients, including patients with epilepsy, but we have not had a patient suffer a grand mal seizure during our TMS therapy sessions. To combat the risk of seizure, we take extra precautions when appropriate, including, but not limited to, taking care of the pulse intensity as well as the location of the pulses delivered to the brain. However, if a patient were to experience a grand mal seizure during treatment, the side effects would be minimal as the patient is seated in a chair and not in a life-threatening environment.