TMS safety. The main contraindication to TMS is the presence of metal in the head, such as a cochlear implant, metal plates or surgical clips. The safety of TMS has been rigorously studied, and as the brain in epilepsy is felt to be hyperexcitable, its safety in epilepsy, quite reasonably, studied independently. One example has been reported in whom single seizures were recorded on two occasions, when single-pulse TMS was delivered to the motor cortex leg region, (Xxxxxxx et al., 1995). The ictal semiology of the TMS induced seizures was in the first case slightly different from their typical spontaneous seizures, and identical to typical spontaneous seizures on the second occasion. The authors interpreted this as direct induction of seizures with TMS, but it is possible that this was coincidence or due to another factor such as anxiety associated with the TMS investigation. A systematic review of TMS induced seizures in people with epilepsy, (Xxxxxxxx et al., 2004) found that, 7/458 patients (1.5%) had a seizure during single pulse TMS, and none of the 118 patients reported to have had paired pulse TMS had a seizure. They reported a large centre-to-centre variability in seizure incidence that could not be accounted for, although the tapering of AEDs and medically intractable epilepsy were reported to be risk factors. The very low occurrence of seizures in epilepsy patients undergoing TMS, and their association with intractable epilepsy, suggests that they might be entirely or predominantly coincidental. Due to this, epilepsy is not considered a contraindication and TMS should be considered extremely safe in this patient group. Repeated stimuli delivered over a short period of time can cause the TMS coil to over-heat potentially to a temperature exceeding the safety limit for medical devices which contact a patient. Magstim devices used in this thesis have auto-shutdown systems which detect overheating.
