Transcranial Magnetic Stimulation (TMS) Mapping

What should the patient expect on the first day of TMS treatment?

The first day of TMS treatment involves “mapping” of the brain in order to determine the appropriate amount of stimulation and the specific treatment location on your head. A cap is placed on the patient’s head. Various measurements are made and specific brain landmarks are marked on the cap. One important area that is determined is called the motor cortex. The exact positioning of the motor cortex is determined by stimulating the brain and watching for a motor response through a thumb twitch.

During the mapping session, a piece of technology called StimGuide is used. StimGuide is a 3D positioning system that is able to detect the patient’s brain in space with a tracking device that is placed on the patient’s forehead. This software also allows the providers to visualize if the stimulation from the TMS coil is eliciting an appropriate response. This is done with the placement of electromyography (EMG) electrodes on the patient’s thumb. StimGuide aids in determining the minimum stimulation needed in order to elicit a motor response.

Once the area of the motor cortex and correct amount of stimulation are determined, the treatment target area can then be found. The area of the brain that is stimulated in TMS is called the dorsolateral prefrontal cortex (DLPFC). StimGuide is also used to detect this location and ensure proper coil placement and alignment. 

The marked cap will be used for the rest of the treatment sessions in order to ensure correct and consistent placement of the TMS coil on the treatment target. 

How long will the mapping session take?

The time allotted for the mapping session is 1 hour. Sometimes, the whole hour is needed and other times the mapping session may not require the entire hour. There are also instances where the motor cortex cannot be found that day and the patient must return the next day for mapping. If this is the case, it is important to not get discouraged. It is nothing that the patient did wrong. 

What happens after the first session?

After mapping is completed and the treatment target is found, the patient will be able to return the following day for the first treatment session. These sessions do not last as long as the mapping. They typically last anywhere from 20-30 minutes. There are a total of 36 treatments.