Transcranial Magnetic Stimulation (TMS) Clinical Q&A

Transcranial magnetic stimulation (TMS) is a magnetic stimulation technology that uses alternating magnetic fields to act on the cerebral cortex to generate induced currents to change the action potentials of cortical nerve cells, thereby affecting the metabolism and neural activity in the brain. It is a painless, non-invasive, safe, and reliable stimulation method of the central and peripheral nerves, which has been widely used in clinical practice.


Transcranial Magnetic Stimulation (TMS)


Q:1. For transcranial magnetic operators, will there be cumulative potential safety risks over time?

A: In 2003, the “International Committee on Non-Radiation Radiation Protection” has proposed the “Guidelines for Electromagnetic Occupational Environment”, which is still in use. For MRI workplaces, the measured amount of electromagnetic radiation is less than 100 times the protection limit value, and the pulse of TMS is used. The maximum field strength of the magnetic field is similar to the static magnetic field strength of MRI, and the real working time of TMS magnetic field radiation is very short, and the magnetic field stimulation coil is not large, and the magnetic field effect decreases with the increase of distance, so the potential safety risk to the staff is small.


Q:2. Can transcranial magnetic TMS cause seizures?

A: Only a dozen cases of TMS-induced seizures have been reported, most of which occurred before the 1998 guidelines for the safe use of TMS. At present, it can be confirmed that the probability of TMS-induced epilepsy is very low. The factors that trigger epilepsy are: 1) TMS stimulation parameters exceed the safe range specified in the safety guidelines, 2) The patient has a history of epilepsy, 3) The patient is taking drugs that lower the seizure threshold, 4) Other diseases affect cortical excitability, Such as stroke, autism, etc. If high-frequency, high-intensity magnetic field stimulation must be used, and the tendency of epileptic seizures needs to be monitored, motor-evoked potentials can be monitored through surface electrodes at multiple locations on the hand, forearm, and upper arm. If excitation spreads, movement will be detected at multiple locations Evoked potential, according to which the stimulation can be reduced or stopped in time.


Q:3. Will the induced current of transcranial magnetism in the cerebral cortex produce a heating effect? Will it damage nerve tissue?

A: The induced current generated by electromagnetic induction has a thermal effect. The effect of single-pulse stimulation on brain tissue is very low, and it is estimated that the temperature rise is less than 0.1 °C. Even pathological tissues with poor blood circulation (cyst, stroke) will not be at risk of heating, especially in areas with rich blood circulation. Safety. However, the thermal effect of the induced current on the metal conductor is not small, and the titanium alloy sheet for skull repair has low conductivity and low heat generation, which is relatively safe.


Q:4. Why do others take so long? My time is so short?

A: Transcranial magnetic stimulation includes low-frequency and high-frequency stimulation, low-frequency stimulation refers to stimulation frequency <5Hz, and high-frequency stimulation refers to stimulation frequency ≥5Hz. Although regular long-term stimulation is not harmful to the human body, studies have shown that prolonged stimulation can increase patient discomfort. Different diseases have different treatment plans; using low-frequency stimulation, low-frequency stimulation takes a long time, while high-frequency stimulation will take a very short time. For the same number of treatments, using 20Hz and 1Hz will definitely take 1Hz longer. , so some patients finished it in about ten minutes, and some patients did it for more than 40 minutes.


Transcranial Magnetic Stimulation (TMS)


Q:5. Is the greater the strength the better?

A: The effect of high strength is definitely good, but at the same time, the side effects will increase, which will cause headache, dizziness, nausea and vomiting, syncope, etc. Severe diabetes, high blood pressure, etc. will cause cardiovascular accidents and other risks. The safe range of transcranial magnetic therapy is the stimulation threshold. 80%-120%, so the strength is not the bigger the better, it is best to reduce the side effects while achieving the curative effect.


Q:6. Why did it take so long and still have no effect?

A: The curative effect is based on the sensitivity, condition, and course of the patient, and there are individual differences. And transcranial magnetic therapy is not effective once or twice, at least more than one course of treatment. The course of treatment varies according to the severity of the patient’s condition. A course of treatment is 20 times.


Transcranial Magnetic Stimulation (TMS)


Q:7. Can I stop taking the oral medication after I get better?

A: It is best not to stop taking oral medication for a long time, and maintain it for more than half a year. Adjusted according to the condition after half a year.


Q:8. Do I need to continue treatment after I get better?

A: After the symptoms improve, intermittent maintenance treatment is recommended, and then the treatment can be increased or decreased according to the situation.

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