Transcranial magnetic stimulation (TMS) was first developed in the early 1980s, but in 2008 it got approved by Food and Drug Administration (FDA).Transcranial magnetic stimulation (TMS) is a non-invasive method and a brain stimulation device which is used to stimulate the nerve cells in the brain to improve the symptoms of depression. Depression is a disease that stems from a lack of activity in certain parts of the brain specifically the prefrontal cortex, the region right above the eyes that helps to regulate emotions.
TMS is usually used when other depression treatments have not been effective. It depends on electromagnetic induction using an insulated coil placed over the scalp of the person receiving the treatment. The coil produces small electric currents which pass easily and painlessly through the skull and into the brain. The coil is connected to a pulse generator or stimulator that delivers electric current to the coil.
The pulses produced are of the same type and forte as those produced by magnetic resonance imaging (MRI) machines. When these pulses are controlled in rapid series, it is termed as repetitive TMS or rTMS, which can yield long-lasting changes in brain activity.
TMS for a migraine was approved by FDA and repetitive TMS (rTMS) is used for in treating major depressive disorder.
How it works
TMS is a different procedure from other brain stimulation therapies. In other therapies like electroconvulsive therapy (ECT) patients are given anesthesia and are stimulated across the scalp with a small electric current in which patients have a short brain seizure. But, in TMS patients don’t have the seizure and they are awake and alert during their stimulation.
During a TMS session, an electromagnetic coil is placed on the scalp near the forehead for nearly 40 minutes. The small electric current passes and delivers a magnetic pulse that stimulates the nerve cells in the part of the brain which intricates in mood control and depression. The coil may activate the regions of the brain which have diminished activity due to depression.
A new TMS device approved by FDA :
Repetitive transcranial magnetic stimulation (rTMS) is used for depression. It does not require surgery or implantation of electrodes. Though the ecology of rTMS how it works is not completely understood, but it has presented to be safe and well-tolerated method and the stimulation seems to work for many patients which comfort the symptoms of depression and mood and who are not aided from anti-depressant medications or cannot tolerate the medications.
TMS coil types
A number of different coil types are available and each of the coil types produces different magnetic field patterns, some of them are:
- Round coil – this is the original type of TMS coil
- Figure eight coil or butterfly coil – results in a more important pattern of activation
- Double-cone coil – adapts to the shape of head, which is useful for deeper stimulation
- Four-leaf coil – for crucial stimulation of peripheral nerves
- H-coil – for deep transcranial magnetic stimulation
Transcranial magnetic stimulation side effects
- Minor headache
- Confined pain underneath the magnetic coil
- Trembling or vibration sensation around the face, cheek and scalp
- Scalp discomfort at the place of stimulation
Exceptional side effects
- Seizures
- Obsession, mainly in people with bipolar disorder
- During treatment, if there is no proper ear protection they may have loss of hearing
However, these exceptional side effects are rare to happen. More study is needed to determine whether rTMS may have any long-term side effects.
“But in some ways, the two procedures are similar,” George says. “We’re trying to reset and wake up connections in the brain that aren’t really working well.
A similar device, using Transcranial Magnetic Stimulation (TMS), has already been designed for buyers, and a company in Sunnyvale, California, called Neuralieve is gradually jolting into the market. Within a year Neuralieve could be seeking approval from the U.S. Food and Drug Administration to sell the TMS device as a migraine therapy, says a member of the company’s scientific advisory board. A TMS device passes a magnetic field into the brain, producing an electric current in a small volume of brain cells. The current is strong enough to cause neurons to fire, but scientists and researchers are just starting to understand magnetic stimulation’s effects in the brain.
In a report published in the 28 September issue of Science, University of California, Berkeley, scientists and researchers demonstrated that whether TMS increases activity in a stimulated brain region depends on what that part of the brain was doing before the stimulation started.
When the Neuralieve device is connected to a person suffering from a migraine, the sudden excitation interrupts a wave of hyperactivity, recalibrating the brain before it can get out of control and lead to a migraine, says Dr. Yousef Mohammad, a neurologist at Ohio State University Medical Center who is testing the device in advanced clinical trials. “If you have a fire in the forest, the fire will spread from one tree to the other,” he says. “What we’re doing with TMS is cutting a few trees in the middle.” Because neurons are actually firing during TMS, the device will probably not have the same long-term therapeutic effect; it probably will be useful only to interrupt the beginning tremors of a migraine.