Transcranial Magnetic Stimulation (TMS) for Depression

Transcranial magnetic stimulation (TMS) is a noninvasive treatment that uses targeted magnetic fields to stimulate specific areas of the brain. There are two types, repetitive TMS (rTMS) and deep TMS (dTMS).

TMS is approved by the Food and Drug Administration (FDA) or treatment of major depressive disorder (MDD, or depression), obsessive-compulsive disorder (OCD), and smoking cessation.

Major depressive disorder is typically treated with medications, psychotherapy, or a combination of both. Some people with depression do not find adequate relief with these measures. When symptoms persist even with standard treatment, this is called treatment-resistant depression (TRD).

Up to 70% of people with treatment-resistant depression who receive rTMS have an improvement in their condition.

Both TMS and electroconvulsive therapy (ECT) are brain stimulation therapies that are considered to be safe and effective, but they have key differences. ECT uses electrical current to stimulate a brief seizure. TMS uses a magnetic field and does not involve inducing a seizure.

ECT may be more effective and produce quicker results for some people than TMS, but there is also a higher risk of side effects.

This article will discuss the safety and efficacy of TMS for depression, what happens during a TMS session, how many sessions are needed, who should not get TMS, costs related to TMS, and where to find TMS treatment.

TMS for Depression: Does It Work? 

Major depressive disorder is a highly prevalent psychiatric disorder marked by characteristics such as:

• Persistently depressed mood
• Anhedonia (loss of interest or pleasure)
• Diminished interest in activities
• Changes in appetite or weight
• Sleep difficulties
• Fatigue or loss of energy
• Difficulty concentrating
• Feelings of worthlessness or excessive guilt
• Impaired functioning in daily life
• Suicidal ideation
  

MDD is typically treated with medication and/or psychotherapy. MDD that does not sufficiently respond to these treatments is classified as treatment-resistant depression.

An estimated two-thirds of people with depression do not experience adequate control of symptoms from the first antidepressant medication they try, with at least some symptoms remaining after two months of treatment. Each medication tried after is less likely than the one before to be sufficiently effective.

People with MDD may also initially experience benefits from standard treatments but lose these effects over time or be unable to tolerate standard therapies.

An alternative (or sometimes complementary) treatment for TRD is therapeutic neuromodulation. This approach recognizes the brain as an electrochemical organ and uses devices to alter electrical activity in the central nervous system.

Neuromodulation approaches include ECT, which uses electric current to induce a brief seizure, and TMS, which stimulates the brain using a magnetic field.

ECT vs. TMS

The gold standard neuromodulation device is ECT, which has been used for over 80 years. It is considered the most effective treatment for TRD and is used regularly throughout the United States.

ECT can have side effects and disadvantages, including:

• Adverse cognitive effects (such as effects on memory)
• Lack of access in many areas
• Substantial relapse rates after successful acute treatment
• Negative public image
• Typically reserved for those with the most serious cases of MDD, ruling out use in many people who have not been responsive to first-line and second-line treatments
  

Since 2008, TMS has been available as a neuromodulation procedure that can be used instead of, or along with, ECT. TMS has several advantages, including the following:

• It has very few adverse effects.
• It is noninvasive.
• It often is better tolerated than medications or other therapeutic neuromodulation therapies.

How Effective Is TMS?

About 50% to 60% of people with depression who have tried but not experienced adequate benefit from medications report a clinically meaningful response to TMS. About 30% to 35% experience remission (their symptoms go away entirely).

This response is not permanent but can last months to over a year. Further TMS treatments may be initiated if symptoms return.

What Happens During a TMS Session

Steps taken before the first session include:

• A comprehensive review of current and previous health conditions, medications, neurologic and psychiatric conditions, and other relevant medical info
• A physical examination
• Other evaluations needed to determine that TMS is a safe and advised treatment option

Treatments take place in a healthcare provider's office or hospital. No medication or anesthesia is needed. The person is awake during the session, sitting in a comfortable reclining chair. Earplugs are worn to protect hearing from the loud clicking sounds the TMS device makes.

The rTMS device (using electromagnetic coils in a figure eight shape) is placed against the scalp near the area of the brain believed to be responsible for the symptoms (such as the left prefrontal cortex for depression).

The dTMS device is contained in a helmet placed on the head. It has coils in a letter "H" pattern and transmits deeper into the brain.

The procedure is noninvasive. The magnetic field is generated on the surface of the scalp. The magnetic field is similar in strength to what is used in magnetic resonance imaging (MRI).

The healthcare provider will give a few test pulses, adjusting the device until the right level is reached. This level can be adjusted during the session if necessary.

Treatment is administered as repeated, short electromagnetic pulses that cause small electrical currents, stimulating brain cells in the targeted area of the brain.

The length of the session varies, with treatment lasting from five minutes to an hour.

What Does TMS Treatment Feel Like?

TMS treatment feels like a series of pricks or pulses. It has been described as feeling like a woodpecker tapping on your head.

Some people may feel discomfort or muscle twitches early on, but this can diminish with more treatments. Levels can be adjusted if they are too strong.

Number of TMS Therapy Sessions to Treat Depression 

The number of TMS sessions needed can vary, but a course of treatment is typically one session per day, five days a week, for four to six weeks.

Positive results typically become noticeable between the third and sixth weeks of treatment. It is important to finish the full course of treatment, even if relief is found early in early sessions.

The FDA has recently cleared a rapid-acting form of TMS for the treatment of TRD. This treatment shows similar effectiveness, but works faster, shortens treatment length, and allows for more rapid symptom relief. Multiple sessions are delivered in a single day, with short breaks taken between sessions.

Maintenance TMS sessions may also be suggested. Some studies have found that additional ongoing TMS treatments a period of time after a successful acute course of TMS treatment may reduce the incidence of relapse of symptoms.

Should Anyone Not Do TMS Therapy for Depression? 

TMS tends to be well-tolerated. Mild to moderate headache, either during or after treatment, is one of the most common side effects of TMS. These usually subside over the first several treatment sessions and can be managed with medications such as Tylenol (acetaminophen), Advil or Motrin (ibuprofen), or aspirin.

Other more common side effects may include:

• Application site discomfort or pain
• Contraction of the muscles around the eye, sensations in the nose and teeth, or tearing (rarely persists after the stimulation stops)

Uncommon potential side effects include:

• Induction of mania or hypomania (watch for symptoms such as agitation or irritability)
• Scalp discomfort or burn due to excessive heating of the TMS coil (rare but can occur with continuous use of the device and high intensity)
• Syncope (fainting) due to a vasovagal response to pain (rare and is more likely with heightened anxiety, hypoglycemia (low blood sugar), hyperventilation, or dehydration)

The most serious potential adverse effect is seizure, but this is rare. In fact, seizure occurs in only 1 in 30,000 (0.003%) ordinary clinical use treatments. Only one seizure was reported in three large-scale controlled clinical trials, and it occurred in a participant who had heavy alcohol use the night before the TMS treatment.

The majority of TMS-related seizures have occurred in people with a preexisting risk for seizure or when the stimulation parameters exceeded the recommended safety recommendations.

TMS is not appropriate for everyone. Some factors that may make TMS unadvised include:

• Medications that lower the seizure threshold
  
• Prior history of epilepsy or seizures (personal or family)
  
• Psychotic features or acute suicidal ideation (other treatments with established efficacy such as ECT should be considered)
• Past stroke
• Neurological or medical conditions that could lower seizure threshold, such as sleep deprivation, electrolyte imbalance, increased intracranial pressure, or withdrawal from substances of abuse or recreational use
• Ferromagnetic (high susceptibility to magnetization) or magnetic-sensitive metal objects implanted in the head or neck areas, such as metal plates, cochlear implants, and others
• Exposure to all metal fragments, including tattoos rendered with ferromagnetic-containing ink, permanent piercings, and other metal sources in the head and neck
• Having implanted deep brain stimulators
  
• Serious neurological issues
• Pregnancy

Your healthcare provider can help you determine if the benefits of TMS outweigh the risks and if the treatment is right for you,

Insurance and Out-of-Pocket Costs 

The cost of TMS varies, but a 2018 source noted the cost for an acute course of TMS (20 to 30 sessions) ranged from $6,000 to $12,000.

Most health insurance plans provide coverage for TMS in the treatment of MDD with a history of no improvement with medication. Insurance coverage for TMS is increasing, so it's worth checking with your insurance provider to see if it is covered.

In some states, a percentage of TMS therapy may be covered by Medicaid. It is covered by Medicare for major depressive disorder if you have had one failed trial of antidepressant medication.

Where to Get TMS Therapy If You Have Depression

If you think TMS might be right for you, start by talking to a primary care provider or mental health provider. The TMS prescriber and TMS device operator should be knowledgeable, trained, and credentialed in TMS.

Summary

TMS is a noninvasive treatment that stimulates the brain using targeted, powerful magnetic fields. It is considered to be safe and effective for treatment-resistant depression.

A course of TMS treatment for depression varies but is typically once daily, five days a week, for four to six weeks.

TMS is usually well-tolerated, with minor, temporary side effects such as discomfort or headache. Seizure is considered a risk with TMS, but is rare. Having risk factors for seizure may mean TMS is not an appropriate treatment for you. Talk to your healthcare provider about the risks vs. benefits of TMS.