Pros and Cons of Transcranial Magnetic Stimulation – Disadvantages of TMS

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Written By Dr. Marcus Yu Bin Pai

MD, PhD. Physical Medicine & Rehabilitation Physician from São Paulo - Brazil. Pain Fellowship in University of São Paulo.

Transcranial Magnetic Stimulation (TMS) is a non-invasive treatment option for various neurological and psychiatric disorders, including major depressive disorder. TMS uses a magnetic field to stimulate nerve cells in the central nervous system.

Although TMS has been around for over a decade, it remains relatively unknown to many patients and healthcare providers. While TMS therapy has fewer and less common side effects compared to medications, it is not entirely devoid of them.

In this blog post, we’ll explore the pros and cons of TMS to help you make an informed decision about whether this treatment is right for you or a loved one.

What is Transcranial Magnetic Stimulation?

Repetitive Transcranial Magnetic Stimulation (rTMS) is a non-invasive procedure that has shown promise in the treatment of various mental health disorders. In this blog post, we explore the clinical indications for rTMS, focusing on treatment-resistant depression, and discuss potential future applications of this innovative therapy.

Treatment-Resistant Depression:

At present, rTMS is best suited for patients with treatment-resistant depression, meaning they have failed to respond to one or two previous treatments.

However, patients with psychotic depression tend not to respond well to rTMS and are better candidates for electroconvulsive therapy (ECT). There is still much to learn about rTMS’s potential applications in non-treatment resistant patients, including those who simply do not wish to take medication.

Potential Expansion to Other Patient Groups

rTMS could potentially benefit other subgroups of patients, such as pregnant women with depression, where drug treatment may not be the best option. However, due to the lack of systematic research and legal concerns, it is difficult to conclusively recommend rTMS for this patient population at this time.

Similarly, adolescent depression could also benefit from rTMS, but further research is needed to understand the impact of the treatment on the developing brain.

Obsessive-Compulsive Disorder (OCD)

Recent developments have seen the FDA approve rTMS for treatment-resistant obsessive-compulsive disorder (OCD), with promising results in clinical practice. Unlike the treatment of depression, which targets the dorsolateral prefrontal cortex (DLPFC), OCD treatment with rTMS focuses on the supplementary motor area (SMA).

Anxiety and Post-Traumatic Stress Disorder (PTSD)

Although there is limited evidence supporting the use of rTMS for anxiety and PTSD, some studies have reported improvements in depression symptoms that are often comorbid with these disorders.

As of the moment, there are not enough controlled research to justify rTMS as a primary treatment for the full spectrum of PTSD or anxiety. However, if depressive symptoms are present, rTMS could be considered, with any improvement in comorbid anxiety or PTSD symptoms being an added bonus.

Pros of Transcranial Magnetic Stimulation

  1. No need for medication changes: One of the significant advantages of TMS is that patients can start the treatment without making any changes to their existing medications. This means TMS can be easily integrated into a patient’s current treatment plan.
  2. Safety: TMS is a safe treatment option with over 10 years of research and clinical use. Compared to taking medications, TMS has very few side effects.
  3. Minimal side effects: During TMS, patients may experience some discomfort in their face where the magnetic stimulation is applied. This sensation is often described as a tapping feeling, which usually subsides as the patient adjusts to the treatment. Apart from this, there are very few side effects associated with TMS. The rarest side effect is a seizure, which can be promptly addressed by stopping the treatment. Precautions are in place to minimize the risk of this happening.
  4. Effectiveness: Transcranial Magnetic Stimulation boasts effectiveness rates of around 60-70%. This is significantly higher than the success rate of adding another medication to a patient’s regimen after failing four medications, which is only about 5%.

Cons of Transcranial Magnetic Stimulation

  1. Lack of awareness: One of the primary drawbacks of TMS is that many people, including healthcare professionals, are not aware of its existence, effectiveness, or long history of use. This lack of knowledge can result in patients not receiving the best possible treatment.
  2. Time commitment: TMS requires a substantial time investment, as patients must attend treatment sessions five days a week for approximately seven weeks. Each session lasts about 20 minutes, with the entire visit taking around 40 minutes.
  3. Cost: Although insurance companies have become more receptive to covering TMS, patients are still required to pay copays for each visit. Depending on the copay amount, the total cost can range from $350 to nearly $1,000 for the entire treatment course.
  4. Limited availability: TMS is not yet widely available, making it challenging for patients to access treatment providers. This limitation can be a significant concern for individuals who need to travel for their 35 treatment sessions.

Contraindications vs. Side Effects

A contraindication refers to a pre-existing condition that prevents a patient from being a suitable candidate for TMS therapy. In contrast, a side effect is an undesired outcome caused by TMS therapy itself.

Common Side Effects of Transcranial Magnetic Stimulation Therapy

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  1. Scalp Discomfort: Transient head or scalp discomfort at or around the location where TMS pulses are applied is the most common side effect.
  2. Facial Twitching: Some patients may experience twitching or movement of the eyelid or jaw during stimulation due to the excitation of superficial nerve branches and muscle contractions.
  3. Headache: Headaches are sometimes reported after Transcranial Magnetic Stimulation treatment, particularly in the early stages. However, TMS-induced headaches typically decrease due to habituation or direct local analgesic effects.

Uncommon Side Effects of Transcranial Magnetic Stimulation Therapy

  1. Manic or Hypomanic Symptoms: The induction of mania or hypomania is an uncommon side effect. If such symptoms are detected, TMS therapy is stopped and the patient is closely monitored.
  2. Decreased Hearing: Decreased auditory acuity may occur if ear protection is not worn during TMS therapy. Proper ear protection, such as foam earplugs, is crucial to prevent potential hearing loss.
  3. Syncope (Vasovagal Response): Syncope can result from heightened anxiety, hypoglycemia, hyperventilation, or dehydration during or after TMS therapy. Additionally, the positioning of the treatment chair may contribute to orthostasis (lightheadedness) or benign paroxysmal positional vertigo (BPPV).
  4. Seizure: TMS-induced seizures are extremely rare, with an estimated risk of 0.001% or approximately 1 in 89,000 treatments. Most TMS-related seizures occur in patients with pre-existing risk factors or when stimulation parameters exceed recommended safety ranges.

Debunking TMS Side Effects Myths

  1. Effects on Cognition: Contrary to popular belief, TMS does not cause memory loss or other adverse cognitive effects. In fact, studies have demonstrated improved performance on measures such as delayed story recall.
  2. Brain Damage: There is no evidence of brain damage resulting from Transcranial Magnetic Stimulation treatment delivered within established safety ranges. Studies in animals and humans have failed to demonstrate evidence of histotoxicity (brain damage) following TMS exposure.
  3. Migraine: While TMS may cause transient headaches, it does not increase the risk of migraine headaches in healthy participants or those with a history of migraines. In fact, the FDA has cleared a single-pulse device (Nerivio) for the treatment of acute migraine headaches.


Transcranial Magnetic Stimulation (TMS) is a promising and effective treatment option for patients with certain neurological and psychiatric disorders. While it has numerous advantages, such as minimal side effects and no need for medication changes, it also has its drawbacks, including a lack of awareness and limited availability.

Although TMS therapy carries some risk of side effects, they are generally less common and less severe compared to traditional treatment options for depression. By understanding the potential side effects and debunking common myths, patients can make informed decisions about their treatment options.

If you’re considering TMS, it’s essential to weigh the pros and cons and consult with a healthcare provider experienced in TMS to determine if it’s the right choice for you.

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MD, PhD. Physical Medicine & Rehabilitation Physician from São Paulo - Brazil. Pain Fellowship in University of São Paulo.

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