TMS Therapy Side Effects

TMS therapy or Transcranial Magnetic Stimulation offers an alternative treatment option for patients suffering from depression who don’t respond to the classical treatment approach of psychotherapy and antidepressants. Unlike medications, TMS therapy has a much shorter list of side effects. TMS therapy side effects are also less common. Nevertheless, TMS therapy could still carry some risk of side effects. 

Many TMS psychiatrists tell patients that TMS is free of side effects! This is not entirely true. To be more specific, TMS Therapy has meager chances of significant side effects. But that doesn’t make TMS therapy utterly free of any side effects. In this article, you will have access to complete scientific evidence of most of the possible side effects resulting from TMS therapy. Please note that TMS therapy is an FDA-cleared treatment that is prescribed for severe depression. All other treatment options prescribed for severe major depressive episodes do have side effects. This article aims to make you more informed, not to deter you from seeking a badly needed treatment option.

Before we start, let’s distinguish the difference between contraindications and side effects. A contraindication is a pre-existing condition that excludes a patient from being a right candidate for TMS therapy. There are contraindications for TMS therapy, like the presence of ferromagnetic or magnetic sensitive metal objects implanted in the head or neck areas close to the TMS coil magnetic fields (e.g., metal plates, clips, electrodes, chips, pumps, stimulators, cochlear implants). On the other hand, a side effect is an undesired outcome that is caused by TMS therapy. In this article I aim to explain the potential side effects of TMS therapy. I will break it down into common side effects, uncommon side effects and a list of debunked myths of TMS side effects.

Common Side Effects Of TMS Therapy

#1 Scalp Discomfort

The most common side effects of TMS during treatment are transient head or scalp discomfort at or around the location where TMS pulses are applied.

#2 Facial Twitching

Sometimes patients may experience twitching or movement of the eyelid or jaw during stimulation due to the excitation of superficial nerve branches and superficial muscle groups’ contraction.

#3 Headache

Headache is sometimes reported after TMS Therapy, particularly early in the course of the treatment when there has been no accommodation to the tapping sensation created by the stimulus. TMS headache typically decreases due to habituation or direct local analgesic effect of TMS. For those who may experience moderate headache we may recommend Tylenol or Ibuprofen 30 minutes before the treatment. We sometimes adjust the treatment intensity to avoid such a headache. We rarely see patients experiencing severe headaches that require quitting the treatment.

Uncommon Side Effects Of TMS Therapy

#4 Manic or Hypomanic Symptoms

An uncommon side effect of TMS is the induction of mania or hypomania. As patients are common daily for treatment we closely watch for manic/hypomanic symptoms (e.g., agitation, irritability) as early signs of mania. In such a case, we stop TMS therapy and follow up closely until symptoms are resolved and they usually do.

#5 Decreased Hearing

Exposure to loud noise could result in decreased auditory acuity. If ear protection is worn that protects at minimum up to 30 dB, hearing will not be affected by TMS. Thus, ear protection for the patient, TMS device operator, and others in the treatment room during active stimulation is warranted to minimize possible hearing loss. Ear-plugs are provided for each patient at the beginning of every single session. Patients must wear earplugs during treatment. 

#6 Syncope

Vasovagal response, particularly in the context of heightened anxiety, hypoglycemia, hyperventilation, or dehydration, can result in syncope during or following TMS. Also the positioning and tilting of the treatment chair could contribute to orthostasis (lightheadedness upon setting up or standing up). The change of position could cause vertigo for those with Benign Paroxysmal Positional Vertigo (BPPV).

#7 Seizure

Inducing a seizure is an extremely rare event during TMS, The risk of tonic-clonic seizure is related to the motor cortex’s direct stimulation or stimulation of adjacent brain areas with the spread of neuronal excitation to the motor cortex. We often watch out the right hand for signs of twitching or movement during stimulation. This helps us ensure that stimulation does not spread from the prefrontal to the primary motor cortex, which can lead to generalized seizure induction with a tonic-clonic movement pattern.

TMS Side Effects Myths Debunked

Again, just like anything in medicine, you will find people spreading unscientific rumors about side effects of TMS therapy not supported by clinical evidence. I picked the top three TMS side effects myths to discuss and present the evidence to fact check them.

#1 Effects On Cognition: TMS Doesn’t Cause Memory Loss

There were no adverse cognitive effects of TMS; in fact, studies demonstrated a better performance trend on measures such as delayed story recall. Several additional safety studies have not reported adverse long-term effects or sustained cognitive function changes in subjects receiving TMS. In several studies, performance on standard neuropsychological tests was not adversely affected by TMS sessions; instead, verbal memory tended to improve, and motor reaction times tended to decrease.

#2 Brain Damage: TMS Doesn’t Cause Brain Damage

There is no evidence of pathological change in brain tissue resulting from TMS Treatment delivered within the safety ranges. Published data show exposure to “accelerated” dosing (an increased number of total daily pulses) generally appears safe as well. Studies in animals, as well as studies of subsequently resected anterior temporal lobes of humans subjected to direct cortical stimulation or TMS, have failed to demonstrate evidence of brain damage. The maximal field strength generated by commercially available stimulators is in the 2 Tesla range. The field is induced for a brief period only and the field’s strength falls off rapidly with distance from the coil. There is no evidence of adverse effects from magnetic field exposure during TMS.

#3 Migraine: TMS May Cause Transient Headache But Not Migraine Headaches

In clinical practice, TMS does not increase migraine headache risk in healthy participants or those with a history of migraine. In fact, the FDA cleared a single-pulse device (eNeura) for the treatment of acute migraine headache.