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Transcranial magnetic stimulation (TMS) matters because it offers an antidepressant option for patients who cannot tolerate, or do not want, the anaesthesia and seizure of electroconvulsive therapy (ECTElectroconvulsive therapy, a treatment that uses a brief controlled seizure to relieve severe depression.Read more →). TMS delivers repeated magnetic pulses (rTMS, repetitive transcranial magnetic stimulation) through the scalp to the left dorsolateral prefrontal cortexThe front part of the brain responsible for planning, judgement and controlling impulses.Read more → (a frontal brain region involved in mood regulation), without any anaesthetic or seizure. For example, imagine an outpatient who needs to drive home and return to work the same day: TMS allows this because the patient stays fully awake throughout. This convenience is why TMS suits milder, non-emergency depression rather than the severe or life-threatening presentations that call for ECT.

TMS targets the left dorsolateral prefrontal cortexThe front part of the brain responsible for planning, judgement and controlling impulses.Read more → with magnetic pulses, aiming to normalise underactive mood-regulating circuits in depression. It is non-invasive, meaning nothing is implanted or surgically placed, and non-convulsive, meaning it does not deliberately trigger a seizure. Unlike ECTElectroconvulsive therapy, a treatment that uses a brief controlled seizure to relieve severe depression.Read more →, TMS causes no memory impairment, because no seizure and no anaesthesia are involved. Take a patient who found ECT's memory side effects unacceptable: TMS is a reasonable next option, though it works more slowly and is generally less powerful than ECT. In practice, the main risk of TMS is a rare seizure, so a personal or family history of epilepsy is checked before starting treatment.

• How is the stimulation intensity for repetitive transcranial magnetic stimulation usually set?
• Which feature would make repetitive transcranial magnetic stimulation unsafe?
• How does the effect sizeA number describing how large a difference or relationship is, not just whether it exists.Read more → of repetitive transcranial magnetic stimulation compare with that of ECTElectroconvulsive therapy, a treatment that uses a brief controlled seizure to relieve severe depression.Read more → in severe depression?

• Electroconvulsive therapy (ECT), requires anaesthesia and induces a seizure, unlike TMS which is non-invasive and causes no seizure.
• Vagus nerve stimulation (VNS), needs a surgically implanted device, whereas TMS is delivered externally through the scalp with no implant.
• Deep brain stimulation (DBS), involves intracranial electrodes for severe, treatment-resistant cases, unlike TMS which is non-invasive and reserved for milder depression.
• Antidepressant medication, acts through neurotransmitterA chemical messenger that nerve cells release to signal to the next cell.Read more → systems over weeks, whereas TMS works through direct cortical stimulation rather than drug pharmacology.

• Comfort guides tolerability rather than setting the therapeutic dose.
• Skull thickness is not measured for this purpose.
• A single fixed output would over-treat some people and under-treat others.
• Treated thyroid disease has no bearing on safety.
• Prior antidepressant treatment is the usual context for referral.

• Identify the drug, receptor, enzyme or pharmacokinetic change named in the stem.
• Translate it into the immediate mechanism before looking at the options.
• Use timing and the adverse-effect pattern to separate the nearest alternatives.
• Check whether the question asks for mechanism, clinical consequence, monitoring or management.