Transcranial Magnetic Stimulation (TMS) is a non-invasive procedure that uses magnetic fields to stimulate specific nerve cells in the brain, often to improve symptoms of major depression and other conditions. Unlike electroconvulsive therapy, TMS does not require anesthesia; patients remain awake and alert throughout the process. The experience involves distinct sensory inputs, which are generally well-tolerated and include sensations on the scalp, auditory effects, and minor muscular reactions.
Preparing for the Session
The treatment begins with the patient seated comfortably in a specialized reclining chair. The technician positions the electromagnetic coil against the head, targeting a specific brain region, such as the left prefrontal cortex for depression treatment. This initial placement may cause a feeling of light pressure where the coil rests against the scalp.
The first step is “mapping” to determine the individual’s Motor Threshold (MT). The technician moves the coil over the motor cortex—the part of the brain that controls movement—while delivering single magnetic pulses. The MT is the minimum magnetic intensity needed to cause a slight, involuntary twitch in the hand or thumb. This process is not painful, but the initial magnetic pulses can feel unusual.
The Sensation of the Magnetic Pulse
Once the treatment intensity is set, the primary sensation is the feeling of the magnetic pulse being delivered through the coil. Most patients describe this as a rapid, rhythmic tapping, clicking, or pinging sensation directly on the scalp beneath the device. This physical feeling is often compared to a gentle tapping with a fingertip.
The magnetic pulses are delivered in patterns, such as a few seconds of stimulation followed by a brief pause, which creates a noticeable rhythm. While the sensation is unusual, it is generally not painful, though some individuals may experience a mild tingling or pressure at the site of stimulation. This feeling is external on the scalp, and the discomfort tends to diminish quickly as patients acclimate over the first few treatment sessions.
Noise and Immediate Physical Responses
A significant part of the sensory experience is the auditory input, as the machine emits a loud, repetitive clicking sound with every pulse. This noise is often likened to a rapid camera shutter, making the use of earplugs or ear protection necessary to protect hearing. The clicking sound runs in sync with the physical tapping sensation on the scalp.
Because the magnetic field stimulates nerves and muscles near the treatment area, patients may experience involuntary motor responses. It is common to feel a slight twitching or fluttering in facial muscles, such as the eyebrow, eyelid, or jaw. These harmless muscle contractions are temporary and stop immediately once the magnetic pulse train ends.
After the Treatment Session
Immediately following the session, which may last anywhere from three to 40 minutes, the coil is removed and all sensations cease. TMS is non-systemic, meaning it does not circulate throughout the body like a medication, so there are minimal systemic side effects. Patients are able to stand up, drive, and immediately resume their normal daily activities.
Some individuals may experience mild, temporary side effects, with the most common being a mild headache or slight scalp discomfort at the treatment site. These symptoms are usually manageable with over-the-counter pain relievers and often resolve within 30 to 60 minutes. This temporary discomfort tends to lessen significantly over the course of the treatment weeks.