I recently started TMS for treatment-resistant depression. My first appointment was an interesting process. Regular visits are fairly straightforward, but there are a lot of steps to complete in a first TMS appointment that set you up for the rest of your treatment. Here’s how mine went.
I arrived at the clinic at my appointment time and went into a room containing a large machine with a digital readout connected to a tube with a peculiar-looking black attachment at the end. The room looks rather like what you’d expect if a therapist with a special interest in neurology suddenly switched fields and became a dentist. There’s a painting with uplifting words and two matching prints of the human brain on the walls, a mechanical reclining chair complete with a little paper bib over the pillow, and a desk with a computer and monitor. The walls are a relaxing shade of dark teal, and there’s a TV mounted at eye-level across from the chair.
The psychiatrist and two technicians were present, and they began by explaining what would happen. The first portion of the appointment would be dedicated to “mapping.” First, they would place a white cap on my head and take lots of measurements that would be used to mark the location of a couple parts of my brain. Then, I was to sit with my right forearm resting on a pillow on my lap while they held the magnetic coil (the black attachment at the end of the tube) up to the left side of my head and delivered pulses of varying intensity into my motor cortex.
The purpose of this part of the process is to determine the lowest intensity that causes the patient’s thumb to twitch involuntarily. That intensity is known as the motor threshold. Mapping allows providers to tailor the patient’s treatment to specific parameters – the exact spot where the coil should be placed and the intensity of magnetic pulses that is most effective for that person.
What Does the Mapping Process Feel Like?
I found this part of my initial TMS appointment to be fascinating and a bit intimidating. As someone who hates being the center of attention, having three (very nice) people hovering over me, touching the cap, and stretching a tape measure over and around my head was uncomfortable. You only do it once, though, so that cap is now used for all of my treatments.
Determining my motor threshold was the fascinating part. I sat with my elbow bent and my forearm on my lap, oriented with my palm slightly up so that my thumb was visible and unhindered. The team placed sticky electrodes on and around my thumb and connected them to a machine next to me. I was asked to relax my arm as much as possible. The coil was held in contact with the cap. It produced a clicking sound and a small tap on the side of my head when pulses were administered. As they worked, the psychiatrist and technicians watched my thumb for movement and checked the readout on the machine for spikes in electrical activity.
Although it was bizarre to feel my hand moving without my conscious direction, nothing about the process was painful. It’s like when you develop a temporary eyelid twitch; it’s maybe a little disconcerting, but that’s about it. Subsequent pulses became less intense and had mixed results. A slightly different spot on my head would cause all of my fingers or even my wrist to move. Eventually, we landed on my motor threshold, and the electrodes were removed from my thumb.
The First TMS Treatment
At this point, I think I put earplugs in, but I might have done that earlier. Once I was tilted back in the chair, the pillow was adjusted, and someone held the sides of it up by my face. The air in the pillow was then vacuumed out, leaving a stiff, shell-like nest for my head to rest in. It feels a bit weird, but it helps keep your head still.
The coil was then attached to a mount connected to the chair. The mount is a mobile arm that allows the coil to be positioned on the patient’s head. Positioning the coil is a delicate business, so the techs did a lot of adjusting, locking it into place, and walking in front of me to look intently at my head from different angles before walking back and adjusting it some more.
There is a paucity of royalty-free TMS images online, and this is one of the only ones that show anything resembling the position of the coil. This image cracks me up. Is it the inexplicable lack of a shirt? Is it the arms held out to the sides? The coil descending from the heavens on a pole? I don’t know, but I love it.
What is “Intensity” in TMS Treatment?
We started at an intensity below that of my motor threshold. Intensity is measured in terms of relative percentages. When mapping, intensity is expressed as a percentage of the total output the particular brand of TMS machine you’re using is capable of producing. The motor threshold exists at some level of intensity, which means that it is also expressed as a percentage. For instance, mine is 32% of the TMS machine’s total power.
As the appointments progress, the intensity of the treatments increases. The easiest way to think of this part is to consider the treatment intensity as a percentage of the motor threshold. So, my motor threshold of 32 is the new 100%, and each treatment is set to an intensity that’s described in relation to my motor threshold. We started at 60% of my motor threshold (19 or so on the machine) and bumped it up a few times during that treatment, reaching about 70% by the time it was over.
What Does TMS Feel Like?
I knew that there would be a series of sounds and accompanying taps on my head, followed by a period of a few seconds of nothing, then more taps, and that would repeat. My insurance will cover the “10 Hz” protocol (10 Hz refers to the frequency of magnetic pulses), which follows a 75-repetition pattern of four seconds of pulses (known as trains) and 11 seconds between trains. A frequency of 10 Hz means that there are 10 pulses per second (and 40 pulses per train). 40 pulses times 75 repetitions equals 3,000 pulses per treatment. Each treatment under this protocol lasts 18 minutes and 26 seconds.
Initially, the “taps” didn’t feel much like taps at all. It was like drops of cold water were falling from a great height into a small hole in my head. The sensation would spread out from the center, although it remained restricted to a very small area. When each train ended, so did the sensations.
Every few minutes, someone would ask me if they could turn the intensity up a notch. As the intensity went up, the pulses felt more like tapping. I found it uncomfortable but not painful at that level.
A woodpecker makes for a good analogy when describing how it feels. At lower intensities, it’s like a small bird — maybe a downy woodpecker — that’s persistently curious about the acoustic properties of your skull. The higher intensities I’ve reached in subsequent appointments have replaced the little woodpecker with a much larger one, like a northern flicker.
Speaking as someone who has been licked on the forehead by a flicker and had one land on the top of their head (I worked at a wildlife rehab center), I can say that, like a TMS machine, they make a lot of noise and have incredible persistence. Thankfully, unlike flickers, TMS machines do not scream, and you can stop them whenever you want.
The machine is pretty loud — both the beeps it emits and the clicking pulses — but the earplugs help muffle the sound. The coil is heavy, and I was very aware of it resting on the side of my head. It did help me remember to stay still, though. Talking was a bit challenging, as I’m used to relying on nodding and shaking my head to supplement my conversational skills. I felt rather stunted without it, but we muddled through.
After that, my first TMS appointment was over. I had been a little apprehensive about it, but it turned out just fine. In fact, it was reassuring to know what it felt like and what I could expect going forward. Sometimes, the best way to handle uncertainty is just to jump in and get started.