Transcranial Magnetic Stimulation (TMS) Protocol
FDA-cleared neurostimulation for localized treatment of depression and OCD, completely bypassing systemic circulation.
Mechanism of Action
TMS uses a rapidly alternating magnetic field to induce a small electrical current in specific focal areas of the brain cortex. For Major Depressive Disorder (MDD), the target is typically the left dorsolateral prefrontal cortex (DLPFC). This region is consistently shown to be underactive in depressed patients on fMRI and qEEG scans.
The Physics of Neurostimulation
We utilize a figure-8 coil design. When rapid pulses of electricity pass through this copper coil, they generate a fluctuating magnetic field perpendicular to the coil. Because magnetic fields pass through the skull and scalp with zero impedance, they induce a secondary electrical current directly in the conductive tissue of the brain (Faraday's Law of Induction).
This allows us to specifically target the cortex without the electrical dispersion that occurs with older technologies (like ECT), which require massive systemic electrical charges to pass through the resistive bone of the skull.
The 10Hz vs 50Hz Debate (Standard vs iTBS)
Historically, standard rTMS utilized a 10Hz pulse frequency over a 37-minute session. Modern hardware now supports intermittent Theta Burst Stimulation (iTBS), delivering pulses in rapid 50Hz triplets.
- Standard (10Hz): 37 minutes, ~3000 pulses. Highly tolerable.
- iTBS (50Hz): 3-19 minutes, ~600-1800 pulses. Clinically non-inferior (THREE-D Trial, 2018), often utilized for accelerated protocols.
Our clinic defaults to 19-minute modified iTBS unless the patient cannot tolerate the rapid pulse rate.
The Protocol Schedule
| Phase | Sessions | Duration |
|---|---|---|
| Mapping | 1 | 60 mins |
| Acute Phase | 30 (5x/week) | 19 mins each |
| Taper Phase | 6 (Over 3 weeks) | 19 mins each |
Common Questions
Does it hurt?
Patients report a tapping sensation on the scalp. It can be uncomfortable for the first 3-5 sessions, after which local nerves acclimate. We adjust amplitude during the acclimation phase to maintain tolerability.
Are there cognitive side effects?
Unlike ECT (Electroconvulsive Therapy), TMS does not require anesthesia, does not induce a seizure, and has zero systemic cognitive side effects like memory loss. You drive yourself home immediately after.