Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive therapeutic technique that uses electromagnetic pulses to modulate neural activity. Primarily used in treatment-resistant psychiatric and neurological conditions, rTMS has emerged as a safe and effective alternative to pharmacotherapy and electroconvulsive therapy (ECT). However, for successful clinical application, careful attention to protocol steps, session timing, and safety measures is essential.
1. Pre-Treatment Preparation
1.1 Indication and Patient Screening
Primary indications: Major depressive disorder (FDA-approved since 2008), OCD (since 2018), chronic neuropathic pain (since 2013), and certain cases of migraine and smoking cessation
A comprehensive clinical evaluation should include psychiatric history, medication review, and neurological examination .
Metal implants in or near the head
Cochlear implants
Pacemakers or intracardiac lines
History of seizures, epilepsy, significant head trauma, combustible devices (e.g. DBS systems)
Patients with active suicidal ideation, psychosis, or acute deterioration should be carefully evaluated, with emergent psychiatric care prioritized over rTMS.
1.2 Informed Consent
Discuss:
Procedure steps and duration
Expected benefits and typical course (e.g., 20–30 sessions over 4–6 weeks)
Side effects: headache, scalp discomfort, hearing effects, rare seizure risk (~0.1%)
Provide written guidelines on pre- and post-session conduct—especially ear protection and seizure-related precautions.
2. Step-by-Step Protocol
Step 1: Motor Threshold (MT) Determination
MT quantifies the minimal stimulus intensity needed to elicit a visible muscle response—typically a thumb twitch—when targeting the motor cortex . It ensures personalized dosing (usually 80–120% of MT).
Procedure:
Position the coil over the primary motor cortex (M1), contralateral to the dominant hand.
Deliver single pulses, increasing intensity until achieving thumb movement in 50% of ~10 stimuli.
Record MT; reassess weekly to ensure consistent dosing
Step 2: Localization of the Target Region
Once MT is determined, clinicians locate the brain region relevant to the patient’s condition:
Left DLPFC for depression
Supplementary Motor Area (SMA) for OCD
Right DLPFC for anxiety/PTSD
Primary Motor Cortex (M1) for pain
5-cm Rule: Move 5 cm anterior from the motor hotspot along the scalp.
Beam-F3 Method: Uses specific scalp measurements to locate F3 (left DLPFC) reliably Neuronavigation: MRI-guided targeting accurate within ~2 mm and beneficial for connectivity-based targeting .
Step 3: Coil Placement and Patient Setup
Patient sits upright in a comfortable chair with head support.
Fit a coil holder or neuronavigation arm for stable coil positioning.
Ensure coil is oriented and angled for targeted stimulation.
Provide ear protection (≥30 dB attenuation) due to coil acoustic noise
Step 4: Stimulation Parameters
Tailored to the condition:
|
Condition |
Frequency |
Intensity (% MT) |
Pulses/session |
Trains/rest interval |
|
Depression |
10–20 Hz |
100–120% |
~3,000 |
4 s on, 26 s off (120 trains) |
|
OCD (SMA) |
1 Hz |
100% |
~1,200 |
Continuous |
|
Anxiety/PTSD |
1 Hz |
100% |
~1,800 |
Continuous |
|
Chronic Pain |
10–20 Hz |
90–100% |
1,500–2,000 |
5 s on, 10 s off |
|
Accelerated iTBS |
50 Hz bursts at theta rhythm |
80–120% |
600–3,000 pulses |
2–10 min between trains |
Inter-train intervals (ITI) should be ≥5 seconds in high-frequency protocols for safety
Step 5: Delivery of rTMS
Double-check settings—frequency, intensity, number of pulses.
Initiate the stimulation sequence.
Observe patient comfort and scalp response.
Adjust coil position as needed.
Monitor for adverse events (headache, discomfort).
After session, remove coil and reassess MT weekly; record the session details.
3. Session Duration and Treatment Course
3.1 Session Length
Classic rTMS: 20–40 minutes due to numerous trains + inter-train rests
Theta-burst (iTBS): 3–5 minutes for a full protocol
Deep TMS (for OCD): Approx. 20 minutes per session
Accelerated protocols: Multiple sessions per day (up to 10/day), total daily time ~30–60 min, over 5 days
3.2 Treatment Frequency & Course
Standard course: Daily weekday sessions (5/week) for 4–6 weeks; total 20–30 sessions
OCD (Deep TMS): Initial 20 sessions over 4 weeks, followed by maintenance at 1–2/week; typical total ~36 sessions
Accelerated protocols: e.g., SAINT—10 iTBS sessions/day for 5 days, totaling 50 sessions
Booster sessions: 1–2 sessions weekly or monthly to prevent relapse
4. Safety and Noticeary Considerations
4.1 Auditory Safety
The coil emits loud clicking sounds (≥130 dB(Z)); earplugs mandated for patient and operator
4.2 Seizure Prevention
Seizure risk is low (~0.1%), but proper MT, ITI, and exclusion of high-risk patients (e.g., with epilepsy) are critical .
Avoid combinations of high-intensity, high-frequency stimulation without appropriate intervals
4.3 Scalp and Neurological Comfort
Headaches and scalp discomfort are common; mild analgesics suffice.
Cooling pads or topical analgesia can alleviate discomfort.
4.4 Patient Monitoring
Observe for dizziness, syncope, or mood change.
Maintain emergent protocols for seizure or arrhythmia.
4.5 Hearing
Baseline and periodic audiograms advised for prolonged regimens .
4.6 Maintenance of MT Accuracy
Weekly MT reassessments prevent drifting dose during a multi-week course .
4.7 Operational Cleanliness & Electromagnetic Safety
Maintain safe distances from electronic implants.
Follow manufacturer guidelines for electromagnetic compatibility
4.8 Training and Documentation
Technicians and clinicians must complete formal rTMS training programs
Session logs should include parameters, MT, coil location, duration, and patient response.
5. Post-Treatment Monitoring and Maintenance
5.1 Immediate Post-Session
Check for headache, dizziness, numbness, and tinnitus.
Allow patient to rest if any adverse effects occur.
Advise against driving for ~30 minutes if unsteady.
5.2 Course Monitoring
Use quantifiable scales: e.g., HDRS, PHQ9, YBOCS, pain inventories.
Weekly reviews to track efficacy and side effects.
Adjust sessions, protocol, or maintenance boosters based on clinical response.
5.3 Long-Term Planning
For responders, consider maintenance:
Weekly or biweekly sessions initially
Monthly thereafter to minimize relapse risk .
6. Specialized Protocols
6.1 Accelerated iTBS
Offers rapid treatment: 600 pulses in about 3 minutes per session, delivered multiple times per day
Optimal inter-session interval likely 50–60 minutes, though 10–30 minutes may suffice, depending on individual physiology
Emerging data shows similar remission rates as standard protocols
Requires more resource intensity (equipment, clinician time).
6.2 Deep TMS for OCD
Uses an H-coil to reach deeper brain circuits (SMA, ACC).
Stimulus intensity and coil position differ from classic figure8 coil rTMS
7. Practical Example: Depression Protocol
Day 1
Review medical history; rule out contraindications; obtain consent.
Fit ear protection.
Measure MT: find motor cortex hotspot for thumb twitch.
Locate left DLPFC via Beam F3 or neuronavigation.
Administer high-frequency rTMS (10 Hz @ 120% MT; 3,000 pulses; 4 s on / 26 s off).
Weeks 1–6
Sessions: Mon–Fri, ~40 minutes each.
Weekly MT checks and clinical scale assessments.
Week 7+
Response evaluation.
If achieved remission: taper to booster schedule (1–2 sessions/week for 1 month).
If partial response: consider protocol intensification or addition of deep TMS/iTBS.
8. Why These Protocols Work
High-frequency rTMS enhances cortical excitability and neuroplasticity, improving mood circuits
Low-frequency stimulation reduces hyperactivity in anxiety circuits (especially right DLPFC).
Deep TMS disrupts SMAACCOFC networks implicated in OCD.
Personalized targeting via neuronavigation and functional connectivity improves accuracy and outcomes
iTBS leverages LTP-like mechanisms, yielding rapid therapeutic effects with fewer pulses .
Summary of Key Protocol Elements
|
Element |
Details |
|
MT Calibration |
First step; ensures individualized dosing; reassess weekly |
|
Targeting Site |
Uses Beam-F3 / 5-cm rule / neuronavigation |
|
Stimulation Params |
Frequency, intensity (80–120% MT), pulses per session, ITI |
|
Session Duration |
20–40 mins for rTMS; 3–5 mins for iTBS; ~20 mins for deep TMS |
|
Treatment Schedule |
Daily (Mon–Fri) for 4–6 weeks; accelerated formats now in use |
|
Safety Practices |
Ear protection, seizure precautions, MT monitoring, trained staff |
|
Monitoring |
Weekly assessments and MT checks; post-session observation |
|
Maintenance |
Booster sessions for sustained effect |
