Motor threshold · Hand and leg

Motor threshold assessment

Hand or leg hotspot assessment, with a pulse-by-pulse response counter and clinician-reviewed threshold record.

Clinician-operated recording aid. This page neither delivers pulses nor reads EMG. Use single-pulse TMS, current safety screening, hearing protection and device-specific limits. Choose EMG or visual observation and keep the muscle relaxed. Visual estimates are not equivalent to EMG-confirmed RMT and may be higher. Use visual assessment only where permitted by the applicable device and clinic protocol. Active MT and treatment dosing are outside this module.

Earlier assessment context · review before reuse

Protocol: Not recorded · Scalp selection:

Earlier entries are context only. Confirm the selected protocol, actual coil, muscle, side and current assessment before use. Changes in earlier steps require review of later entries.

1. Prepare

Response methodAssessmentRecorded limb sideRecorded muscleExact stimulatorExact threshold coilPulse waveform

Hand / leg preparation guidance

Hand hotspot search

For a focal figure-of-eight coil, Groppa describes an initial search region about 5 cm lateral and 0–1 cm anterior to the vertex. Refine using the contralateral muscle MEP. A posterolateral handle at approximately 45° is a conventional hand-M1 starting orientation; verify coil and waveform-specific current direction.

Support the hand and forearm, use the selected muscle’s surface EMG montage, inspect background relaxation, and compare nearby positions while keeping intensity and pose consistent.

Recorded coil orientation / reference convention

2. Mark the measured hotspot

Measured lateral offset from Cz (cm)Measured anterior offset from Cz (cm)

Negative lateral = patient left. Negative anterior = posterior. Grid spacing represents 1 cm in the record only; measure on the actual scalp. A selected dot is not proof of a hotspot.

I have identified and marked the hotspot from observed responses and recorded its actual scalp reference and coil pose.Clinician-set output ceiling (% MSO)Safety screening, hearing protection, response-monitoring setup and resting-muscle baseline have been checked.

Setup locks once trials are recorded. Reset before changing muscle, side, hotspot, coil or waveform.

3. Count responses

Check limits35% MSO

Lower failing bound: —% · Upper qualifying bound: —%

How this counting workflow works

Start at 35% MSO only if appropriate for the patient and within the clinician-set ceiling. Adjust the starting value if necessary.
Record Yes or No for each valid pulse, up to 10. Five positives in total qualify a search block, whether consecutive or not. Six negatives mean it cannot meet 5 of 10.
Save the block to see the next suggested level: 5 points up after a failing level, or 5 points down after a qualifying level, until both bounds are found.
Then refine downward from the upper bound in 1-point steps. Complete all 10 pulses at each of the final adjacent bounds before clinician verification.

This is a requested CTDS adaptation of relative-frequency counting. Groppa describes ascending to consistent EMG responses, then descending by 1%; the early-stop bracketing here is not that exact algorithm or a validated adaptive estimator. Buttons record choices; they do not control the stimulator.

Current intensity (% MSO)Optional measured MEP (µV peak-to-peak)

Positive means: A valid resting MEP ≥50 µV peak-to-peak on EMG.

Before recording

Complete preparation checks
Confirm the measured hotspot
Enter the exact coil
Enter the stimulator
Choose the waveform
Record coil orientation
Check intensity and output ceiling

0 Yes0 No0/10 tested

Pulse 1Not tested

Pulse 2Not tested

Pulse 3Not tested

Pulse 4Not tested

Pulse 5Not tested

Pulse 6Not tested

Pulse 7Not tested

Pulse 8Not tested

Pulse 9Not tested

Pulse 10Not tested

Threshold not established

Enter a valid intensity and clinician-set output ceiling before recording.

Saved assessment blocks · 0
Block	% MSO	Yes / tested	Response sequence	Status

4. Review the result

Assessment notes (no patient identifiers)

MT assessment report

MOTOR THRESHOLD — CTDS BRACKETING RECORD
Response method: EMG. Positive = resting MEP ≥50 µV peak-to-peak; Yes/No entered by clinician.
right hand; muscle: APB
Device: not recorded; coil: not recorded; waveform: not recorded
Hotspot relative to Cz: lateral -5 cm (negative=patient left), anterior 0.5 cm (negative=posterior). Manually entered schematic record, not image-derived anatomy.
Hotspot verified: no; pose: not recorded
Clinician-set ceiling: not recorded% MSO.
Unfinished block: 0/10 at 35% MSO; responses: 
THRESHOLD NOT ESTABLISHED. Enter a valid intensity and clinician-set output ceiling before recording.
CTDS custom 5-point bracketing / 1-point refinement; not the exact Groppa algorithm or a validated adaptive estimator. Final adjacent bounds require complete 10-pulse blocks. Groppa et al. 2012 doi:10.1016/j.clinph.2012.01.010. No hardware control or treatment-dose prescription.

Hand and leg thresholds, and thresholds measured with different coils, waveforms or response methods, are not interchangeable.

Temporary assessmentKept in this browser tab across pages and refreshes. Clear when finished. No patient identifiers.

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Method, source and limitations

Groppa et al. (2012), A practical guide to diagnostic transcranial magnetic stimulation: Report of an IFCN committee. Clinical Neurophysiology 123:858–882. §3.3.1 describes relative-frequency EMG threshold assessment; §6.1 and §9–10 inform hotspot, hand and leg guidance. CTDS adds the clinician-selected 5-point bracketing and early search prompts; these have not been clinically validated. Five consecutive positives are simply five total positives, not a separate threshold rule.

Read Groppa et al. ↗

Visual observations do not establish EMG RMT. Visual threshold assessment can overestimate EMG threshold; confirm that the exact therapeutic device protocol permits the selected method.

Visual versus EMG threshold study ↗