Tremor reduction using multi-focus transcranial ultrasound stimulation system targeting the thalamus

Shirshak Shrestha, Alan Coreas, Janet Adeoti, Georgia Peacock, Catherine A. Swytink-Binnema, Nishaad Sheth, Ana Arantes, Conrad P. Rockel, Davide Martino, G. Bruce Pike, Zelma H.T. Kiss, Samuel Pichardo

Brain Stimulation 2026, 19, 102979 · 10.1016/j.brs.2025.11.006

human patientessential tremorparkinsons diseasebehaviour

Specieshuman

Subjects18 participants

Sessions per subjectnot reported

Randomisedno

Blindingnone

Sham / controlnone

Auditory controlnot reported

Readout timingoffline

Anaesthesianot applicable

Readoutsbehaviour — Tri-axial accelerometer recordings of resting/postural tremor (wing-beating position in ET; foot-tapping-induced hand tremor in PD), analysed via power spectral density

Direction of effectinhibitoryTUS to the Vim produced statistically significant tremor reduction overall and in ET patients specifically; PD patients showed only a modest, non-significant change, consistent with an inhibitory neuromodulatory effect on the thalamus.

Adverse eventsnone observedThe procedure lasted approximately 2 hours and was well tolerated by the participants, with no reports of paresthesia or any adverse effect.

Exposures

Exposure 1: Multi-focus TUS to left/right Vim of thalamus (ET and PD patients)

Target: ventral intermediate nucleus — “ventral intermediate nucleus (Vim) of the thalamus”
Device: not reported

Pulse timing
Waveform	pulsed
Fundamental frequency (kHz)	250	✓✓✓
Pulse duration (ms)	not reportedimplied by duty cycle ÷ PRF: 1 ms (not stated by the paper)	⚑
Pulse repetition frequency (Hz)	100	✓✓✓
Duty cycle (%)	10	✓✓✓
Sonication duration (s)	not reported

Pressure and intensity, by domain
Free-field pressure (kPa)	not reported
Free-field Isppa (W/cm²)	46.9	✓✓✓
Free-field Ispta (W/cm²)	not reported
In-situ estimate	simulationsingle value
In-situ pressure (kPa)	not reported
In-situ Isppa (W/cm²)	10	✓✓✓⚑
In-situ Ispta (W/cm²)	not reported

Protocol, in the paper’s words

Multi-focus phased-array TUS delivered via optically-tracked neuronavigation guided by acoustic simulation (Babel-Brain); multiple focal spots were used on and around the intended Vim target to increase the effective stimulation area and mitigate small targeting errors. The whole procedure lasted approximately 2 hours; tremor was measured with an accelerometer before and after TUS delivery.

Flags from extraction

n_subjects — 18 patients were enrolled but 3 were excluded from analysis for incomplete data collection (n=15 analysed); enrolled number (18) is reported here per convention, flagged for the enrolled/analysed discrepancy.
n_sessions_per_subject — the paper does not explicitly state the number of TUS sessions per participant; the procedure is described as a single ~2 hour session but this is not stated in session-count terms.
exposures[0].device.family — the phased-array transducer and driving hardware are not named/attributed to a manufacturer in the main text.
exposures[0].timing.pulse_duration_ms — pulse duration is not explicitly stated in the main text; only PRF (100 Hz) and duty cycle (10%) are given, from which pulse duration could be computed (1 ms) but this was not done per instructions.
exposures[0].in_situ.isppa_w_cm2 — the abbreviation for the reported in-situ intensity is garbled in the source text ('I ' with a missing subscript); interpreted as spatial-peak pulse-average intensity (ISPPA) based on the wording 'spatial-peak pulse-average intensity'.