Exploratory Optimization of Focused Ultrasound Parameters for Selective Peripheral Nerve Fiber Inhibition
Namrata Sangwan, Lidia Mergelian, Michael Klukinov, Morteza Mohammadjavadi, Riya Navani, Cholawat Pacharinsak, Kim Butts Pauly, David C. Yeomans, Thomas A. Anderson
Anesthesia & Analgesia 2026 · 10.1213/ane.0000000000008386
rodentotherbehaviour
Speciesrat (Sprague-Dawley)
Subjects19 animals
Sessions per subjectnot reported
Randomisedyes
Blindingnot reported
Sham / controlno treatment control
Auditory controlnot reported
Readout timingoffline
Anaesthesiaanaesthetised
Readoutsbehaviour — Randall-Selitto mechanical withdrawal threshold; modified Hargreaves thermal latency; hindpaw flexion and extension scores
Direction of effectinhibitoryHigher total acoustic energy to the sciatic nerve produced progressively greater inhibition; lower energies preferentially inhibited Adelta/C nociceptive behaviours, higher energies inhibited behaviours mediated by all fibre types.
Adverse eventsnot reported
Exposures
Exposure 1: FUS1 to FUS5 parameter sets to the sciatic nerve
Target: sciatic nerve — “the sciatic nerve 1 cm proximal to its trifurcation”
Device: other named manufacturer · Sonele Inc · 1.5 MHz FUS transducer (co-aligned with 50 MHz diagnostic transducer, Capistrano Lab) ✓
| Waveform | continuous | |
|---|---|---|
| Fundamental frequency (kHz) | 1,500 | ✓✓✓ |
| Pulse duration (ms) | not applicable | |
| Pulse repetition frequency (Hz) | not applicable | |
| Duty cycle (%) | 100 | ✓✓✓ |
| Sonication duration (s) | 45, 53, 60swept | ✓✓✓⚑ |
| Free-field pressure (kPa) | not reported | |
|---|---|---|
| Free-field Isppa (W/cm²) | not reported | |
| Free-field Ispta (W/cm²) | not reported | |
| In-situ estimate | not reported | |
| In-situ pressure (kPa) | not reported | |
| In-situ Isppa (W/cm²) | not reported | |
| In-situ Ispta (W/cm²) | not reported | |
| Pressure, domain unspecified (kPa) | 4,040, 4,140, 5,500, 5,550, 6,100swept | ✓✓✓⚑ |
| Isppa, domain unspecified (W/cm²) | 530, 556, 986, 1,000, 1,210swept | ✓✓✓⚑ |
Protocol, in the paper’s words
Five illustrative parameter sets (FUS1 to FUS5) of increasing total energy at 100% duty cycle, 45 to 60 s sonication to the sciatic nerve under general anaesthesia before hindpaw incision; pressure, duty cycle and duration were systematically adjusted iteratively.
Flags from extraction
n_subjects— 130 rats used during the iterative process; only 19 animals in five FUS groups (plus 6 HPI-only) are shown in the table. Whether all 130 were sonicated is not stated.exposures[0].unspecified_domain.pressure_kpa— Pressure and Isppa given in the table without saying whether free-field or in situ; FUS1 and FUS3 values are means (SD) of values that varied among applications.exposures[0].timing.sonication_duration_s— Durations listed are the distinct values across the five illustrative sets (FUS1 mean 53 s, FUS3 45 s); the 130-animal iterative set may have used others.exposures[0].timing.waveform— Duty cycle stated as 100% for all applications; waveform recorded as continuous on that basis, PRF and pulse duration not stated.exposures[0].unspecified_domain.isppa_w_cm2— Table footnote says total energy = Isppa x duty cycle x duration while the Methods say Isppa x duration; irrelevant at 100% duty cycle.