Effects of external low intensity focused ultrasound on electrophysiological changes in vivo in a rodent model of common peroneal nerve injury
Abigail Hellman, Teresa Maietta, Kanakaharini Byraju, Yunseo Linda Park, Andrea Liss, Tarun Prabhala, Paul Neubauer, Emery Williams, Clif Burdette, Damian S. Shin, Goutam Ghoshal, Julia Nalwalk, Aira Agrawal, Jiang Qian, Julie Pilitsis
Neuroscience 2020 · 10.1016/j.neuroscience.2020.01.016
Abstract
Non-invasive treatment methods for neuropathic pain are lacking. We assess how modulatory low intensity focused ultrasound (liFUS) at the L5 dorsal root ganglion (DRG) affects behavioral responses and sensory nerve action potentials (SNAPs) in a common peroneal nerve injury (CPNI) model. Rats were assessed for mechanical and thermal responses using Von Frey filaments (VFF) and the hot plate test (HPT) following CPNI surgery. Testing was repeated 24 h after liFUS treatment. Significant increases in mechanical and thermal sensory thresholds were seen post-liFUS treatment, indicating a reduction in sensitivity to pain (p < 0.0001, p = 0.02, respectively). Animals who received CPNI surgery had significant increases in SNAP latencies compared to sham CPNI surgery animals (p = 0.0003) before liFUS treatment. LiFUS induced significant reductions in SNAP latency in both CPNI liFUS and sham CPNI liFUS cohorts, for up to 35 min post treatment. No changes were seen in SNAP amplitude and there was no evidence of neuronal degeneration 24 h after liFUS treatment, showing that liFUS did not damage the tissue being modulated. This is the first in vivo study of the impact of liFUS on peripheral nerve electrophysiology in a model of chronic pain. This study demonstrates the effects of liFUS on peripheral nerve electrophysiology in vivo. We found that external liFUS treatment results in transient decreased latency in common peroneal nerve (CPN) sensory nerve action potentials (SNAPs) with no change in signal amplitude.
Abstract via europepmc.
Exposures
Exposure 1: external liFUS to L5 DRG
Target: dorsal root ganglion — “L5 dorsal root ganglion (DRG)”
Device: other named manufacturer · Acoustic Medical Systems · TheraVision ultrasound system and ultrasonic therapy transducer probe ✓
| Waveform | pulsed | |
|---|---|---|
| Fundamental frequency (kHz) | 11,000 | ✓✓✓ |
| Pulse duration (ms) | 13 | ✓✓✓⚑ |
| Pulse repetition frequency (Hz) | 38 | ✓✓✓ |
| Duty cycle (%) | not reportedpulse duration × PRF gives 49.4% | |
| Sonication duration (s) | 180 | ✓✓✓ |
| 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 |
liFUS was administered at 8 W for 3 min with 11 MHz pulsed at 38 Hz with a period of 90 ns, and a pulse width of 13 ms. SNAP recordings occurred concurrently with liFUS or sham treatment; behavioural testing repeated 24 h later.
Flags from extraction
exposures[0].timing.pulse_duration_ms— Text gives a 13 ms pulse width and a 38 Hz PRF together with a 'period of 90 ns'; the three are not mutually consistent. Recorded as written.n_subjects— Total never stated; group sizes from the Fig. 3 legend (CPNI liFUS 8, CPNI shamliFUS 6, sham CPNI liFUS 5, sham CPNI shamliFUS 4). Fig. 5 legend gives 13 CPNI and 9 sham animals, and the text gives n=12 and n=8, so counts differ between places.exposures[0].free_field— Paper gives power (8 W) only; no pressure or intensity.exposures[0].target— DRG treated percutaneously using external landmarks; a peripheral target, not CNS.