Low Intensity Focused Ultrasound Modulation of Vincristine Induced Neuropathy
Abigail Hellman, Teresa Maietta, Kanakaharini Byraju, Yunseo Linda Park, Miriam Shao, Andrea Liss, Paul Neubauer, Clif Burdette, Goutam Ghoshal, Jiang Qian, Julia Nalwalk, Julie G. Pilitsis
Neuroscience 2020 · 10.1016/j.neuroscience.2020.01.021
Abstract
Previously, we showed internal low intensity focused ultrasound (liFUS) improves nociceptive thresholds in rats with vincristine-induced neuropathy (VIN) for 48-h post-treatment. Here, we perform more rigorous behavioral testing with the internal device and introduce external liFUS treatment. Behavioral testing confirmed VIN (Von Frey fibers, VFF; hot plate, HPT; locomotion, OFT). This was followed by internal or external liFUS treatment (2.5 W or 8 W, for 3 min, respectively) to the left L5 dorsal root ganglia (DRG). A thermocouple placed at the DRG documented temperature changes during treatment, to confirm the modulatory nature of our treatment. Behavioral testing was performed pre-liFUS, and for five consecutive days post-liFUS. Groups included: (1) VIN/liFUS, (2) saline/liFUS, (3) VIN/sham liFUS, and (4) saline/sham liFUS. Significant improvements in mechanical (VFF) and thermal (HPT) nociceptive thresholds were seen in the VIN/liFUS group following both internal and external treatment. Hematoxylin and Eosin, and Fluorojade staining showed no histological damage to the DRG. Internal liFUS treatment produced a mean temperature rise of 3.21 ± 0.30 °C, whereas external liFUS resulted in a mean temperature rise of 1.78 °C ± 0.21 °C. We demonstrate that, in a VIN rat model, external liFUS treatment of the L5 DRG significantly reduces nociceptive sensitivity thresholds without causing tissue damage.
Abstract via pubmed.
Exposures
Exposure 1: Internal liFUS to L5 DRG
Target: dorsal root ganglion — “left L5 dorsal root ganglion (DRG)”
Device: other named manufacturer · Acoustic MedSystems · Thera-Vision ultrasound ablation system (internal 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 |
Internal liFUS treatment was administered at 2.5 W for 3 minutes with 11 MHz, pulsed at 38 Hz with a period of 90 ns, and a pulse width of 13 ms, applied via a laminectomy-exposed probe placed directly on the DRG. A single liFUS treatment was given, with behavioral testing pre-treatment and at 24, 48, 72 and 120 h post-treatment.
Exposure 2: External liFUS to L5 DRG
Target: dorsal root ganglion — “left L5 dorsal root ganglion (DRG)”
Device: other named manufacturer · Acoustic MedSystems · External liFUS transducer (Acoustic MedSystems) ✓
| 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 |
External 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, delivered non-invasively through the skin with the transducer positioned over the posterior superior iliac spine and aimed at the DRG under VEVO 3100 ultrasound image guidance. A single liFUS treatment was given, with behavioral testing pre-treatment and at 24, 48, 72 and 120 h post-treatment.
Flags from extraction
n_subjects— Total combines the internal liFUS cohort (n=27: VIN/liFUS 12, saline/liFUS 5, VIN/sham 5, saline/sham 5) and external liFUS cohort (n=25: VIN/liFUS 8, saline/liFUS 7, VIN/sham 5, saline/sham 5); only about 32 of these 52 animals (the liFUS, non-sham groups) received active ultrasound, the remainder were sham-treated controls.exposures[0].timing.pulse_repetition_frequency_hz— The text states the pulse is '38 Hz with a period of 90 ns', but 90 ns corresponds to the period of the 11 MHz carrier, not to a 38 Hz repetition period (which would be ~26 ms); recorded both stated numbers verbatim without reconciling the apparent inconsistency.exposures[0].free_field.ispta_w_cm2— Only acoustic power in Watts (2.5 W internal, 8 W external) is given; no spatial-peak intensity (W/cm2) or pressure value is reported for either exposure, so all pressure/intensity fields are not_reported.sham_type— Sham animals underwent the same surgery/anesthesia as treated animals but received no liFUS; classified as inactive_transducer as the closest match, though the paper does not explicitly say the transducer was present but unpowered.