Abstract
Background: Potential peripheral sources of deep pain can require invasive evocative tests for their assessment. Here we perform research whose ultimate goal is development of a non-invasive evocative test for deep painful tissue.Methods: We used a rat model of inflammation to show that intense focused ultrasound (iFU) differentially stimulates inflamed versus control tissue and can identify allodynia. To do so we applied iFU to inflamed and normal tissue below the skin of rats' hind paws and measured the amount of ultrasound necessary to induce paw withdrawal.Results: iFU of sufficient strength (spatial and temporal average intensities ranged from 100-350 W/cm2) caused the rat to withdraw its inflamed paw, while the same iFU applied to the contralateral paw failed to induce withdrawal, with sensitivity and specificity generally greater than 90%. iFU stimulation of normal tissue required twice the amount of ultrasound to generate a withdrawal than did inflamed tissue, thereby assessing allodynia. Finally, we verified in a preliminary way the safety of iFU stimulation with acute histological studies coupled with mathematical simulations.Conclusions: Given that there exist systems to guide iFU deep to the skin, image-guided iFU may one day allow assessment of patient's deep, peripheral pain generators.
Original language | English (US) |
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Article number | 8 |
Journal | Journal of Therapeutic Ultrasound |
Volume | 2 |
Issue number | 1 |
DOIs | |
State | Published - Feb 25 2014 |
Externally published | Yes |
Funding
This work received financial support from the Life Sciences Discovery Fund of Washington State, the NIH (UL1 RR025014, R41 NS 049719–01), the Veterans Administration, and direct funding from PhysioSonics, Inc.
Keywords
- Allodynia
- Focused ultrasound
- Inflammatory pain
ASJC Scopus subject areas
- Radiology Nuclear Medicine and imaging