title: Intense focused ultrasound preferentially stimulates subcutaneous and focal neuropathic tissue: preliminary results.
abstract: OBJECTIVE
  Potential peripheral sources of pain from subcutaneous tissue can require invasive evocative tests for their localization and assessment. Here, we describe studies whose ultimate goal is development of a noninvasive evocative test for subcutaneous, painful tissue.
  
  
  METHODS
  We used a rat model of a focal and subcutaneous neuroma to test the hypothesis that intense focused ultrasound can differentiate focal and subcutaneous neuropathic tissue from control tissue. To do so, we first applied intense focused ultrasound (2 MHz, with individual pulses of 0.1 second in duration) to the rat's neuroma while the rat was under light anesthesia. We started with low values of intensity, which we increased until intense focused ultrasound stimulation caused the rat to reliably flick its paw. We then applied that same intense focused ultrasound protocol to control tissue away from the neuroma and assayed for the rat's response to that stimulation.
  
  
  RESULTS
  Intense focused ultrasound of sufficient strength (I(SATA) of 600 +/- 160 W/cm(2) ) applied to the neuroma caused the rat to flick its paw, while the same intense focused ultrasound applied millimeters to a centimeter away failed to induce a paw flick.
  
  
  CONCLUSIONS
  Successful stimulation of the neuroma by intense focused ultrasound required colocalization of the neuroma and intense focused ultrasound supporting our hypothesis.
authors.affiliation: Department of Neurological Surgery, University of Washington, Seattle, Washington 98195-6470, USA.
authors.forename: Abbi M
authors.initials: AM
authors.lastname: McClintic
authors.forename: Trevor C
authors.initials: TC
authors.lastname: Dickey
authors.forename: Michael
authors.initials: M
authors.lastname: Gofeld
authors.forename: Michel
authors.initials: M
authors.lastname: Kliot
authors.forename: John D
authors.initials: JD
authors.lastname: Loeser
authors.forename: Philippe
authors.initials: P
authors.lastname: Richebe
authors.forename: Pierre D
authors.initials: PD
authors.lastname: Mourad
mesh_terms: D000818:Animals; D019220:High-Energy Shock Waves; D009437:Neuralgia / Q000175:diagnosis* / Q000503:physiopathology*; D010147:Pain Measurement / Q000379:methods*; D017288:Pain Threshold / Q000502:physiology* / Q000528:radiation effects*; D010812:Physical Stimulation / Q000379:methods*; D010865:Pilot Projects; D051381:Rats; D017207:Rats, Sprague-Dawley; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity