Authors: Julie G. Pilitsis, MD, PhD, FAANS; Abigail Hellman, BA; Teresa Maietta, BS; Julia Nalwalk, MS; Paul Neubauer, BSE; Harini Byraju; Damian Shin, PhD; Emery Williams, PhD; Clif Burdette, PhD (Albany, NY)

Neuromodulation is typically electrical; we examine an alternative, pulsed low-intensity focused ultrasound(FUS). Effects of FUS modulation on peripheral nerves have been shown in situ, yet no similar work has been performed in vivo. Previously we showed increased mechanical thresholds 5 days post FUS treatment without histological damage. Here we measure the downstream effects of dorsal root ganglia(DRG)FUS. We induced common peroneal nerve injuries(CPNI) in male Sprague-Dawley rats(200-300g). After one week, we utilized Von Frey Fibers(VFF) to confirm allodynia. External ring electrodes were placed around the knee cap and the base of the ankle with electrode gel as recording and reference electrodes. An invasive stimulating electrode was placed in muscle adjacent to the sciatic nerve. 8W of pulsed FUS was delivered for 3min at a frequency of 38 Hz and pulse width of 90μs. Sensory nerve action potentials(SNAPs) were recorded at baseline and every 5min for 60min after FUS. SNAPs were obtained with a data acquisition system coupled to a noise suppressor and digitized at 1KHz through a low pass filter to 100Hz. Latency and amplitude were calculated. Animals had allodynia following CPNI measured through VFF. VFF normalized 24 hours after FUS (p<0.001; n=7).FUS resulted in significantly increased latencies in the sciatic nerve immediately after FUS. Latencies remained significantly increased for 25min, (p=0.01;n=7). They returned to baseline at 50min. No changes in amplitude were noted. We are the first to demonstrate the effects of pulsed FUS of the DRG on peripheral nerves in vivo. Prior work is limited to in situ findings that show FUS temporarily blocks tissue it targets. Downstream and upstream effects have not been documented. We present an iterative step in bringing pulsed FUS to the clinic for treatment of chronic pain