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Presented by Louis Vera-Portocarrero, Medtronic Neurostimulation Research

Influence of Different Lengths of Stimulation on the Effectiveness of SQS in a Rodent Model of Neuropathic Pain. Presented by Louis Vera-Portocarrero, Medtronic Neurostimulation Research Co-Authors: Toni Cordero 1 , Paul Wacnik 1 , Lisa Johanek 1 , Tina Billstrom 2 , Kim Swearingen 2

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Presented by Louis Vera-Portocarrero, Medtronic Neurostimulation Research

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  1. Influence of Different Lengths of Stimulation on the Effectiveness of SQS in a Rodent Model of Neuropathic Pain Presented by Louis Vera-Portocarrero, Medtronic Neurostimulation Research Co-Authors: Toni Cordero1, Paul Wacnik1, Lisa Johanek1, Tina Billstrom2, Kim Swearingen2 1Medtronic Neurostimulation Research 2Medtronic Physiological Research Laboratories

  2. Disclosure • The authors are employees of Medtronic, Inc. • This presentation and associated abstract discuss uses that the U.S. Food and Drug Administration has not approved for Medtronic Implantable Neurostimulation Systems.

  3. Background • SQS (subcutaneous electrical stimulation) is a technique that targets the peripheral nervous system. • Parameters used for SQS vary and there is little understanding ofoptimal parameters. • Using a recently developed rodent model, we have beguna systematic investigation of parameters to help inform future pre-clinical studies examining mechanisms of SQS.

  4. Background: SQS Model Development Anesthetized 20 min SQS Lead placement Stim day 1 2 3 4 Proximal end for connection to ENS Awake 20 min SQS L. Vera-Portocarrero; NANS 2010, INS 2011

  5. Background: SQS compared to TENS • TENS was not effective in reducing hypersensitivity. • SQS reduced hypersensitivity in the neuropathic pain model. The effect reached a peak at day 5, suggesting that the effects of SQS could be cumulative over time. Vera-Portocarrero et al., submitted to Neuromodulation

  6. Hypothesis, Design and Outcome Measures Hypothesis: Longer lengths of stimulation yield greater effectiveness. Design: Stimulation lengths were 30, 60 and 120 minutes applied to awake rodents. Tester was blind to the frequency of SCS (0Hz or 60 Hz). Amplitude was 80-90% of motor threshold with 250 msec pulse width. Outcome measures: • Allodynia, measured by von Frey filaments • Number of responders • The criteria for a responder was a return to at least 50% value of their pre-injury baseline.

  7. Methods Spared Nerve Injury Decosterd and Woolf, 2000 7 days Day 3 Day 4 Day 5 Day 1 Day 2 Testing and stim Testing and stim Testing and stim stim stim Pre-Injury SNI surgery and Testing SQS lead implantation

  8. Results

  9. Results

  10. Conclusions • SQS was effective while stimulation was turned ON. • SQS administered at a specific amplitude (80 – 90% MT) for 30 and 60 minutes produced a carry-over effect while 120 minutes did not. • Preliminary study; replication is necessary • If the phenomenon is real, neuromodulatory mechanisms could be investigated • The results of this study set the stage for future studies examining other parameters (amplitude, frequency, pulse widths).

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