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Final Program


Final Program

1018 - Understanding the Role of Central Mechanisms in Pain Relief Following Peripheral Nerve Blocks: A Pilot Study in Patients with Chronic Low Back Pain

Friday, February 28, 2025
5:00 PM - 6:30 PM MST

    Presenting Author(s)

  • SY

    Samir Yellapragada, BS, BA

    Medical Student
    University of Pittsburgh School of Medicine
    SEWICKLEY, Pennsylvania, United States

    • Co-Author(s)

  • SB

    Scott Brancolini, MD

    Chronic Pain Physician
    University of Pittsburgh Department of Anesthesiology and Perioperative Medicine
    Pittsburgh, Pennsylvania, United States

  • SM

    Sean McDermott, MD

    Chronic Pain Physician
    University of Pittsburgh Department of Anesthesiology and Perioperative Medicine
    Pittsburgh, Pennsylvania, United States

  • AW

    Ajay Wasan, MD

    Chronic Pain Physician
    University of Pittsburgh Department of Anesthesiology and Perioperative Medicine
    Pittsburgh, Pennsylvania, United States

  • BA

    Benedict Alter, MD, PhD

    Chronic Pain Physician
    University of Pittsburgh Department of Anesthesiology and Perioperative Medicine
    Pittsburgh, Pennsylvania, United States

Objectives: Lumbar medial branch blocks (MBB) are nerve blocks that involve a small amount of local anesthetic to block the medial branch nerves that supply the facet joints of the spine. Offset analgesia (OA) is a sensory phenomenon initially described in lab psychophysical studies which is defined as exaggerated pain relief following a more intense pain. The sensory phenomenon of OA may contribute to the rapid reduction of low back pain in some individuals following the lumbar MBB. The central objective of this study is to better understand mechanisms underlying pain intensity changes following a lumbar MBB.

Design:

This is an ongoing mechanistic, prospective, observational study with one main study visit and one follow-up phone call. We are recruiting patients ≥ 18 years who have had daily chronic low back pain for ≥ 3 months. When patients arrive 2 hours early to their scheduled block, they complete surveys regarding their low back pain, a standardized medical interview, and baseline quantitative sensory testing (QST). A sample of 30 will be powered to detect a moderate correlation between offset analgesia and change in low back pain.

Results:

Thus far, this study has collected data from 10 participants (2 males and 8 females) with a mean age of 62.4 years. Patients experienced a rapid decrease in pain immediately following the block. Patient rating of procedural pain yielded a median score of 2 and a range of 2. Other categories analyzed included both minimum pain rating after the block over 24 hours (M=1, R=1) as well as maximum pain relief after the block over 24 hours (M=90%, R=20%).

Conclusions:

Interestingly, 80% of study participants have reported a maximal pain rating of 2 within seconds of administration of the local anesthetic highlighting the importance of this research’s aim to differentiate between central and pharmacologically induced mechanisms of pain relief.