VCOM Louisiana Research Day Program Book 2024

Clinical Research

Zachary Dickey, OMS-III; Navneet Sharma, MD VCOM; Green Clinic 28 ARTERIAL DILATION AND INCREASED BLOD FLOW FOLLOWING LUMBAR SYMPATHETHIC BLOCK - A LOOK AT A PROPOSED THERAPEUTIC MECHANISM

Background: Sympathetic nerve blocks are growing in their utility as we better understand the relationship of pain and its relationship to the autonomic nervous system, however, the mechanism of their benefit is still poorly understood. Lumbar sympathetic blocks (LSB) are currently being used for a wide range of conditions such as CRPS, phantom limb pain, painful vascular insufficiencies, neuropathic pain, vascular pain, hyperhidrosis, shingles, raynouds, ulcers/wound care, and cancer induced pain. LSBs are proposed to decrease norepinephrine from sympathetic nerve endings, decrease sensory and vasomotor nerve fibers associated with pain, and increase blood flow. While these mechanisms are still very poorly understood we aimed to investigate the role of vasodilation in the lower extremity following sympathetic blocks to explore the potential therapeutic benefit via increased blood flow. Objective: To explore the effect of LSB on arterial dilation and blood flow to further examine if significant arterial dilation occurs following LSB to aid in the amelioration of pain and symptoms patients experience following block. Methods: A LSB was performed on a patient with chronic paresthesia and neuropathic

symptoms of the left foot refractory to treatment. Ultrasound, capillary refill, and temperature were also used to explore the effect of LSB on arterial dilation and blood flow to further examine a proposed mechanism of therapeutic benefit. Results: Following LSB the patient experienced decreased pain, paresthesia, an increase in sensation, and observed erythema in the symptomatic foot approximately 45 minutes post LSB. Significant dilation of the posterior tibial artery (PTA) was observed following the LSB via ultrasound. Prior to LSB, PTA measured .17cm in diameter then dilated to .27cm in diameter following the LSB. Arterial blood flow velocity measured 65.1 cm/s pre-block to 57.4 cm/s 30 minutes post-block. Capillary refill was measured at x � 3.92 seconds pre-block and x � 1.30 seconds immediately post-block. Temperature of the foot was measured at 34.4 degrees Celsius pre-block and increased to 37.2 degrees Celsius 90 minutes post-block. Conclusions: LSB have long been used for the treatment of chronic lower extremity pain and for conditions such Complex Regional Pain Syndrome. However, with better understanding of the autonomic nervous system and its function these blocks have grown in their utility. This case explores the potential mechanism

of the therapeutic benefit of LSB by showing a significant dilation of the PTA and increased blood flow following LSB. This study examines both the clinical application and will also be the first known reported study to quantify arterial dilation and blood flow following LSB.

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