Neural Correlates of Lidocaine Analgesia

Study Overview
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Brief Summary
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The purpose of this study is to characterize the effects of intravenous lidocaine on pain processing and cognitive function. Functional magnetic resonance imaging will be used to identify the neural correlates of these phenomena. The study will consist of 1 visit and involves no long-term follow up.

Detailed Description
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This is an observational cohort study of volunteer subjects, which will employ neuroimaging and behavioral measures to characterize the effects of intravenous lidocaine on pain processing and cognitive function. A steady-state effect-site concentration of lidocaine will be achieved, and a short battery of cognitive behavioral tasks will be employed. At the dose target, pain task functional MRI and resting-state connectivity will be determined. This work will use a systems neuroscience approach to fill an important knowledge gap about the central effects of intravenous lidocaine, a commonly-used opioid alternative analgesic agent. Aim1: Determine cognitive behavioral effects of a steady-state dose of IV lidocaine using a short battery of tasks. The investigators hypothesize that the administration of lidocaine will correlate to decreased pain ratings, slowed psychomotor response, and decreased memory encoding. Aim2: Determine the neural effects of a steady-state dose of IV lidocaine in response to acute pain, and on resting connectivity. The investigators hypothesize that pain task-related activation will decrease in the insula and anterior cingulate, corresponding to decreased ratings of pain intensity and unpleasantness. Additionally, the investigators expect widespread decreases in long-range functional connectivity between brain areas know to be involved in these two areas and other known to be involved in pain processing.

Official Title
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Neural Correlates of Lidocaine Analgesia

Conditions
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Anesthesia, Pain

Intervention / Treatment
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* Device: Peripheral Nerve Stimulation
* Drug: Lidocaine IV


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Adults aged 18 to 70 Be of normal body-weight Be generally healthy Have none of the specific exclusion criteria Have a valid email address and phone number throughout the study Exclusion Criteria: Pregnancy Body mass index > 40 Having moderate to severe sleep apnea Having chronic pain requiring the regular use of pain medicine 3 or more times per week Having neurologic or psychiatric disease, including benign tremor, anxiety, and depression Having a history of seizures Having history of cardiac rhythm disturbance (such as heart block, or atrial fibrillation) Being severely claustrophobic Having metal implants or non-removable metal piercings Having metal-containing tattoos, particularly on the face Having a history of adverse reaction to lidocaine Are regularly taking: antiepileptics, antidepressants, anti-psychotics, anti-anxiety medication, stimulants, sleep-aids, or pain medication Are taking prescribed medications for psychiatric or neurological conditions Having hypersensitivity to lidocaine or to any other local anesthetics of the amide type Having Wolff-Parkinson-White syndrome Having known renal or hepatic dysfunction having glucose-6-phosphate dehydrogenase deficiency or history of methemoglobinemia

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 70 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Lidocaine<br>Subjects will receive lidocaine during the drug portion of the experiment. | Device: Peripheral Nerve Stimulation<br>* Experimental acute pain stimulus will be delivered using an electric nerve stimulator.<br>* Other names: Electric Nerve Stimulation;Drug: Lidocaine IV<br>* Subjects will receive an intravenous infusion of lidocaine for about 30 minutes.<br>* Other names: Xylocaine;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Brain activation to painful stimulation difference: drug-free condition minus lidocaine condition | Blood oxygen-level dependent (BOLD) functional MRI (fMRI) activation (T-score for task periods minus rest periods), in response to painful stimulation comparing drug-free condition minus the value calculated during the steady-state dose of lidocaine. | 4.5 minutes | 
| Resting-state functional connectivity difference: drug-free minus lidocaine | Functional connectivity (correlation coefficient) for resting-state BOLD oscillations between pain-processing brain areas, comparing value during drug-free condition minus the value during the steady-state dose of lidocaine. | 8 minutes | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Pain score difference, drug-free condition minus lidocaine condition | Numerical rating scale (0-10) pain score difference, comparing drug-free to the steady-state dose of lidocaine. Higher pain scores indicate more pain; a positive difference between pain score during the drug-free condition minus the value during the lidocaine condition indicates pain reduction (a better outcome). | 12 minutes | 
| Memory performance difference, drug-free minus lidocaine condition | Performance on a short computer-based test of memory for visual pictures will be quantified using signal detection metric d-prime, reflecting ability (in standard deviation units) to detect previously-seen images from the background noise of previously un-seen images. Differences will be determined between the drug-free condition and the lidocaine condition. Higher values of d-prime indicate stronger memory performance; a positive difference for drug-free minus lidocaine condition would indicate the expected decrease in memory performance. | 3 minutes | 
| Motor response times | Response times (in ms) after hearing a tone will be recorded and compared between the drug-free and Lidocaine condition. Higher values will reflect slower responses, which are expected under the lidocaine condition. | 1 minute | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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lidocaine, functional MRI, electric nerve stimulation, functional connectivity