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Cortical and spinal assessment - a comparative study using encephalography and the nociceptive withdrawal reflex
I W Fischer1, M Gram2, T M Hansen3
1Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; Mech-Sense, Department of Gastroenterology & Hepatology, Aalborg University Hospital, Mølleparkvej 4, 9000 Aalborg, Denmark.
Journal of Pharmacological and Toxicological Methods
|December 20, 2016
Summary
Morphine analgesia was assessed using electroencephalogram (EEG) and nociceptive withdrawal reflex. Cold pressor EEG and reflex amplitude changes show morphine
Area of Science:
- Neuroscience
- Pharmacology
- Pain Management
Background:
- Objective assessment of opioid analgesia is crucial for understanding central nervous system mechanisms.
- Opioids like morphine can act at both cortical and spinal levels.
- Investigating the correlation between cortical and spinal actions of morphine is essential.
Purpose of the Study:
- To investigate the effects of morphine on cortical and spinal levels.
- To analyze the correlation between cortical processing and spinal transmission of pain.
- To evaluate objective methods for assessing opioid analgesic effects.
Main Methods:
- Double-blinded, two-way crossover study with 39 healthy participants.
- Administration of 30mg oral morphine or placebo.
- Electroencephalogram (EEG) recording during rest and cold pressor test; nociceptive withdrawal reflex amplitude measurement.
Main Results:
- Morphine did not alter resting EEG activity.
- During cold pressor stimulation, morphine decreased delta band activity and increased alpha band activity in EEG.
- Morphine significantly reduced nociceptive withdrawal reflex amplitude.
Conclusions:
- Cold pressor EEG and nociceptive reflex are sensitive objective measures for opioid effects.
- Resting EEG is less sensitive to morphine analgesia than stimulated EEG and reflex measures.
- No correlation was found between spinal and cortical analgesic effects of morphine.
