Suggestion and Pain in Migraine: A Study by Laser Evoked Potentials
Abstract:Belief and expectation are part of placebo effect. Migraine patients are characterized by a dysfunctional modulation of pain processing, though a clear placebo effect emerges in clinical trials. The aim of the study was to evaluate the effect of visual and verbal suggestion on subjective pain sensation and cortical responses evoked by CO2 painful laser stimuli in migraine without aura patients vs healthy controls. Twenty-six patients were recorded during the inter-ictal phase and compared to 26 sex and age-matched controls. The right hand and the right supraorbital zone were stimulated during a not conditioned and a conditioned task, where laser stimuli were delivered after a verbal and visual cues of decreased (D), increased (I) or basal (B) intensity, which was left unmodified during the entire task. In control subjects pain rating changed, according to the announced intensity, while in migraine patients the basal hyper-algesia remained unmodified. The N1 and N2 amplitudes tended to change coherently with the stimulus cue in controls, while an opposite paradoxical increase in decreasing condition emerged in migraine. The P2 amplitude modulation was also reduced in migraine, differently from controls. The altered pattern of pain rating and N2 amplitude modulation concurred with frequency of migraine, disability and allodynia.
In controls suggestion influenced cortical pain processing and subjective pain rating, while in migraine a peculiar pattern of cortical activation contrasted external cues in order to maintain the basal hyper-algesia. This scarce influence of induced suggestion on pain experience seemed to characterize patients with more severe migraine and central sensitization.
Document Type: Research Article
Affiliations: Neurophysiopathology of Pain Unit, Neuroscience and Sensory Systems Department, University of Bari Aldo Moro, Policlinico General Hospital, Neurological Building, Piazza Giulio Cesare 11 70124 Bari, Italy.
Publication date: March 1, 2012
- CNS & Neurological Disorders - Drug Targets aims to cover all the latest and outstanding developments on the medicinal chemistry, pharmacology, molecular biology, genomics and biochemistry of contemporary molecular targets involved in neurological and central nervous system (CNS) disorders e.g. disease specific proteins, receptors, enzymes, genes. Each issue of the journal will contain a series of timely in-depth reviews written by leaders in the field covering a range of current topics on drug targets involved in neurological and CNS disorders. As the discovery, identification, characterization and validation of novel human drug targets for neurological and CNS drug discovery continues to grow; this journal will be essential reading for all pharmaceutical scientists involved in drug discovery and development.